chapitre viii

. pp. 426–429).

He commenced his experiments in 1801, and first recorded them in a memoir which was crowned the same year by the Batavi Scientific Society of Haarlem. His other papers on the same subject followed in rapid succession, mainly through L. W. Gilbert’s _Annalen der Physik_, under such heads as: “Sketch of a New Theory of Galvanic Electricity, and Concerning the Decomposition of Water,” etc. (“Combination of Induction and Chemical Action,” Gilb., Vol. XII. p. 49, Seypfer, p. 200), “How to Measure Electricity,” “Relative to the Electrometer,” “The Effects of the Condenser,” and “The Theory of Volta Concerning Galvanic Electricity,” all of which appeared in Vol. LXI. of the _Annalen_. These papers were alluded to in his letter to the editors of the _Annales de Chimie et de Physique_ (_An. Ch. et Phys._, Vol. XLII. p. 45), and were afterward greatly amplified in his “Treatise on Natural Philosophy.”

Parrot started with the determination to demolish completely the theories of Volta and to thoroughly instruct him anew (_instruire de toutes pièces le procès du physicien de Pavie_), and it must be admitted that the many important facts enounced by Parrot were such as would have ordinarily created a disturbing influence, but they became known after Volta’s views had been thoroughly espoused by many German and French scientists and consequently attracted comparatively little attention.

At p. 466, Vol. II of Dr. Thomas Young’s “Course of Lectures,” London, 1807, reference is made to a paper in Gilbert’s _Annalen der Physik_ (X. p. 11, also XIII. p. 244), concerning Parrot’s theory of evaporation, with mention of the fact that the same paper contains a proposal for inoculating the clouds with thunder and lightning, by projecting bombs to a sufficient height.

Parrot also devised a scheme for telegraphing, which is described in the _Mem. Acad. Petropol._, ser. vi. Vol. I for 1838, and is alluded to in the Report on Telegraphs for the United States, made at request of the Hon. Levi Woodbury, Secretary of the Treasury, by the Committee on Science and the Arts of the Franklin Institute. The proposed telegraph, as worded in the Report, “consists of a single arm or _indicator_, which should be about nine feet long and one foot wide, with a cross-piece at one end, about three feet long and one wide; the whole being movable about an axis at its centre.... The movements may be communicated with ease and certainty, either by an endless chain passing over a wheel on the axis, and a wheel in the building; or by a cog-wheel on the axis, and an endless screw on a vertical bar. For night signals, three lamps are used, one swinging beyond the end of the arm, the other two beyond the ends of the cross-piece.”

REFERENCES.--Gilbert’s _Annalen_, Vols. XXI for 1805, LV for 1817, LX for 1819; J. H. Voigt’s _Magazin_, Vol. IV; Grindel’s “Russ. Jahrb. f. Chem. u. Pharm.,” XI, 1810; L. Turnbull, “Elec. Mag. Tel.,” p. 19; “Naturwiss. Abhandl. aus Dorpat.,” I, 1823; “Roy. Soc. Cat. of Sc. Papers,” Vol. IV. pp. 765–767; _Annales de Chimie_, Vol. XLII, 1829, pp. 42–45, and Vol. XLVI, 1831, p. 361; “Mém. sixième série Sc. Mathém.,” first part of Vols. III and V; “Pander’s Beitr. z. Naturk, I.”

=A.D. 1802–1806.=--Berzelius (Baron Jöns Jacob Freiherr von), M.D., one of the greatest of modern chemists, native of East Gothland, Sweden, publishes his “De Electricitatis ...” or “Physical Researches on the Effect of Galvanism upon Organized Bodies,” which established his reputation as an experimental philosopher and procured for him the appointment of Assistant Professor of Medicine, Botany and Chemical Pharmacy at Stockholm. Of the very great number of scientific papers which he communicated to learned Societies, that entitled “An Essay on the Division of Salts through Galvanism” deserves especial mention, for in it, he lays down the electro-chemical theory, the honour of being the original propounder of which is by many claimed for Sir Humphry Davy.

In conjunction with Gottlieb Gahn, with W. Hisinger, of Elfstorps Bruk, and with the Swedish physician, Magnus Martin de Pontin, Berzelius made many very extensive observations and published numerous treatises, the most important of which are embraced in the papers named at foot (Sir Humphry Davy, “Bakerian Lectures,” London, 1840, more particularly at pp. 13, 20, 109, 111, 122–123).

As has been before observed, the brilliant investigations of Berzelius and Hisinger, together with those of Nicholson and Carlisle, of Dr. William Henry and of Sir Humphry Davy, actually created a new epoch in the history of chemistry. Prof. Wm. B. Rogers better expressed the fact in his address of Jan. 16, 1879, when saying that “through the labours mainly of Berzelius and of Davy, the great generalization of electro-positive and electro-negative substances was established, and with it the fruitful theory of the electro-chemical exposition of compound bodies.” Such of the experiments of Berzelius as were repeated by Sir Humphry Davy before the English Royal Institution, are embodied in Davy’s paper (partly alluded to above in “Bakerian Lectures”) which was read before the Royal Society, June 30, 1808. According to J. F. W. Herschel, Berzelius and Hisinger ascertained it as a general law, that in all of the chemical decompositions which they effected, the acids and oxygen become transferred to, and accumulated around, the positive pole, and hydrogen, alkaline earths and metals around the negative pole of a voltaic circuit; being transferred in an invisible, and, as it were, a latent or torpid state, by the action of the electric current, through considerable spaces, and even through large quantities of water or other liquid, again to reappear with all their properties at their appropriate resting-places.

Berzelius discovered selenium while examining certain substances found in the acid manufactured at Gripsholm, Sweden. He includes selenium among the metals; but as it is a nonconductor of electricity, also a most imperfect conductor of heat, and as, in other respects, it bears much analogy to sulphur, it is generally placed among the non-metallic combustibles (Brande, “Manual of Chemistry,” London, 1848, Vol. I. p. 435; Berzelius, “Lehrbuch der Chemie,” “Traité,” etc., Paris, 1846, Vol. II. p. 184; “Annales de Chimie et de Physique,” Vol. IX. p. 160; “Annals of Philosophy,” Vol. XIII. p. 401 and Vol. VIII, N.S. p. 104). The important rôle which the high electrical resistance of selenium has in its early days been made to play by Mr. Willoughby Smith, Dr. Werner Siemens and others, is alluded to at pp. 791–794 of Vol. IV supplement to “Ure’s Dict. of Arts,” etc., London, 1878.

For full accounts of Berzelius’ numerous contributions to science, attention is called to the following:

REFERENCES.--“Royal Society Catal. of Sc. Papers,” Vol. I. pp. 330–341; “Gedächtnissrede auf Berzelius ...” Berlin, 1851; G. Forchammer, “J. J. Berzelius,” 1849; Poggendorff, Vol. I. pp. 172–175; “Afhandl. i Fisik. ...”; Jos. Thomas, “Dict. of Biography,” 1870, Vol. I. p. 341; “Report Smiths. Inst.” for 1862, p. 380; “Vetensk. Acad. Handl.”; “La Grande Encyclopédie,” Vol. VI. p. 478. See likewise, “Journal Frankl. Inst.,” 3rd Ser., Vol. XVI. pp. 343–348; Faraday’s “Experim. Researches,” Arts., 746, 870, 960, and Vol. II. pp. 226–228; Gahn at p. 226 of Becquerel’s “Eléments d’El. Ch.,” Paris, 1843; “Annalen der Physik,” Vol. XXVII. pp. 270, 311, 316, and Vol. XXXVI. p. 260; Gehlen’s “Journal für die Chem. und Phys.,” Vol. I. p. 115 and Vol. III. p. 177; John Black, “An Attempt ... Electro-Chem. Theory,” London, 1814; Gmelin’s “Chemistry,” Vol. I. pp. 400, 457–458, 461–462; “Encycl. Metrop.” (Galvanism), Vol. IV. pp. 221–222; “Sc. Am. Suppl.,” No. 284, p. 4523, for report of Helmholtz’s Faraday Lecture of April 5, 1881, taken from the “Chemical News”; Sturgeon’s “Annals,” Vol. VII. pp. 300–303; Vol. VIII. p. 80; Whewell, “History of the Inductive Sciences,” 1859, Vol. II. pp. 304, 347–348; Thos. Thomson, “An Outline of the Sciences ...” London, 1830, Chap. XIV. p. 532; Berzelius and Wöhler on Volcanoes, in Poggendorff’s “Annalen,” Bd. I. s. 221, and Bd. XI. s. 146; “Journal des Savants” for June 1892, pp. 375–385; J. Berzelius and F. Wöhler, Leipzig, 1901; “Svenskt Biografiskt Handlexikon,” Herm. Hofberg, Stockholm, pp. 88–89; “Bibl. Britan.,” Vol. LI, 1812, pp. 174–183 (“Nicholson’s Journal,” July 1812) for John Gough’s remarks on the hygrometer of Berzelius (Phil. Mag., Vol. XXXIII. p. 177); “Annales de Chimie,” Vol. LI. pp. 167, 171; Vol. LXXXVI for 1813, p. 146; Vol. LXXXVII. pp. 286, etc.; also Vol. LXXIII. pp. 198, 200–201, the last named giving an account of the ammoniacal amalgam which Berzelius and Pontin were the first to explain.

=A.D. 1802.=--Thompson (Sir Benjamin), Count Rumford, an eminent scientist, native of Woburn in Massachusetts, Knt., F.R.S., one of the founders of the English Royal Institution, publishes his “Philosophical Memoirs ... being a collection of ... Experimental Investigations ... of Natural Philosophy.”

Though more properly identified with important observations and researches on heat, the question of the nature of which, Dr. Edward L. Youmans says, he was the first to take out of the domain of metaphysics, where it had stood since the days of Aristotle, he has given accounts of some highly important experiments regarding the relative intensities and the chemical properties of light, heat and electricity, which can be seen at pp. 273, etc., Vol. LXXVI. part ii. of the _Phil. Trans._ for 1786. Heat spreads in every direction, whilst the electrical fluid may be arrested in its progress by certain bodies, which have on that account been called non-conductors, but he shows that the Torricellian vacuum affords, on the contrary, a ready passage to the electrical fluid while being a bad conductor of heat.

At p. 30 of George E. Ellis’ “Memoir of Sir Benjamin Thompson,” published in Boston (no date), is reproduced Rumford’s “Account of what expense I have been at toward getting an electrical machine” during 1771, and at pp. 481–488, Vol. I, also pp. 350, 351, Vol. III of the “Complete Works of Count Rumford,” published by the American Academy of Sciences, allusion is made to the galvanic influence in the construction of utensils.

REFERENCES.--Sir W. Thomson, “Mathematical and Physical Papers,” London, 1890, Vol. III. pp. 123, 124; _Phil. Mag._, Vol. IX for 1801, p. 315; Silliman’s _American Journal of Science_, Vol. XXXIII. p. 21; “Biog. Universelle,” Tome XXXVII. p. 81; “Journal des Savants,” for Dec. 1881 and Jan. 1882; “Bibl. Britan.,” Vol. LVI., 1814, pp. 398–401 (necrology).

=A.D. 1802.=--Pepys (William Haseldine, Sr.), son of an English manufacturer of surgical instruments, who became F.R.S. and was one of the founders of the Askesian Society, as well as of both the London Institution and of the London Geological Society, constructs, during the month of February 1802, the strongest pile hitherto known. It consists of sixty pairs of zinc and copper plates, each six feet square, held in two large troughs filled with thirty-two pounds of water containing two pounds of azotic, or nitric, acid.

It is said that with this battery he succeeded in melting iron wires ranging in diameter from one two-hundredth to one-tenth of an inch, the combustion developing an extremely bright light, while platinum wires, one thirty-second of an inch in diameter, turned to white heat and melted in globules at the point of contact. Charcoal was permanently ignited a length of nearly two inches and the galvanic action was strong enough to light it after passing through a circuit of sixteen persons holding one another by the hand. Gold leaf displayed a bright white light, accompanied with smoke; silver leaf gave an intense green light without sparks, but with still more smoke; while sheets of lead burned actively, with accompaniment of very red sparks mixed with the flame (Figuier, “Exposition,” etc., Paris, 1857, Vol. IV. p. 347).

Later on, another battery was constructed by him for the London Institution. This consisted of 400 pairs of plates five inches square, and of 40 pairs one foot square. With it, Davy ignited cotton, sulphur, resin, oil and ether, melted a platinum wire, burned several inches of an iron wire one three-hundredth of an inch in diameter, and boiled easily such liquids as oil and water, even decomposing and transforming them into gases. It was during the year 1808 that Pepys finished the enormous battery of 2000 double plates already alluded to under the Cruikshanks (A.D. 1800) and the Davy (A.D. 1801) articles, and which is to be found described at p. 110 of the “Elements of Chemical Philosophy.”

One year before that (1807) Pepys constructed a new form of eudiometer, of which a description was given before the Royal Society on the 4th of June, as shown at p. 270 Vol. I of the “Abstracts of Papers,” etc., of that Institution, as well as in the 1807 volume of the _Philosophical Transactions_.

Of the many ingenious experiments by which Pepys distinguished himself, scarcely none attracted more attention than those which are referred to in the last-named _Transactions_ for 1866, pp. 339–439. It is only since 1815, when he employed the electric current to heat iron wire and diamond dust together, whereby he obtained steel, that the direct carburization of iron by the diamond has been clearly established. Prior to this date, during 1798, Clouet had melted a little crucible of iron weighing 57·8 grammes containing a diamond weighing 0·907 gramme, and produced a fused mass of steel. Guyton de Morveau reported upon Clouet’s experiment in the _Annales de Chimie_ for 1799 (Vol. XXXI. p. 328) and his investigations were repeated by many scientists, notably by Margueritte, as recently as 1865. The latter’s observations, which were communicated to the _Annales de Chimie et de Physique_ (Tome VI), showed that, although carburization can be effected by simple contact of carbon and iron in a gaseous atmosphere, it is nevertheless true that in the ordinary process of cementation the carbonic oxide gas plays an important part, which had until then been overlooked (Translation of Prof. W. C. Roberts-Austen, F.R.S. For Mr. Children’s investigations in the same line, see the _Phil. Trans._ for 1815, p. 370, also A.D. 1809).

Sir Humphry Davy employed in his experiments on the decomposition and composition of the fixed alkalies two mercurial gasometers of Pepys’ design, described in No. 14 of the _Phil. Trans._ for 1807, in conjunction with the same apparatus used by Messrs. Allen and Pepys for the combustion of the diamond (“Bakerian Lectures,” London, 1840, pp. 84 and 93).

During the year 1822 Pepys constructed for electro-magnetic experiments a very large spiral galvanic battery, which was put together for the London Institution on the plan of the one first built by Dr. Robert Hare, Professor of Chemistry in the University of Pennsylvania. Pepys called it a _calorimotor_, by reason of its remarkable power of producing heat, and it is well illustrated in the 8th Edit. “Encyclopædia Britannica” article on “Voltaic Electricity.” It consisted only of two metallic sheets, copper and zinc, fifty to sixty feet long by two feet wide, coiled around a cylinder of wood and prevented from coming together by three ropes of horse-hair, the whole being suspended over a tub of acid so that, by a pulley or otherwise, it could be immersed or taken up. As stated in Vol. V of the _Trans. of the Amer. Phil. Soc._, this battery required nearly fifty-five gallons of fluid, and the solution used contained about one-fortieth of strong nitrous acid.

When, as Noad observes, it is stated that a piece of platinum wire may be heated to redness by a pair of plates only four inches long and two broad, the calorific power of such an arrangement as the above may be imagined to have been immense. The energy of the simple circle depends on the size of the plates, the intensity of the chemical action on the oxidizable metal, the rapidity of its oxidation, and the speedy removal of the oxide. Pouillet is said to have constructed one of these batteries with twelve couples for the Paris Faculté des Sciences, and found it very powerful in producing large quantities of electricity with low tension. The best liquid for this battery was water with one-fortieth in volume of sulphuric acid and one-sixtieth of nitric acid. With the above-described battery of Mr. Pepys, Sir Humphry Davy performed a remarkable experiment which is to be found described in the _Phil. Trans._ for 1823. A similar apparatus was produced independently, at about the same time, by Dr. Seebeck, of Berlin.

Another of Pepys’ inventions is the substitution, for the tinfoil coatings within the glass of Bennet’s electroscope, of two plates, forming an acute angle, which, by means of a regulating screw, can be adjusted to any required distance from the gold leaves. The angular

## part is secured to the bottom; the open part perpendicularly upward.

By this mode of approximating the coatings to the gold leaves, the resistance being diminished, a weaker intensity of electricity suffices for their disturbance.

REFERENCES.--_Quarterly Journal of Science_, Vol. I for 1816; _Phil. Mag._, Vol. XXI. p. 241; XLI. p. 15; Becquerel, Vol. I. p. 34. Mr. William H. Pepys, Jr., published descriptions of the newly invented galvanometer and of the large galvanic apparatus in the _Phil. Mag._, Vol. X., June 1801, p. 38, and Vol. XV for 1803, p. 94; “Cat. Sc. Papers Roy. Soc.,” Vol. II. p. 192; “Bibl. Britan.,” Vol. XVIII, 1801, p. 343, and Vol. XXII, 1803, p. 297.

=A.D. 1803.=--Geoffroy Saint-Hilaire (Etienne), a very eminent French naturalist, once the pupil of Haüy, whose life he was the means of saving during the massacre of September 1792, is the first to give a thoroughly complete description of the electrical organs and functions of the _raia torpedo_, of the _gymnotus electricus_, of the _silurus electricus_, and of other similar species of fishes. His work on the subject, entitled “Sur l’anatomie comparée,” etc., is alluded to in Vol. I. An. xi. No. 5 of the “Annales du Museum,” whence it is translated for the fifteenth volume of the _Phil. Mag._

His analyzation of the fluid in the cells of the _torpedo_ showed it to consist of albumen and gelatine; and he discovered some organs analogous to those of the _torpedo_ in different species of the same genus _raia_, which, strange to say, do not appear possessed of any electrical power.

The electrical organs of the _silurus electricus_ he found to be much less complicated than those of other electrical fishes. They lie immediately below the skin and stretch all around the body of the animal. Their substance, he says, is a reticulated mass, the meshes of which are plainly visible, and these cells are filled, like those of other electrical fishes, with an albuminous gelatinous matter. The nerves distributed over the electrical organs proceed from the brain, and the two nerves of the eighth pair have a direction and nature peculiar to this species. (Consult C. Matteucci, “Traité des Phénomènes ...” Paris, 1844, Chaps. VI and VII. pp. 301–327.)

In his great work on Egypt (Pl. XII, 2) Geoffroy gives the figure of a _malapterus electricus_ (see Adanson, A.D. 1751) which is opened to show the viscera, but, by a singular inaccuracy, says Mr. James Wilson, the fish is represented as scaly, whereas there are no scales whatever upon this fish, and no fish known to possess electric powers has either scales or spines. The _torpedo_, the _gymnotus_ and the _malapterus_ have all naked skins. The _tetraodon electricus_ (see Shaw at A.D. 1791) is also destitute of spines on the skin, although all its congeners have skins as bristly as those of a hedgehog.

Geoffroy Saint-Hilaire (Isidore), son of Etienne, was also a distinguished naturalist. He became Assistant Professor of Zoölogy to his father in 1829, likewise his assistant at the Faculté des Sciences in 1837, and, when Etienne became blind, during the year 1841, he succeeded to the Professorship of Zoölogy at the Museum of Natural History. He is the author of “The Life, Works and Theories (_Vie, Travaux et Doctrine_) of Etienne Geoffroy Saint-Hilaire,” Paris, 1847.

REFERENCES.--Gilbert’s _Annalen_, XIV. p. 397; _Bulletin Soc. Phil._, No. 70; Geo. Wilson’s “Life of Cavendish,” London, 1851, p. 469, alluding to the later experiments on electrical fishes made by Faraday (1838), Dr. James Stark, of Edinburgh (1844), Prof. Goodsir (1845), and Dr. C. Robin (1846). Consult also, _Journal de Physique_, Vol. LVI. p. 242, and the complete list of Geoffroy’s works in Callisen’s “Medicinisches-Schriftsteller Lexicon”; “Memoir of M. Isidore G. Saint Hilaire,” by M. De Quatrefages, in “Report of Smithsonian Institution” for 1872, pp. 384–394; “Journal des Savants” for May-Aug., 1864; “Roy. Soc. Cat. of Sc. Papers,” Vol. II. pp. 824–832; Vol. VI. p. 669; Vol. VII. p. 757.

=A.D. 1803.=--Carpue (J. C. S.), English scientist, relates, in his “Introduction to Electricity and Galvanism,” published in London, some noteworthy experiments on the curative action of common electricity.

He repeated many of the investigations of Giovanni Aldini, and, in the presence of Dr. Pearson and other medical gentlemen, experimented upon the body of Michael Carney, immediately after his execution for murder. Carpue’s main object was to ascertain whether galvanism, applied at once to the nerves, could excite action in the internal parts, and especially in the respiratory organs. He first made an opening into the windpipe and, after introducing about three pints of oxygen into the lungs, he applied conductors to the phrenic nerve as well as to other parts of the body, the lungs being at the same time occasionally inflated, but no action could be excited in the diaphragm. The application of conductors to the inside of the nostrils and elsewhere, however, excited very considerable contractions in the right auricle more than three hours after death, the ventricles being, as in Aldini’s experiments, perfectly motionless.

REFERENCES.--“Galvanic Experiments Made by Carpue on the Body of Michael Carney,” etc., London, 1804 (_Phil. Mag._, Vol. XVIII. p. 90); the “Encyclopedia Metropolitana,” article “Galvanism,” Vol. IV. pp. 105, 106, also the “Introduction,” etc., above named for descriptions of Mr. Cuthbertson’s plate electrical machine and of Mr. Read’s condenser.

=A.D. 1803.=--Hachette (Jean Nicholas Pierre), a protégé of Monge, who became professor at the Paris Ecole Polytechnique, where he had among his pupils Poisson, Arago and Fresnel, presents to the Institut National the dry pile which was the result of the many experiments he had carried on in conjunction with Charles Bernard Desormes, who was then known as a prominent French scientist and manufacturer of chemical products.

Their idea was to establish the development of electricity by simple contact, and they sought to obtain a substance which would satisfactorily replace the wet discs, and not be affected by the metals, as had been all the liquids hitherto employed (H. Boissier, “Mémoire,” etc., Paris, 1801). After numerous investigations they adopted a compound consisting of common starch and either salts, varnishes or gums, with which they made the necessary discs. These discs were dried and placed alternately between the copper and zinc couples, but were afterward found to be too easily affected by moisture to prove very effective (D. Tommasi, “Traité des Piles Electriques,” Paris, 1889, p. 529).

In the columns of the _Annales de Chimie_, named below, will be found detailed the numerous experiments with the galvanic pile carried on individually and collectively by Hachette, Desormes and other scientists; those of Hachette and Thénard upon the ignition of metallic wires claiming especial notice. Prof. John Farrar (“Elem. of Elec. Magn.,” etc., Cambridge, 1826, p. 167) calls attention to the latter and in the _Phil. Mag._ for 1821 will be found an account of the researches of the above-named scientists made during the year 1805, to establish more properly the analogy between galvanism and magnetism. Hachette and Desormes endeavoured to ascertain the direction which would be taken by a voltaic pile, whose poles were not joined, when freely suspended horizontally. Their pile, as Fahie gives it, was composed of 1480 thin plates of copper tinned with zinc, of the diameter of a five-franc piece, and was placed upon a boat floating on the water of a large vat; but it assumed no determinate direction, although a magnetized steel bar, of a weight nearly equal to that of the pile, and likewise placed upon the boat, would turn, after some oscillations, into the magnetic meridian.

REFERENCES.--_Annales de Chimie_, Vol. XXXVII. pp. 284–321; XLIV. pp. 267–284; XLVII (Biot’s Observations), p. 13; XLIX. pp. 45–54, and XLV for 1808. See also, the _Annales_ for 1834, as well as Vol. XLII. p. 125, for experiments of MM. Desormes and Clement on the fixed alkalies; _Journal de Physique_ of Sept. 1820, for the paper of Hachette and Ampère on the electro-magnetic experiments of Oersted and Ampère; _Annales de Chimie et de Physique_, Vol. II for May 1816, pp. 76–79, and V. p. 191; _Phil Mag._, Vol. LVII. p. 43; L. W. Gilbert, _Annalen der Physik_, Vols. IX. pp. 18–39; XVII. pp. 414–427; _Journal de l’Ecole Polytechnique_, Vol. IV for 1802; XI. p. 284; Leithead, “Electricity,” p. 252; _Bull. de la Soc. Philomathique_, No. 83; P. Sue, aîné, “Hist. du Galv.,” Paris, An. X, 1802, Vol. II. pp. 160, 167, 188, 345 (Hachette et Thénard), and p. 371; Joseph Izarn, “Manuel du Galvanisme,” An. XII, 1804, s. 4. p. 179; Poggendorff, Vol. I. pp. 562, 985; Larousse, “Dict. Universel,” Vol. VI. p. 576; “Royal Society Catalogue of Scientific Papers,” Vol. III. pp. 106–109.

=A.D. 1803.=--Biot (Jean Baptiste), who, in 1800, at the age of twenty-six, was made Professor of Natural Philosophy at the “Collège de France,” and afterward ranked among the first astronomers and mathematicians, gives an account of his journey to Aigle, in the Department of l’Orne, whither he was sent by the Government to examine and report upon a very extraordinary shower of meteorites. The facts obtained by him were communicated to the Institute on the 29th Messidor, An. XI, and also appeared at the time in the Paris _Journal des Débats_ (_Phil. Mag._, Vol. XVI. p. 299).

On the 23rd of August of the year following (1804) Biot accompanied Gay-Lussac in the latter’s first memorable balloon ascent. This aeronautic voyage, sanctioned by the French Government mainly through the efforts of Berthollet and Laplace, was the first of the kind undertaken solely for a scientific object.

Besides numerous barometers and electrometers, Biot and Gay-Lussac carried with them two compasses, a dipping needle and other instruments. For the examination of the electricity of different strata of the atmosphere, they had several metallic wires from 60 to 300 feet in length, also a small electrophorus feebly charged, while for galvanic experiments they added some discs of copper and zinc, together with a supply of frogs, insects and birds. An account of the exceedingly important results obtained by those scientists at different elevations, of which the highest reached exceeded four miles, was read before the National Institute, Aug. 27, 1804. It was also published in London during the latter year, and alluded to at p. 371, Vol. XIX of the _Philosophical Magazine_. Mary Somerville remarks (“Connection of the Physical Sciences,” 1846, p. 334) that according to the observations of Biot and Gay-Lussac, the magnetic action is not confined to the surface of the earth, but extends into space. The moon has become highly magnetic by induction, in consequence of her proximity to the earth, and because her greatest diameter always points toward it. Her influence on terrestrial magnetism is now ascertained; the magnetism of the hemisphere that is turned toward the earth attracts the pole of our needles that is turned toward the south and increases the magnetism of our hemisphere; and as the magnetic, like the gravitating force, extends through space, the induction of the sun, moon and planets must occasion perpetual variations in the intensity of terrestrial magnetism, by the continual changes in their relative positions.

In 1805 Biot published an investigation of the laws which should govern the dip and intensity, in the hypothesis of a magnet situated at the centre of the earth, having its poles infinitely close to each other and directed to opposite points on the surface of the globe and, as justly adds Major Edward Sabine (Report Seventh Meeting Brit. Asso.), it is a well-known consequence of this hypothesis that the lines of equal dip and equal intensity on the earth’s surface should everywhere be parallel to each other. The phenomena of electricity had been brought within the pale of mixed mathematics by C. A. Coulomb (A.D. 1785), whose considerations mainly attached to the distribution of electricity upon the surface of spheres, and his investigations were at once diligently pursued by the French scientists, Biot, Laplace and Poisson. Laplace, who undertook to investigate the distribution of electricity upon the surface of ellipsoids of revolution, showed that the thickness of the coating of the fluid at the pole was to its thickness at the equator as the equatorial is to the polar diameter, or, what is the same thing, that the repulsive force of the fluid, or its tension at the pole, is to that at the equator as the polar is to the equatorial axis. Biot extended this investigation to all spheroids differing little from a sphere, whatever may be the irregularity of their figure, and his solution of the problem will be found in No. 51 of the _Bulletin des Sciences_. He also determined, analytically, that the losses of electricity form a geometrical progression when the two surfaces of a jar or plate of coated glass are discharged by successive contacts, and he found that the same law regulated the discharge when a series of jars or plates are placed in communication with each other (Whewell, “History of the Inductive Sciences,” Vol. II. pp. 208, 223; Noad’s “Manual,” p. 15; Eighth “Britannica,” Vol. VIII. p. 531. For Biot’s experiments, touching upon electrical attraction and demonstrating practically the distribution of electricity upon the surface of a conductor, see the last-named volume of the “Britannica,” pp. 552, 556, and Noad, p. 56).

In conjunction with Frederick Cuvier, Mr. Biot investigated the connection of chemical charge with the production of electricity. Like Mr. W. H. Pepys, they examined the effect produced by the pile on the atmosphere in which it is located. Mr. Pepys placed the pile in an atmosphere of oxygen, and found that in the course of a night 200 cubic inches of the gas had been absorbed, but that in an atmosphere of azote the pile ceased to act. Biot and Cuvier likewise observed the quantity of oxygen absorbed, and inferred from their experiments that “although, strictly speaking, the evolution of electricity in the pile was produced by oxidation, the share which this had in producing the effects of the instrument bore no comparison with that which was due to the contact of the metals, the extremity of the series being in communication with the ground.” Their investigation was attended by the discovery that as long as any oxygen remained to be absorbed, the chemical and physiological effects of the apparatus still continued, but with decreasing intensity; so that if the conducting wires attached to the two poles are made to return from under the receiver in tubes of glass they may be used to decompose water and communicate shocks to the organs. All these effects, however, cease when the surrounding oxygen is exhausted (_Annales de Chimie_, Vol. XXXIX. p. 242; _Soc. Philomathique_, An. IX. p. 40; Sue, “Histoire du Galv.,” Vol. II. p. 161).

In the second volume of Biot’s “Traité de Physique” will be found recorded his many observations on the nature and origin of the electric light, extracts from which are given by Sir David Brewster in the electricity article of the “Britannica.” Biot remarks that the light which is observed during an electric explosion was for a long time considered by philosophers as a modification of the electric principle itself, which they supposed to be the quality of becoming luminous at a certain degree of accumulation (John Farrar, “Elem. of Elec., Mag. and El. Mag.,” 1826, p. 118). Brewster adds that this eminent French writer, however, considered the opinion as erroneous, and he has devoted a whole chapter to prove that electricity has the same origin as the light disengaged from air by mechanical pressure, “and that it is purely the effect of the compression produced on the air by the explosion of electricity.” In order to establish this theory, Mr. Biot has stated, on the authority of several experiments, “that the intensity of electric light depends always on the ratio which exists between the quantity of electricity transmitted and the resistance of the medium”; and he has shown, by an experiment with Kinnersley’s thermometer, “that at each spark the air of the cylinder, driven by the repulsive force, presses on the surface of mercury, which rises suddenly in the small tube, and falls back again immediately after the explosion.” He adds:

“This indication proves the separation produced between the particles of the mass of air where the electricity passes; and from what we know of its extreme velocity it is certain that the particles exposed immediately to its shock ought in the first moment to sustain individually all the effect of the compression. They ought, then, from this cause alone to disengage light, as when they are subjected to any other mechanical pressure. Thus one part at least of the electric light is necessarily due to this cause; and this being the case, there is no experiment which can lead us to conjecture that it is not all due to this cause.”

REFERENCES.--“Encycl. Brit.,” 1857, Vol. XIV. pp. 7, 63, and _Journal de Physique_, Vol. LIX. p. 450. For Mr. Biot’s observations on the magnetism of metals and minerals, and on the distribution of magnetism in artificial magnets, as well as for his improvement upon Coulomb’s method of constructing the latter, see the last-named volume of the “Britannica,” pp. 23, 26, 71, and Noad’s “Manual of Electricity,” London, 1859, pp. 528, 535, while, for Biot’s very ingenious theory relative to the aurora, see Lardner and Walker’s “Manual of Elec. Mag. and Meteor.,” London, 1844, Vol. II. p. 235, and Noad, pp. 232, 233. The observations concerning the laws regulating the intensity of electro-magnetic phenomena, made by MM. Biot and Savary, are alluded to by Noad at pp. 644, 645, in the “Encycl. Metropol.” (Elec. Magn.), Vol. IV. p. 427; and Whewell’s “History of the Inductive Sciences,” 1859, Vol. II. pp. 245–249; “Scientific papers of the Royal Society,” Vol. I. pp. 374–386; Biot’s “Traité de Phys. Exp. et Math.,” Vol. II. p. 457; _Journal de Physique_, Vol. LIX. pp. 315, 318; Wilkinson’s “Elem. of Galv.,” Vol. II. pp. 38, 123, 154, 361, Chap. XVI; Humboldt’s “Cosmos,” treating of Aerolites, of the Zodiacal Light and of the figure of the earth; Noad, “Manual,” p. 530; Eighth “Ency. Brit.,” Vol. VIII. p. 580; Sir H. Davy, “Bakerian Lectures,” London, 1840, p. 3, alluding to Biot and Thénard in No. 40 of the _Moniteur_ for 1806; “Encycl. Metropol.,” Vol. IV. (Electro-Magn.), p. 7; Harris “Rudim. Magn.,” Part III, London, 1852, pp. 116, 117; Gautherot at A.D. 1801; Figuier, “Exposition,” etc., Paris, 1857, Vol. iv. p. 429; “Lib. of Useful Knowl.” (Electricity), p. 64 and (Magnetism), p. 89; “Soc. Philomath.,” An. IX. p. 45; An. XI. pp. 120, 129; Becquerel’s “Traité,” 1856, Vol. III. p. 11; _Phil. Mag._, Vols. XVI. p. 224; XXI. p. 362; “Mém. de l’Institut” for 1802, Vol. V; “Annales des Mines” for 1820, relative to the experiments on electro-magnetism made by Oersted, Arago, Ampère and Biot; _Phil. Mag._, Vol. XXII. pp. 248, 249, for the magnetical observations made by Biot and Arago; _Comptes Rendus_ for 1839, I Sem., VIII, No. 7, p. 233, for the observations of Biot and Becquerel on the nature of the radiation emanating from the electric spark; “Chemical News,” London, 1868, Vol. XVI for John Tyndall’s lecture on some experiments of Faraday, Biot and Savary; “Atti dell’ Accad. dei Nuovi Lincei, Ann.,” XV. Sess., IV. del 2 Marzo 1862, for the biography of J. B. Biot, who died Feb. 2, 1862, within two months of the completion of his eighty-eighth year. “Journal des Savants” for June and July 1820, April 1821, and for Feb.-Mar.-April 1846.

J. B. Biot’s son, Edward Constant Biot (1803–1850), is the author of the extended catalogue of shooting stars and other meteors observed in China during twenty-four centuries, which was presented to the French Academy during 1841, and a supplement to which was published at Paris in 1848 (_Acad. des Sciences_, _Savants Etrangers_, Tome X).

=A.D. 1803–1805.=--Acting upon the discovery of Gautherot, the Bavarian philosopher Johann Wilhelm Ritter (1776–1810) is the first to construct an electrical accumulator.

Ritter’s “ardency of research and originality of invention” had, as far back as 1796, shown itself in the numerous very able scientific papers relating to Electricity, Galvanism and Magnetism which he had communicated mainly through L. W. Gilbert’s _Annalen der Physik_, J. H. Voigt’s _Mag. für Naturkunde_ and A. F. Gehlen’s _Journal für die Chemie_, all which obtained recognition in several foreign publications. These papers secured for him membership in the Munich Academy during the year 1805.

From Prof. H. W. Dove’s discourse before the Society for Scientific Lectures, of Berlin, the following is extracted:

“As the (then considered) essential portions of a galvanic circuit were two metals and a fluid, innumerable combinations were possible, from which the most suitable had to be chosen. This gigantic task was undertaken by Ritter, an inhabitant of a village near Leignitz, who almost sacrificed his senses to the investigation. He discovered the peculiar pile which bears his name, and opened that wonderful circle of actions and reactions which, through the subsequent discoveries of Oersted, Faraday, Seebeck and Peltier, drew with ever-tightening band the isolated forces of nature into an organic whole. But he died early, as Günther did before him, exhausted by restless labour, sorrow and disordered living.”

Ritter’s _charging or secondary pile_ consists of but one metal, the discs of which are separated by circular pieces of cloth, flannel or cardboard, moistened in a liquid which cannot chemically affect the metal. When the extremities are put in communication with the poles of an ordinary voltaic pile it becomes electrified and can be substituted for the latter; and it will retain the charge, so that for a time there can be obtained from it sparks, shocks, as well as the decomposition of water.

The writer of the article at p. 268 of the April 1802 _Monthly Magazine_, making reference to _an artificial magnet_ discovered at Vienna (Bakewell, “Elec. Science,” p. 40), no doubt alludes to the above-named charging or secondary pile, in the construction of which Ritter made many modifications. At first he arranged 32 copper and card discs in three series, two of which series contained 16 copper discs while the intermediate series consisted of 32 card discs. He then placed them so that the discs alternated, employing but 31 discs of copper, and he also used 64 as well as 128 copper discs alternating with similar ones of cardboard. In each case he compared the chemical

## action through the decomposition of water as well as the physiological

effect or shock and the physical property or electrical tension. The results obtained are given in his many papers alluded to below.

Independently of the English scientists he discovered the property possessed by the voltaic pile of decomposing water as well as saline compounds, and of collecting oxygen and acids at the positive pole while hydrogen and the bases collect at the negative pole. He conceived that he had procured oxygen from water without hydrogen, by making sulphuric acid the medium of the communication at the negative surface, but, as Davy says, in this case sulphur is deposited, while the oxygen from the acid and the hydrogen from the water are respectively repelled, and the new combination produced.

A correspondent in Alex. Tilloch’s _Philosophical Magazine_ (Vol. XXIII for 1805–1806, pp. 51–54--Extracts from a letter of M. Christ. Bernoulli abridged from Van Mons’ _Journal_, Vol. VI) thus alludes to some of Ritter’s experiments communicated in May 1805 to the Munich Royal Society:

“I have seen him galvanize a louis d’or. He places it between two pieces of pasteboard thoroughly wetted, and keeps it six or eight minutes in the circuit of the pile. Thus it becomes charged, though not immediately in contact with the conducting wires. If applied to the recently bared crural nerves of a frog the usual contractions ensue. I put a louis d’or thus galvanized into my pocket, and Ritter told me, some minutes after, that I might discover it from the rest by trying them in succession upon the frog. I made the trial, and actually distinguished, among several others, one in which only the exciting quality was evident. The charge is retained in proportion to the time that the coin has been in the circuit of the pile. Thus, of three different coins, which Ritter charged in my presence, none lost its charge under five minutes. A metal thus retaining the galvanic charge, though touched by the hand and other metals, shows that this communication of galvanic virtue has more affinity with magnetism than with electricity, and assigns to the galvanic fluid an intermediate rank between the two. Ritter can, in the way I have just described, charge at once any number of pieces. It is only necessary that the two extreme pieces of the number communicate with the pile through the intervention of wet pasteboards. It is with metallic discs charged in this manner and placed upon one another, with pieces of wet pasteboard alternately interposed, that he constructs his charging pile, which ought, in remembrance of its inventor, to be called the _Ritterian pile_. The construction of this pile shows that each metal galvanized in this way acquires polarity, as the needle does when touched with a magnet.”

The same correspondent alludes to experiments made with Ritter’s battery of 100 pairs of metallic plates, the latter having their edges turned up so as “to prevent the liquid pressed out from flowing away” (_Phil. Mag._, Vol. XXIII. p. 51), but he says he was unable to see either Ritter’s great battery of 2000 pieces, or the one of 50 pieces, each 36 inches square, the action of which is said to have continued very perceptibly for a fortnight. He writes as follows:

“After showing me his experiments on the different contractibility of various muscles (“Beiträge zur nähern Kenntniss,” etc., Jena, 1802, B. II) Ritter made me observe that the piece of gold galvanized by communication with the pile exerts at once the action of two metals, or of one voltaic couple, and that the face which in the voltaic circuit was next the negative pole became positive, and the face toward the positive pole negative. Having discovered a way to galvanize metals, as iron is rendered magnetic, and having found that the galvanized metals always exhibit two poles as the magnetized needle does, Ritter suspended a galvanized gold needle on a pivot, and perceived that it had a certain dip and variation, or deflection, and that the angle of deviation was always the same in all his experiments. It differed, however, from that of the magnetic needle, and it was the positive pole that always dipped.”

It can truly be said that the nearest approach to a solution of the question as to the analogy between electric and magnetic forces, which had remained unsettled since the time of Van Swinden (see A.D. 1784), was given by Ritter, who announced “that a needle composed of silver and zinc arranged itself in the magnetic meridian and was slightly attracted and repelled by the poles of a magnet; that by placing a gold coin in the voltaic circuit, he had succeeded in giving to it positive and negative electric poles; that the polarity so communicated was retained by the gold after it had been in contact with other metals, and appeared therefore to partake of the nature of magnetism; that a gold needle under similar circumstances acquired still more decided magnetic properties; that a metallic wire, after being exposed to the voltaic current, took a direction N.E. and S.W.” Dr. Roget gives these same extracts in his article on “Electro-Magnetism,” and justly remarks that Ritter’s speculations were of too crude a nature to throw any distinct light on the true connection between magnetism and electricity, nor was much notice taken of Ritter’s announcements, owing to the vague manner in which they were made. No satisfactory results were in fact obtained until Oersted (at A.D. 1820) made his famous discovery which forms the basis of the science of electro-magnetism.

REFERENCES.--The “Encyclopædia Britannica” article relating to the influence of magnetism on chemical action, for an account of Ritter’s other experiments; also Faraday’s “Experimental Researches,” No. 1033; Ritter’s “Physisch. Chem. Abhand.,” etc., 3 vols., Leipzig, 1806; Poggendorff, Vol. II. p. 652; Tyndall’s notes on Electric Polarization; Donovan’s “Essay on the Origin, Progress and Present State of Galvanism,” Dublin, 1816; “Société Philomathique,” An. IV. p. 181; An. IX. p. 39; An. XI. pp. 128, 197; An. XII. p. 145; _Bull. Soc. Phil._, Nos. 53, 76, 79; _Nuova Scelta d’Opus._, Vol. I. pp. 201, 334; _Bibl. Brit._, XXXI; “Reichsanzeiger,” 1802, Bd. I, No. 66, and Bd. II, No. 194; also F. L. Augustin’s “Versuch einer geschichte ...” 1803, p. 75; Gilbert’s _Annalen_, II, VI, VII, VIII, IX, XIII, XV, XVI; Voigt’s _Magazin_, Vol. II. p. 356; Gehlen’s _Journal_, Vol. III for 1804, and Vol. VI for 1806; “Denkschr. d. Münch.,” 1808 and 1814; _Phil. Mag._, Vol. XXIII. chap. ix. pp. 54, 55 (for experiments from Van Mons’ _Journal_, No. 17), Vols. XXIV. p. 186; XXV. p. 368; LVIII. p. 43; L. F. F. Crell, “Chemische Annalen” for 1801; _Nicholson’s Journal_, Vols. IV. p. 511; VI. p. 223; VII. p. 288, VIII. pp. 176, 184; “Gottling’s Almanach” for 1801; Leithead, “Electricity,” p. 255; “Encycl. Metropolitana,” article “Galvanism,” Vol. IV. p. 206; “Biographie Générale,” Vol. XLII. p. 322; Larousse, “Dict. Universel,” Vol. XIII. p. 1234; Pierre Sue, aîné, “Histoire du Galvanisme,” Paris, An. X, 1802, Vol. I. pp. 226, 266; Vol. II. pp. 112–119, 156; Joseph Izarn, “Manuel du Galvanisme,” Paris, An. XII, 1804, pp. 84–87, 249, 255–261; Brugnatelli, “Notizie ... nell’ anno 1804,” Pavia, 1805, p. 16, also his _Annali di chimica_, Vol. XXII. p. 1; _Journal de Physique_, Vol. LVII. pp. 345, 406; _Annales de Chimie_, Vols. XLI. p. 208; LXIV. pp. 64–80; _Jour. de Chim. de Van Mons_, No. 14, p. 212, for the experiments of Van Marum and Oersted, made with Ritter’s apparatus; Sturgeon’s “Scientific Researches,” Bury, 1850, pp. 7, 8, and Prof. Millin’s “Magazin Encyclopédique”; “Allgemeine Deutsche Biographie,” Leipzig, 1875, Vol. XXVIII. pp. 675–678; “Bibl. Britan.,” Vol. XXXI. 1806, p. 97, Vol. XXV. 1807, pp. 364–386 (Lettre de M. le Dr. Thouvenel).

=A.D. 1803.=--Basse (Frédéric Henri), of Hamel, makes one of the earliest trials of the transmission of galvanism through water and soil, the results of which appear in his work, “Galvanische Versuche,” etc., published at Leipzig the year following.

Along the frozen water of the ditch or moat surrounding the town of Hamel he suspended, on fir posts, 500 feet of wire, at a height of six feet above the surface of the ice, then making two holes in the ice and dipping into them the ends of the wire, in the circuit of which were included a galvanic battery and a suitable electroscope, he found the current circulating freely. Similar experiments were made in the Weser; afterwards, with two wells, 21 feet deep and 200 feet apart; and, lastly, across a meadow 3000 to 4000 feet wide. Whenever the ground was dry it was only necessary to wet it in order to feel a shock sent through an insulated wire from the distant battery. Erman, of Berlin, in 1803, and Sömmering, of Munich, in 1811, performed like experiments, the one in the water of the Havel, near Potsdam, and the other along the river Isar.

Fahie, from whom we take the above, alludes to Gilbert’s _Annalen der Physik_, Vol. XIV. pp. 26 and 385, as well as to Hamel’s “Historical Account,” p. 17, of Cooke’s reprint, and adds that Fechner, of Leipzig, after referring to Basse’s and Erman’s experiments in his “Lehrbuch des Galvanismus,” p. 268, goes on to explain the conductibility of the earth in accordance with Ohm’s law. As he immediately after alludes to the proposals for electric telegraphs, he has sometimes been credited with the knowledge of the fact that the earth could be used to complete the circuit in such cases. This, however, is not so, as we learn from a letter which Fechner addressed to Prof. Zetzsche, on the 19th of February 1872.

REFERENCES.--Zetzsche’s “Geschichte der Elektrischen Telegraphie,” p. 19. See Dr. Turnbull’s Lectures in the _Journal of the Franklin Institute_, Vol. XXI. pp. 273–274; “Scientific Papers of the Royal Society,” Vol. I. p. 203.

=A.D. 1803.=--Thillaye-Platel (Antoine), French savant, who was afterward appointed pharmacist in the Paris _Hôtel-Dieu_, gives out as the result of numerous investigations a great many useful precepts on the medical application of electricity and galvanism, which will be found in his thesis presented to the Paris Ecole de Médecine on the 15th Floréal, An. XI. These precepts, De la Rive says (“Treatise on Elect.,” translated by C. V. Walker, London, 1858, Vol. III. pp. 587, 588), are followed to this day and are extremely simple, requiring only the use of metallic brushes held by an insulated handle and put into communication with the conductor of the machine; and directing the application of electricity in its mildest form as well as its gradual increase to as much as the invalid is able to support, besides allowing of the concurrent employment of other means acting in the same direction, such as frictions, blisters, etc.

Antoine Thillaye-Platel’s uncle, Jean Baptiste Jacques Thillaye (1752–1822), French physician and Professor of Anatomy at Rouen and in Paris, published “Eléments de l’Elect. et du Galv.,” Paris, 1816–1817, ten years after the death of his nephew (Poggendorff, Vol. II. p. 1094; Larousse, “Dict. Univ.,” Vol. XV. p. 131).

De la Rive alludes to cures effected by several specialists and

## particularly to Father R. B. Fabre-Palaprat’s translation made in 1828

of La Beaume’s English work on the medical efficacy of electricity and galvanism, originally published in 1820–1826. The latter, he says, is preceded by a preface wherein the translator rivals the author on the wonderful effects of the electric fluid as a sovereign remedy for nearly all maladies.

REFERENCES.--For M. Thillaye’s experiments with M. Butet on galvanic electricity, made at the Paris École de Médecine, see the _Bulletin des Sciences de la Soc. Philom._, No. 43, Vendémiaire An. IX, also Vol. IX. p. 231, of the “Recueil Périodique de la Soc. Libre de Médecine du Louvre.” Consult likewise, Poggendorff, Vol. II. p. 1094; “Royal Society Catalogue of Scientific Papers,” Vol. V. p. 954; De la Rive’s “Treatise,” Vol. III. pp. 587, 588; P. Sue, aîné, “Histoire du Galvanisme,” Vol. III. p. 14. Some of the other authors who have treated of the same subject are: F. Zwinger, 1697–1707; W. B. Nebel, 1719; Oppermanno, 1746; E. Sguario, 1746; G. C. Pivati, 1747–1750; G. Veratti, 1748–1750; O. de Villeneuve, 1748; L. Jallabert, 1748–1750; G. F. Bianchini, 1749; Mellarde, of Turin, 1749; Palma, 1749; F. Sauvages de la Croix, 1749–1760; J. B. Bohadsch, 1751; O. M. Pagani, 1751; S. T. Quellmaz, 1753; A. von Haller, 1753–1757; Linné (Linnæus), 1754; P. Paulsohn, 1754; E. F. Runeberg, 1757; P. Brydone, 1757; Lower, 1760; De Lassone, 1763; Wm. Watson, 1763; G. F. Hjotberg, 1765; J. G. Teske, 1765; P. A. Marrherr, 1766; Gardane, 1768–1778; J. G. Krunitz, 1769; R. Symes, 1771; Sigaud de la Fond, 1771; C. A. Gerhard, 1772; Abbé Sans, 1772–1778; J. Janin de Combe Blanche, 1773; J. B. Becket, 1773; Marrigues à Montfort L’Amaury, 1773; G. F. Gardini, 1774; J. G. Schaffer, 1776; Mauduyt, 1776–1786; De Thouri, 1777; A. A. Senft, 1778; Masars de Cazéles, 1780–1788; P. F. Nicolas, 1782; Bonnefoy, 1782; Niccolas, 1783; K. G. Kuhn, 1783, 1797; C. W. Hufeland, 1783; Cosnier, Maloet, Darcet, etc., 1783; J. P. Marat, 1784; G. Vivenzio, 1784; Carmoy, 1784–1785; G. Piccinelli, 1785; L. E. de Tressan, “Essai ...” 1786, p. 233, etc.; Krunitz-Kirtz, 1787; Porna and Arnaud, 1787; F. Lowndes, 1787–1791; J. H. D. Petetin, 1787, 1808; G. Pickel, 1788; Van Troostwijk and Krayenhoff, 1788; R. W. D. Thorp, 1790; G. Wilkinson, 1792; C. H. Pfaff, 1793; G. Klein, 1794; M. Imhof, 1796; C. H. Wilkinson, 1799; C. A. Struve, 1802; Maurice, 1810; J. Morgan, 1815; Le Blanc, 1819; P. A. Pascalis, 1819; J. Price, 1821; K. Sundelin, 1822; Girardin, 1823; Ch. Bew, 1824; Sarlandière, 1825; S. G. Marianini, 1833; F. Puccinotti, 1834; François Magendie, 1836, 1837; Gourdon, 1838; C. Matteucci, Piria, etc., 1838, 1858; Breton Frères, 1844; B. Mojon, Jr., 1845; J. E. Riadore, 1845; A. Restelli, 1846; Budge, 1846; F. Hollick, 1847; R. Froriep, 1850; C. V. Rauch, 1851; H. Valerius, 1852; Burci, 1852; Marie-Davy, 1852–1853; W. Gull, 1852; C. Beckensteiner, 1852–1870; F. Channing, 1852; F. F. Videt, 1853; R. M. Lawrance, 1853–1858; G. M. Cavalleri, 1854, 1857; Briand, 1854; M. Kierski, 1854; P. Zetzell, 1856; Ad. Becquerel, 1856–1860; E. Pfluger, 1856, 1858; Pulvermacher, 1856; P. C. Pinson, 1857; H. Ziemssen, 1857–1866; Philipeaux, 1857; J. Dropsy, 1857; M. Meyer, 1857–1869; Nivelet, 1860–1863; A. Tripier, 1861; J. Rosenthal, 1862; Desparquets, 1862; M. P. Poggioli (Mémoire lu à l’Institut, Oct. 31, 1853; “Annual of Scientific Disc.,” 1865, p. 327); G. Niamias, “Della elettr. ... medicina,” 1851 (“An. of Sci. Disc.,” 1865, p. 327); A. C. Garrat, 1866; H. Lobb, 1867; Aug. Beer, 1868; H. M. Collis (“An. of Sci. Dis.,” 1869, p. 175); Toutain, 1870; J. R. Reynolds, 1872; Onimus and Legros, 1872; as well as Jobert de Lamballe, Richter and Erdmon, T. Guitard, J. J. Hemmer, H. van Holsbeek, T. Percival, J. D. Reuss and Mr. Ware (in Kuhn, Hist. II. p. 183).

=A.D. 1803.=--Berthollet (Claude Louis de), very eminent French scientist, who was the first of the leading chemists to openly endorse the antiphlogistic doctrine propounded by Lavoisier (A.D. 1781), and who with Laplace founded the well-known scientific Société d’Arcueil, admits in his “Essai de Statique Chimique” the analogy existing between caloric and the electric fluid. He believes that the latter during the oxidation of metals does not give out much heat, but causes only a dilatation of bodies which separates their molecules, and he also believes that electricity aids metallic oxidation by lessening cohesion (Delaunay, “Manuel de l’Electricité,” p. 16).

When Berthollet and Charles passed heavy electrical charges through platinum wire, they observed that the latter acquired a temperature about equal to that of boiling water, and therefore not sufficient to fuse the wire. If the metal is one easily oxidized, the separation of the molecules causes them to unite with the oxygen of the air, and it is therefore the oxidation itself which produces the consequent high degree of heat.

REFERENCES.--“Essai de Statique,” Vol. I. pp. 209 and 263. See also “Biographie Générale,” Vol. V. p. 716; Young’s “Lectures,” London, 1807, Vol. II. p. 423, and _Nicholson’s Journal_, Vol. VIII. p. 80; Larousse, “Dict. Univ.,” Vol. II. p. 617; “Sci. Papers of Roy. Soc.,” Vol. I. pp. 321–323; Sir H. Davy, “Bakerian Lectures,” London 1840, pp. 41, 94, regarding more particularly Berthollet’s elaborate experiments on the decomposition of ammonia by electricity alluded to in _Mém. de l’Acad._, 1782, p. 324, also Delaunay, “Manuel,” pp. 17, 150.

=A.D. 1804.=--Jacotot (Pierre), Professor of Astronomy at the Lyceum of Dijon, states, at p. 223, Vol. I of his “Eléments de Physique Expérimentale,” that Wlik, teacher of natural philosophy at Stockholm, invented the electrophorus during the year 1762. Jacotot, of course, refers to Johannes Carolus Wilcke (see A.D. 1757) who, during the month of August 1762, constructed a resinous apparatus to which he gave the name of _perpetual_ electrophorus (Scripta Academiæ Suec., 1762). Books V, VI and VII of the same volume treat respectively of Electricity, Galvanism and Magnetism.

REFERENCES.--With regard to the _perpetual_ electrophorus, see L. S. Jacquet de Malzet “Lettre d’un Abbé de Vienne ...” Vienna, 1775, translated into German by “A. H.” (A. Hildebrand), Wien, 1776; also C. Cuyper’s “Exposé d’une méthode ...” La Haye, 1778; and, for other improvements, Marsiglio Landriani, _Scelta d’Opuscoli_, 12mo, XIX. p. 73; J. F. Klinkosch, _Mém. de l’Acad. de Prague_, III. p. 218. Consult J. C. Poggendorff, “Biog.-Litter. Hand. ...” Vol. I. pp. 1, 182, and Larousse, “Dictionnaire Universel,” Vol. IX. p. 868.

=A.D. 1804.=--Hatchett (Charles), F.R.S. and foreign member of the Paris Academy, communicates through a paper entitled “An Analysis of the Magnetical Pyrites ...” his conclusions that iron must be combined with a large portion of either carbon, phosphorus or sulphur in order to acquire the property of receiving permanent magnetic virtue, there being, however, a limit beyond which an excess of either of the above-named substances renders the compound wholly incapable of exhibiting the magnetic energy. In this connection, the interesting observations of Messrs. Seebeck, Chenevix and Dr. Matt. Young on anti-magnetic bodies, in Vol. XIV. p. 27, of the eighth “Encyclopædia Britannica,” will repay perusal.

Three years before, on the 26th of November 1801, Mr. Hatchett had communicated to the Royal Society an interesting paper on _columbium_, a new metallic substance found in an ore from the State of Massachusetts.

REFERENCES.--“Abstracts of the papers ... of the _Phil. Trans._,” Vol. I. p. 155; also the _Phil. Trans._ for 1804, p. 315; _Phil. Mag._, Vol. XXI. pp. 133 and 213; Poggendorff, Vol. I. p. 1031; “Cat. Sc. Papers Roy. Soc.,” Vol. I. p. 155.

=A.D. 1804.=--M. Dyckhoff publishes in _Nicholson’s Journal_, Vol. VII. pp. 303 and 305, “Experiments on the activity of a galvanic pile in which thin strata of air are substituted instead of the wet bodies.” His description of what has by many been called the first practical dry pile is as follows:

“I constructed a pile with discs of copper and zinc, and little bits of thin green glass about the size of a lentil, three of which I placed triangularly in the intervals that separated the metallic plates. Thus between each pair of metals I had a thin stratum of air instead of a wet substance. A pile of ten pairs tried by the condenser affected the electrometer as powerfully as a common (voltaic) pile of five pairs.”

It was in the year following, 1805, that Wilhelm Behrends, of Frankfort, constructed his dry pile consisting of eighty pairs of discs of copper, zinc and gilt paper (De la Rive, “Treatise on Electricity,” Vol. II. p. 852).

The investigations of Maréchaux, De Luc, Zamboni and others in the same line will appear in due course.

REFERENCES.--Young’s “Lectures,” London, 1807, Vol. II. p. 430, and _Nicholson’s Journal_, Vol. VII. pp. 303 and 305, Becquerel, Paris, 1851, p. 34; Sturgeon’s “Lectures on Galvanism,” p. 73; Sturgeon’s _Annals of Electricity_, Vol. VIII. pp. 378, etc.; _Journal de Chimie de Van Mons_, No. 11, p. 190, and also No. 12, p. 300, for Bouvier de Jodoigne’s experiments; “Catalogue Scientific Papers of the Royal Society,” Vol. II. p. 432; Gilbert, XIX. pp. 355–360, and Wilkinson’s denial of the effectiveness of Dyckhoff’s pile, in _Nicholson’s Journal_, Vol. VIII. p. 1.

=A.D. 1804.=--Gay-Lussac (Joseph Louis), one of the most prominent of modern scientists, who was for a time assistant to Berthollet, makes, in Paris, two ascents in a balloon, at heights varying between 12,000 and 23,623 feet, for the purpose of carrying out extensive observations upon terrestrial magnetism. The latter are recorded at length in the _Journal de Physique_, Vol. LIX, and are alluded to in the articles “Aeronautics” and “Meteorology” of the “Encycl. Brit.,” likewise at Biot, A.D. 1803, and in paragraphs 2961 and 2962 of Faraday’s “Experimental Researches in Electricity,” while at p. 193, Vol. XXI of the _Phil. Mag._ will be found the account of a very interesting aerial voyage made during January of the same year (1804) by M. Sacharof, of the St. Petersburg Academy of Sciences.

In conjunction with Louis Jacques Thénard (alluded to at Fourcroy, A.D. 1801), Gay-Lussac communicates to the _Annales de Chimie_ for 1810 (Vol. LXXIII. p. 197, etc.), a paper relative to their “preparation of an ammoniacal amalgam through the agency of the voltaic pile” which had been read at the “Institut National” during the month of September 1809, and which is also alluded to at pp. 250, etc., of the _Annales de Chimie_, Vol. LXXVIII for 1811. Their united “physico-chemical researches on the voltaic pile ...” are reviewed at pp. 243, etc., of the last-named volume and are likewise alluded to at p. 36 of Vol. LXXIX for the same year. The largest of the many piles they employed in their several experiments consisted of 600 pairs with a square surface of 1800 feet (Figuier, “Exposition et Histoire ...” 1857, Vol. IV. pp. 387 and 433; _Journal des Mines_, Vol. XXX. pp. 5–56; Schweigger’s _Journal_, Vol. II. pp. 409–423).

At pp. 76, etc., of the second volume of the _Annales de Chimie et de Physique_ for the month of May 1816, are to be found the observations of Gay-Lussac on dry voltaic piles, especially upon those of Desormes et Hachette, De Luc and Zamboni. He remarks that the last named does not appear to have so constructed his pile as to enable the oscillations of the needle to indicate an exact measure of time (Schweigger’s _Journal für Chemie_, Vol. XV. pp. 113, 130–132), but that the so-called electric clocks of M. Ramis, of Munich, and of M. Streizig, of Verona, readily pointed the hours, minutes and seconds (Schweigger’s _Journal_, Vol. XIII. p. 379; Ronalds’ “Catalogue” for notices of his own as well as of the clocks of Ramis and of Streizig).

The investigations of Gay-Lussac and Humboldt, relative to the magnetic intensity and dip or inclination, throughout France, Germany, Switzerland and Italy, will be found recorded in the first volume of _Mém. d’Arcueil_, 1807, while at p. 284, Vol. X, and at pp. 305–309 of the _Annales de Chimie_ are observations of Gay-Lussac and Arago, and at p. 509 of the fourth volume of Figuier’s “Exposition et Histoire,” etc., Paris, 1857, appears an extended account of the special report upon lightning rods, which Gay-Lussac was authorized by the Natural Philosophy Division of the French Academy of Sciences to prepare during the year 1823, and the outcome of which appears in the _Comptes Rendus des Séances_ ... Vol. XXXIX. p. 1142.

REFERENCES.--Faraday’s “Experimental Researches,” 1839, Vol. I. p. 217, note, as well as paragraph No. 741 “Recherches Physicochimiques,” p. 12, and J. Farrar’s “Elem. of Elec. Mag.,” 1826, pp. 150–152; while for Gay-Lussac and Thénard’s repetition of Sir Humphry Davy’s experiments on the decomposition of the alkalies, see _Phil. Mag._, Vol. XXXII. p. 88; “Instruction sur les parat ...” for Gay-Lussac, Fresnel, Lefevre, Gineau and others, Paris, 1824, and for Gay-Lussac and Pouillet, Paris, 1855. Other reports on lightning rods not hitherto specially mentioned are: J. Langenbucher, 1783; Beyer, 1806–1809; P. Beltrami, 1823; Bourges, at Bordeaux, 1837; Boudin, 1855, and J. Bushee, Amer. Assoc., 1868. The observations of Thénard and Dulong are recorded at paragraphs 609, 612, 636, 637 of Faraday’s “Experimental Researches,” as well as at Vols. XXIII. p. 440; XXIV. pp. 380, 383 and 386 of the _Annales de Chimie_, and those of Thénard, Fourcroy, and Vauquelin will be found in the _Mém. des Soc. Sav. et Lit._, Vol. I. p. 204. See “Royal Society Catalogue of Sc. Papers,” Vol. II. pp. 800–807; Vol. V. pp. 944–948; Vol. VI. p. 666; Vol. VII. p. 748; Vol. VIII. p. 1072; “Discours de M. Becquerel ...” _Inst. Nat. Acad. des Sciences_; _Phil. Mag._, Vols. XX. p. 83; XXI. p. 220; _Sci. Am. Supp._, p. 11794; _Edin. Magazine_, Vol. V. p. 471; _Annales de Chimie et Physique_ for 1818, Vol. VIII. pp. 68, 161, 163; the eighth “Britannica,” Vol. VIII. pp. 532, 539, 573 for Gay-Lussac’s additional experiments; the ninth “Britannica,” Vol. X. pp. 122, etc.; also _Report Brit. Asso._, London, 1838, pp. 7–8, for the magnetic observations of Gay-Lussac and Humboldt on the European Continent, likewise Sir Humphry Davy “Bakerian Lectures,” London, 1840, pp. 134–137; Humboldt, at A.D. 1799, and Cruikshanks, at A.D. 1800. For a description of the Volta eudiometer invented by Gay-Lussac, see _Ann. de Ch. et Phys._, Vol. IV. p. 188, also Dr. Hare in _Silliman’s Journal_, Vol. II. p. 312, and for the “Memoir of Louis Jacques Thénard,” by M. Flourens, see the “Report of the Smithsonian Institution” for 1862, pp. 372–383; “Journal des Savants” for Dec. 1850; Meyer’s “Konversations-Lexikon” Leipzig und Wien, 1894, Vol. VII. pp. 140–141; “Dict. Général de Biog. et d’Histoire,” Paris, 2nd ed., pp. 1218–1219.

=A.D. 1805.=--Mr. Joseph Davis submits to the London Society of Arts an improvement upon the telegraph of Lord George Murray (A.D. 1795), consisting of the addition of a seventh shutter, which, instead of being poised on a horizontal axis, is made to slide up and down in grooves in the centre of the framework; so that it may either range with the six shutters or, if not required at all, may descend into a space provided for it in the roof of the Observatory. By this simple device the power of the apparatus is quadrupled, it being made capable of indicating in all 252 changes.

The night signals are given by a coloured lamp mounted in the centre of the seventh or sliding shutter and by six white lights fastened to the outside of the frame, to produce, through their display or concealment by slides, the same signals as, under ordinary circumstances, are given by the opening and closing of the shutters.

=A.D. 1805.=--Grotthus--Grothuss--(Theodor--more properly Christian Johann Dietrich, Baron von) makes known his theory of electro-chemical decompositions, through the “Mémoire,” etc., published in 12mo at Rome, and of which an English translation appeared in London during 1806.

As Lardner and Fahie have it, Grotthus’ theory was the most plausible of the many proposed at this early period of experimental inquiry to explain chemical decomposition by the voltaic apparatus. The above-named “Mémoire ...” which appeared in the _Phil. Mag._ for 1806, Vol. XXV. pp. 330–334, is analyzed by both of these writers (Lardner, “Electricity, Mag. and Meteor.,” Vol. I. pp. 135–137, or “Popular Lectures,” 1851, Vol. I. pp. 348, 349; Fahie, “Hist. of Elec. Teleg.,” pp. 210, 211), but it may be briefly stated in the words of Sir David Brewster as follows:

“Grotthus (_Annales de Chimie_ for 1806, Vol. LVIII. p. 61) regards the pile as an electric magnet with _attracting_ and _repelling_ poles, the one attracting hydrogen and repelling oxygen, and the other attracting oxygen and repelling hydrogen. The force exerted upon each molecule of the body is supposed to be inversely as its distance from the poles, and a succession of decompositions and recompositions is supposed to exist among the intervening molecules.”

In this connection it will be well to add here, by way of contrast, and again according to Sir David Brewster, the views held by other experimentalists of the same period. Sir Humphry Davy adopts the idea of attractions at the poles, diminishing to the middle or neutral points, and he thinks a succession of decompositions and recompositions probable. Messrs. Riffault and Chompré regard the negative current as collecting and carrying the acids on to the positive pole, and the positive current as doing the same, with the bases toward the negative pole. Biot attributes the effects to the opposite electrical states of the decomposing substances in the vicinity of the two poles. M. De la Rive considers the portions decomposed to be those contiguous to both poles, the current from the positive pole combining with the hydrogen or the bases which are there present, and leaving the oxygen or acids at liberty, but carrying the substances in union with it across to the negative pole, where it is separated from them, entering the conducting metal, and leaving on its surface the hydrogen or its bases. Faraday regards the poles as exercising no specific action, but merely as surfaces or doors by which the electricity enters into or passes out of the substance undergoing decomposition. He supposes that “the effects are due to a modification of the electric current and the chemical affinity of the particles through or by which that current is passing, giving them the power of acting more forcibly in one direction than in another, and consequently making them travel by a series of successive decompositions and recompositions in opposite directions, and finally causing their repulsion or exclusion at the boundaries of the body under decomposition in the direction of the current, and that, in larger or smaller quantities, according as the current is more or less powerful.”

In 1810 Grotthus published his “Uber d. elektricität ... wassers entwickelt,” one of his curious observations being the fact that when water is rapidly frozen in a Leyden jar, the outside coating, not being insulated, receives a weak electrical discharge, the inside being positive and the outside negative, and when the ice is rapidly thawed, the inside is negative and the outside positive.

REFERENCES.--Faraday’s “Experimental Researches,” articles 481, 485, 489, 492, 507, etc.; also _Phil. Mag._, Vols. XXIV. p. 183, and XXVIII. pp. 35 and 59; Joseph Izarn, “Manuel du Galvanisme,” pp. 280–284 for M. Riffault and N. M. Chompré; Whewell, “History of the Inductive Sciences,” Vol. II. p. 304; Noad, “Manual,” pp. 364, 365; William R. Grove, “On Grotthus’ Theory ...” London, 1845; J. S. C. Schweigger’s _Journal_, Vols. III, IV, IX, XXVIII and XXXI; A. F. Gehlen’s _Journal_ for 1808; L. W. Gilbert’s _Annalen der Physik_, Vol. LXVII; Ostwald, “Elektrochemie,” 1896, pp. 309–316; A. N. Scherer’s _Allgem. nördliche Annal. d. Chemie_, Vol. IV; _Annales de Chimie_, Vol. LXIII; _Phil. Mag._, Vol. LIX. p. 67; J. C. Poggendorff, “Biog. Literarisches,” etc., Vol. I. pp. 959, 960; “Royal Society Catalogue of Scientific Papers,” Vol. III. pp. 29–31.

Grotthus’ theory was extended by Rudolf Clausius, and the latter’s theory in turn gave way to that of Svante Arrhénius. Clausius maintained that the exchanges were going on continuously, although no current was flowing; while the assumption of Arrhénius was that in every electrolyte, a certain number of molecules break up into ions and that all electrolytes contain some of these free ions. This is the much controverted dissociation theory (Dr. Henry S. Carhart’s Presidential Address).

The “Encycl. Amer.,” New York, 1903, Vol. II says that the establishment of the theory of electrolytic dissociation, which is due to the noted Swedish chemist, Svante Arrhénius, supplies a reasonable explanation of many chemical phenomena otherwise insoluble, and correlates various facts between which no connection was previously discovered. Two important publications by Arrhénius are “Sur la conductibilité galvanique des electrolytes” (1884), and a treatise in German on electro-chemistry (1902). (See “Le Moniteur Scientifique,” Avril 1904, pp. 241–243.)

Rudolf Clausius, German scientist (1822–1888), “one of the most celebrated mathematical physicists of the nineteenth century,” communicated in 1850 to the Berlin Academy of Sciences the paper wherein he announced the second law of thermo-dynamics, that “heat cannot of itself pass from a colder to a hotter body.” The honour of establishing the science of thermo-dynamics upon a scientific basis he thus shares with Rankine and Thomson (“Encycl. Amer.,” Vol. V. n. p.; “New Inter. Encycl.,” New York, 1902, Vol. IV. p. 711. For biography, consult Riecke, “Rudolf Clausius,” Göttingen, 1889; “Meyer’s Konversations-Lexikon,” Leipzig, 1894, Vol. IV. p. 213).

=A.D. 1805.=--Alexander Tilloch’s _Philosophical Magazine_, Vol. XXI. p. 279, has a letter addressed by W. Peel to the editor, under date Cambridge, April 23, 1805, relative to the “Production of Muriate of Soda by the Galvanic Decomposition of Water.” This is followed by a communication dated Pisa, May 9, 1805, from Dr. Francis G. Pacchiani, Professor of Philosophy at the Pisa University (Rees’ Encyclopedia, “Galvanism,” p. 15), to Lawrence Pignotti, Historiographer to the King, entitled “Formation of Muriatic Acid by Galvanism,” as well as by two letters, one from W. Peel, dated Cambridge, June 4, 1805, on “The Production of Muriates by the Galvanic Decomposition of Water,” and the other from Dr. Wm. Henry, dated Manchester, July 23, 1805, relative to the above-named processes and to the latter’s own experiments in the same direction.

REFERENCES.--_Phil. Mag._, Vol. XXII. pp. 153, 179, 188; XXIII. p. 257; XXIV. p. 183; XXVII. p. 82; XXVIII. p. 306; Sir Humphry Davy’s allusion to above, as well as his earlier experiments communicated to Dr. Beddoes, Sir James Hall, Mr. Clayfield and others, in “Bakerian Lectures,” London, 1840, pp. 2, 3; Sylvester, at A.D. 1806, and Donovan, at A.D. 1812; Lardner’s “Lectures on Science and Art,” Vol. I. p. 350; Faraday’s “Experimental Researches,” No. 314; J. F. Macaire, _Ann. Ch. et Phys._, XVII. 1821; Marni “Sulla formazione ...”; G. B. Polcastro, “Giorn. Ital. Letter del Dal Rio,” X. p. 182, 1805; Cioni and Petrini, _Phil. Mag._, XXIV. 167, 1806; The Paris Galvani Society, _Phil. Mag._, XXIV. p. 172, and _Ann. de Ch._, Vol. LVI, 1806; A. B. Hortentz, _Phil. Mag._, Vol. XXIV. p. 91, 1806; Leop. de Buch, _Phil. Mag._, Vol. XXIV. p. 244, 1806; Veau Delaunay, _Phil. Mag._, XXVII. p. 260, 1807; G. Innocenti, _Nuova Scelta d’ Opuscoli_, II. p. 96, 1807; P. Alemanni, _Phil. Mag._, Vol. XXVII. p. 339, 1807; C. H. Pfaff, _Phil. Mag._, XXVII. p. 338, and XXIX. p. 19; _Ann. de Chim._, Vols. LX. p. 314; LXII. p. 23, 1807–8; Wm. Henry, _Phil. Mag._, Vols. XXII. p. 183; XL. p. 337, 1805–1812; F. G. Pacchiani, in _Nuova Scelta d’ Opuscoli_, I. p. 277; Brugnatelli, _An. di Chimica_, Vol. XXII. pp. 125, 134 and 144; _Edin. Med. and Surg. Journal_, of July 1, 1805; _Phil. Mag._, Vol. XXIV. p. 176, for his letter to Fabbroni. For Dr. Wm. Henry, consult “Bibl. Britan.,” Vol. XV, An. VIII. pp. 35, 293; _Phil. Mag._, Vols. VII for 1830, p. 228; XXII. p. 183; XXXII. p. 277, and XL. p. 337; _Phil. Trans._,

## Part II for 1808.

=A.D. 1806.=--On Oct. 16, Mr. Wm. Skrimshire, Jr., addresses from Wisbech a letter to Mr. Cuthbertson on the absorption of electric light by different bodies.

In this letter, which is given in full at pp. 281–283 of the fifteenth volume of _Nicholson’s Journal_, he says he was led to his experiments by the well-known fact that when the electric current is passed through a lump of sugar it makes the latter appear luminous. He tried many calcareous species, chalk, Kelton stone, the phosphate, nitrate, sulphates of lime, etc. etc., and he details some of the results obtained, the most interesting being that given by the sulphuret of lime, commonly called Canton’s phosphorus, which, he says, is, by the electric explosion, rendered the most luminous of all the substances tried.

=A.D. 1806.=--Heidmann (J. A.), physician at Vienna, publishes his “Theorie der Galvanischen Electricität ...” or “Theory of Galvanic Electricity deduced from Actual Experimentation” (London, 1807). This had been preceded by other important electrical reviews at Vienna during the years 1799, 1803 and 1804.

As stated by Guyton de Morveau, Heidmann has given us in the above the complete history of galvanic electricity--including the experiments and observations of Aldini, Arnim, Biot, Boeckman, Carminati, Cavallo, Creve, Davy, Fontana, Fowler, Gilbert, Haldane, Hallé, Helebrandt, Humboldt, Nicholson, Pepys, Pfaff, Reil, Reinhold, Ritter, Valli, Vassalli-Eandi, etc. etc.--together with the description of the construction and the relation of all parts of the galvanic pile, which is called by him a galvanic battery. Heidmann also gives an account of his many interesting experiments with frogs placed in different liquids as well as with the galvanic chain, and he reviews all the known phenomena presented by the voltaic pile.

REFERENCES.--“Annales de Chimie,” Vol. LXI. p. 70; _Phil. Mag._, Vol. XXVIII. p. 97.

=A.D. 1806.=--Dr. Joseph Baronio of Milan constructs a galvanic pile composed exclusively of vegetable substances. He makes his discs, two inches in diameter, of beet roots (_bietola rossa_) and of walnut wood (_legno di noce_), the latter having been freed from all of its resinous substance by treatment in a solution of vinegar and cream of tartar. Through this pile, he produced convulsions in a frog by excitation with a leaf of _cochlearia_ (spoon wort or scurvy-grass).

REFERENCES.--“Annales de Chimie,” Vol. LVII. pp. 64–67; Vol. LXII. p. 212; _Phil. Mag._, Vol. XXIII. p. 283; “Nota di Brugnatelli sopra una pila di sostanze vegetabili,” Pavia, 1805 (“Am. di Chim. di Brugnatelli,” Vol. XXII. p. 301); Volta, in _Giorn. Fis. Med._, Vol. II. p. 122.

=A.D. 1806.=--Sylvester (Charles), the author of the articles on “Galvanism and Voltaism” in Rees’ “Encyclopædia,” announces that he obtains muriatic acid from pure water by passing through it the galvanic current. Mr. Wollaston, however, asserts this cannot be done unless the current traverses some vegetable or animal substance containing that acid.

His first paper on the subject appeared in _Nicholson’s Journal_, 1806, Vol. XIV. pp. 94–98; in Gehlen’s _Journ. der Chemie_, Vol. II for 1806, pp. 152–153, and in Gilbert’s _Annalen der Physik_, Vol. XXV. pp. 107–112, 454–457. The paper following is entitled “Repetition of the Experiment in which Acids and Alkalies are Produced in Pure Water by Galvanism (no animal or vegetable matter, nor oxidable metal being present).”

REFERENCES.--_Nicholson’s Journal_, Vol. XV. pp. 50–52; Vol. XXIII. pp. 258–260; Gehlen’s _Journal_, Vol. II, 1806, pp. 155–158. For his other papers, consult _Nicholson’s Journal_, Vol. IX. p. 179; Vol. X. pp. 166–167; Vol. XIX. pp. 156–157; Vol. XXVI. pp. 72–75; Gilbert’s _Annalen_, Vol. XXIII. pp. 441–447; “Roy. Soc. Catal. of Sc. Papers,” Vol. V. pp. 900–901; Sturgeon’s _Scientific Researches_, Bury, 1850, p. 153; Sir Humphry Davy’s lecture “On some chemical agencies of electricity,” read Nov. 20, 1806; _Annales de Chimie_, Vol. LX. p. 314; Vol. LXI. pp. 330–331; “Bibl. Britan.,” Vol. XXXIII, 1806, p. 324.

=A.D. 1806.=--Maréchaux (Peter Ludwig), correspondent of the French Galvani Society at Wesel, is the first to construct an effective dry pile containing paper discs. He makes known through M. Riffault (_Annales de Chimie_, Vol. LVII for January 1806, p. 61), that water is not essential to the production of galvanic effects, and his experiments are repeated for the Chemical Society by M. Veau Delaunay, as shown in _Journal de Physique_, Messidor, An. XIV.

This “Maréchausian Pile,” or _colonne pendule_, as it was originally denominated, consists of pairs of oven-dried cardboard, pasteboard, or blotting-paper, and of copper discs all pierced in such manner as to be suspended by three silken cords which hold them fast in position. Sturgeon remarks (“Researches,” pp. 199 and 239) that in this dry column the electric pulsations are, in consequence of the very great number of interrupting papers, less frequent than in either the processes of Volta or in that of Seebeck, notwithstanding which the instrument produces slow pulsatory currents.

REFERENCES.--W. Sturgeon’s “Annals of Electricity,” Vol. I. p. 256, note; Vol. VIII. pp. 379, 484; _Phil. Mag._, Vol. XXIV. p. 183; Poggendorff, Vol. II. p. 46; “Roy. Soc. Cat. of Sci. Papers,” Vol. IV. p. 236; Gilbert’s _Annalen der Physik_, Vols. X.-XXVII _passim_, also Vol. XV. p. 98 and Vol. XVI. p. 115 giving a description of the Maréchaux electro-micrometer (screw and silver leaf), likewise Vol. XXII, containing an account of the observations made by M. Paul Erman.

=A.D. 1807.=--Young (Thomas), M.D., a very celebrated English scientist, “eminent alike in almost every department of human learning,” who was the associate of Davy at the Royal Institution, and who became the successor of Volta as Foreign Associate of the French Academy of Sciences, publishes his very elaborate “Course of Lectures on Natural Philosophy and the Mechanical Arts,” upon which he was assiduously engaged for five years, and a new edition of which was issued (with additional references and notes) by the Rev. P. Kelland, M.A., F.R.S., during the year 1845.

The above-named work comprises the sixty lectures which Dr. Young delivered during his connection with the Royal Institution and includes also his optical and other memoirs, as well as a very extended classified catalogue of publications in every leading department of science. His biographer in the “English Encyclopædia” remarks that Young’s lectures embody a complete system of natural and mechanical philosophy, drawn from original sources, and are distinguished not only by extent of learning and accuracy of statement, but by the beauty and originality of the theoretical principles. One of these is the principle of interferences in the undulatory theory of light. “This discovery alone,” says Sir John Herschel, “would have sufficed to have placed its author in the highest rank of scientific immortality, were even his other almost innumerable claims to such a distinction disregarded.” The first reception, however, of Dr. Young’s investigations of light was very unfavourable. The novel theory of undulation especially was attacked in the _Edinburgh Review_, and Dr. Young wrote a pamphlet in reply, of which it is said but one copy was sold, but it is now generally received in place of the molecular or emanatory theory.

His review and treatment of the field of electrical and magnetic phenomena, as may be imagined from the foregoing, is very extensive, and as no justice could be done it by making therefrom such extracts as would suitably come within the scope of the present “Bibliographical History,” only an extract from the lecture treating of “Aqueous and Igneous Meteors” will here be given.

Speaking of the aurora borealis, he says “that it is doubtful if its light may not be of an electrical nature. The phenomenon is certainly connected with the general cause of magnetism. The primitive beams of light are supposed to be at an elevation of at least 50 or 100 miles above the earth, and everywhere in a direction parallel to that of the dipping needle; but perhaps, although the substance is magnetical, the illumination, which renders it visible, may still be derived from the passage of electricity, at too great a distance to be discovered by any other test.... It is certainly in some measure a magnetical phenomenon; and if iron were the only substance capable of exhibiting magnetic effects, it would follow that some ferruginous particles must exist in the upper regions of the atmosphere. The light usually attending this magnetical meteor may possibly be derived from electricity, which may be the immediate cause of a change in the distribution of the magnetic fluid contained in the ferruginous vapours that are imagined to float in the air.”

The assumption of ferruginous particles or vapours, remarks Prof. Robert Jameson, of the Edinburgh University, seems, however, purely gratuitous and imaginary; and as iron is not the only substance or matter capable of exhibiting magnetic effects, light itself being susceptible of polarization, the above hypothesis is, therefore, untenable even on the ground upon which it has been rested by its author. But it is, nevertheless, certain that the cause of this luminous meteor is intimately connected with magnetism and electricity; or, rather, as the magnetic is variously modified and effected by the electric power, with the phenomena of electro-magnetism.

REFERENCES.--Young’s Catalogue for “Aurora Borealis” and “Terrestrial Magnetism” (“Lectures,” London, 1807, Vol. II. pp. 440–443, 488–490), “Journal Roy. Inst.,” Vol. I; Dr. George Peacock’s “Life of Thomas Young”; also “Miscellaneous Works of T. Young,” London, 1855; “Memoirs of the Life of Thos. Young,” London, 1831; also Vol. XIII of John Leitch’s “Hieroglyphical Essays and Correspondence,” all of which contain every contribution made by the scientist to the _Phil. Trans._, as well as many other important articles communicated by him to other scientific publications of his time; “Eloge Historique de Dr. Thomas Young,” par M. Arago, in _Mém. de l’Acad. Roy. des Sc._, etc., Tome XIII. p. 57; _Quarterly Review_ for April 1814; Tyndall, “Heat as a Mode of Motion,” 1873, pp. 267, 268; _Annales de Chimie_, Feb. 1815; Whewell, “History of the Inductive Sciences,” 1859, Vol. II. pp. 92, 96, 106, 111–118.

=A.D. 1808.=--Pasley (Charles William), F.R.S., D.C.L., K.C.B., who was at the time aide-de-camp to Sir John Moore, became Major-General in 1841 and Lieutenant-General in 1851, gives at pp. 205, 292, Vol. XXIX, and at p. 339, Vol. XXXV of Tilloch’s _Philosophical Magazine_, a description of the original and improved methods of constructing his “polygrammatic telegraph.”

The apparatus, as first devised by him between the years 1804 and 1807, consists of four posts, each bearing a pair of pivoted arms, which latter can be placed at different angles to indicate all desired numerals and letters. After he had seen the French semaphore during 1809 he improved his telegraph, employing but one post, upon which were three pairs of pivoted arms representing hundreds, tens and units.

In 1823 Pasley (then a Lieutenant-Colonel, Royal Engineers) issued a pamphlet entitled “Description of the Universal Telegraph for Day and Night Signals,” wherein he announces the abandonment of the polygrammatic principle. For day service he employs an upright post with two movable arms attached to the top on a pivot. Each arm is capable of assuming seven different positions, besides the quiescent position called the _stop_, in which the arms are turned down and concealed by the post. To prevent signals being seen in reverse, another arm, called an _indicator_, is added to one side of the post. For night signals he places a central lamp at the top of the post, as well as a lamp at the end of each arm, and suspends a fourth lamp, as an indicator, upon a light crane projecting horizontally beyond the range of both movable arms. Motion to the arms was communicated by means of an endless chain passing over two pulleys. Up to this time the semaphores employed by the Admiralty had been constructed without provision being made for the display of night signals.

Pasley was the first to apply the heating power of the galvanic battery to a useful practical purpose. While engaged on the River Thames he was written to by Mr. Palmer (Alfred Smee, “Electro-Metallurgy,” p. 297), who advised him to employ the galvanic battery instead of the long fuse then in common use, and as soon as he was made acquainted with the method of operating he at once adopted it and applied it effectively, during the year 1839, to the removal of the sunken hull of the “Royal George,” at Spithead.

REFERENCES.--Sturgeon’s “Scientific Researches,” Bury, 1850, p. 174; Knight’s “Mech. Dict.,” Vol. I. p. 784; also “Documents relatifs à l’emploi de l’Electricité,” etc., Paris, 1841, taken from the _United Service Journal_ and the “Militaire Spectateur Hollandais.” Consult likewise, “Trans. of the Society ... Arts,” Vol. XXXIX, London, 1821, for Peter Barlow, XL. pp. 76–100, and for Lieut. Nicolas Harris Nicolas, XL. p. 104; also Vol. XLII, London, 1824, for Mr. A. Westcott, pp. 165–166. A patented telegraph by James Boaz is alluded to in Vol. XII. pp. 84–87 of the _Phil. Magazine_.

Following close upon Pasley’s original telegraphic contrivance were several other methods of conveying intelligence at a distance, introduced at this period, worthy of mention here.

The Chevalier A. N. Edelcrantz, Swedish savant, sent to the London Society of Arts a model of his apparatus, which is to be found minutely described in Vol. XXVI. pp. 20, 184–189, of the _Transactions_ of that institution. A description of his earlier contrivances for the same purpose had already been published at Stockholm in the year 1796, and after being translated into French had been noticed in William Nicholson’s _Journal of Natural Philosophy_ for 1803. The one he finally adopted in 1808 consisted of ten boards placed in three vertical ranks, the central one having four boards and the side ranks three boards each. By this arrangement 1024 signals could be clearly shown, and it was possible, by observing the _order_ in which the boards were exhibited, to make as many as 4,037,912 changes. He subsequently advised attaching lamps to the boards for night service. His system of working the boards, though very complicated, could be controlled by only one person, while the English method required several men to hold the shutters during heavy weather. As it was, his method is said to have been in constant use for fully twelve years prior to 1808 on both sides of the Baltic, and to have likewise served to transmit signals between Sweden and England.

Mr. Henry Ward, who had observed the difficulty with which the telegraph was worked at Blandford, in Dorsetshire, contrived the apparatus described in Vol. XXVI. pp. 20, 207–209 of the London _Journal of the Society of Arts_. The grooved wheels which are fixed upon the axis of the shutters to receive the ropes by which they are turned have the grooved portion of the rim formed in two segments, which are so attached to the periphery of the wheels by steel springs that they fly off and remain a little distance off when there is no strain upon the ropes, although so soon as a rope is pulled its pressure forces the segments into close contact with the solid rim of the wheel. In the segments are two notches, which, when the shutters are in either of their required positions, engage with a fixed catch so soon as the strain on the ropes is relaxed, and thus hold the shutters steady without any aid from the attendant. The pulling of a rope by drawing the segments close to the wheel releases the catch, and consequently enables the attendant to return any shutter to its original position.

Lieutenant-Colonel John Macdonald, F.R.S., who was already favourably known by two Reports on the Diurnal Variation of the Magnetic Needle observed at Fort Marlborough, Sumatra, and at St. Helena (_Philosophical Transactions_ for 1796, p. 340, and for 1798, p. 397, also “Eighth Encycl. Brit.,” Vol. XIV. p. 54), publishes (1808–1817) two treatises upon his “Terrestrial Telegraph,” accompanied by an extensive “Telegraphic Dictionary.” His contrivance consists of thirteen boards or shutters arranged, like those of Edelcrantz, into three vertical ranks representing hundreds, tens and units. Twelve of the boards are capable of producing 4095 distinct combinations, and the thirteenth or auxiliary board, which is mounted over the centre of the apparatus, doubles that number. A flag or vane is added to the hundred side to distinguish it in whatever direction it may be viewed, and a ball sliding upon the staff which supports it affords the means of again doubling the number, so that, on the whole, 16,380 distinct signals can be obtained. He subsequently adopted a modification of the contrivance introduced by Pasley in 1809, and also described a sort of a “Symbolic Telegraph,” in which symbols like those of Dr. Hooke, but representing numerals instead of alphabetical characters, were dropped into open spaces denoting hundreds, tens and units. He further suggested a useful flag telegraph for the navy and devised several schemes for night telegraphs both for land and sea, one of which latter consists of three sets of four lights each, with an additional or _director_ light to each set, affording the same extensive powers as his large board or shutter telegraph (_Phil. Mag._, Vols. LVII. pp. 88–93, and LVIII. pp. 99–103).

Major Charles Le Hardy communicates in 1808 to the London Society of Arts, Vol. XXVI. pp. 20, 180–183, a novel contrivance consisting of a large framework with nine radiating bars, representing the numerals from 1 to 9, and four sets of other bars intersecting them so as to form four concentric polygons, which latter express units, tens, hundreds and thousands; thousands being shown by the innermost polygon. Attached to the centre of the apparatus are four slender arms, carrying four square boards, the lengths of these arms being such that the board of one may, during the revolution of the arm, traverse the polygon which represents thousands, that of another the polygon representing hundreds, etc. By the addition of two other boards at the upper corners, one of which denotes 10,000 and the other 20,000, or, when displayed together, 30,000, the total range of the telegraph is from 1 to 39,999 (_Philosophical Magazine_, Vol. XXXIII. p. 343).

In the twenty-seventh volume of the _Transactions_ of the London Society of Arts will be found the telegraphic devices of Knight Spencer and of Lieutenant James Spratt (pp. 20, 163–169), while the thirty-third volume contains (at pp. 23, 118–121) a description of the contrivance of Alexander Law, intended for service on both sea and land. These, it may be said, are the only additional telegraphic methods worthy of note introduced up to the time when the English Admiralty adopted the system proposed by Sir Home Popham in 1816. The “anthropo-telegraph” of Knight Spencer, though laid before the Society of Arts in 1808, had been used as early as 1805. It consisted merely of two circular discs of wicker work, painted white with a black circle in the centre, to be held in different positions with respect to each other. The device of Lieutenant Spratt was more simple still, for it consisted only in holding a kerchief in various positions; yet, simple as it was, it served as a means of communication between vessels before the battle of Trafalgar, and it was also successfully used to converse between Spithead and the ramparts at Portsmouth, etc.

REFERENCES.--For Mr. Knight Spencer’s other papers, see the _Philosophical Magazine_, Vols. XXXVI. p. 321, and XL. p. 206, and, for different methods of telegraphing, see Mr. Macdonald’s “Treatise,” published in 1817, as well as, more particularly, Vols. XXVI, XXXIV, XXXV, XXXVI of the _Transactions of the Society of Arts_; likewise Rohde’s “Système complet de Signaux ...” published 1835.

=A.D. 1808.=--Callender--Calendar (Elisha), of Boston, Mass., obtains, on Oct. 3, 1808, for his lightning rod, an American patent, which latter is the first one in the line of electricity issued by the United States.

REFERENCES.--H. L. Ellsworth’s “Digest of Patents,” Washington, 1840, p. 234; Edmund Burke, “A List of Patents,” Washington, 1847, p. 185; “List of United States Patents,” Washington, 1872, p. 67.

=A.D. 1808.=--Bucholz (Christoph--Christian--Friedrich), distinguished German chemist, receives his diploma as a physician at Rinteln, prior to graduating at the Erfurt University, and publishes “Ueber die Chimischen ... metallen,” giving a description of the chain bearing his name. The latter was the result of experiments made by him to prove that the electricity in the pile results from the oxidation of one of the metals and also to establish a comparison between the quantity of electricity obtained and the amount of oxygen absorbed by the one metal.

REFERENCES.--“Biographie Universelle,” Bruxelles, 1843–1847, Vol. III. p. 227; A. F. Gehlen, _Jour. für Chem. und Phys._, Vol. V; L. Figuier, “Exp. et Hist.,” Paris, 1857, Vol. IV. p. 426; “La Grande Encyclopédie,” Vol. VIII. p. 315, and also the letter of J. B. Van Mons to Bucholz, Brussels, 1810.

=A.D. 1808.=--Amoretti (Carlo), Italian naturalist, who was allowed (1772) to withdraw from the order of St. Augustine that he might devote himself exclusively to scientific researches, gives, in his “Della rabdomanzia ossia elettrometria,” a complete history of the divining rod, and treats also therein of animal magnetism, etc. His investigations of the electric polarity of precious stones show, among other results, that the diamond, the garnet and the amethyst are - E, while the sapphire is + E.

REFERENCES.--For a further account of the _Virgula Divina_, or divining rod (_baguette divinatoire_), see the “Gentleman’s Magazine” for 1751, Vol. XXI; also the notes at foot of pp. 91–106 of Baron Karl Von Reichenbach’s “Physico-Physiologicæ Researches,” translated by Dr. John Ashburner, London, 1851. In the latter, reference is made to Pierre Le Lorrain de Vallemont’s “La Physique Occulte,” etc. (1693), to a work written by Count J. de Tristan, to the “Mémoire,” etc., of Tardy de Montravel (1781) and to Pierre Thouvenel’s “Mémoires,” etc., the last named bearing the Paris-London imprint of 1781–1784, and attempting to show relations existing between the rod and electricity and magnetism. Allusion is likewise made in the afore-named work to the translation by Dr. Hutton (1803) of Jean Etienne Montucla’s (1778) improvement of Jacques Ozanam’s “Récréations Mathématiques et Physiques,” originally built upon Leurechon’s “Récréations Mathématiques,” and first published in Paris during the year 1724. For Reichenbach, see “Le Cosmos,” Nos. 703–705 for July 16, 23 and 30, 1898; “Cat. Sc. Pap. Roy. Soc.,” Vol. I. pp. 139–140; Vol. VIII. pp. 720, 721. Besides the above, reference should be had to the lecture of Prof. Rossiter W. Raymond before the Philadelphia Electrical Exhibition of 1884, and to the article in Paris _Cosmos_ of Jan. 3, 1891, which alludes to the works of P. Lebrun (1702), Albert Fortis (1802), Dr. Charpignon (1848), Abbé Chevalier (1853), and M. E. Chevreul “De la baguette ...” (1854). Consult also, Eusebe Salverte, “The Philosophy of Magic.,” Vol. II. chap. xi. speaking of Pryce’s “Mineralogia Cornubiensis” (1778); Theod. Kirchmaier, “De Virgula divinatrice,” 1678; F. Soave, (_Opus. Scelti_, III. p. 253), 1780; F. M. Stella (_Opus. Scelti_, XIII. p. 427), 1790; G. B. San Martino (_Opus. Scelti_, XVII. p. 243), 1794; L. Sementini, “Pensieri e Sperimenti ...” 1811; A. M. Vassalli-Eandi (_Opus. Scelti_, XIX. pp. 215, etc.); Kiesser, _Archiv._, Vol. IV. p. 62; at Vol. I. p. 265, of Blavatsky’s “Isis Unveiled”; “Biographie Générale,” Vol. II. pp. 290, 291; “Roy. Soc. Catal. of Sc. Papers,” Vol. I. p. 58.

=A.D. 1808.=--Lebouvier-Desmortiers (Urbain René Thomas), French writer, who had called attention to the danger attending the bodily application of the galvanic fluid, through the _Journal de Physique_ of 1801 (p. 467), transmits another Mémoire to the same publication upon an improved electrical (_briquet_) tinder box.

The cylinder, which had previously been made of copper, he constructed of glass as illustrated by Delaunay at Plate IX. fig. 105, of his “Manuel,” etc., Paris, 1809. With the new contrivance he was enabled to exert considerable force upon the piston, and it was generally necessary to push the latter suddenly in order to so compress the air as to light the (_amadou_) spunk attached to the lower portion of the cylinder.

REFERENCES.--See his “Examen des principaux systèmes ...” Paris, 1813; J. C. Poggendorff, _Biogr. Liter. Hand._ ... Vol. I. p. 1399; Larousse, _Dict. Univ._, Vol. X. p. 290; _Journal de Médecine_, Vol. XXVI. pp. 298–303; _Catal. Sc. Pap. Roy. Soc._, Vol. III. p. 910; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Vol. I. p. 461; V. Delaunay, “Manuel de l’Electricité,” Paris, 1809, pp. 151–153; Detienne, “De l’électricité de pression” (_Journal de Physique_, 1777, Vol. IX).

=A.D. 1809.=--Krafft (Wolfgang Ludwig), Professor of Experimental Philosophy in the Imperial Academy of Sciences of St. Petersburg is the author of “Uber ein hypothet ...” wherein is given the result of his investigations of the phenomena of terrestrial magnetism.

Comparing Biot’s examination of the dip observations previously made by Humboldt, Krafft simplified the former’s conclusions, showing that if we measure the latitude from the magnetic equator, the tangent of the dip is double the tangent of such latitude, or, as he expresses it: “If we suppose a circle circumscribed about the earth, having the two extremities of the magnetic axis for its poles, and if we consider this circle as a magnetic equator, the tangent of the dip of the needle, in any magnetic latitude, will be equal to double the tangent of this latitude.”

Krafft gave a complete theory of the _electrophorus_ in the first part of the 1778 “Acta Acad. Petrop.,” which latter also contains his experiments with Canton’s phosphorus and his observations on the aurora of February 6–17 of the same year. The results of many of his other investigations are to be found in Part XI of the work mentioned as well as in Vols. XV, XVII and XIX of the “Novi Commentarii Academiæ Petropolitanæ.”

=A.D. 1809.=--Pinkerton (John), gives in his “Voyages and Travels,” published at London (Vol. IV. pp. 1–76) a reprint of the rare volume entitled “Account of Paris at the close of the Seventeenth Century,” by Martin Lister, M.D., wherein are detailed several surprisingly interesting experiments made by Mr. Butterfield with his wonderful collection of loadstones. It is therein stated that one of these loadstones, when unshod, weighed less than a dram and would suspend a dram and a half, but when shod would attract 144 drams of iron, whilst another of the loadstones, weighing 65 grains, attracted 14 ounces, or 140 times its own weight; another would work through a wall eighteen inches in thickness, etc. etc.

=A.D. 1809.=--Children (John George), an English scientist to whom reference has already been made, more particularly under Cruikshanks, A.D. 1800, communicates to the _Philosophical Transactions_, “An account of some experiments performed with a view to ascertain the most advantageous method of constructing a voltaic apparatus for the purposes of chemical research.” This paper appears also in Vol. XXXIV of the _Philosophical Magazine_.

Four years later (1813) he publishes a description of his magnificent galvanic battery, the largest ever constructed on the plan suggested by Dr. Wollaston. This consisted of twenty pairs of copper and zinc plates, each six feet long and two feet eight inches wide, the united capacities of the cells being 945 gallons. With this battery he confirmed Davy’s observation that “intensity increases with the number (of plates) and the quantity of the electricity with the extent of surface.” It is reported that, when in full action, the battery rendered a platinum wire five feet six inches long and ¹¹⁄₁₀₀ of an inch in diameter red-hot throughout so as to be visible in full daylight; that eight feet six inches of platinum wire ⁴⁴⁄₁₀₀ of an inch in diameter were easily heated red; that a bar of platinum one-sixth of an inch square and two and a quarter inches long was heated red-hot and fused at the end; and that a round bar of the same metal, ²⁷⁶⁄₁₀₀₀ of an inch in diameter and two and a half inches long, was heated bright red throughout.

The result of many other investigations which he also made in 1813 and during 1815 showed that metallic wires (eight inches long and ¹⁄₃₀ of an inch diameter) became red-hot in the following order: platinum, iron, copper, gold, zinc, silver; and he deduced that their conducting power was in the inverse order, silver conducting best and platinum least. Tin and lead fused immediately at the point of contact, and the oxides of tungsten, uranium, cerium, titanium, iridium and molybdenum were also fused. An opening made with a saw across an iron wire having been filled with diamond powder, the diamond was liquefied and the contiguous iron became steel. (See the Pepys entry at A.D. 1802.)

REFERENCES.--For Children’s other experiments, consult “_Phil. Mag._,” Vol. XLII. p. 144; Vol. XLVI. pp. 409–415; _Phil. Trans._ for 1815, pp. 368–370, also Dr. Wm. Henry’s “Elem. of Exper. Chem.,” London, 1823, Vol. I. pp. 168–174; Dr. Thomas Thomson, “Outline of the Sciences,” London, 1830, pp. 524–526; Louis Figuier, “Expos. et Hist. ...” Paris, 1857, Vol. IV. pp. 389–390; Becquerel, Vol. I. p. 52; “Encycl. Metrop.,” Vol. IV. pp. 179, 222; Gmelin’s “Chemistry,” Vol. I. p. 424; “Cat. Sc. Papers Roy. Soc.,” Vol. I. p. 317; Vol. II. p. 26; “Bibl. Britan.,” Vol. XLIII, 1810, p. 67 and Vol. I of the N.S. for 1816, p. 109.

=A.D. 1809–1810.=--Oken (Lorenz)--originally Lorenz Ockenfuss--celebrated German naturalist, while occupying the post of Extraordinary Professor of Medicine at the University of Jena, publishes the great work “Lehrbuch der Naturphilosophie,” which was translated into English by Dr. A. Tulk and published in London, during 1847, by the Royal Society, under the title of “Elements of Physico-Philosophy.”

This work, says his biographer in the “English Cyclopædia” (Vol. IV. p. 557), takes the widest possible view of natural science: it is interesting as a document in the history of a great mental movement and contains the germs of those principles which are now regarded as the secure generalization of well-observed facts.

From the epitome of the work given in the “Encyclopædia Britannica,” the following is extracted: “Polarity is the first force which appears in the world.... Galvanism is the principle of life ... the vital force ... the galvanic process is one with the vital process.... There is no other vital force than the galvanic polarity.”

According to Dr. Richard Owen, Lorenz Oken contends that organism is galvanism residing in a thoroughly homogeneous mass. A galvanic pile, pounded into atoms, must become alive. In this manner, nature brings forth organic bodies. The basis of electricity is the air; of magnetism, metal; of chemism (the name he gives to the influence that produces chemical combination), salts. The basis of galvanism, in like manner, is the organic mass. Accordingly, whatever is organic is galvanic; whatever is alive is galvanic. Life, organism, galvanism, are one. Life is the vital process; the vital process is an organic or galvanic process. Galvanism is the basis of all the processes of the organic world.... God did not make man out of nothing, but took an elemental body then existing, an earth-clod or carbon, moulded it into form, thus making use of water, and breathed into it life, viz. air, whereby galvanism or the vital process arose.... Organization is produced by the co-operating process of light and heat. The ether imparts the substance, the heat the form, the light the life.... The life of an inorganic body is a threefold action of the three terrestrial elements, in which three processes galvanism consists. The nutrient process is magnetic, present and entire in every part of the body, and wheresoever it is withdrawn there is death.... These three processes constitute the galvanic process. Thus the galvanic circle is complete, and motion is the manipulation of galvanism. The process of motion is synonymous with the galvanic process--this is the vital process.

REFERENCES.--The extended biography of Lorenz Oken, embracing a list of his chief works and original essays at pp. 498–503, Vol. XVI of the Eighth “Encycl. Britan.”; Dr. William Whewell’s “History of the Inductive Sciences,” 1859, Vol. II. p. 477; “Hist. des Sciences,” par F. L. M. Maupied, Paris, 1847, Vol. II. pp. 466–514.

=A.D. 1809.=--Luc (Jean André de), celebrated natural philosopher of Swiss extraction (though from 1773 until his death in 1817, a resident of England, where he became reader to Queen Charlotte, the consort of George III), transmits to the Royal Society a long paper treating of the separation of the chemical from the electrical effects of the pile, with a description of the electric column and aerial electroscope.

In this communication, says Dr. Young, he advanced opinions so little in unison with the latest discoveries of the day, especially with those of the President of the Royal Society, that the Council probably thought it would be either encouraging error or leading to controversy to admit them into the _Philosophical Transactions_. He had, indeed, on other occasions shown somewhat too much scepticism in the rejection of new facts; and he had never been convinced even of Mr. Cavendish’s all-important discovery of the composition of water.

The paper was afterwards published in _Nicholson’s Journal_ (Vol. XXVI), and the dry column described in it was constructed by various experimental philosophers. It exhibited a continual vibrating motion, made sensible by the sound of a little bell, which was struck by the pendulum at each alternation; and during many months the vibration was more or less rapid, according to circumstances affecting the column.

This dry column consists of discs of Dutch gilt paper, alternated with similar discs of laminated zinc, so arranged that the order of succession will be maintained throughout. When sufficiently dry these are piled upon each other, the gilt side of the paper being in contact with the zinc, and all are pressed together in a glass tube by a brass cap and screw connected at each end with a metallic wire. The column presented by De Luc to the Royal Society consisted of 300 discs of zinc and of 300 discs of gilt paper. It is said that, with a larger column, the vibration of a brass ball suspended between two bells was so continued as to maintain a perpetual ringing for over two years; that with an apparatus comprising 20,000 groups of silver, zinc and double discs of writing paper, sparks have been obtained, while a Leyden jar was charged in ten minutes with sufficient electricity to produce shocks and to fuse an inch of platinum wire of an inch in diameter; and that a similar pile, in the Clarendon Laboratory at Oxford, rang ten small bells continuously for over forty years.

In Vols. XXXV, XXXVI and XXXVII of the “Phil. Mag.,” and in Vols. XXVII and XXVIII of “Nicholson’s Journal,” André de Luc shows how the dry column can be used for determining the insulating qualities and conducting power of bodies, it having been also employed as are aerial electroscopes to indicate the electrical changes taking place in the atmosphere. The other volumes of the same publications named below contain additional papers upon electricity, galvanism, etc., while at p. 392, Vol. L of the _Phil. Mag._ will be found an account of De Luc’s life and principal works, the latter being likewise mentioned in Vol. XXV of the “Biographie Universelle.”

REFERENCES.--B. M. Forster, “Description ... elec. col. ... De Luc ...” London, 1810; _Phil. Mag._, Vol. XXXVII. p. 197; J. D. Maycock, _Phil. Mag._, Vol. XLVIII. pp. 165, 255; L. Configliachi, “Osservazioni sulle pile a secco”; M. Delezenne, “Expériences sur les piles sèches”; _Bibl. Brit. Sci. et Arts_, Vol. XLVII, 1811, pp. 3, 113, 213, 313; Vol. XLIX, 1812, pp. 88–92 (Necrology of J. A. De Luc), Vol. L, 1812, p. 351 (“Nicholson’s Journal,” No. 126), also the “Bibl. Britan.” for 1812, Vol. L. pp. 279–290 (Nicholson’s _Journal_, April 1812), for J. D. Maycock’s reply to De Luc’s objections concerning voltaic plates (“Phil. Mag.,” Vol. XLVIII. pp. 165, 255); Gmelin’s “Chemistry,” Vol. I. pp. 424–427; G. J. Singer’s “Elements of Electricity” and William Sturgeon’s _Annals of Electricity_, _passim_, as well as his “Researches,” Bury, 1850, pp. 147, 199, 261; De la Rive’s “Treatise on Electricity,” Vol. II. p. 852; _Annales de Chimie et de Physique_, Vol. II. pp. 79–82 for May 1816; Gilbert’s _Annalen_, Vol. XLIX; also Vols. VII, 1801, to Vol. LXXIV, 1821, for various articles upon the dry pile, etc.; G. Schübler, “Uber De Luc’s Elektr. saüle ...” 1813; Geo. Wilson’s “Life of Cavendish,” London, 1851, p. 66, etc.; “Nicholson’s Journal,” Vols. XXI, XXII, XXXII, XXXIII, XXXV; _Phil. Mag._, Vols. XLII, XLV, the last named containing, at pp. 359–363, Mr. G. J. Singer’s paper on “The Electric Column considered as ... first mover for Mechanical Purposes,” while at pp. 466, 467 is the communication of Mr. Francis Ronalds on De Luc’s electric column. The latter is also specially referred to in Vols. XLIII. pp. 241, 363; XLVI. p. 11; XLVII. pp. 47, 48; XLVIII. pp. 165, 255; LVII. pp. 446, 447; while at p. 55 of Vol. XLIX is a paper relative to a “combination of the electric column, the thermometer, barometer and hygrometer in one instrument, for electro-atmospherical researches.”

=A.D. 1809.=--Sömmering (Samuel Thomas von), German anatomist and physiologist, first employs voltaic, or contact, electricity for the transmission of telegraphic signals.

Both his original and perfected working instruments were constructed between July 9 and August 6, 1809 (_Journal Franklin Institute_, 1859, Vols. XXXVII and XXXVIII; _Journal Society of Arts_, Vol. VII. p. 235). The complete apparatus consists of thirty-five gold rods placed into glass tubes starting from a reservoir of acidulated water and connecting with thirty-five silk-covered wires, which are run into thirty-five apertures of copper (corresponding with twenty-five letters and ten figures) upon a wooden stand into each opening of which the wires of the voltaic pile can be inserted. When the latter are connected, the bubbles rising through the decomposition of the water are made to enter the lettered glass receivers through which the messages can be deciphered. On August 8, 1809, he was able to transmit intelligence a distance of 1000 feet, and twenty days later he presented his apparatus to the Bavarian Academy of Sciences (Fahie, “Hist. of Electric Telegraphy,” p. 228).

Sömmering’s telegraph was carried by Dominique Jean Larrey, chief surgeon of the French armies, to Paris, where it was delivered by him to the French Academy of Sciences, Dec. 5, 1809, and Dr. Hamel states that Biot, Carnot, Charles and Monge were appointed by that body to report upon the new invention (_Journal of the Franklin Institute_ for 1859, Vol. XXXVIII. p. 398). In 1810 and 1811, Sömmering reduced the number of wires in his apparatus to twenty-seven. These brass or copper wires were first insulated with a covering of gum lac and then with silk thread, after which they were united into a thread-covered cable 1000 feet in length. The cable was in turn covered with heated gum lac or with a ribbon plunged in a solution of the same substance. The Russian Count Jeroslas Potocki took the new instrument to Vienna and submitted it, July 1, 1811, to the Emperor Francis I, while another model of the apparatus was sent to William Sömmering, then at Geneva, where it was shown to De la Rive, Auguste Pictet and other scientists. During March 1812 this instrument carried intelligence 10,000 feet, or ten times the distance previously reached.

REFERENCES.--Dr. Hamel, Cooke’s reprint, pp. 7, 8. See Sömmering’s own description of this, the first electro-chemical telegraph, in “Der Elektrische,” etc., published by his son William at Frankfort, 1863, or the translations at p. 751 of Noad’s “Manual,” London, 1859, and at pp. 230–234 of Fahie’s “Hist, of Elec. Tel.,” London, 1884; Dr. Hamel, in _Jour. Soc. of Arts_, for 1859, p. 453, or the reprint of W. F. Cooke in 1859, Vol. VII. pp. 595–599 and 605–610; Du Moncel, “Exposé,” etc., Vol. III; _Comptes Rendus_, Tome VII for 1838, p. 81; “De Bow’s Review,” Vol. XXV. p. 551; Highton’s “Elec. Tel.,” p. 39; Harris, “Galvanism,” p. 35; Sturgeon’s _Ann. of Elec._, Vol. III, March 1839, pp. 447–448; “Turnbull, Electric Magn. Tel.” “Denkschr. Münch. Akad. ...” for 1809 and 1810, alluding to his first experimental instrument made in 1807; Schweigger, _Journal_, II. pp. 217, 240 of Vol. XX for 1817; Poggendorff’s _Annalen_, Vol. CVII. pp. 644–647; “Smithsonian Report” for 1878, pp. 269–271; _Journal of the Franklin Institute_ for 1851, Vol. XXI. pp. 330–332; Prime’s “Life of Prof. Morse,” 1875, pp. 263–275; “Bibl. Britan.,” Vol. XLIX, 1812, p. 19; “Traité de tél. sous-marine,” E. Wünschendorff, Paris, 1888.

=A.D. 1810.=--Prechtl (Johann Joseph), German mathematician and chemist, director of the School of Arts and Navigation in Trieste, also professor in the Vienna Polytechnic Institute, is the author of several very interesting articles on electricity, magnetism, etc., which appeared in Gilbert’s _Ann. der Physik_ from Vol. XXXV for 1810, to Vol. LXVIII for 1821, as well as in Gehlen’s _Jour. für Chemie, Physik und Mineralogie_, Vols. V-VII. According to Figuier (“Expos, et Hist. ...” 1857, Vol. IV. p. 433) we owe to Prof. Prechtl a still more lucid explanation of the theory of electric distribution and equilibrium in the voltaic pile than was conveyed even by the learned Prof. Jäger (A.D. 1802).

Of the many separate treatises which he wrote up to 1836, and which are contained in the numerous publications cited below, the most important, by far, is doubtless that treating of the fundamental state of the magnetic phenomena of the electrical connecting wire and on the transverse electrical charge (“Uber d. transversal-magnetismus ...”) which is to be found in Schweigger’s _Journal für die Chemie und Physik_, Vol. XXXVI. pp. 399–410, and in Dr. Thomas Thomson’s _Annals of Philosophy_, N.S., Article I. vol. iv. pp. 1–6 for July 1822. Alluding to the last named, Mr. Sturgeon says (“Scientific Researches,” Bury, 1850, p. 29) that an _attempt_ is made by M. Prechtl to explain the manner in which the connecting wire acts upon the needle, but that his diagrams and his mode of reasoning are too complex to be entered into the “Researches.”

REFERENCES.--Poggendorff’s “Biograph.-Liter. ...” Vol. II. pp. 519, 520; Larousse, “Dict. Univ.,” Vol. XIII. p. 45; “Catal. Sc. Papers Roy. Soc.,” Vol. V. pp. 3–5; Gehlen’s _Journal_, Vols. VII. pp. 141–282; VIII. pp. 297–318; Gilbert’s _Annalen_, Vols. XXXV, 1810, pp. 28–104; XLIV, 1813, pp. 108–111; LXVII, 1821, pp. 81–108, 221, 222, 259–276; LXVIII, 1821, pp. 104–106, 187–206; LXXVI, 1824, pp. 217–228; Brugnatelli’s “Giornale,” Vol. III, 1810, pp. 477–486; Kastner, “Archiv. Natur.,” II, 1824, pp. 151–167; Wien, “Jahrb. Pol. Inst.,” Vol. XIV, 1829, pp. 144–160, and Poggendorff’s _Annalen der Physik und Chemie_, Vol. XV, 1829, pp. 223–238.

=A.D. 1810.=--The compiler of this “Bibliographical History” will doubtless be pardoned for introducing here an additional mode of “communicating intelligence” promptly at great distances. Reference is made to the first germ of pneumatic telegraphy sown by the English engineer, George Medhurst, during the year 1810.

The London _Telegraphic Journal_, which gives an extract from the specification of Medhurst’s patent “for a new method of conveying letters and goods with great certainty and rapidity by air,” states that the process took practical form only in 1854, when Latimer Clark laid down a one-and-a-half-inch lead pipe between the Electric Telegraph Company’s central station, Lothbury, and the London Stock Exchange. The system was extended in 1858 to Mincing Lane, and, two years later, Varley introduced the use of compressed air, so that messages were drawn one way by a vacuum, and propelled in the opposite direction by a prenum, instead of employing a vacuum both ways, as Latimer Clark had previously done. During the year 1865 the system, then considerably modified, was introduced into Paris, and it was also made use of, at about the same time, by the Messrs. Siemens, who employed it between the Bourse and the telegraph station in the city of Berlin.

=A.D. 1810.=--Jacopi (Joseph), Italian physician, anatomist and physiologist (1774–1813), pupil of the famous Scarpa, makes known through his “Elementi di Fisiologia e Notomia comparata” (“Eléments de Physiologie et d’Anatomie comparée”), the results of his very extended investigations of the electrical organs of the _torpedo_.

To him is due the first clear description of the electrical lobes situated in the _torpedo’s_ brain and of its relation to the eighth pair of nerves distributed throughout the hexagonal columns, which latter received also from him a very extended notice in the above-named work. The fifth ramification of nerves was first observed by Carus, and the most valuable investigation relative to the fourth and last important group of nerves directly connected with the electrical organs was made by the celebrated Italian professor, Carlo Matteucci.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. IX. p. 867; C. Matteucci, “Traité des Phénomènes Electro-Phys.,” Paris, 1844, pp. 283–318; Geoffroy St. Hilaire at A.D. 1803.

Another author, Delle Chiaje, likewise gave a description of the rhomboidal sinus-shaped protuberance which he calls _lobo pagliarino_ (straw-coloured lobe), and which he considers as formed of one mass but does not admit its important connection with the electrical organs.

=A.D. 1811.=--Poisson (Siméon Denis), a very able French scientist, communicates to the “Institut des Mathématiques et Physiques” and publishes at Paris under the caption “Traité de Mécanique,” his analytical observations of the electric phenomena which, it has been truly said, actually establish a new branch of, and is the best elementary work extant upon, mathematical physics. One of his biographers remarks that Poisson’s object was “to leave no branch of physics unexplored by aid of the new and powerful methods of investigation which a school, yet more modern than that of Lagrange and Laplace, had added to the pure mathematics.”

As shown, notably by Sir David Brewster in his able article on “Electricity” in the eighth “Encycl. Brit.” (Vol. VIII. p. 531), and by Noad, in his “Manual” (London, 1859, pp. 15, 16):

“Poisson adopted as the basis of his investigations the theory of two fluids, proposed by Symmer and Dufay, with such modifications and additions as were suggested by the researches of Coulomb. He deduced theorems for determining the distribution of the electric fluid on the surfaces of two conducting spheres, when they are placed in contact or at any given distance, the truth of which had been established experimentally by Coulomb before the theorems themselves had been investigated. On bodies of elongated forms, or those which have edges, corners or points, it is shown as a consequence of the theory of two fluids that the electric fluid accumulates in greater depths about the edges, corners or points than in other places. Its expansive force, being therefore greater at such parts than elsewhere, exceeds the atmospheric pressure and escapes, while at other points of the surface it is retained.”

In the latter connection Mary Somerville remarks:

“There can hardly be a doubt but that all the phenomena of magnetism, like those of electricity, may be explained on the hypothesis of one ethereal fluid, which is condensed or redundant in the positive pole, and deficient in the negative; a theory that accords best with the simplicity and general nature of the laws of creation; nevertheless, Poisson has adopted the hypothesis of two extremely rare fluids, pervading all the particles of iron, and incapable of leaving them. Whether the particles of these fluids are coincident with the molecules of the iron, or that they only fill the interstices between them, is unknown and immaterial. But it is certain that the sum of all the magnetic molecules, added to the sum of all the spaces between them, whether occupied by matter or not, must be equal to the whole volume of the magnetic body.... M. Poisson has proved that the result of the

## action of all the magnetic elements of a magnetized body is a force

equivalent to the action of a very thin stratum covering the whole surface of a body, and consisting of the two fluids--the austral and the boreal, occupying different parts of it; in other words, the attractions and repulsions externally exerted by a magnet are exactly the same as if they proceeded from a very thin stratum of each fluid occupying the surface only, both fluids being in equal quantities, and so distributed that their total action upon all the points in the interior of the body is equal to nothing. Since the resulting force is the difference of the two polarities, its intensity must be greatly inferior to that of either” (J. C. Wilcke at A.D. 1757, “Conn. of the Phys. Sci.,” 1846, s. 30 pp. 308, 309).

The “Mémoires de l’Institut” for 1811 contain Poisson’s very able papers showing the manner in which electricity is distributed on the surfaces of bodies of various figures and the thickness of the stratum of electricity existing throughout these bodies. Mrs. Somerville further observes of work already cited (s. 28):

“Although the distribution of the electric fluid has employed the eminent analytical talents of M. Poisson and M. Ivory, and though many of their computed phenomena have been confirmed by observation, yet recent experiments show that the subject is still involved in much difficulty. Electricity is entirely confined to the surface of bodies; or, if it does penetrate their substance, the depth is inappreciable; so that the quantity bodies are capable of receiving does not follow the proportion of their bulk, but depends principally upon the form and extent of surface over which it is spread; thus the exterior may be positively or negatively electric, while the interior is in a state of perfect neutrality.” (Consult J. Farrar, “Elem. of Elect. Magn. and Electro-Magn.,” 1826, pp. 50–56.)

In his treatment of the theories of magnetism, Brewster alludes again to the masterly investigations of Poisson, who, says he, appears to have been “the first to conceive the idea of absolute magnetic measurement.” In a short but luminous article at the end of the “Connaissance des Temps” for 1828, he describes the method for obtaining the value of H[ symbol] in absolute measure. His first and second “Mémoire sur la Théorie du Magnétisme” appeared during 1824–1825, at pp. 247, 488, Vol. V of the Transactions of the Paris Royal Academy, and were closely followed (Vol. VI. p. 441) by his Memoir on the theory of Magnetism in motion. _Translations_ of these will be found at pp. 336–358, 373, Vol. I and pp. 328–330, Vol. V of the _Edin. Jour. of Sci._ and at pp. 334, 335 of John Farrar’s “Elem. of Elect. Magn. and Electro-Mag.,” all published during the year 1826.

Poisson’s theoretical prediction of magne-crystallic action is thus alluded to by Dr. John Tyndall in his “Researches on Diamagnetism,” etc., London, 1870, pp. 13 and 66, 67:

“In March 1851, Professor William Thomson (Lord Kelvin) drew attention to an exceedingly remarkable instance of theoretic foresight on the part of Poisson, with reference to the possibility of magne-crystallic

## action.

“Poisson,” says Sir William, “in his mathematical theory of magnetic induction founded on the hypothesis of magnetic fluids (moving within the infinitely small magnetic elements), of which he assumes magnetizable matter to be constituted, does not overlook the possibility of those magnetic elements being non-spherical and symmetrically arranged in crystalline matter, and he remarks that a finite spherical portion of such a substance would, when in the neighbourhood of a magnet, act differently according to the different positions into which it might be turned with its centre tube fixed. But (such a circumstance not having yet been observed), he excludes the consideration of the structure which would lead to it from his researches, and confines himself in his theory of magnetic induction to the case of matter consisting either of spherical magnetic elements or of non-symmetrically disposed elements of any forms. Now, however, when a recent discovery of Plucker’s has established the very circumstance, the observation of which was wanting to induce Poisson to enter upon a full treatment of the subject, the importance of working out a magnetical theory of magnetic induction is obvious.

“Sir William Thomson then proceeds to make the necessary ‘extension of Poisson’s Mathematical Theory of Magnetic Induction,’ and he publishes a striking quotation from the ‘Mémoires de l’Institut,’ 1821–1822, Paris, 1826.”

REFERENCES.--Biography in “English Encycl.,” Vol. IV. p. 899; _Phil. Mag._ for 1851; Roy. Soc. Catal. of Sci. Papers, Vol. IV. pp. 964–969; G. M. Racagni, “Sopra una Memoria ...” 1839; Johnson’s “Encycl.,” 1878, Vol. III. p. 227; eighth “Britannica,” Vol. XV. p. 98; ninth “Britannica,” Vol. XV. pp. 241, 249; _Ann. de Chimie_ for Feb. 1824; “Le Globe,” No. 87; Harris, “Magnetism,” p. 131; Whewell, “Hist. of the Inductive Sciences,” 1859, Vol. II. pp. 43, 208, 209, 222, 223; Sir William Thomson’s works, 1872; Thomas Thomson, “An Outline,” etc., 1830, p. 351; _Mém. de l’Acad. des Sci._ for 1824–1826, 1838; _Soc. Philom._ for 1803, 1824–1826; Humboldt’s “Cosmos,” London, 1849, Vol. I. pp. 104, 105, 130, 165–169; N. Bowditch, “Of a mistake which exists in the calculation of M. Poisson relative to the distribution of the electric matter upon the surfaces of two globes, in Vol. XII of the “Mém. ... Sc. Math. ... de France”; _Mem. Amer. Acad._, O.S., Vol. IV. part i. p. 307; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 228. Mention is made of Poisson’s principal writings, in Vol. XI. pp. 179–191 of M. Max Marie’s “Hist. des Sciences Mathém.,” Paris, 1888, but the complete list will be found in Vol. II of the works of Arago.

=A.D. 1811.=--Schweigger (Johann Salomo Christoph), a chemist of Halle (1779–1857), inserts at p. 240, Vol. II of his _Journal für die Chemie und Physik_, the memoir of Sömmering, relative to his electro-chemical telegraph, as well as an appendix thereto, wherein he points out the difficulties likely to attend the employment of so many different wires. He suggests the use of but two wires, and of two piles of unequal power. With these, all desired characters could be transmitted, through a preconcerted code regarding the meaning of such letters and figures as would be represented by the weaker or the stronger pile, in conjunction with the duration of the gas evolutions or the space of time separating them. He also suggested, for an alarum, the use of a pistol, by connecting a battery to the pile, in lieu of liberating an alarm by means of accumulated gas as Sömmering had done.

Two months after Oersted’s great discovery, which was announced in July 1820, Schweigger read at Halle (September 16, 1820) and communicated to the German _Literary Gazette_ (No. 296 for November 1820), a paper relative to an important improvement made in his _galvano magnetic indicator_. The latter, which had been described at pp. 206–208 of Gehlen’s (1808) _Journal für Chemie_, was merely an electroscope, employed to indicate the attraction and repulsion of ordinary frictional electricity in lieu of a Coulomb balance, the improved apparatus being the result of his discovery that, by coiling an _insulated_ wire several times around a magnetic needle, the deflecting power of the voltaic current increases with the number of turns (Kuhn, “Ang. Elek.-Lehre,” p. 514).

Alluding to Schweigger’s multiplier, the Abbé Moigno says:

“A conducting wire twisted upon itself and forming one hundred turns will, when traversed by the same current, produce an effect one hundred times greater than a wire with a single turn: provided always that the electric fluid pass through circumvolutions of the wire without passing laterally from one contour to another” (_Cornhill Magazine_, Vol. II for 1860, pp. 61, 64).

It was, however, shown by Dr. Seebeck that the power of multiplication does not increase with the number of windings in the uniting wire, for the resistance to transmission naturally increases with the length of the wire, thus diminishing its conducting power.

To his new instrument Schweigger gave the name of _electro-magnetic multiplier_ (_multiplicator_) or _galvanometer multiplier_, and it has become the most important for indicating and measuring the strength of the galvanic current.

Prof. W. B. Rogers says that Schweigger’s apparatus as improved by Nobili (_Ital. Soc. Mem._, Vol. XX. p. 173) became indispensable in the measurement of current electricity, and that through the later improvements given it by Sir William Thomson (also by Du Bois Reymond), it has been made one of the most perfect and delicate of all known means of measuring force. Schweigger’s multipliers with improvements made thereon by Oersted and Nobili are illustrated at p. 642, Vol. XXI of the eighth “Ency. Britannica,” where reference is made to drawings on a large scale shown at Plate 522, article “Thermo-Electricity,” of the “Edinburgh Encyclopædia.”

According to a footnote, p. 273 of “Report Smithsonian Inst.” for 1878, Schweigger’s multiplier is alluded to in the “Additions to Oersted’s Electroma-gnetic Experiments,” a memoir read at the _Naturforschende Gesellschaft_ at Halle, September 16 and November 4, 1820. An abstract of this paper was published in the _Allgemeine Literatur-Zeitung_ of Halle (4to), November 1820, No. 296, Vol. III. col. 621–624, whilst the full memoir appeared in the _Journal für Chemie und Physik_, 1821, Vol. XXXI. pp. 1–17; and “Additional Remarks ...” by Dr. Schweigger, in the same volume, pp. 35–41. It is further stated in the afore-mentioned note that:

“A galvanometer of somewhat different form, having a vertical helix and employing an unmagnetized needle, was very shortly afterward independently devised by Johann Christian Poggendorff, of Berlin; and as he preceded Schweigger in publishing an account of it, he is sometimes regarded as the original inventor. Schweigger designated his device an ‘Electro-magnetic Multiplicator’; Poggendorff designated his arrangement a ‘Galvano-magnetic Condensator.’ Prof. Oersted remarks: ‘Immediately after the discovery of electro-magnetism, M. Schweigger, professor at Halle, invented an apparatus admirably adapted for exhibiting by means of the magnetic needle the feeblest electric currents.... M. Poggendorff, a distinguished young savant, of Berlin, constructed an electro-magnetic multiplier very shortly after M. Schweigger, with which he made some striking experiments. M. Poggendorff’s work having been cited in a book on electro-magnetism by the celebrated M. Erman (published immediately after the discovery of these phenomena), became known to several philosophers before that of M. Schweigger’ (_Annales de Chimie et de Physique_, 1823, Vol. XXII. pp. 358–360).

“The researches of Schweigger and Bart leave us little or no doubt that the ancients were well acquainted with the mutual attraction of iron and the lodestone, as well as with the positive and negative properties of electricity, by whatever name they may have called it. The reciprocal magnetic relations to the planetary orbs, which are all magnets, was with them an accepted fact, and aerolites were not only called by them magnetic stones, but used in the Mysteries for purposes to which we now apply the magnet.”

REFERENCES.--“Isis Unveiled,” Vol. I. pp. 281, 282. See also _Annales de Chimie et de Physique_, 1816, Vol. II. pp. 84, 86; Thos. Thomson, “An Outline of the Sciences ...” London, 1830, Chap. XV. p. 564; “Encycl. Brit.,” seventh edition, “Voltaic Electricity,” p. 687; _Polytechnisches Centralblatt_; _Sc. Am. Supp._, No. 404; Sturgeon’s “Scientific Researches,” Bury, 1850, p. 19; L. F. Kaemtz, _Phil. Mag._, Vol. LXII. p. 441; Poggendorff, Vol. II. pp. 873–875; Du Moncel, “Exposé ...” Vol. III; Whewell’s “Hist. of Ind. Sci.,” Vol. II. p. 251; “Abhandl. d. Naturf. Gesellsch. zu Halle” for 1853–1856; Schweigger’s _Journal für Chemie und Physik_, Vol. II. part iv. pp. 424–434; Vol. X for 1814 and Vol. XXXVIII for 1823; “Cat. Sc. Papers Roy. Soc.,” Vol. V. pp. 589–592; “Bibl. Britan.,” Vol. XVI, N.S., 1821, p. 197; Larousse, Vol. XIV. pp. 386–387. _Edinburgh Philosophical Journal_, July 1821, Vol. V. p. 113. For Seebeck, see _Phil. Mag._, Vol. LXI, 1823, p. 146. For Poggendorff, see “Cat. Sc. Pap. Roy. Soc.,” Vol. IV. pp. 952–956; Vol. VIII. pp. 638–640; “Bibl. Britan.,” Vol. XVIII, N.S., 1821, p. 195; Pogg., “Annalen,” Vol. CLX (biography).

In the editorship of Schweigger’s _Journal_, which followed Gehlen’s _Journal_, Mr. J. S. C. Schweigger was assisted, from 1828, by Franz W. Schweigger-Seidel, who was the author of “Lit. d. Math. Natur.,” published in 1828. (For the joint magnetic work of J. S. C. Schweigger and Wilhelm Pfaff, see _Jour. f. Ch. u. Ph._, Band X. heft i. for 1814.)

=A.D. 1811.=--Monsieur Dessaignes is first to establish a relation between electricity and phosphorescence, as is shown in the extract published in London from the Memoir which he had presented two years before to the French Institute. The general view he takes is that phosphorescence is produced by a particular fluid, which is set in motion by light, by heat, by electricity, as well as by friction, and that it is dissipated by overheating or by too long exposure to light.

It is asserted by Fahie (“Hist. of El. Tel.,” pp. xiv, 297) that it was Dessaignes and not Seebeck who first discovered thermo-electricity. “Dessaignes,” he says, “showed us how difference of temperature or heat could produce electricity.” This was in 1815, or six years before Seebeck, who is always credited with the observation (Bostock’s “History of Galvanism,” London, 1818, p. 101). Many observations bearing on _thermo-electricity_ had been made even long before Dessaignes.... In 1759 Æpinus called attention to the same phenomena, and pointed out that electricity of opposite kinds was developed at opposite ends of the crystal (tourmaline). In 1760 Canton observed the same properties in the topaz; and between 1789 and 1791 Haüy showed the thermo-electric properties of various other substances, as mesotype, prehnite, Iceland spar, and boracite.

REFERENCES.--Priestley’s “History of Electricity,” 1767, pp. 314–326. For Dessaignes’ other observations, see J. Farrar, “Elem. of Elec., Mag. and Electro-Mag.,” 1826, p. 125, and _Phil. Mag._, Vol. XLIV. p. 313. See also _Phil. Mag._, Vol. XXXVIII. p. 3; _Journal des Mines_, Vol. XXVII. p. 213; Poggendorff, Vol. I. p. 563; “Cat. Sci. Pap. Roy. Soc.,” Vol. II. pp. 272, 273; Chap. III. s. 3 of the “Electricity” article of the “Ency. Britannica.”

=A.D. 1811.=--The idea of placing a lightning conductor through the body of a ship is first suggested by Mr. Benjamin Cook, of Birmingham, and is carried out by Mr. William Snow Harris, of Plymouth. Mr. William Sturgeon, who mentions the fact (“Lectures of Electricity,” London, 1842, p. 208), adds that Mr. Harris “has formed the conductors into strips of copper, which are inserted in grooves in the after side of the masts from top to bottom and through the keelson to the sea. In one of the smaller men-of-war Mr. Harris carried his mizzen conductor through the powder magazine!!! The evils attending these conductors arise principally from lateral explosions and electro-magnetic influence.”

REFERENCES.--For Wm. Sturgeon, consult _Phil. Mag._, Vol. XI, 1832, pp. 195, 270, 324; “Cat. Sc. Papers Roy. Soc.,” Vol. V. pp. 876–878, Vol. VI. p. 758 and Vol. VIII. p. 1042.

=A.D. 1811–1812.=--Schübler (Gustav), Professor, of Tübingen, is the first to present a connected series of observations upon the electricity of the air, which were made at Stuttgart, during all kinds of weather and at regular daily intervals, between May 1811 and June 1812. Other observations previously carried on by Schübler, during 1805 and subsequent years, at Ellvanguen and Stuttgart are detailed at pp. 579, 580, Vol. VIII--and are also alluded to in article “Meteorology”--of the eighth “Britannica.”

While De Lor was the first to observe, in 1752, the existence of electricity in the atmosphere, even when no lightning is visible, Schübler made the earliest known report upon the daily periodicity of the intensity of the electricity. The annual periodicity had been previously demonstrated by G. B. Beccaria, who published at Turin two able treatises on the subject during 1769 and 1775.

The origin of atmospheric electricity was, by Lavoisier, Laplace and Sir H. Davy, attributed in great part to the constant combustion taking place upon the earth’s surface. Volta and Saussure believed it to arise from the process of evaporation, while Pouillet pointed out the influence of the processes of vegetation; Reich, however, showed that as neither developed electricity they could not produce it in the atmosphere. Peltier advanced the theory that mere evaporation without chemical action is not enough, and the experiments of Faraday and Armstrong showed that evaporation without friction is likewise insufficient. These theories are treated of in “Gaea-Natur und Leben,” Köln and Leipzig, 1873, p. 322, and in Lardner’s “Popular Lectures,” 1859, Vol. II. pp. 149–160. The last named gives tables of many observations, and reports, among other matters, that the series of observations on the diurnal changes of atmospheric electricity which Schübler made, in 1811–1812, were repeated and confirmed at Paris in 1830 by M. Arago. During the month of March 1811 Schübler found that the mean time of the morning maximum was eight hours thirty minutes, and M. Arago ascertained the mean time for the same month to be eight hours forty-eight minutes.

REFERENCES.--_Edin. Jour. of Sci._, new series, Vol. III; _Biblio. Univers._, Vol. XLII; _Annales de Ch. et de Ph._ for 1816, Vol. II. p. 85; “Jahrbuch der Ch. und Ph.,” 1829; Gilbert’s _Annalen_, Vols. XXXIX, XLIX, LI; Schweigger’s _Journal_, Vols. II. p. 377; III. p. 133; VIII. pp. 21, 22, 25, 26, 28, 29; IX. pp. 348, 350, 351; XV. p. 130; XIX. pp. 1 and 11; XXV. p. 249; XXXI. p. 39; _Jour. de Phys._, Vol. LXXV. p. 177; Vol. LXXXIII. p. 184; “Lehrbuch der Meteor,” L. F. Kaemtz, Halle, 1832, Vol. I. p. 337; Vol. II. pp. 411, 414; “Annual of Sc. Disc.” for 1862, pp. 99–103; L. Palmieri in _Lum. Elec._, Paris, Oct. 31, 1891, pp. 209–212; “Sci. Pap. Roy. Soc.,” Vol. V. pp. 559–562; Vol. VI. p. 755; “Bibl. Britan.,” Vol. II, N.S. for 1816 pp. 93–113 (atmosph. electricity); Poggendorff, Vol. II. p. 853; Report on Atmospheric Electricity by F. J. F. Duprez, 1858, Part III. chap. ii. pp. 363–368; Foggo, p. 124, Vol. IV of _Edin. Jour. Sci._; J. J. Hemmer’s observations at Mannheim from 1783 to 1787, Lehrbuch, etc., Vol. II. p. 418, and the recorded investigations of De Luc, Girtannier, Mayer, Monge, Pouillet, Becquerel, De Tressan, Arago, De Saussure, Delezenne, Helwig and Kaemtz.

=A.D. 1811.=--In the first volume of his “Cosmos” (London, 1849, Vol. I. pp. 240–241) Humboldt speaks of _islands of eruption_, or marine volcanoes, which can properly be classed among electrical phenomena, and alludes to the one observed on the 13th of June 1811 by Captain Tillard (Tilland), and to which he gave the name “Sabrina.”

This volcano, which had previously appeared June 11, 1638 and December 31, 1719, off the island of St. Michael, in the Azores, is thus described in the _Philosophical Transactions_:

“Imagine,” says Captain Tillard, “an immense body of smoke rising from the sea, the surface of which was marked by the silver rippling of the waves occasioned by the slight and steady breezes incidental to those climates in summer. In a quiescent state, it had the appearance of a circular cloud, revolving on the water like a horizontal wheel, in various and irregular involutions, expanding itself gradually on the lee side, when suddenly a column of the blackest cinders, ashes, and stones, would shoot up in the form of a spire, rapidly succeeded by others, each acquiring greater velocity and breaking into various branches resembling a group of pines; these again forming themselves into festoons of white feathery smoke. During these bursts, the most vivid flashes of lightning continually issued from the densest portion of the volcano, and the columns rolled off in large masses of fleecy clouds, gradually expanding themselves before the wind, in a direction nearly horizontal, and drawing up a quantity of water spouts, which formed a striking addition to the scene. In less than an hour, a peak was visible, and, in three hours from the time of our arrival, the volcano then being four hours old, a crater was formed twenty feet high, and from four to five hundred feet in diameter. The eruptions were attended by a noise like the firing of cannon and musketry mixed; as also with shocks of earthquakes sufficient to throw down a large part of the cliff on which we stood.” (See description of the sudden appearance of the Island of St. Michael, etc., in Lectures by Dr. Webster, Professor of Chemistry and Mineralogy at Harvard College, Boston, 1822.)

=A.D. 1811–1818.=--Ure (Andrew), M.D., F.R.S., the first astronomer appointed to the Glasgow Observatory and the author of a Dictionary of Chemistry (the undisputed standard until the appearance of a similar work by Henry Watts), makes known the result of his electrical experiments in the same line as those made by Aldini (A.D. 1793) upon the body of a recently executed criminal. Noad, who gives a greatly detailed account of the investigations, at pp. 338–341 of his “Manual,” remarks that they “serve to convey a tolerably accurate idea of the wonderful physiological effects of the electrical agent, and will be impressive from their conveying the most terrific expressions of human passion and human agony.”

Dr. Ure is the inventor of an improved eudiometer, for detonating or exploding gases by means of an electric shock or spark, which is fully described and illustrated in the “Electricity” article of the “Britannica.”

REFERENCES.--De la Rive, “Treatise on Electricity,” Vol. II. pp. 489–490, also “Encycl. Metropol.,” Vol. IV (Galv.), p. 197. Another report of Ure’s experiments appears at pp. 634, 635 of the “Encycl. Brit.,” article on “Voltaic Electricity,” also in No. 12 of the _Journal Sci. and Arts_, and at p. 56, Vol. LIII of the _Philosophical Magazine_.

=A.D. 1812.=--Through the _New York Columbian_, of July 1812, Mr. Christopher Colles informs the public that the operation of his new telegraphs “will be shown from the top of the Custom House on Tuesdays, Thursdays and Saturdays from four to six o’clock in the afternoon.”

In an explanatory pamphlet, he states that “eighty-four letters can be exhibited by this machine in five minutes, to the distance of one telegraphic station averaged at ten miles, and by the same proportion a distance of 2600 miles in fifteen minutes, twenty-eight seconds.”

James D. Reid, who mentions this fact at p. 5 of his “Telegraph in America,” says that the above was nothing but the already well-known European semaphore or visual signal, and that Colles worked his “machine” between New York and Sandy Hook for several years.

=A.D. 1812.=--On April 1 and 15, May 13 and June 17, Mr. M. Donovan, secretary of the Kirwanian Society of Dublin, reads before the latter body a long communication “On the Inadequacy of the Hypothesis at Present Received to Account for (explain) the Phenomena of Electricity,” which was afterward ably criticized by J. A. de Luc, as will be seen by reference to the _Philosophical Magazine_, Vols. XLV. pp. 97, 200, 329–332, and XLVI. pp. 13, 14. In his treatment of Eeles’ hypothesis (see A.D. 1755) Donovan gives some attention to the designed suppression by Priestley of Eeles’ valuable papers from the _Philosophical Transactions_.

The above communication was followed by still more valuable and much longer ones, read by Mr. Donovan before the same society, February 22, March 8, and March 22, 1815, entitled “On the Origin, Progress and Present State of Galvanism ... and Inadequacy of the Hypotheses to Explain Its Phenomena ...” a modified form of which obtained for its author the prize of the Irish Royal Society.

The sketch of the history of galvanism is divided into three periods. The first treats of the discoveries attaching to muscular contraction, and alludes to the observations of Sulzer, Galvani, Fabbroni, Humboldt, Pfaff, Fontana, Valli, Monro, Vassalli-Eandi, Fowler, Smuck, Marsigli, Grapengieser, Giulio, Rossi, Aldini and Wells. The second period reviews the gradual development of the physical and chemical power of combined galvanic arrangements, beginning with Nicholson and Carlisle, and refers to the many conclusions reached by Cruikshanks, Henry, Haldane, Ritter, Robertson, Brugnatelli, Fourcroy, Vauquelin, Thénard, Lehot, Trommsdorff, Simon, Helwige (Major Helvig), Twast, Bourguet, Erman, Grapengieser, Wollaston, Davy, Pfaff, Van Marum, Biot, Cuvier, Desormes, Bostock, Cuthbertson, Aldini, Lagrave, Jordan, Ritter and Wilkinson. The third period commences with the well-known generalizations of the chemical effects of galvanism made by Hisinger and Berzelius; their experiments on the invisible transfer of elements at a distance, and the explanation given by Grotthus of the invisible transfer of the elements of water. Following this, Donovan alludes to the announced decomposition of muriatic acid by W. Peel, Francis Pacchiani, and others, as well as the discovery of the source of mistakes in the Galvani Society investigations by Pfaff, Biot, Thénard and Davy; after which reference is made to the special observations of Sylvester, Grotthus, Wilson, Erman, Davy, Pontin, Gay-Lussac and Thénard, Children, De Luc, Singer, Murray and Maycock.

On the 5th of April 1815, Donovan reviewed the hypotheses of Volta and Fabbroni, as well as of the British philosophers Wollaston, Bostock and Davy, and, on the 19th of the same month, he read an additional paper on the inadequacy of the galvanic hypothesis, having previously (Dec. 28, 1814, and Jan. 11, 1815) presented to the Kirwanian Society a communication relative to a new theory of Galvanism.

REFERENCES.--_Phil. Mag._, Vols. XXXIX. p. 396; XLIV. pp. 334, 401; XLV. pp. 154, 222, 308, 381; XLVI. p. 401; XLVII. pp. 167, 204; also Vol. XXXVII. pp. 227, 245, on Mr. Davy’s erroneous hypothesis of electro-chemical affinity, and Vols. XXII and XXIII of the _Trans. Royal Irish Academy_ for Mr. Donovan’s papers relating to improvements in the construction of galvanometers, on galvanometric deflections, etc. etc.

=A.D. 1812.=--Zamboni (Giuseppe), Italian physicist, Professor of Natural Philosophy in the Verona Lyceum, makes known through his “_Della pila elettrica a secco_” an improved method of constructing dry piles. He dispenses entirely with the zinc plates of De Luc and employs only discs of paper having one side tinned and the other coated with a thin layer of black oxide of manganese pulverized in a mixture of flour and milk (“Note historique sur les piles sèches,” _Annales de Chimie et de Physique_, Vol. XI. p. 190).

His pile terminates in metallic plates, compressing the paper discs by means of silk ligatures, and the column is insulated by giving it a coating of either sulphur or shellac. In this apparatus the tinned surface is the positive element, the negative being the oxide of manganese, which replaces M. De Luc’s Dutch gilt paper. In the later forms of Zamboni’s pile the discs were formed of gilt and silvered paper pasted back to back. William Sturgeon remarks (“Scientific Researches,” Bury, 1850, p. 200) that the Zamboni piles are those which have been the most securely protected against the action of the ambient air and which alone have maintained their original electrical intensity.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. XV. p. 1452; K. F. Anton Von Schreibers in Gilbert’s _Annalen_, LV; Placidus Heinrich (Schweigger’s _Journal_, XV); Gustav Schübler, “Uber Zamboni’s Trockne Säule,” 1815–1816; G. F. Parrot (Gilbert’s _Annalen_, LV); K. C. F. Jäger in Gilbert’s _Annalen_, Vol. XLIX for 1815, pp. 47–66; De la Rive, “Treatise on Electricity,” Vol. II. p. 852; A. M. Ampère, _Ann. de Chimie et de Phys._, XXIX; John Farrar, “Elem. of Electricity,” etc., 1826, p. 179; Zamboni and Ambrogio Fusinieri, _Ann. ... Reg. Lomb., Veneto_, Vols. IV. pp. 128, 132; VI. pp. 31, 142, 143, 293; G. Resti-Ferrari, “Elettroscopio ... del Zamboni”; _Ann. ... Reg. Lomb., Ven._, Vols. II. p. 229; III. p. 290; “Verona Poligrafo” for 1831, p. 87; _Mem. Soc. Ital._, Vols. XXI, XXIII; _Mem. dell’ Istit. Veneto_, Vol. II. pp. 239, 251; G. A. Majocchi, _Annali di Fisica_, Vol. VIII. p. 14; “Comm. dell’ Ateneo di Brescia,” 1832, p. 38; Sturgeon’s “Researches,” Bury, 1850, pp. 147, 199, etc., for observations of A. de la Rive and Francis Watkins; _Phil. Mag._, Vol. XLV. pp. 67, 261; _Ann. Ch. et Phys._ for May 1816, Vol. II. pp. 76, etc., 82–87, and _Bibl. Britan._, Vol. LVII. p. 225; also Vol. LVIII. p. 111 of the O.S., Vol. II, N.S. for 1816, p. 21 as well as Vol. XL. p. 190; “Bibl. Univ.,” Bruxelles, 1831, Vol. XLVII. p. 183 (horloge électrique); “Edin. New Phil. Journal,” 1829, Vol. XXI. p. 357. See likewise the references at Hachette (A.D. 1803), Dyckhoff (A.D. 1804), Maréchaux (A.D. 1806), De Luc (A.D. 1809); the illustration and description of M. Palmieri’s dry pile in _Sci. Am. Supp._, Nos. 512, 519, and the accounts of investigations made more

## particularly by MM. Beetz, Belgrado, Burstyn, Crosse, Du Bois

Reymond, De la Rive, D’Arsonval, Desruelles, Edelmann, Faraday, Gassiot, Gassner, Germain, Roul, Guérin, Haussman, Keiser, Schübler, Minotto, Pollak, Riess, Schmidt, Trouvé, Wagner, Watkins and Wolf.

=A.D. 1812.=--Schilling (Pawel Lwowitch), Baron (of Kannstadt), attaché to the Russian Embassy in Munich, and who had been two years before associated with S. T. Von Sömmering (Kuhn, p. 836), devises what he calls his “sub-aqueous galvanic conducting cord”--a copper wire insulated with a thin coating of india-rubber and varnish. This was laid both underground and under the sea, and, it is asserted that, by means of an arrangement of charcoal points, he was enabled to explode powder mines across the Neva, near St. Petersburg, as well as also across the Seine, during the occupation of Paris by the allied armies.

REFERENCES.--Hamel, “Bull. Acad. Petersb.,” II and IV; also Wm. F. Cooke’s reprint, 1859, pp. 20–22; Fahie’s “History,” p. 309.

From the moment Schilling first saw the telegraph of Sömmering (Aug. 13, 1810) he made many experiments (Prime’s “Life of Morse,” p. 277) with the view of introducing it into Russia and finally took a model of it to St. Petersburg during the year 1812 (“Sc. Am. Suppl.,” No. 405). Hamel states (at p. 41 of Cooke’s reprint) that one of his contrivances was exhibited to the Emperor Alexander as early as 1825. Of this, Dr. E. N. Dickerson, in his Henry Memorial Address before Princeton College, gives the date as 1824. Be that as it may, it was only after his return from China in 1832 (two years after Sömmering’s death) that, following Ampère’s suggestion as to the availment of Oersted’s discovery, he submitted the apparatus which established for him the credit of having invented the electro-magnetic telegraph.

Many authors have erroneously described Schilling’s apparatus as consisting of a number of platinum wires insulated and bound together with a silken cord which put in motion thirty-six magnetic needles placed vertically in the centre of the multiplier by means of a species of key connecting with a galvanic pile. This account appeared at p. 43 of the “Journal des Travaux de l’Acad. de l’Industrie Française” for March 1839. The fact is that he employed but one magnetic needle and multiplier, with two leading wires, as proposed by Fechner, and was enabled by means of a combination of the deflections of the needle to the right and left to give all necessary signals for a complete correspondence by changing the poles of the battery at the ends of the wires. His call signal was given by a bell in connection with a clockwork, released by the deflection of a magnet.

REFERENCES.--For a detailed explanation of the working of Schilling’s telegraph, J. S. T. Gehler’s “Physikalisches Wörterbuch” for 1838, Vol. IX. p. 111; Fahie’s “History,” pp. 310–313; “Sc. Am. Suppl.,” No. 405, p. 6467.

From the account of the telegraphic collection at the 1873 Exposition, published by Dr. Edward Zetzsche in the “Austellungblatte” of the Vienna “Neue Freie Presse,” the following is extracted: “Even after Prof. Oersted, of Copenhagen, had observed the deviation of a magnetic needle under the influence of the current, neither the proposition of Ampère, at Paris, in 1820 (of employing thirty needles and sixty wires) nor that of Fechner, at Leipzig, in 1829 (twenty-four needles and forty-eight wires) gave any impulse to telegraphy. Only in 1832 did the Russian Councillor of State, Baron Schilling de Kannstadt (who had seen the telegraph of his friend Sömmering, and had made it known in Russia), invent a new instrument with but five wires, which number he subsequently reduced to one. In it, the movements of the needle were rendered more perceptible by means of little discs of paper attached to a silk thread, holding the needle in suspension. This telegraph, it is true, was not put in application on a large scale, for Schilling died in 1837, but, on the 23rd of Sept. 1835, he had already brought out his apparatus at Bonn and at Frankfort-on-the-Main, where it was seen amongst other persons by Prof. Muncke, who doubtless constructed a similar one which he took with him to Heidelberg.”

It was only one year before his death that Schilling succeeded in obtaining the support of the Russian Government for his telegraph, and it was only after Muncke had shown it (March 6, 1836) to Wm. Fothergill Cooke, then a student in medicine at Heidelberg, that the latter produced his needle telegraph, which was followed by Cooke and Wheatstone’s still more perfect instrument in 1837 (Prime’s “Life of Morse,” pp. 265, 276). Some improvements in Schilling’s so-called deflective telegraph had, in the meantime, been made by Gauss and Weber at Göttingen, as well as by Steinheil at Munich.

Prior to his visiting Bonn (Meeting of Naturalists--Isis, Nog., 1836) Schilling had taken the working model of his telegraph to Vienna, where he made many experiments with it in conjunction with Baron Jacquin and with Prof. Andreas von Ettinghausen. Upon his return home from Germany in 1836, he declined invitations made him to bring his instruments to England (Dr. Hamel’s St. Petersburg lecture on “The Telegraph and Baron Paul Schilling”), whilst, by direction of the Russian Commission of Inquiry, he set up an experimental telegraph in two chambers of the Palace of the Admiralty connecting the apparatus by a long line over ground and by a cable laid in the waters of the canal. The results proved so satisfactory that in May 1837 the Emperor Nicholas ordered a submarine line to be laid between St. Petersburg and Cronstadt. Schilling’s death, on the 25th of July following, prevented, however, the execution of the project.

REFERENCES.--Biography in _Sci. Am. Supp._, No. 547, p. 8737; _Polytechnic Central Journal_, Nos. 31, 32 for 1838; _Lumière Electrique_ for March 17, 1883; “Allg. Bauztg.,” 1837, No. 52, p. 440; L. Turnbull, Electro. Magn. Tel. p. 223; (Hibbard’s Ev. 31; Channing, Ev. 41); Poggendorff, Vol. II. p. 798; _Annales Télégraphiques_ for November to December 1861, p. 670; _Journal Soc. of Arts_ for July 22, 1859, p. 598; References at Ronalds’ “Catalogue,” p. 457; Du Moncel, “Exposé,” Vol. III. p. 8 and “Traité Théorique et Pratique du Tel. Elect.,” Paris, 1864, p. 217; _Comptes Rendus_, Vol. VII for 1838, p. 82; _Journal Franklin Inst._ for 1851, p. 60; H. F. E. Lenz, “Uber die Praktische ... Galvanismus,” 1839; “Report of Smithsonian Inst.,” 1898, pp. 224–225.

=A.D. 1812–1813.=--Morichini (Domenico Pini), eminent Italian physician, is the first to announce that unmagnetized steel needles can be rendered magnetic by making the focus of violet solar rays collected through a lens pass repeatedly from the middle to one end of the needle, without touching the other half (Zantedeschi, II. p. 214).

The long contention created by this announcement and the ingenious experiments of Mrs. Somerville, together with the results obtained by P. T. Riess and L. Moser, are detailed at p. 48 of Brewster’s (1837) “Treatise on Magnetism.” At p. 12 of his article (Vol. XIV of the eighth “Britannica”), Sir David Brewster states that Morichini’s experiments were successfully repeated by both Dr. Carpi at Rome and the Marquis Ridolfi at Florence; but M. d’Hombre Firmas, at Alais, in France; Prof. Pietro Configliachi, of Pavia, and M. Berard, of Montpelier, failed in obtaining decided effects from the violet rays. In 1814 Morichini exhibited the actual experiment to Sir Humphry Davy, and in 1817 Dr. Carpi showed it to Prof. Playfair. A few months later Sir David Brewster met Davy at Geneva, and learned from him the fact that he had paid the most diligent attention to one of Morichini’s experiments, and that he had actually seen with his own eyes an unmagnetized needle rendered magnetic by violet light. Then follow in the same article the account of Dr. Carpi’s experiment as given to Brewster by Prof. Playfair, also details of the investigations of Mrs. Somerville, Mr. Christie, Sir William Snow Harris, Prof. Zantedeschi, of MM. Baumgartner and Barlocci, as well as those of Riess and Moser above alluded to.

REFERENCES.--“Elogio storico del Cavaliere D. Morichini” in _Mem. della Soc. Ital._, Vol. XXVI. p. 3; Riess and Moser in _Phil. Mag. or Annals_, Vol. VIII. p. 155, 1830 and in Edin. _Trans._, Vol. X. p. 123; “Library of Useful Knowledge” (El. Mag.), p. 97; _Zeitschrift_, Vol. I. p. 263; Noad, “Manual,” pp. 532, 533; the article of Col. George Gibbs in Silliman’s _Amer. Jour. of Sci._, 1818, Vol. I. pp. 89, 90; _Annales de Chimie_, Vol. XLII. p. 304; Brewster’s “Optics,” p. 92; also articles “Optics,” p. 596, “Light,” p. 452 and “Electricity,” p. 569 of the eighth “Britannica”; _Edin. Jour. of Sci._, No. 4, p. 225; B. Gandolfi, “Antologia Romana,” 1797; Harris, “Rud. Mag.,” Parts I, II. p. 69; _Phil. Trans._ for 1826, pp. 132, 219; D. Olmstead, “Int. to Nat. Phil.,” 1835, Vol. II. p. 194. See also Thomas Thomson’s “Outline of the Sci.,” p. 514, and Berzelius’ “Traité de Chimie,” Vol. I. p. 138 for Morichini’s observations on galvanic energy; “Bibl. Brit.,” Vol. LII, 1813, p. 21; Vol. LIII, 1813, p. 195; Vol. LIV, 1813, p. 171 (Experiments of G. Babini in Florence); Vol. IV, N.S., 1817, pp. 1–8; Vol. V, N.S., 1817, p. 167; Vol. VI, N.S., 1817, p. 81; Vol. XI, N.S., 1819, p. 29 for the experiments of L. A. d’Hombre Firmas on Morichini’s violet rays, whilst p. 174 of the same issue gives J. Murray’s investigations as recorded in the “Phil. Mag.” for April 1819.

Peter (Pietro) Configliachi, already named, was the successor of Volta as Professor of Natural Philosophy at the Pavia University, and became editor of the “Biblioteca Fisica d’Europa,” the “Biblioteca Germanica,” the “Biblioteca Italiana” and the “Giornale di Fisica, Chimica e Storia Naturale” (Larousse, “Dict. Univ.,” Vol. IV. p. 908; J. J. Prechtl, in Schweigger’s _Journal_, Vol. IV for 1812; Fr. Mochetti, “Lettera al P. Configliachi,” Como, 1814; “Bibl. Britan.,” Vol. LVIII, 1815, p. 305 and Vol. IV of the N.S. for 1817, pp. 1–8).

=A.D. 1813.=--Sharpe (John Robert), of Doe Hill, near Alfreton, transmits to the _Repertory of Arts_ a letter, which appeared in its Vol. XXIX, second series, p. 23, wherein he alludes to p. 188, Vol. XXIV of the same series, containing an account of Sömmering’s apparatus. He says:

“Without the slightest wish to throw a doubt over the originality of Mr. Sömmering’s invention, I beg leave to mention that an experiment, showing the advantages to be obtained from the application of the certain and rapid motion of the electric principle through an extensive voltaic circuit to the purpose of the ordinary telegraph, was exhibited by me before the Right Hon. the Lords of the Admiralty, in the beginning of February 1813.”

It is said that the Lords of the Admiralty spoke approvingly of it, but stated that as the war was over, and money scarce, they could not carry it into effect (_Saturday Review_ for August 21, 1858, p. 190).

Ronalds says (“Catal.,” p. 473):

“No description of this telegraph appears to have been printed. It was mentioned at the Admiralty after the invention and full description of Sömmering’s, described fully and with figures in the Denkschriften of the Academy of Munich for 1809–1810, issued in 1811.”

Mr. Benjamin Sharpe, nephew of J. R. Sharpe, is the author of “A Treatise on the Construction and Submersion of Deep-Sea Electric Telegraph Cables,” London, 1861, wherein he alludes to the above, and asserts that his uncle “conveyed signals a distance of seven miles under water” (Fahie’s “History,” pp. 244–246; _Sci. Am. Supp._, No. 404, pp. 6, 446).

=A.D. 1813.=--Deleuze (Joseph Philippe François), French physician, publishes his “Histoire Critique du Magnétisme Animal,” containing the result of observations made by him during the previous twenty-five years upon animal magnetism.

According to Dr. Allen Thomson, of the University of Glasgow, Deleuze believed in the existence of an all-pervading magnetic fluid. This fluid, says he, is under the control of the will, and is constantly escaping from our bodies, forming around them an atmosphere, which, having no determinate current, does not act sensibly on the person near us; but, when urged and directed by our volition, it moves with all the force which we impress upon it; it is moved like the luminous rays emitted by substances in a state of combustion. The chief difference between the Deleuze and Puységur schools has reference to the various modes in which the magnetic fluid should be brought into action, and the suitable occasions for its employment.

During the year 1815 the Magnetic Society was established in Paris, with M. De Puységur as its president and M. Deleuze as vice-president, but it expired in 1820. In 1819 M. Deleuze had published his “Défense du Magnétisme Animal,” in reply to the attack made upon the subject by M. Virey through the “Dictionnaire des Sciences Médicales,” and he was followed, more particularly, by M. Bertrand, who issued in 1823 his “Traité du Somnambulisme,” and in 1826 his still more important work, “Du Magnétisme Animal en France,” etc. Respecting the last named Deleuze says:

“Of all the attacks directed against magnetism up to the present day, this is the most powerful, the most imposing, and the most ably combined. The author is a man of genius, etc. He has been occupied with magnetism for some years. He has joined its practice to that of medicine, and he has even taught its doctrines in public lectures. A more attentive examination and new experiments have dissuaded him from a belief which he himself propagated; he undertakes to undeceive others, and to prove that magnetism is a mere chimera. Certainly his conviction must be very strong.”

REFERENCES.--Article “Somnambulism,” in the “Britannica,” more especially for a review of, and extracts from, Deleuze’s great work, also the translation of the latter by T. C. Hartshorn, of which the enlarged fourth edition was published at London in 1850, accompanied by notes and a life by Dr. Foissac.

=A.D. 1813.=--Brande (William Thomas), F.R.S., succeeds Sir Humphry Davy as Professor of Chemistry to the Royal Institution after having long been his assistant.

He was already favourably known through a long line of interesting chemical experiments, one of which, treating of the effects of the galvanic current on albumen, had attracted very particular attention at the time it was communicated to the _Philosophical Transactions_. When he applied Davy’s method to fluids containing albumen, the albumen and acid were found at the positive pole and the albumen and alkali at the negative pole, and he also observed that, although it remained fluid with a weak battery, a stronger one caused it to be separated in a coagulated form. In like experiments subsequently made by Golding Bird, coagulation took place in the positive vessel, while none occurred in the negative; after a time the contents of the former had an acid taste, and of the latter a caustic alkaline flavour. When all in the positive vessel was coagulated by the galvanic action, he found there hydrochloric acid mixed with chlorine and the alkali in the negative vessel.

He also repeated the experiments of Davy on the light developed by charcoal points connected with a powerful galvanic battery, and found that this light was as effectual as solar light in decomposing muriate of silver and other bodies, and in acting upon hydrogen and chlorine gases, causing them to detonate, but he could not produce the same effect by the moon’s rays or by any other light.

The electricity developed in flame, which had received much attention from Paul Erman and others, was likewise investigated by Prof. Brande, whose conclusions are to be found detailed at Sec. III. chap. iii.

## part i. of the “Electricity” article in the “Encyclopædia Britannica.”

Therein is recalled the fact that A. L. Lavoisier, P. S. Laplace and Aless. Volta previously obtained clear indications of electricity by the combustion of charcoal, while H. B. de Saussure failed to develop electricity either by the combustion or explosion of gunpowder, and Humphry Davy could not obtain it through the combustion of charcoal or of iron in air or in pure oxygen. In the above-named article will also be found an account of the investigations of Pouillet and of Becquerel in the same line; some of the other well-known scientists who have treated more or less directly upon the subject being E. F. Dutour, J. S. Waitz, J. J. Hemmer, Heinrich Buff, G. Gurney, Carlo Matteucci, W. R. Grove, Michael Faraday, M. A. Bancalari, W. G. Hankel, F. Zantedeschi and M. Neyreneuf.

REFERENCES.--_Phil. Mag._, Vol. XLIV. p. 124; _Phil. Mag. or Annals_, Vol. IX. p. 237; _Annales de Chimie_, 5^e série, Vol. II; _Phil. Trans._ for 1809 and 1820; _Mémoires de Mathématiques_, Vol. II. p. 246; “Cat. Sc. Pap. Roy. Soc.,” Vol. I. p. 48; “Bibl. Britan.,” Vol. LVII, 1814, p. 11.

=A.D. 1813.=--Colonel Mark Beaufoy (already alluded to at Graham, A.D. 1722), describes in the first volume of Dr. Thomas Thomson’s _Annals of Philosophy_ what has by many been called the most perfect form known of the variation compass. It is also to be found illustrated at p. 81, Vol. XIV of the eighth “Britannica,” wherein it is said that he employed it in the valuable series of magnetic observations made by him between the years 1813 and 1821. It consists of a telescope, underneath the axis of which is a magnetic needle whose position is alterable in order to indicate the exact angle of deviation, or the declination of the needle from the true meridian.

Brewster states (eighth “Brit.,” Vol. XIV. p. 54) that when the diurnal variation of the needle was first discovered it was supposed to have only two changes in its movements during the day. About 7 a.m. its north end began to deviate to the west, and about 2 p.m. it reached its maximum westerly deviation. It then returned to the eastward to its first position, and remained stationary till it again resumed its westerly course in the following morning. When magnetic observations became more accurate, it was found that the diurnal movement commences much earlier than 7 a.m., but its motion is to the east. At 7.30 a.m. it reaches its greatest easterly deviation, and then begins its movement to the west till 2 p.m. It then returns to the eastward till the evening, when it has again a slight westerly motion; and in the course of the night, or early in the morning, it reaches the point from which it set out twenty-four hours before. The most accurate observations made in England were those of Colonel Beaufoy, when the variation was about 24½´ west. In these the absolute maxima were earlier than in Canton’s observations, and the second maximum west about 11 p.m. Dr. Thomas Thomson alludes to the diurnal investigations of Barlow and Christie and others, and gives (“Outline of the Sciences,” London, 1830, pp. 543–550) a table of the mean monthly variation of the compass from April 1817 to March 1819 as determined by Colonel Beaufoy. Mr. Peter Barlow, he says, has given in his “Essay on Magnetic Attractions” a very ingenious and plausible explanation of the daily variation by supposing the sun to possess a certain magnetic

## action on the needle.

REFERENCES.--_Phil. Mag._, Vol. LIII, 1819, p. 387; LV, 1820, p. 394; W. S. Harris, “Rud. Mag.,” Parts I, II, pp. 150–152; “Encycl. Metrop.,” Vol. III (Magnetism), pp. 766, 767; _Annals of Phil._, series 1, Vols. II, VI, IX, XVI, and N.S., Vol. I. p. 94, for Beaufoy’s own summary of all his observations.

=A.D. 1814.=--Mr. Thomas Howldy addresses to the _Philosophical Magazine_ a letter, dated Hereford, March 24, 1814, relative to “Experiments evincing the influence of atmospheric moisture on an electric column composed of 1000 discs of zinc and silver,” wherein he also makes reference to the dry pile of J. A. De Luc alluded to at A.D. 1809.

REFERENCES.--_Phil. Mag._, Vol. XLIII. pp. 241, 363, and _Nicholson’s Journal_, Vol. XXXV. p. 84; also the _Phil. Mag._, Vol. XLI. p. 393, for a description of the electric column of 20,000 pairs of zinc and silver plates, and others, constructed during the previous year (1813) by Mr. George J. Singer.

The above-named letter was followed (_Phil. Mag._, Vols. XLVI. pp. 401–408, and XLVII. p. 285) by a communication on the “Franklinian Theory of the Leyden Jar ... with Some Remarks on Mr. Donovan’s Experiments,” and by another letter sent to MM. R. Taylor and R. Phillips (_Phil. Mag. or Annals_, Vol. I. p. 343) relative to the paper of William Sturgeon “On the Inflammation of Gunpowder by Electricity,” which appeared at p. 20 of the last-named book.

An interchange of correspondence not long since through the columns of the London _Electrical Review_, for the purpose of ascertaining the period of the earliest use of carbon as a resistant, brought forth an extract from the “Treatise on Atmospheric Electricity,” published at London and Edinburgh, 1830, by Mr. John Murray, of Glasgow, which reads as follows: “Mr. Howldy, of Hereford, an ingenious electrician, has by some novel experiments clearly proved the increased power of electricity if retarded in its progress; instead of using tubes of glass filled with water, as Mr. Woodward had done, he has employed a glass tube supplied with lamp black.”

=A.D. 1814.=--Murray (John), Scotch physician and chemist, also Ph.D., and Professor of Chemistry and Materia Medica in the Edinburgh University, is the author of works entitled, “On Electrical Phenomena, and on the new substance called Jod (Iode),” also “On the Phenomena of Electricity,” published at London, respectively, during the years 1814 and 1815 (Tilloch’s _Phil. Mag._, Vols. XLIII. pp. 270–272; XLV. pp. 38–41; “Catalogue Sci. Pap. Roy. Soc.,” Vol. IV. pp. 556–557).

Dr. John Murray died July 22, 1820, in Edinburgh, the place of his birth, as will be seen by reference to Larousse, “Dict. Univ.,” Vol. XI. p. 706, and to Poggendorff, Vol. II. pp. 243, 244. He should not be confounded, as has been done by many, with _Mr._ John Murray, whose papers, read before the Royal Society (“Catalogue Scientific Papers,” Vol. IV. pp. 557–559; Vol. VI. p. 731), treat of the relations of caloric to magnetism, of the unequal distribution of caloric in voltaic

## action, etc., of aerolites, of the decomposition of metallic salts

by the magnet, of the ignition of wires by the galvanic battery, of lightning rods, conductors, etc. (These papers appear in Tilloch’s _Phil. Mag._, Vols. LIV, 1819, pp. 39–43; LVIII, 1821, pp. 380–382; LX, 1822, pp. 358–361; LXI, 1823, p. 207; LXII, 1823, p. 74; LXIII, 1824, pp. 130, 131; L. F. von Froriep, “Notizen ...” for 1823, Vol. IV. col. 198; _Edin. Phil. Jour._, Vols. XIV for 1826, pp. 57–62; XVIII for 1828, pp. 88–91; and in Sturgeon’s _Annals_, Vols. III for 1838–1839, pp. 64–68; VII for 1841, pp. 82–83.)

Mr. John Murray is said to have been a lecturer on experimental philosophy, and one of his most interesting reviews is the one appearing at p. 62, Vol. XLIII of the _Phil. Mag._ regarding Ezekiel Walker’s theory of combustion as deduced from galvanic phenomena. Murray thinks there is much obscurity in Mr. Walker’s solution, which arises “from his using indiscriminately the terms heat (caloric) and combustion. Now caloric (the matter of heat) and combustion (the act of ignition) are not identical. What may be collected, however, from the general tenor of that paper is the theory of Lavoisier in a new dress.”

At p. 17 of this same volume is a paper from Mr. John Webster on the agency of electricity in contributing the peculiar properties of bodies and producing combustion, while, at p. 20, is a letter from Mr. George J. Singer wherein he calls Mr. Walker a novice in the science of electricity, saying that among other things he “has yet to learn that a conducting body supported by dry glass and surrounded by dry air may be still very far from being insulated.”

The treatise of Mr. John Murray on “Atmospheric Electricity” previously alluded to (at Thomas Howldy, A.D. 1814) was translated into French (“Mém. de l’Elec. Atm.”) by J. R. D. Riffault, Paris, 1831.

REFERENCES.--_Phil. Mag._, Vols. XLIII. p. 175; L. pp. 145, 312; LII. p. 60; LIII. pp. 268, 468; LVIII. p. 387; LX. p. 61; LXI. p. 394; LXII. p. 456; LXIII. p. 130; also pp. 306, 307 of Fahie’s “History,” regarding John Murray’s “Notes to Assist the Memory in Various Sciences.”

=A.D. 1814.=--Wedgwood (Ralph), member of the family whose name is inseparably connected with one of the most beautiful manufactures of pottery, completes an electric telegraph, upon which he has been steadily at work from 1806. Of its construction or mode of action he appears, however, to have left no particulars.

At pp. 178 and 180 of “The Wedgwoods ...” by Llewellyn Jewett, London, 1865, appears the following:

“This Thomas Wedgwood was, I believe, cousin to Josiah, being son of Aaron Wedgwood, etc., etc. ... He was a man of high scientific attainments, and has the reputation of being the first inventor of the electric telegraph (afterward so ably carried out by his son Ralph) and of many other valuable works.... In 1806 Ralph Wedgwood established himself at Charing Cross, and soon afterward his whole attention began to be engrossed with his scheme of the electric telegraph, which in the then unsettled state of the kingdom--in the midst of war, it must be remembered--he considered would be of the utmost importance to the government. In 1814, having perfected his scheme, he submitted his proposals to Lord Castlereagh, and most anxiously waited the result ... was informed that ‘the war being at an end, the old system was sufficient for the country.’ The plan, therefore, fell to the ground, until Prof. Wheatstone, in happier and more enlightened times, again brought up the subject with such eminent success. The plan thus brought forward by Ralph Wedgwood, in 1814, and of which, as I have stated, he received the first idea from his father, was described by him in a pamphlet, entitled ‘An Address to the Public on the Advantages of a Proposed Introduction of the Stylographic Principle of Writing Into General Use; And Also an Improved Species of Telegraphy, Calculated for the Use of the Public, as Well as for the Government.’”

The pamphlet is dated May 29, 1815. Fahie gives (“History,” pp. 125–127) extracts both from this pamphlet, regarding the electric Fulguri-Polygraph, and from the communication of Mr. W. R. Wedgwood to the _Commercial Magazine_ for December 1846, urging his father’s claims to a share in the discovery of the electric telegraph.

REFERENCES.--“Life of Wedgwood,” by Miss Meteyard, 2 vols., 1865–1866; J. D. Reid, “The Telegraph in America,” p. 70.

=A.D. 1814.=--Singer (George John), distinguished English scientist and writer, publishes the first edition of his valuable “Elements of Electricity and Electro-Chemistry,” of which translations were made, in French by M. Thillaye, Paris, 1817, as well as in German and in Italian during the year 1819.

Mr. Singer is the inventor of the improvement upon Mr. Bennet’s electroscope, which is to be found illustrated and described in nearly all works upon natural philosophy and the main design of which is to diminish, if not totally prevent, the amount of moisture generally precipitated upon the surface of insulators. Mr. Singer remarks that his arrangement so effectually precludes moisture that some of the “electrometers constructed in 1810 and which have never yet (1814) been warmed or wiped, have still apparently the same insulating power as at first.” The use of this apparatus is strongly recommended by Dr. Faraday, whose instructions for the use of electrometers are given at great length at pp. 617–619, Vol. VIII of the eighth “Britannica.”

After describing the above-named electrometer, Mr. William Sturgeon remarks (“Lectures,” London, 1842, pp. 42, 43):

“It is frequently exceedingly difficult, without extensive reading, to confer the merit that is due to invention on the right party, and even then we sometimes err for want of proper information. Mr. Singer has hitherto, with most writers, had the exclusive merit of insulating the axial wire of the electroscope from the brass cap, by a glass tube; and it would appear from the description he gives of this improvement in his excellent treatise on electricity that he was not aware of anything of the kind being previously done. It appears, however, by an article of Mr. Erman in the _Journal de Physique_, Vol. LIX. p. 98, and _Nicholson’s Journal_, Vol. X, published in 1805, that a Mr. Weiss had applied the glass tube for the purpose of insulating the axial wire of Bennet’s electroscope. The account runs thus: ‘The electrometer he (Mr. Erman) used was that distinguished in Germany as the electrometer of Weiss.’ From this it would appear to have been long known. ‘The length of its leaves of gold is half an inch, and the diameter of the glass cylinder which encloses them is three-quarters of an inch, the height being an inch and a half. Its cover of ivory does not project above the glass, and is perforated in the middle with a hole in which a _smaller glass tube is fixed, and through this last tube passes the metallic rod that serves to suspend the gold leaves_.’ Singer’s improvement, first published in 1814, would, therefore, consist in adding the brass ferrule, which covers the glass tube first introduced by Weiss.”

Singer is also the inventor of one of the best-known amalgams for the cushions of the electric machine. It is described at p. 536, Vol. VIII of the eighth “Britannica,” where it is said that a mixture of one part tin and two parts mercury is very effective, as is also the amalgam consisting of mosaic gold and the deutosulphuret of tin. (Other descriptions of the application of mosaic gold on the rubber are to be found at p. 432, Vol. II of “Young’s Course of Lectures”; Woulfe, _Phil. Trans._, 1771, p. 114; Bienvenu and Witry de Abt, _Lichtenb. Mag._, Vols. II. p. 211, and IV. st. 3, pp. 58–61; Marquis de Bouillon, “Observ. de Physique,” XXI.)

The dry electric columns which Mr. Singer invented are alluded to in _Phil. Mag._, Vols. XLI. p. 393 and XLV. p. 359, while the results of his experiments on the electric fusion of metallic wires and the oxidation of metals, as well as those made upon the electricity of sifted powders and also in order to ascertain the effects of electricity upon gases, are to be found recorded at pp. 564, 592, 593 and 597, Vol. VIII of the 1855 “Britannica,” and at p. 46 (“Electricity”) of “Library of Useful Knowledge.”

REFERENCES.--pp. 15, 16 of the last-named work; Poggendorff, Vol. II. pp. 938, 939; Figuier, “Exp. et Hist.,” 1857, Vol. IV. p. 267; Sturgeon’s “Lectures,” 1842, p. 11; _Phil. Mag._, Vols. XXXVII. p. 80; XLII. pp. 36, 261; XLIII. p. 20; XLVI. pp. 161, 259; likewise Ch. Samuel Weiss, at Poggendorff, Vol. II. pp. 1287–1289; “Bibl. Britan.,” Vol. XLIII, 1810, p. 166; Vol. XLVII, 1811, pp. 3, 113, 213, 313; Vol. LVI, 1814, pp. 197, 318.

=A.D. 1814–1815.=--Fraunhofer--Frauenhofer (Joseph von), a practical Bavarian physicist and optician, who had been assistant to the celebrated George Reichenbach, publishes his observations on spectra in a pamphlet entitled “Bestimmung des Brechungs und Farbenzerstreuungs-Vermögens ...”

In the latter work will be found detailed his experiments with the electric spark, which he found to give a different spectrum from all other lights. Sir David Brewster says that in order to obtain a continuous line of electrical light Fraunhofer brought to within half an inch of each other two conductors, and united them by a very fine glass thread. One of the conductors was connected with an electrical machine and the other communicated with the ground. In this manner the light appeared to pass continuously along the fibre of glass, which consequently formed a fine and brilliant line of light. When this luminous line was expanded by refraction, Fraunhofer saw that, in relation to the lines of its spectrum, electric light was very different both from the light of the sun and from that of a lamp. In this spectrum he met with several lines partly very clear, and one of which, in the green space, seemed very brilliant compared with other parts of the spectrum (_Edin. Jour. of Sci._, No. XV. p. 7). He saw in the orange another line not quite so bright, which appeared to be of the same colour as that in lamplight spectra; but in measuring its angle of refraction he found that its light was much more strongly refracted, and nearly as much as the yellow rays of lamplight. In the red rays toward the extremity of the spectrum, he observed a line of very little brightness, and yet its light had the same degree of refrangibility as the clear line of lamplight, while in the rest of the spectrum he saw the other four lines sufficiently bright. In a subsequent paper read at Munich in 1823 (“Neue Modifikation des Lichtes ...” or “New Modification of Light”) and in Schumacher’s “Astronomische Abhandlungen,” Fraunhofer states that, by means of the large electrical machine in the cabinet of the Academy of Munich, he obtained a spectrum of electric light in which he recognized a great number of light lines, and that he had determined the relative place of the lightest lines as well as the ratios of their intensities.

The introduction of the electric spark for the purpose of volatilizing metals was an important step in the development of spectral analysis, but although used by both Wollaston and Fraunhofer its true value in that particular line was not realized for many years after their time.

Fraunhofer is not only celebrated as one of the founders of spectrum analysis, but he is well known also as the inventor of many important philosophical instruments, being the constructor of the great Dorpat parallactic telescope, called by Struve _the giant refractor_. It was during the year 1814 that he measured and described the innumerable dark lines of the solar spectrum known as Fraunhofer’s lines, which were first noticed by Wollaston and reported upon by the latter to the Royal Society in 1802.

REFERENCES.--M. Merz, “Das Leben und Wirken Fraunhofers,” Landshut, 1865; Ninth “Encycl. Brit.,” Vol. IX. p. 727; “Abh. der K. Bayer, Akad. d. Wiss.” for 1814 and 1815; Fraunhofer’s biography in the “Memoirs of the Astronomical Society of London,” Vol. III. p. 117; his “Determination ...” München, 1819; Whewell, “Hist. of Ind. Sci.,” 1859, Vol. II. p. 475; _Sci. Am._, Nov. 19, 1887, p. 321; _Phil. Trans._ for 1814, pp. 204, 205, and for 1820, p. 95; Tyndall, “Heat as a Mode of Motion,” 1873, pp. 485, 486; article “Optics” in eighth “Encycl. Brit.,” Vol. XVI. pp. 544, 588, 591; Sir David Brewster’s article on “Electricity” in the “Encycl. Brit.”; “Mem. of the Roy. Bav. Acad. of Sci.” for 1822; “On the Spectrum of the Electric Arc,” in Jas. Dredge’s “Elec. Illum.,” Vol. I. pp. 32, 36; _Edin. Trans._, Vol. VIII for 1822; _Edin. Jour. Sci._, Vol. XIII. pp. 101, 251; _Biblioth. Univ._, Vol. VI. p. 21, as per Becquerel’s “Traité ...” Vol. I. p. 23; Dr. William A. Miller’s first and third lectures before the Royal Institution in 1867; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 136; Rich. A. Proctor, “Old and New Astronomy,” 1892, p. 787.

=A.D. 1815.=--Bohnenberger (Johann Joseph Friedrich von), 1765–1831, Professor of Mathematics and of Astronomy at the Tübingen University, constructs an extremely sensitive electrometer by suspending a single strip of gold leaf upon a wire midway between, though apart from, the insulated terminating discs of De Luc’s column.

With this contrivance he found that, however slightly the leaf was electrified, it was drawn to one of the poles according to the nature of the electricity affecting it, and he was thus enabled to observe not only the presence of the slightest electrical influence, but the kind of electricity which was present.

Noad gives, at p. 30 of his “Manual,” an illustration of the electrometer as subsequently improved by Becquerel, and states that Mr. Sturgeon describes (“Lectures on Galvanism,” 1843) a somewhat similar arrangement, the delicacy of which he states to be such that the cap (plate) being of zinc and of the size of a sixpence, the pendant leaf is caused to lean toward the negative pole by merely pressing a plate of copper, also the size of a sixpence, upon it, and when the copper is suddenly lifted up the leaf strikes. The different electrical states of the inside and outside of various articles of clothing were readily ascertained by this delicate electroscope.

M. Gottlieb Christian Bohnenberger, of Neuenberg (1732–1807), is the author of several works treating particularly of the electrical machine, the electric spark, the electric doubler, etc., published at Stuttgart between 1784 and 1798.

REFERENCES.--“La Grande Encyclopédie,” Vol. VII. p. 84; L. W. Gilbert, _Annalen der Physik_, Vols. XXIII (for Behrend’s); XLIX, LI (for “Beschreibung ... empfindlichen elektrometers ...”); _Annales de Chimie et de Physique_, Vol. XVI. p. 91; J. C. Poggendorff, “Biogr.-Liter. Handwörterbuch ...” Vol. I. p. 226; _Sci. Am. Supp._, No. 519, p. 8290, for Pouillet’s remarks upon the effectiveness of dry pile electroscopes; De la Rive, “Treatise on Electricity,” Vol. I. pp. 54–56.

=A.D. 1815.=--Mr. B. M. Forster sends to the _Philosophical Magazine_ (Vol. XLVII. pp. 344–345) the description of an electrical instrument called “The Thunderstorm Alarum,” which can be made to show the effect produced by the passage of a charged cloud over an _atmospherical electrometer_.

He had several years before described, at p. 205 of the same publication, a method of fitting up in portable form one of De Luc’s electrical columns, respecting which latter he subsequently addressed communications, which appeared in Vols. XXXV. pp. 317, 399, 468; XXXVI. pp. 74, 317, 472; XXXVII. pp. 197, 265, also relative to one which he constructed and which ran continuously for five months.

REFERENCES.--_Phil. Mag._, Vol. IV for 1828, p. 463; eighth “Britannica,” Vol. XXI. p. 619.

=A.D. 1815.=--Gregory (Olinthus Gilbert), LL.D., Professor of Mathematics at the Royal Military Academy, Woolwich, in his “Treatise on Mechanics,” London, 1815 (Vol. II. pp. 442–449), describes the methods of transmitting distant signals introduced by Polybius, the Marquis of Worcester, Robert Hooke, Amontons and Chappe, and alludes to an improved telegraph described in the “Gentleman’s Magazine,” as well as to the so-called nocturnal telegraph, of which an account is to be found in the _Repertory of the Arts and Manufactures_ (“Biographie Générale,” Tome XXI. p. 903).

=A.D. 1815.=--In the _Philosophical Magazine_ (Vol. XLVI. pp. 161, 259), will be found an account of the electrical experiments of M. De Nelis, of Mechlin, or Malines, in the Netherlands, with an extension of them by George J. Singer and Andrew Crosse.

These allude to many investigations made during previous years by M. De Nelis, who reported upon them to Mr. Tilloch and to M. de la Méthérie, and which show “very remarkable and permanent evidence of the expansive power of the electric charge.” Singer adds: “It is difficult to contemplate such extraordinary mechanical effects without admitting that the power by which they are produced has at least the leading characteristics of a material substance.” At p. 127, Vol. XLVIII of the _Phil. Mag._, is an account of some further electrical experiments of M. De Nelis, one of which is intended to improve the simple current with an apparatus not insulated by discs. In this communication, which bears date July 10, 1815, he discourses upon the theory of the two fluids.

=A.D. 1816.=--Coxe (John Redman), M.D., Professor of Chemistry in the University of Pennsylvania, is the second to propose a system of transmitting signals, based, like Sömmering’s (A.D. 1809), upon the discovery of Nicholson and Carlisle.

In the first series of Dr. Thos. Thomson’s _Annals of Philosophy_ for 1816 (not 1810), Vol. VII. pp. 162, 163, will be found Coxe’s letter “On the Use of Galvanism as a Telegraph,” wherein he says:

“I have contemplated this important agent as a probable means of establishing telegraphic communication with as much rapidity, and perhaps less expense, than any hitherto employed. I do not know how far experiment has determined galvanic action to be communicated by means of wires; but there is no reason to suppose it confined as to limits, certainly not as to time. Now, by means of apparatus fixed at certain distances, as telegraphic stations, by tubes for the decomposition of water, metallic salts, etc., regularly arranged, such a key might be adopted as would be requisite to communicate words, sentences or figures, from one station to another, and so on to the end of the line.... As it takes up little room, and may be fixed in private, it might in many cases of besieged towns, etc., convey useful intelligence with scarcely a chance of detection by the enemy. However fanciful in speculation, I have no doubt that, sooner or later, it will be rendered in useful practice. I have thus, my dear sir, ventured to encroach on your time with some crude ideas that may serve perhaps to elicit some useful experiments in the hands of others. When we consider what wonderful results have arisen from the first trifling experiments of the junction of a small piece of silver and zinc in so short a period, what may not be expected from the further extension of galvanic electricity? I have no doubt of its being the chief agent in the hands of nature in the mighty changes that occur around us. If metals are compound bodies, which I doubt not, will not this active principle combine their constituents in numerous places so as to explain their metallic formation; and if such constituents are in themselves aeriform, may not galvanism reasonably tend to explain the existence of metals in situations in which their specific gravities certainly do not entitle us to look for them?”

Coxe does not appear, however, to have at any time made satisfactory experiments, and his systems were considered impracticable until worked out by Alex. Bain during the year 1840.

At pp. 99–110, Vol. II of Dr. Coxe’s _Emporium of Arts and Sciences_, Philadelphia, 1812, will be found his illustrated “Description of a Revolving Telegraph,” for conveying intelligence by figures, letters, words or sentences, upon which plan, he says, he constructed a small telegraph that worked “readily and appropriately, although by no means fitted with the various pulleys, etc., to facilitate the motion of the ropes.”

REFERENCES.--For full explanation of Coxe’s systems, see L. Turnbull, “Elect. Mag. Tel.” Highton’s “Electric Telegraph,” p. 39; _Jour. Franklin Inst._, Vol. XXI. for 1851, pp. 332, 333; _Comptes Rendus_ for 1838, Vol. VII. pp. 593, etc.; _Sci. Am. Supp._, Nos. 404, p. 6446, and 453, p. 7234; Alfred Vail, “The American Electro-Magnetic Telegraph,” pp. 128, 129; Prime’s “Life of Morse,” p. 263.

=A.D. 1816.=--In Part I of the _Philosophical Transactions_ for 1816, and at p. 14, Vol. XLVII of the _Philosophical Magazine_, will be seen an account of the observations and experiments made by Mr. John T. Todd on the _torpedo_ off the Cape of Good Hope, during the year 1812 (“Abstracts of Papers ... Roy. Soc.,” Vol. II. p. 57).

It is said that the _torpedo_ in this locality is never more than eight nor less than five inches in length, and never more than five nor less than three and a half inches in breadth. Mr. Todd found the columns of their electrical organs to be larger and less numerous in proportion than those described by Hunter, and that they appeared to be of a cylindrical form, while from a number of experiments he drew, among other conclusions, the fact that a more intimate relation exists between the nervous system and electrical organs of the _torpedo_, both as to structure and functions, than between the same and whatsoever organs of any known animal. (See Hunter at A.D. 1773.)

Reports of another series of experiments, carried on by Mr. Todd at La Rochelle during 1816, will be found in the _Phil. Trans._ for the year following as well as at p. 57, Vol. II of the “Abstracts of Papers ... of the _Phil. Trans._, 1800–1830.” The last-named investigations were made especially to determine whether the _torpedo_ possessed any voluntary power over the electrical organs, either in exciting or interrupting their action, except through the nerves of these organs.

=A.D. 1816.=--Philip--Phillip--(Wilson), English physician, publishes in the _Philosophical Transactions_ a continuation of researches made by him to establish the relations existing between the phenomena of life and voltaic electricity. Noad gives (“Manual,” pp. 341–344) an account of some of the experiments made on animals to prove the analogy existing between the galvanic energy and the nervous influence, and he alludes also to the fact of asthma having been relieved by galvanism through Dr. Philip, whose treatment had received the endorsement of Dr. Clarke Abel, of Brighton.

REFERENCES.--_Journal of Science_, Vol. IX. See also Faraday’s “Experimental Researches,” 1791 and note; “Abstract of Papers ... _Phil. Trans._, 1800–1830,” Vol. II for 1822, p. 156.

=A.D. 1816.=--The Rev. James Bremmer, of the Shetland Islands, is rewarded by the Society of Arts for his night telegraph, the operation of which consists in the alternate exhibition and concealment of a torch in manner similar to that devised by Joachimus Fortius for Bishop Wilkins, as stated at A.D. 1641. This plan is said to have been successfully operated between the Copeland Island lighthouse and Port Patrick on the other side of the English Channel.

## Particulars of the above-named night telegraph, as well as of the

apparatus devised for day service, will be found in the _Trans. of the Soc. of Arts_, Vol. XXXIV. pp. 30, 213–227. The day telegraph consisted of a framework, having two circular openings, in each of which was a semicircular screen or shutter which, revolving upon an axis in the centre of the circle, was capable of assuming four different positions. This contrivance expressed an alphabet of sixteen letters, by dividing the latter into four classes of four each, and making one screen or shutter express the class, while the other indicated the number of the letter in that class.

=A.D. 1816.=--Sir Home Riggs Popham (1762–1820) British naval officer, who had been a rear-admiral in 1814, introduces his land semaphore which shows a great improvement upon all previous ones and at once replaces the Murray apparatus heretofore used by the English Admiralty (see A.D. 1795). It consists only of two arms placed upon the same hollow hexagonal mast, and movable upon separate pivots, each of which can be made to assume six different positions, giving together forty-eight different signals. It is fully described and illustrated at pp. 30, 167–177, Vol. XXXIV of the _Trans. of the Soc. of Arts_, and also appears in the “Telegraph” article, Vol. II of the “Encycl. of Useful Arts,” as well as at p. 149, Vol. XXIV of the “Penny Encycl.,” at pp. 67, 68, Vol. VIII of the (“Arts and Sciences”) “English Encycl.,” and in the “Telegraph” article by Sir John Barrow, one of the secretaries to the Admiralty, in the seventh “Britannica.”

In this same year (1816), Sir Home Popham also introduced a ship semaphore, which latter, as well as other similar devices of his construction, is to be found in the several publications already mentioned (the “Navy” article of the “Britannica” and pp. xii, xiii of Ronalds’ “Catalogue”).

=A.D. 1816.=--Ronalds (Francis), English experimentalist (1788–1873)--F.R.S., 1844, knighted 1870--whose serious attention to the development of electrical science appears to date from his meeting with M. De Luc in 1814, constructs at Hammersmith his telegraph which is the type of all dial instruments and which first presents the employment of two synchronous movements at the two stations. The telegraph is fully described and illustrated in the “Description of an Electrical Telegraph and of Some Other Electrical Apparatus,” 8vo, 83 pages, which Mr. Ronalds issued in pamphlet form, London, 1823, and which is said to be the first work published on electric telegraphy. Copious extracts from this are to be found at pp. viii-xi of the Ronalds “Catalogue,” and at pp. 129, 135–145, of Fahie’s “History,” the latter also containing several fine plates reproduced from the original work.

For his experimental line, Ronalds “erected two strong frames of wood at a distance of 20 yards from each other, and each containing 19 horizontal bars; to each bar he attached 37 hooks, and to the hooks were applied as many silken cords, which supported a small iron wire (by these means well insulated), which (making its inflections at the points of support) composed in one continuous length a distance of rather more than eight miles.” After making many experiments with this overhead line, he thus laid one underground:

“A trench was dug in the garden 525 feet in length, and four feet deep. In this was laid a trough of wood two inches square, well lined on the inside and out with pitch, and within this trough thick glass tubes were placed, through which the wire ran.”

His biographer, Mr. Frost, adds:

“In order to prevent the tubes from breaking by the variation of temperature, each length was laid a short distance from the next length, and the joint made with soft wax. The trough was then covered with pieces of wood, screwed upon it whilst the pitch was hot. They were also well covered with pitch, and the earth then thrown into the trench again.”

Mr. Edward Highton, at p. 40 of his work, the “Electric Telegraph,” 1852, says:

“Ronalds employed an ordinary electric machine and the pith-ball electrometer in the following manner. He placed two clocks at two stations; these two clocks had upon the second hand arbor a dial with twenty letters on it; a screen was placed in front of each of these dials, and an orifice was cut in each screen, so that only one letter at a time could be seen on the revolving dial. The clocks were made to go isochronously; and as the dials moved round the same letter always appeared through the orifices of each of these screens. The pith-ball electrometers were hung in front of the dials. The attention of the observer was called through the agency of an inflammable air gun fired by an electric spark.”

Realizing the value of his invention, Ronalds strove to bring it before the English Government, but was met (Aug. 5, 1816), with much the same encouragement we have seen vouchsafed Sharpe (A.D. 1813), and Wedgwood (A.D. 1814), viz. “Telegraphs of any kind are now wholly unnecessary and no other than the one now in use will be adopted.” The one alluded to was the semaphore line between London and Portsmouth, originally of the Chappe pattern and improved upon by Charles W. Pasley and Rear Admiral Popham.

Alluding to Mr. (afterward Sir) John Barrow’s letter in a note at p. 24 of his work Ronalds says:

“... Should they again become necessary, however, perhaps electricity and electricians may be indulged by his Lordship and Mr. Barrow with an opportunity of proving what they are capable of in this way.”

He was so disappointed that he not long after announced his “taking leave of a science which once afforded him a favourite source of amusement,” and that he was “compelled to bid a cordial adieu to electricity.” Fortunately for the scientific world, however, he afterward gave his attention again to electrical matters as is evidenced by many important papers contained in the publications noted below.

In Ronalds’ afore-named work the phenomenon of retardation of signals in buried wires is clearly foreseen and described, although Zetzsche endeavours to combat this assertion at p. 38 of his “Geschichte der Elektrischen Telegraphie,” Berlin, 1867. Speaking of the apprehended difficulty of keeping the wire charged with electricity, Ronalds suggests that when not at work “the machine be still kept in gentle motion to supply the loss of electricity by default of insulation; which default, perhaps, could not be avoided, because (be the atmosphere ever so dry, and the glass insulators ever so perfect), conductors are, I believe, robbed of their electricity by the same three processes by which Sir Humphry Davy and Mr. Leslie say that bodies are robbed of their sensible heat, viz. by radiation, by conduction, and by the motion of the particles of air.” He also gives descriptions of an improved electrical machine (eighth “Britannica,” Vol. VIII. p. 536; _Sci. Am. Supp._, No. 647, p. 10326; Noad’s “Manual,” p. 69), of a new method of electrical insulation and of some experiments on Vesuvius (_Quarterly Jour. of Sci._, Vols. II. p. 249; XIV. pp. 332–334), of a new electrograph for registering the charge of atmospheric electricity, of a pendulum doubler (_Edin. Phil. Jour._, Vol. IX, 1823, pp. 323–325) and of an attempt to apply M. De Luc’s electric column to the measurement of time. His other contributions relative to the dry pile are to be found in the _Phil. Mag._, Vols. XLIII. p. 414, and XLV. p. 466.

REFERENCES.--“Biog. Mem. of Sir Francis Ronalds, F.R.S.,” by Alfred J. Frost, in Ronalds’ “Catalogue”; “Mem. of Dist. Men of Science,” by William Walker; Ronalds’ “Corres. and Memoir.,” in 1848–1849, to 1853, to April 17, 1855, to June 5, 1856, to Sept. 2, 1862, and in 1866–1870; Ronalds’ “Walk Through ... Exh. of 1855”; _Illustrated London News_ of April 30, 1870; eighth “Britannica,” Vol. VIII. pp. 622, 627, for Ronalds’ improved electrometers and his telegraph; _Nature_, London, Nov. 23, 1871, Vol. V. p. 59; _Journal of the Telegraph_, March 15, 1875, Vol. VIII. p. 82, reporting the inaugural address of Mr. Latimer Clark before the English Society of Tel. Engineers; _Comptes Rendus_ for 1838, Vol. VII. pp. 593, etc.; _Sci. Am. Supp._, No. 384, pp. 6, 127; No. 547, p. 8735, and No. 659, p. 10521, for his Telegraph; “Bombay Mag. Observatory,” 1850; _Fortschrift des Phys._, Vol. III. p. 586, and Buys-Ballot “Meteor. Preisfrage,” 1847, for Ronalds’ apparatus to measure atmospheric electricity; _Phil. Mag._, Vols. XLIV. p. 442; XLV. p. 261; XLVI. p. 203; and third series, Vols. XXVIII for 1846; XXXI. p. 191; British Ass. Reports for 1845, 1846, and Reports concerning the Kew Observatory for 1845, 1850, 1852; _Phil. Trans._ for 1847, Moigno’s _Le Cosmos_, Vol. XIII; L. Von Forster, “All. Bauzeitung” for 1848, p. 238; Noad’s “Manual,” pp. 184, 185, 748; Knight’s “Mechanical Dictionary,” Vol. I. p. 708; Turnbull’s “Electro-magnetic Telegraph,” p. 22; _Annals of Electricity_, Vol. III. p. 449; “English Cyclop.” (Arts and Sci.), Vol. VIII. pp. 71, 72; _Jour. Soc. Teleg. Eng._, 1879,

## Part XV, xxxviii; Vol. VIII, first part, p. 361; Reply to Mr. W.

F. Cooke’s pamphlet, “The Elec. Teleg.: Was it Invented by Prof. Wheatstone?” London, 1855; Du Moncel, Vol. III; “Telegraphic Tales,” 1880, p. 42; J. D. Reid, “The Telegraph in America,” 1887, p. 71; Ure’s “Dict. of Arts,” etc., London, 1878, Vol. II (Elect. Metal.), p. 230; T. P. Schaffner, “Tel. Man.,” 1859, pp. 147–156; Silliman, “Principles of Physics,” 1869, p. 617; “Edin. Phil. Journal,” 1823, Vol. IX. pp. 322, 395.

=A.D. 1816.=--Porret (Robert) (1783–1868) communicates to the _Annals of Philosophy_ (Vol. VIII. p. 74) a paper “On Two Curious Galvanic Experiments” (Electrovection, Voltaic Endosmose, or Electro-chemical Filtration).

He observed that when water was placed in a diaphragm apparatus, one side of which was connected with the positive and the other side with the negative electrode of the battery, that a considerable portion of the liquid was transferred from the positive toward the negative side of the arrangement. It has since been found that the same result occurs in a minor degree when saline solutions are electrolyzed, and, generally, the greater the resistance which the liquid offers to electrolysis the greater is the amount which is thus mechanically carried over.... It appears from the researches of Wiedemann (Pogg., _Ann._, Vol. LXXXVII. p. 321), which have been confirmed by those of Quincke, that the amount of liquid transferred, _cæteris paribus_, is proportioned to the strength or intensity of the current; that it is independent of the thickness of the diaphragm by which the two portions of liquid are separated; and that when different solutions are employed, the amount transferred in each case, by currents of equal intensity, is directly proportional to the specific resistance of the liquid. Miller, from whom the above is taken, says that this transfer has been minutely studied by Quincke, and gives an account of the latter’s work extracted from the _Ann. de Chimie_, LXIII. p. 479. Brewster’s allusion to Porret and Wiedemann (eighth “Britannica,” Vol. VIII. p. 630) is followed by the statement that Mr. Graham considers ordinary endosmose as produced by the electricity of chemical action.

REFERENCES.--Graham, Vol. II. p. 266; De la Rive’s “Electricity,” Chap. IV. pp. 424–443; “Roy. Soc. Cat. of Sci. Papers,” Vol. IV. pp. 987, 988; Wm. Henry, “Elem. of Exp. Chem.” 1823, Vol. I. p. 178; C. Matteucci, “Traité des Phénom. Elect. Phys.,” 1844, p. 262 for Porret and Becquerel; Sturgeon’s “Sc. Researches,” Bury, 1850, p. 544; Poggendorff, Vol. II. p. 503; “Bibl. Britan.,” Vol. III, N.S., 1816, p. 15 (Thomson’s “Annals” for July 1816).

=A.D. 1817.=--Mr. J. Connolly makes known through an English and French pamphlet, entitled “An Essay on Universal Telegraphic Communication,” the details of his portable telegraph.

As shown in the thirty-sixth volume of the _Transactions of the Society of Arts_ and in the twenty-fourth volume of the “Penny Cyclopædia,” his apparatus consists merely of three square boards painted with simple devices, like triangles, crescents, etc., the colours on the one side being the reverse of those on the other. Each of the six figures thus obtained is capable of producing four different distinct signals, making in all twenty-four, by successively turning each side of the board downward. In experiments made at Chatham, boards only eighteen inches square were found to answer for a distance of two miles, with a telescope having a magnifying power of twenty-five; and Mr. Connolly had also, it is said, exhibited these signals between Gros-nez and Sarque, a distance of seventeen miles, with boards twelve feet square.

At pp. 205, 208, of the _Transactions of the Society of Arts_, 1818, Vol. XXXV, and at p. 98, Vol. XXXVI for 1819, will be found Mr. Connolly’s system of telegraphing by means of flags in manner different from that of Lieut.-Col. John Macdonald alluded to at Pasley, A.D. 1808.

=A.D. 1817.=--In the “Encycl. Brit.” article treating of the influence of magnetism on chemical action, it is said that M. Muschman, Professor of Chemistry in the University of Christiania, made experiments to ascertain the effect of the earth’s magnetism on the precipitation of silver.

Desirous of explaining the chemical theory of the tree of Diana (_Arbor Dianæ_, first observed by Leméry), “he took a tube like a siphon and poured mercury into it, which accordingly occupied the lower part of the two branches; above the mercury he poured a strong solution of nitrate of silver. He then placed the two branches of the siphon so that the plane passing through them was in the magnetic meridian, and after standing a few seconds the silver began to precipitate itself with its natural lustre; but it accumulated particularly in the northern branch of the siphon, while that which was less copiously precipitated in the other branch had a less brilliant lustre, and was mixed with the mercurial salt deposited from the solution.” Muschman and Prof. Hansteen, having repeated this experiment with the same result, concluded that the magnetism of the earth had an influence on the precipitation of silver from a solution of its nitrate, and Muschman inferred from the experiment the identity of galvanism and magnetism (eighth “Britannica,” Vol. XIV. p. 42).

=A.D. 1817.=--Freycinet (Claude Louis Desaulses de) (1779–1842), captain in the French navy, is sent in command of an expedition fitted out by the French Government for the purpose of making scientific observations in a voyage round the world. The experimental stations were the Island of Rawak (near the coast of Guinea), Guam (one of the Ladrones), the Isle of France, Mowi (one of the Sandwich Islands), Rio Janeiro, Port Jackson, Cape of Good Hope, Paris and the Falkland Islands, as described in his “Voyage Autour du Monde ...” Paris, 1842.

His observations on the diurnal variations of the needle, which confirm the investigations made by Lieut.-Col. John Macdonald (A.D. 1808), are to be found at p. 54, Vol. XIV of the eighth “Britannica.”

REFERENCES.--His “Voyage de Découvertes ... 1800–1804 ...” (F. Péron and Louis Freycinet), also his “Navigation et Géog. ...” 1815; the note at p. 158, Vol. I of Humboldt’s “Cosmos,” London, 1849; _Phil. Mag._, Vol. LVII. p. 20.

=A.D. 1817.=--In Vol. XLII. pp. 165, 166, of the _Transactions of the Society of Arts_ will be found a record of the explanation of his magnetic guard for needle pointers which Mr. Westcott made before the Committee of Mechanics during the year 1817. This is said to consist of several “bar magnets smeared over with oil placed in a frame behind the grindstone.”

=A.D. 1818.=--Bostock (John) (1774–1846), English physician, F.R.S., lecturer at Guy’s Hospital, publishes in London his “Account of the History and Present State of Galvanism,” which is scarcely more than a compilation of works treating of that branch of science.

One of the passages is, however, worth quoting, for it reflects the opinion shared by many physicists of the time that the resources of the galvanic field were already wellnigh exhausted. It thus appears at p. 102: “Although it may be somewhat hazardous to form predictions respecting the progress of science, I may remark that the impulse which was given in the first instance by Galvani’s original experiments, was revived by Volta’s discovery of the pile, and was carried to the highest pitch by Sir H. Davy’s application of it to chemical decomposition, seems to have, in a great measure, subsided. It may be conjectured that we have carried the power of the instrument to the utmost extent of which it admits; and it does not appear that we are at present in the way of making any important additions to our knowledge of its effects, or of obtaining any new light upon the theory of its

## action.”

Bostock is also the author of “Outline of the History of the Galvanic Apparatus”; “On the Theory of Galvanism” (_Nicholson’s Journal_ for 1802); “On the Hypothesis of Galvanism” (_Annals of Philosophy_, III, 1814), and of other works upon different scientific subjects. Reference is made by Mr. William Leithead (“Electricity,” London, 1837, Chap. VI. pp. 296, 297) to Bostock’s “Elementary System of Physiology,” 1827, Vol. II. pp. 413, etc., wherein is shown among other results, that, contrary to the views of Dr. Philip, there is no necessary connection between “the nervous influence” and the action of the glands. At p. 306 of Leithead appears another extract, from the third volume of Bostock, relative to the application of the electro-physiological theory in elucidating the phenomena of disease.

REFERENCES.--Poggendorff, Vol. I. pp. 249, 250; “Nicholson’s Journal,” Vols. II. p. 296, and III. p. 3; Figuier, “Expos. et Histoire,” 1857, Vol. IV. p. 425; Gilbert, Vol. XII. p. 476.

=A.D. 1819.=--Hansteen (Christoph) (1784–1873), Norwegian astronomer and physicist, embodies in his notable work, “Untersuchungen über den Magnetismus der Erde ...” (“Inquiries regarding the magnetism of the earth”), the result of his extensive researches concerning terrestrial magnetism, the account of which is accompanied by a chart indicating the magnetic direction and dip at numerous places. This work, which is said to have been practically completed in 1813 (Humboldt, “Cosmos,” 1859, Vol. V. p. 66), was translated by the celebrated Peter Andreas Hansen (Poggendorff, Vol. I. pp. 1013–1015) from the original manuscript and published in German. It attracted much attention throughout the scientific world, and so highly was it thought of that in almost all the voyages of discovery afterwards undertaken most magnetic observations were made according to its directions.

Through the “Encyclopædia Britannica” we learn that Hansteen’s able work was first made known in England by Sir David Brewster through two articles in the _Edin. Phil. Journal_ for 1820, Vol. III. p. 138, and Vol. IV. p. 114, and that an account of his subsequent researches, drawn up by Hansteen himself, appeared in the _Edin. Journal of Science_ for 1826, Vol. V. p. 65. It is also stated that the Royal Society of Denmark proposed in 1811 the prize question, “Is the supposition of one magnetical axis sufficient to account for the magnetical phenomena of the earth, or are two necessary?” Prof. Hansteen’s attention had been previously drawn to this subject by seeing a terrestrial globe, on which was drawn an elliptical line round the south pole and marked _Regio polaris magnetica_, one of the foci being called _Regio fortior_, and the other _Regio debilior_. As this figure professed to be drawn by Wilcke, from the observations of Cooke and Furneaux, Hansteen was led to compare it with the facts; and the result of his researches was favourable to that part of Halley’s theory which assumes the existence of four poles and two magnetic axes. Hansteen’s Memoir, which was crowned by the Danish Society, forms the groundwork of his larger volume published in 1819. “In his fifth chapter, on the Mathematical Theory of the Magnet, he deduces the law of magnetic action from a series of experiments similar to those of Hauksbee and Lambert.... In determining the intensity of terrestrial magnetism Professor Hansteen observed that the time of vibration of a horizontal needle varied during the day. Graham had previously suspected a change of this kind, but his methods were not accurate enough to prove it. Hansteen found that the minimum intensity took place between ten and eleven a.m., and the maximum between four and five p.m. He concluded also that there was an annual variation, the intensity being considerably greater in winter near the perihelion, and in summer near the aphelion; that the greatest monthly variation was a maximum when the earth is in its perihelion or aphelion, and a minimum near the equinoxes; and that the greatest daily variation is least in winter and greatest in summer. He found also that the aurora borealis weakened the magnetic force, and that the magnetic intensity is always weakest when the moon crosses the equator.”

According to Dr. Whewell (“History of Induc. Sciences,” 1859, Vol. II. p. 226), the conclusions reached by Hansteen respecting the position of the four magnetic “poles” excited so much interest in his own country that the Norwegian Storthing, or Parliament, by a unanimous vote provided funds for a magnetic expedition which he was to conduct along the north of Europe and Asia, and this they did at the very time when, strange to say, they refused to make a grant to the King for building a palace at Christiania. The expedition was made in 1828–1830, and verified Hansteen’s anticipations as to the existence of a region of magnetic convergence in Siberia, which he considered as indicating a “pole” to the north of that country. The results were published in Hansteen and Due’s “Resultate magnetischer ...” (“Magn., Astron. and Méteor. Obs. on Journey through Siberia”) which appeared in 1863.

In the Sixth Dissertation, Chap. VII of the “Encycl. Brit.,” it is said that, next to Prof. Hansteen, science is mainly indebted for the great extension of our knowledge of the facts and the laws of terrestrial magnetism to two illustrious German philosophers, Baron Alexander von Humboldt and Prof. Karl Friedrich Gauss (1777–1855). An account is therein given of Gauss’s individual investigations, as well as of the researches he made in conjunction with Wilhelm Eduard Weber (1804–1891), who was likewise a professor at Göttingen. Of Alex. von Humboldt, we have spoken fully under date 1799, and of Gauss and Weber, mention has already been made at Schilling (A.D. 1812).

The very valuable contributions of Gauss and Weber appear throughout all the many scientific publications of the period, notably in the “Abhandlung d. Gött. Geselsch. d. Wiss.,” their joint work being shown to advantage in the important “Resultate ... des Magnet. Vereins,” published in Leipzig, 1837–1843.[58]

REFERENCES.--For M. Hansteen’s scientific papers and for an account of additional magnetic results obtained by himself and others, consult the eighth “Britannica,” Vols. I. p. 745; IV. p. 249; XIV. pp. 15, 23, 42 (experiment with M. Muschman), 50, 55, 57–64, _et seq._, for Morlet and others; Thomson’s “Outline of the Sciences,” London, 1830, pp. 546–548; Whewell, “History of the Induc. Sci.,” Vol. II. pp. 613, 615, also p. 219 for Yates and Hansteen; Johnson’s new “Univer. Encycl.,” 1878, Vol. III. pp. 231–234 for Morlet, etc.: Weld’s “Hist. of Roy. Soc.,” Vol. II. p. 435; “Edin. Jour. of Sci.,” London, 1826, Vols. I. pp. 87, 334; V. pp. 65–71, 218–222; “Report of Seventh Meeting British Association,” London, 1838, Vol. VI. pp. 76, 82; J. G. Steinhauser’s articles published between 1803 and 1821; Harris’ “Rudimentary Magnetism,” London, 1852, Part. III. pp. 38, 39, 111; _Phil. Mag._, Vol. LIX. p. 248, and _Phil. Mag._ or _Annals_, Vol. II. p. 334; “Zeitschr. f. pop. Mitth.,” I. p. 33; Schweigger’s _Journal_, 1813–1827; Poggendorff’s _Annalen_, 1825–1855; “Académie Royale de Belgique” for 1853, 1855, 1865; C. Hansteen and C. Fearnley, “Die Univ.-Sternwarte ...” 1849; Hansteen, Lundh and Muschman, “Nyt. Mag. for Naturvid,” 1823–1856. See likewise his biography in the “English Cyclop. Supplement,” pp. 642, 643; “Catal. Roy. Soc. Sc. Pap.,” Vol. III. pp. 167–172; Vol. VI. p. 681, Vol. VII. p. 905; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 157; “Edin. Phil. Journal,” 1823, Vol. IX. p. 243; “Annual Rec. Sc. Disc.,” 1873, p. 683; 1875, p. 155; Knight’s “Amer. Mech. Dict.,” 1875, Vol. II. p. 1374, and eighth “Britan.,” Vol. XIV. p. 49, regarding Hansteen’s lines of no variation for 1787; Humboldt’s “Cosmos,” 1859, Vol. V. pp. 110–111, for the investigations of Hansteen, Sir Ed. Belcher and others, those of the last named being treated of at p. 493 of the _Phil. Trans._ for 1832; Noad, “Manual,” pp. 529, 530, 534, 616, 617, etc.; Appleton’s “New Am. Cycl.,” Vol. XI. p. 64.

=A.D. 1819.=--Hare (Robert) (1781–1858) who was for twenty-nine years Professor of Chemistry in the Pennsylvania University, publishes in Philadelphia “A New Theory of Galvanism, Supported by Some Experiments and Observations Made by Means of the Calorimotor ...” of which an English edition appears in London the same year. (A full review of this work is to be found more particularly at p. 206, Vol. LIV of the _Philosophical Magazine_; in the “Encycl. Metropol.,” Vol. IV (Galvanism), p. 222; in Ure’s “Dictionary of Chemistry,” Am. ed., article “Calorimotor”; at p. 187 of the _Phil. Trans._ for 1823; at pp. 409, 410, Vol. I of Gmelin’s “Chemistry,” and at pp. 413–423, Vol. I of Silliman’s _Am. Jour. of Sci._, the last named being accompanied by a very fine illustration of the Calorimotor.)

This apparatus, which has already been alluded to (Pepys, A.D. 1802), consists of sheets of zinc about 9 inches by 6, and of copper about 14 inches by 6, coiled around one another nearly half an inch apart; there being in all 80 coils, 2½ inches in diameter, which are let down by means of a lever into glass vessels containing the acid solution. Dr. Hare observes:

“Volta considered all galvanic apparatus as consisting of one or more electromotors, or movers of the electric fluid. To me it appeared that they were movers of both heat and electricity; the ratio of the quantity of the latter put in motion to the quantity of the former put in motion being as the number of the series to the superficies. Hence the word _electromotor_ can only be applicable when the caloric becomes evanescent, and electricity almost the sole product, as in De Luc’s and Zamboni’s columns; and the word _calorimotor_ ought to be used when electricity becomes evanescent and caloric appears the sole product.”

“It afterwards appeared quite natural,” remarks Mr. W. B. Taylor (Note B, “Mem. of Jos. Henry,” p. 376) “to distinguish these classes of effects by the old terms--‘intensity’ for electromotive force, and ‘quantity’ for calorimotive force. There is obviously a close analogy between these differences of condition and resultant, and the more strongly contrasted conditions of mechanical and chemical electricity; and indeed the whole may be said to lie in a continuous series, from the highest ‘intensity’ with minimum quantity, to the greatest ‘quantity’ with minimum intensity.”

Two years later (1821), Dr. Hare constructed his _galvanic deflagrator_. It consists of two pairs of troughs, each ten feet long, and containing 150 galvanic pairs, so arranged that the plates can all be simultaneously immersed into or withdrawn from the acid. Each pair turns on pivots made of iron, coated with brass or copper, and a communication is established between these and the voltaic series within by means of small strips of copper. The “Encycl. Brit.” gives a full description of the construction and working of the apparatus, as do also the “Encycl. Metropol.,” Vol. IV (Galv.), p. 176; Noad (“Manual,” pp. 266, 267); Gmelin (“Chemistry,” Vol. I. pp. 409, 410), and Silliman (“Journal of Sci. and Arts,” Vol. VII. p. 347). The first-named publication says of Dr. Hare’s _deflagrator_:

“A brilliant light, equal to that of the sun, was produced between charcoal points, and plumbago and charcoal were fused by Profs. Silliman and Griscom. By a series of 250, baryta was deflagrated, and a platina wire, three-sixteenths of an inch in thickness, ‘was made to flow like water.’ In the experiments with charcoal, the charcoal on the copper side had no appearance of fusion, but a crater-shaped cavity was formed within it, indicating that the charcoal was volatilized at this side and transferred to the other, where it was condensed and fused, the piece of charcoal at this pile being elongated considerably. This fused charcoal was four times denser than before fusion. In a letter from Prof. Silliman, which was transcribed in the _Sc. Am. Sup._ for Sept. 21, 1878, he says: ‘Undoubtedly the earliest exhibitions of electric light from the voltaic battery were those made with the deflagrators of Dr. Hare by Prof. Silliman at New Haven in 1822, and subsequently on a magnificent scale at Boston in 1834, when an arc of over five inches diameter was produced by the simultaneous immersion of 900 large-sized couples of Hare’s deflagrator. But no means had then been devised for the regulation of the electric light to render it constant, and although the writer as early as 1842 used this light successfully to produce daguerreotypes, the progress of invention had yet to make further use of the discovery of science before electrical illumination was possible.’”

The description of Dr. Hare’s electrical machine (before alluded to at Van Marum A.D. 1785), wherein the plate is mounted horizontally so as to show both negative and positive electricity, was published in London during 1823, and can be found in Vol. LXII of the _Phil. Mag._, as well as at pp. 538, 604, 605, Vol. VIII of the 1855 “Encycl. Brit.” In the last-named article mention is made of the introduction of a band (illustrated Fig. 7, Plate CCXXII) which prevents the plate from being cracked, as it frequently is, through some hasty effort to put it in motion while it adheres to the cushions. It is also therein stated that in order to offset the heavy expense attending the breakage of large cylinders and plates, M. Walkiers de St. Amand, of Brussels, among many others, made an apparatus of varnished silk 25 feet long and 5 feet wide, capable of giving sparks 15 inches long (see A.D. 1785), while Dr. Ingen-housz constructed machines with pasteboard discs four feet in diameter, soaked in copal or amber varnish dissolved in linseed oil, which gave sparks of one and even two feet in length.

In the fifth volume, new series, of the _Amer. Phil. Trans._ will be found Dr. Hare’s “Description of an Electrical Machine,” with a plate four feet in diameter, so constructed as to be above the operator; also of a battery discharger employed therewith, and some observations on the causes of the diversity in the length of the sparks erroneously distinguished by the terms positive and negative. Hare is also the inventor of a single gold-leaf electroscope of such great delicacy that it has, he says, enabled him to detect the electricity produced by one contact between a zinc and copper disc, each six inches in diameter (Noad, “Manual,” p. 29; Harris’ “Rudim. Elect.,” p. 50; Silliman’s _Journal_, Vol. XXXV). He invented several other electrical appliances, and he is likewise the author of numerous important memoirs which it would be impossible to detail in the narrow limits of this “Bibliographical History.” They will, however, be found recorded in the publications named below.

REFERENCES.--_Phil. Trans._ for 1769, Vol. LXIX. p. 659. See also, for Walkiers de St. Amand, the entry at A.D. 1785, as well as Lichtenberg’s _Magazin_, Vol. III, 1st, p. 118, for the last-named year. To these might be added the machines made by Mundt, of silken strips (Gren’s _Journal der Physik._, Vol. VII. p. 319); by N. Rouland, “Descript. des mach, elec. à taffetas,” Amsterdam, 1785; by Croissant and Thore; of paper by W. H. Barlow (_Phil. Mag._, Vol. XXXVII. p. 428), of gutta percha; as well as machines of rubber by Fabre and Kunneman, as shown at Th. Du Moncel’s “Exposé des appl. de l’El.,” second ed., p. 399, and third ed., 1872, Vol. II. pp. 78, 122, 265, besides the peculiarly constructed machines of Erdmann Wolfram (Ferussac, “Bulletin des Sciences Tech.” for 1824); of G. H. Seiferheld, “Beschreib ... elektrische mach,” 1787; of F. E. Neuman, as modified by F. Zantedeschi (“Ann. Sci. Lom.-Ven.,” XII. p. 73), and of those described at p. 420, Vol. II, and at p. 4, Vol. III of _Nicholson’s Magazine_. Consult likewise, pp. 335, 340, second Am. ed. of the “New Edin. Encycl.,” 1817. Poggendorff, Vol. I. pp. 1018, 1019; “Cat. Sci. Papers of Roy. Soc.,” Vol. III. pp. 177–182; Vol. VI. p. 182; Silliman’s _Am. Jour. Sci. and Arts_, Vols. II. pp. 312, 326; III. p. 105; IV. p. 201; V. p. 94; VII. pp. 103, 108, 351; VIII. pp. 99, 145; X. p. 67; XII. p. 36; XIII. p. 322; XV. p. 271; XXIV. p. 253, XXV. p. 136; XXXI. p. 275; XXXII. pp. 272, 275–278, 280–285; XXXIII. p. 241; XXXV. p. 329; XXXVII. pp. 269, 383; XXXVIII. pp. 1, 336, 339; XXXIX. p. 108; XL. pp. 48, 303; XLI. p. 1, and XLIII. p. 291; _Phil. Mag._, Vols. LVII. p. 284; LXII. pp. 3, 8, etc.; _Phil. Mag._ or _Annals_, Vol. VI. pp. 114, 171; _Journal of the Franklin Institute_, third series. Vol. XV. pp. 188, etc.; _Trans. of the Am. Phil. Soc._, N.S., Vol. VI. p. 297 (for Hare and Allen) also pp. 339, 341, 343, and Vol. VII for 1841; “Mem. Jos. Henry,” Washington, 1880, p. 82; Figuier, “Exp. et Hist.,” 1857, Vol. IV. pp. 391, 401, 402; Dr. Thomas Thomson, “Outline of the Sc.,” London, 1830, pp. 515, 517; Appleton’s “New Amer. Cycl.,” Vol. VII. p. 66; Appleton’s “Dict. of Machines, Mechanics ...” 1861, pp. 432, 433; Dr. William Henry, “Elem. of Exper. Chem.,” London, 1823, Vol. I. p. 169, and Supplement, Chap. VII. p. 29; “Annual of Sc. Disc.” for 1862, p. 99.

=A.D. 1819.=--Gmelin (Leopold), the most distinguished member of the family of that name, publishes, at Frankfort, 1817–1819, the first edition of his celebrated “Handbuch d. theoret. Chemie,” which embodies the whole extent of chemical science as it then existed and the fourth and last edition of which, under the author’s supervision, appeared during 1843–1845. This extensive work is well known, both in its original form and through the very able translation of it made by Mr. Henry Watts. In the report of the Council of the Chemical Society for 1854, it is said that “the greatest service which Gmelin rendered to science--a service in which he surpassed all his predecessors and all his contemporaries--consists in this: that he collected and arranged in order all the facts that have been discovered in connection with chemistry. His Handbuch der theoret Chemie stands alone. Other writers on chemistry have indeed arranged large quantities of materials in systematic order, but for completeness and fidelity of collation and consecutiveness of arrangement, Gmelin’s Handbuch is unrivalled.”

Although many references have been made herein to Leopold Gmelin’s treatment of such departments of science as directly appeal to the readers of this compilation, it is well to mention some of the headings under which they are to be found. They are, “Electricity,” “Electro-chemical Theories,” “Electrolysis,” “Technical Apparatus of Electricity,” “Theory of Galvanism,” “Galvanic Batteries,” “Magnetic Condition of All Matter,” etc., etc., the whole occupying pp. 304 to 519, Vol. I of Gmelin’s English edition. The list of many of Leopold Gmelin’s valuable contributions to science is given in the “Catalogue Sc. Papers Roy. Soc.,” besides which may be mentioned his “Uber e angebl. meteorische masse” (Gilbert, _Annalen_, LXXIII for 1823), and his “Versuch einer elektro-chemisch. theorie” (Poggendorff’s _Annalen der Physik und Chemie_, Vol. XLIV for 1838, while at pp. 547–550 of Mr. J. J. Griffin’s able work, published in London during 1858, will be found the results obtained by Prof. G. Magnus and by Prof. Faraday with a summary of Gmelin’s conclusions under the heading of “The Evidence of Electrolysis in Favour of the Radical Theory.”

GMELIN FAMILY

This family, which, through four generations, has been continuously distinguished for its valuable contributions to chemistry as well as to the natural and medical sciences, deserves equally well here of such a special mention as was accorded to the Bernoulli and Cassini families, under dates A.D. 1700 and 1782–1791.

Johann Georg Gmelin (1674–1728), a very able chemist and pharmaceutist of Tübingen, was the father of:

Johann Conrad Gmelin (1707–1759), physician and author in the same city of Tübingen.

Johann Georg Gmelin (1709–1755), distinguished naturalist and chemist, who graduated as M.D. in his nineteenth year, became a member of the St. Petersburg Acad. of Sc. and was sent by the Empress Anna, in company with G. A. Müller and other noted scientists, upon a ten years’ exploring expedition through Siberia. He was one of the first explorers of Northern Asia, and a genus of Asiatic plants was named Gmelina after him by Linnæus.

Philip Friedrich Gmelin (1722–1768), Professor of Botany and of Chemistry at Tübingen, author of many scientific monographs.

Samuel Gottlieb Gmelin (1744–1774), elder son of Philip Friedrich, who, like his uncle, graduated M.D. at nineteen and was sent two years later by the Empress Catherine II upon a scientific tour through South-Eastern Russia, is the author of “Historia Fucorum ...” as well as of other contributions which were edited through the famous Pallas. His biographical notice appears in the last volume of the “Reise durch Russland ...” published at St. Petersburg.

Johann Friedrich Gmelin (1748–1804), M.D., succeeded his father, Philip Friedrich, in the chair of chemistry and botany at the Tübingen University, became Professor of Medicine at Göttingen in 1778 and a member of “l’Académie des Curieux de la Nature.” He is the author of the thirteenth edition of Linnæus’ “Systema Naturæ,” which, notwithstanding Cuvier’s severe criticism of it, is said to be the only work which even professes to embrace all the objects of natural history described up to the year 1790 (“Encycl. Brit.,” 1855, Vol. IX. p. 4). He is also the author of “Geschichte der Chemie ...” Göttingen, 1797–1799, and of “Prælectio de col. metal. a Volta ...” (“Commentat. Soc. Gött.” XV (Phys.) for 1800–1803, p. 38). (See J. C. Poggendorff, “Biogr.-Literar. Handwörterbuch,” Vol. I. pp. 914–915.)

His son, Leopold Gmelin (1788–1853), who has already been noticed, practised chemical manipulation in the Tübingen pharmaceutical laboratory of Dr. Christian Gmelin, the son of Johann Conrad, and studied at Göttingen, Vienna and in Italy, after which he became medical and chemical professor at Heidelberg, 1817–1851 (Poggendorff, Vol. I. pp. 915–916).

Ferdinand Gottlob von Gmelin (1782–1848), elder son of Dr. Christian Gmelin, was Professor of Medicine and of Natural History in the Tübingen University, and wrote “Diss. sistens obs. phys. et chem. de electricitate et galvanismo” during 1802 (Poggendorff, Vol. I. pp. 916–917).

Christian Gottlob Gmelin (1792–1860), brother of the last named, M.D., was Professor of Chemistry and Pharmacy at the Tübingen University, and the author of “Experimenta electricitatem ...” 1820; “Uber d. Coagulat. ... d. Electricität” (Schweigger’s “Journal,” Vols. XXXVI for 1822); “Analyse d. turmalins ...” (Schweigger’s “Journal,” Vols. XXXI for 1821 and XXXVIII for 1823--Poggendorff’s “Annalen,” Vol. IX for 1827), as well as of a “Handbuch der Chemie,” published 1858–1861 (Poggendorff, Vol. I. p. 917; _Phil. Mag._ or _Annals_, Vol. III. p. 460).

REFERENCES.--Gmelin and Schaub, “Effets Chimiques de la col. metal ...” (“Magas. Encyclop.,” Vol. VI. p. 201); Eberhard Gmelin’s letter to M. Privy Councillor Hoffmann of Mayence (1787), and his new investigations (1789) on the subject of animal magnetism (“Salzb. Med. Chir. Zeit.,” 1790, I. p. 358); Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. II. p. 348.

=A.D. 1819.=--Dana (J. F.), M.D. (1793–1827), Chemical Assistant in Harvard University and Lecturer on Chemistry and Pharmacy in Dartmouth College, writes, Jan. 25, 1819, to Prof. Benjamin Silliman concerning his new form of portable electrical battery.

This apparatus, consisting of alternate plates of flat glass and of tinfoil, the sheets of which latter are connected together, is fully described at pp. 292–294, and is illustrated opposite p. 288, Vol. I of Silliman’s _American Journal of Science_, 1818, wherein it is stated that, while “in a battery of the common form, 2 feet long, 1 foot wide and 10 inches high, containing 18 coated jars, there will be no more than 3500 square inches of coated surface,” a battery of Dana’s construction will have no less than 8000 square inches covered with tinfoil, allowing the sheet of glass and of foil to be a quarter of an inch thick. In a brief description of this apparatus, which appears at p. 468, Vol. V of Tilloch’s _Phil. Mag. and Journal_, it is stated that a “battery constructed in this way contains, in the bulk of a quarto volume, a very powerful instrument; and when made of glass it is extremely easy, by varnishing the edges, to keep the whole of the inner surfaces from the air, and to retain it in a constant state of dry insulation.”

=A.D. 1820.=--Oersted--Örsted (Hans Christian), native of Denmark (1770–1851), Professor of Natural Philosophy and founder of the Polytechnic School in Copenhagen, makes known, through a small four-page pamphlet entitled “Experimenta circa effectum conflictus electrici in acum magneticam,” his great discovery of the intimate relation existing between electricity and magnetism (Thomson’s _Annals of Philosophy_ for October 1820, Vol. XVI, first series, pp. 273–276). He thus lays the foundation of the science of electro-magnetism, which subsequently was so materially developed by Ampère and Faraday.

It is said that after taking his doctor’s degree in 1799, he gave much attention to galvanism, and that in the year 1800 he made important discoveries as to the action of acids during the production of galvanic electricity. He was one of the earliest to show the opposite conditions of the poles of the galvanic battery, also that acids and alkalies are produced in proportion as they neutralize each other. Upon his return from a trip to France and Germany, 1801–3, he lectured on electricity and the cognate sciences, publishing thereon a number of essays. (These are to be found, more particularly, in J. H. Voigt’s _Magazin_, Vol. III. p. 412; Van Mons’ _Journal_, No. IV. p. 68; the _Bulletin of the Société Philomathique_, No. LXVII. an. xi. p. 128; A. F. Gehlen’s _Neues Allgem. Journal d. Chemie_, Vols. III for 1804, VI for 1806, VIII for 1808; Schweigger’s _Journal_, Vol. XX; _Phil. Mag._, Vol. XXIII. p. 129; the “Skand. Lit.-Selskabs Skrifter,” Vol. I; “Oversigt over det Kongl. ... Forhandlinger,” 1814–1815; “Nyt Biblioth. f. Physik,” etc., Vol. IX, and in the _Journal de Physique_ as well as in the _Journal du Galvanisme_.)

He revisited Germany during 1812, and, at the suggestion of Karsten Niebuhr, published in Berlin his work “Ansicht der Chemischen Naturgesetze. ...” (“Inquiry into the identity of chemical and electric forces”), a translation of which was made by M. P. Marcel T. de Serres under the title of “Recherches sur l’Identité. ...” (Fahie, “Hist. of Electric Teleg.,” 1884, pp. 270–273). The last-named work appeared at Paris during 1813, and not, as stated at p. 41, Vol. LVII of the _Philosophical Magazine_, during 1807, which was the date of the original small German edition.[59]

One of his biographers says that Oersted was lecturing one day to a class of advanced students, when, as a means of testing the soundness of the theory which he had long been meditating, it occurred to him to place a magnetic needle under the influence of a wire uniting the ends of a voltaic battery in a state of activity. “In galvanism,” said he, “the force is more latent than in electricity, and, still more so in magnetism than in galvanism; it is necessary therefore to try whether electricity, in its latent state, will not affect the magnetic needle.” He tried the experiment upon the spot and found that the needle tended to turn at right angles to the wire, thus proving the existence of electro-magnetism, or the relation of electricity and magnetism as mutually productive of each other, and as evidences of a common source of power. Previous to this time the identity of magnetism and electricity had only been suspected. For several months Oersted prosecuted experiments on the subject, and on the 21st of July 1820 promulgated his discovery through the Latin pamphlet above alluded to. Therein he contends that there is always a magnetic circulation around the electric conductor, and that the electric current in accordance with a certain law always exercises determined and similar impressions on the direction of the magnetic needle, even when it does not pass through the needle but near it (the eighth edition of the “Encycl. Britannica,” Fifth Dissertation, pp. 739, 740, 745; and the Sixth Dissertation, pp. 973–976; Schaffner, “Tel. Manual,” 1859, Chap. VIII; _Practical Mechanic_, Glasgow, 1842, Vol. III. p. 45).

For this discovery, which naturally excited the wonder of the entire scientific world, he received the Copley medal of the English Royal Society, the Dannebrog order of knighthood and numerous testimonials from nearly every quarter of Europe. As observed by Mr. J. D. Forbes (Sixth Disser. “Encycl. Brit.,” Vol. I), “the _desideratum_ of a clear expression of the manifest alliance between electricity and magnetism has been so long and so universally felt that the discovery placed its author in the first rank of scientific men.... The prize of the French Institute, which had been awarded to Davy for his galvanic discoveries, was bestowed upon Oersted.”

Oersted’s experiments were repeated before the French Academy of Sciences by M. De la Rive on Sept. 11, 1820, and, seven days later, as we shall see, Ampère made known the law governing electro-magnetism (Mme. Le Breton, “Hist. et. Appl. de l’Elect.,” Paris, 1884, pp. 72, 73; W. Sturgeon, “Sci. Researches,” Bury, 1850, p. 18; Higg’s Translation of Fontaine’s “Electric Lighting,” London, 1878, p. 54).

The many investigations subsequently carried on by Oersted in different branches of sciences are alluded to in the works named below. Perhaps the most interesting, outside of the ones already spoken of, are those attaching to thermo-electricity which he made in conjunction with Baron Fourier, and independently of Dr. Seebeck.

REFERENCES.--Eighth “Britannica,” pp. 651 and 652, Vol. XXI, as well as pp. 11 and 12, Vol. XIV of Oersted’s “Efterretning om nogle nye, af Fourier og Oersted ...” Kiobenhaven, 1822–1823, translated into French as mentioned in Vol. XXII of the _Annales de Chimie et de Physique_; “Oversigt over det Kongl. ...” for 1822–1823 and 1823–1824; Poggendorff, Vol. III. pp. 309–312; “Catal. Sci. Papers Roy. Soc.,” Vol. I. pp. 697–701; Biog. Sketch by P. L. Möller, “Oersted’s Character und Leben,” 1851, also Hauch und Forchammer, 1853; Obituary notice in _Jour. Frankl. Inst._, 1851, Vol. XXI. p. 358; Humboldt, “Cosmos,” 1849, Vol. I. pp. 182, 185 and the 1819–1820 entry of “Magnetic Observations,” in Vol. V; “Oversigt over det Kongl. danske Videnskabernes Selskabs Fordhandlinger” for 1822, 1832, 1834–1835, 1836–1837, 1840–1842, 1847–1849; Poggendorff’s _Annalen_, Vol. LIII; “Ursin’s Magaz. f. Kunstnere ...” Vols. I and II; “Dict. of Electromagn.,” 1819; Sturgeon’s _Annals of Electricity_, Vol. I. p. 121; Hatchett “On the Experim. ... of Oersted and Ampère” (_Phil. Mag._, Vol. LVII. p. 40), _Phil. Mag._, Vols. LVI. p. 394; LVII. pp. 47–49; LIX. p. 462; _Phil. Mag._ or _Annals_, Vol. VIII. p. 230; _Annales de Chimie_ for Aug. 1820, p. 244; S. S. Eyck, “Over de magnetische ...” (_Bibl. Univ._, 1821); Translation by H. Sebald, of H. C. Oersted’s “Leben,” 1853; Michaud, “Biog. Univ.,” Vol. XXXI. p. 196; P. L. Möller, “Der Geist in der Natur” (”The Spirit in Nature”); Elie de Beaumont, “Memoir of Oersted” (“Smith. Rep.” for 1863); Gilbert’s _Annalen_, Vol. LXVI. p. 295, 1820; Callisen, “Medicinisches Schriftseller-Lexikon”; W. Sturgeon’s “Sci. Researches,” Bury, 1850, p. 8 (for 1807), and pp. 9–12 for English version of Oersted’s pamphlet which was translated in German in Vol. XXIX of Schweigger’s “Journal,” as well as in Vol. LXVI of Gilbert’s _Annalen_, and which appeared in French in Vol. XIV of the _Annales de Chimie et de Physique_ for 1820, as well as in Vol. II. pp. 1–6 of “Collection de Mémoires relatifs à la Physique,” Paris, 1885. See also “Biogr. Gén.,” Vol. XXXVIII. pp. 522–535; “Göttinger Gelehrte Anz.,” No. 171; Sturgeon’s “Sc. Researches,” pp. 17, 18, 28, 415; Thomson’s “Annals of Philosophy,” Vol. XVI. p. 375 for second series of observations; Van Marum on “Franklin’s Theory of Electricity,” pp. 440–453; “Galvanism,” by Mr. John Murray, p. 467; “Note sur les expériences ... de Oersted, Ampère, Arago, et Biot,” (_Annales des Mines_, 1820); L. Turnbull, “Elec. Mag. Tel.,” 1853, pp. 45, 221; J. F. W. Herschel’s “Preliminary Discourse,” 1855, pp. 244, 255; Fahie, “Hist. Elec. Tel.,” 1884, pp. 270–275, Harris, “Rud. Elec.,” 1853, p. 171; Ostwald’s _Klassiker_, No. 63 and “Elektrochemie,” 1896, p. 67; Mrs. Somerville, “Con. of Phys. Sci.,” 1846, p. 314; Noad, “Manual,” p. 642; “Lib. Useful Know.” (El Magn.), pp. 4, 79; Lardner’s “Lectures,” 1859, Vol. II. p. 119; Tomlinson’s “Cycl. Useful Arts,” Vol. I. p. 559; Ure’s “Dict. of Arts,” 1878, Vol. II. p. 233; Henry Martin’s article in Johnson’s “New Cyclopædia,” 1877, Vol. I. pp. 1512, 1514; “Nyt Biblioth. f. Physik,” Band I auch Scherer’s Nord. Arch., II; “Tidskrift f. Natur ...” I 1822: Schumacher’s “Astron. Jahrbuch” for 1838; L. Magrini, “Nuovo metodo ...” Padova, 1836; Boisgeraud “On the Action of the Voltaic Pile ...” (_Phil. Mag._, Vol. LVII. p. 203); _Sci. Am. Suppl._, No. 454, p. 7241; Schweigger’s _Journal_, Vols. XXXII, XXXIII, LII; Figuier, “Expos. et Hist.,” 1857, Vol. IV. p. 393; “Engl. Cycl.,” “Arts and Sci.,” Vol. III. p. 782; Brande’s “Man. of Chem.,” London, 1848, Vol. I. p. 248; Prime’s “Life of Morse,” pp. 264, 451; Dr. Henry’s “Elm. of Exper. Chem.,” London, 1823, Vol. I. pp. 193–203; _Jour. of the Frankl. Inst._ for 1851, Vol. XXI. p. 403; “_La Lumière Electrique_” for Mar. 19, 1887, p. 593, and for Oct. 31, 1891, pp. 201, etc.: Sir William Thomson, “Math. Papers,” reprint, etc., 1872; “Encyl. Metrop.” (Elect. Mag.,); G. B. Prescott, “Elect. and the El. Tel.,” 1885, Vol. I. p. 91; “Smithsonian Report” for 1878, pp. 272, 273, note; Bacelli (L. G.), “Risultati ...” Milano, 1821; “Bibl. Britan.,” Vol. XVII, N.S. p. 181; Vol. XVIII, N.S. p. 3; “Edin. Phil. Journal,” Vol. X. p. 203; “Journal of the Soc. of Tel. Eng.,” 1876, Vol. V. pp. 459–464, for a verbatim copy of Oersted’s original communication on his discovery of electro-magnetism, and pp. 464–469 for a translation thereof by the Rev. J. E. Kempe under the title of “Experiments on the effect of electrical action on the Magnetic Needle.” For the interesting electro-magnetic experiments of J. Tatum, at this same period, consult the _Phil. Mag._, Vol. LVII, 1821, p. 446; Vol. LXI, 1823, p. 241; Vol. LXII, 1823, p. 107, and, for additional investigation, the Vols. XLVII and LI for years 1816 and 1818.

=A.D. 1820.=--On Oct. 9, M. Boisgeraud, Jr., reads, before the French Académie des Sciences, a paper concerning many of his experiments, which prove to be merely variations of those previously made by Oersted.

He observed that connecting wires, or arcs, placed anywhere in the battery, affect the needle, and he noticed the difference of intensity in the effects produced when electrical conductors are employed to complete the circuit. He proposed to ascertain the conducting power of different substances by placing them in one of the arcs, cells or divisions of the battery, and bringing the magnetic needle, or Ampère’s galvanometer, toward another arc, viz. to the wire or other connecting body used to complete the circuit in the battery. With regard to the positions of the needle and wire, as observed by Boisgeraud, they are all confirmatory of Prof. Oersted’s statement (“Ency. Met.” (Electro.-Mag.), Vol. IV. p. 6).

One month later, Nov. 9, 1820, Boisgeraud reads, before the same Académie, his paper “On the Action of the Voltaic Pile upon the Magnetic Needle,” which will be found on pp. 203–206 and 257, 258, Vol. LVII of the _Philosophical Magazine_.

=A.D. 1820.=--Banks (Sir Joseph) (1743–1820), a very eminent English naturalist and traveller, to whom reference has been made under the A.D. 1775 date, deserves mention here were it alone for the fact that while occupying the presidential chair of the Roy. Soc., during the extraordinary long and unequalled period of over _forty-two years_ (1777, date of Sir John Pringle’s retirement, to 1820, the date of President Banks’ death) he was instrumental in bringing prominently before the world many of the most important discoveries and experiments known in the annals of magnetism and electricity.

Sir Joseph Banks was succeeded in the presidency of the Royal Society by William Hyde Wollaston, M.D., June 29, 1820, and by Sir Humphry Davy, Bart., Nov. 30, 1820, the last named holding the office seven years (R. Weld, “Hist. Roy. Soc.,” 1848, Vol. II. p. 359). Banks and Dr. Solander, the pupil of Linnæus, had sailed (1768–1771) with Captain Cook in his voyage around the globe, in the capacity of naturalists, and afterwards (1772) visited Iceland, where they made many important discoveries. In 1781 Banks was created a baronet; he received the Order of the Bath in 1795 and subsequently had many honours conferred upon him by different English and foreign societies. It is said that he was never known to be appealed to in vain by men of science, either for pecuniary assistance or for the use of his extensive library.

REFERENCES.--Tilloch’s _Phil. Mag._ for 1820, Vol. LVI. pp. 40–46; “Cat. Sci. Papers Roy. Soc.,” Vol. I. p. 176; Dr. Thomas Thomson, “Hist. Roy. Soc.,” London, 1812, p. 12; _Gentleman’s Magazine_ for 1771, 1772 and 1820; “Biog. Univ.,” Vol. LVII, Suppl. p. 101; Larousse, “Dict. Univ.,” Vol. II. p. 155; “Eloge Historique de Mr. J. Banks, lu à la Séance de l’Académie Royale des Sciences, le 2 Avril 1821”; Sir Everard Home, “Hunterian Oration,” Feb. 14, 1822. See besides, the _Phil. Mag._, Vol. LVI. pp. 161–174, 241–257, for “A review of some of the leading points in the official character and proceedings of the late President of the Royal Society,” contrasting the respective personal merits and achievements of Sir John Pringle and of Sir Joseph Banks; “Lives of Men of Letters and Science,” by Henry, Lord Brougham, Philad., 1846, pp. 199–229, 294–295.

=A.D. 1820.=--Barlow (Peter), F.R.S. (1776–1827), who taught mathematics at the Military Academy of Woolwich from 1806 to 1847, brings out the first edition of his “Essay on Magnetic Attractions,

## Particularly as Respects the Deviation of the Compass on Shipboard

Occasioned by the Local Influence of the Guns, etc., with an Easy Practical Method of Observing the Same in all Parts of the World.” One of his biographers states that through this valuable publication, which received the Parliamentary reward from the then existing Board of Longitude, as well as presents from the Russian Emperor, he was the first to reduce to strictly mathematical principles the method of compensating compass errors in vessels (_Edin. Jour. of Sci._, London, 1826, Vols. I. pp. 181, 182; II. p. 379).

This work contains the results of the many experiments to ascertain the influence of spherical and other masses of iron upon the needle, which Barlow instituted, more particularly after Prof. Hansteen’s investigations became generally known. Sir David Brewster details Barlow’s work in the “Encycl. Brit.,” and refers to the separate observations of Mr. Wm. Wales (at A.D. 1774), Mr. Downie (at A.D. 1790), Captain Flinders (at A.D. 1801), and Charles Bonnycastle (at A.D. 1820), mentioning the fact that it is to Mr. W. Bain we owe the distinct establishment and explanation of the source of error in the compass arising from the attraction of all the iron on board of ships. The small 140-page book which Mr. Bain published on the subject in 1817 is entitled “An Essay on the Variation of the Compass, Showing how Far it is Influenced by a Change in the Direction of the Ship’s Head, with an Exposition of the Dangers Arising to Navigators from not Allowing for this Change of Variation.” Brewster remarks that additional light was thrown upon Mr. Bain’s observations by Captains Ross, Parry and Sabine, but that we owe to Prof. Barlow alone a series of brilliant experiments which terminated in his invention of the neutralizing plate for correcting in perfect manner this source of error in the compass (Noad’s “Manual,” pp. 531, 532; Olmstead’s “Introduct. to Nat. Hist.,” 1835, pp. 206, 210). The simple contrivance therein alluded to is described and illustrated at pp. 9 and 90–91 of the “Britannica,” article on “Navigation,” and may briefly be said to consist of only a thin circular plate of iron placed in a vertical position immediately behind the binnacle or compass (Fifth Dissertation of “Britannica,” Vol. I. p. 745, and article “Seamanship,” in Vol. XX. p. 27). Such plates were immediately tried in all parts of the world and were at once applied to the English vessels “Conway,” “Leven” and “Barracouta” (_Trans. Soc. of Arts_ for 1821, Vol. XXXIX. pp. 76–100; Harris’ “Rud. Mag.,” III. pp. 69–76; John Farrar, “Elem. of El. ...” 1826, pp. 376–383; _Westminster Review_ for April 1825; “Encycl. Metropol.,” Vol. III (Magnetism), pp. 743, 799).

For Mr. Barlow’s experiments on the influence of rotation upon magnetic and non-magnetic bodies, the result of which was communicated by him to the Royal Society, April, 14, 1825, six days before the receipt of S. H. Christie’s paper “On the Magnetism of Iron, Arising from its Rotation,” communicated by J. F. W. Herschel, see pp. 10, 33, 34, of the “Britannica,” Vol. XIV above referred to (_Edin. Jour. of Science_, 1826, Vols. III. p. 372, and V. p. 214. Consult also, J. Farrar, “Elem. of El.,” 1826, pp. 387–395. For his extensive observations regarding the influence of heat on magnetism and relative to the variation, as well as for the mode of constructing his artificial magnets, consult the same volume of the “Britannica,” at pp. 35, 36, 50–53 _et seq._ and p. 73. See likewise, for the variation, Dr. Thomas Thomson’s “Outline of the Sciences,” London, 1830, pp. 549–556; Harris, “Rud. Mag.,” I, II. pp. 152–153. For Samuel Hunter Christie, consult “Abstracts of Papers ... Roy. Soc.,” Vol. II. pp. 197, 225, 243, 251, 270, 305, 321, 347 and 351).

The new variation chart which Prof. Barlow constructed and in which he embraced the magnetic observations made in 1832 by Sir James Ross, R.N., is described and illustrated in _Phil. Trans._ for 1833, pp. 667–675, Plates XVII, XVIII. He remarks that the very spot where his officer found the needle perpendicular, “that is, the pole itself, is precisely that point in my globe and chart in which, by supposing all the lines to meet, the several curves would best preserve their unity of character, both separately and conjointly as a system” (eighth “Britan.,” Vol. XIV, note, p. 50; Noad, “Manual,” p. 617; D. Olmstead, “Intr. to Nat. Phil.,” 1835, p. 192).

Mr. Barlow’s electro-magnetic globe was exhibited by Dr. Birkbeck in his lectures on “Electro-Magnetism” at the London Institution, May 26, 1824. (Its construction is fully described, more particularly, at p. 65 of the English “Encycl. Brit.” (Magnetism); p. 91 of the “Lib. of Useful Knowledge” (Electro-Magnetism); pp. 139–140, Vol. I of the _Edin. Jour. of Science_, London, 1826, and pp. 120–122, Part III of Harris’ “Rud. Mag.”) Its purpose was to show that what had hitherto been considered as the magnetism of the earth might be only modified electricity, and it was also intended to illustrate the theory advanced by M. Ampère, who, as is well known, attributed all magnetic phenomena to electric currents. In the words of Dr. Brewster:

“Barlow considers it as probable that magnetism as a distinct quality has no existence in Nature. As all the phenomena of terrestrial magnetism can be explained on the supposition that the magnetic power resides on its surface, it occurred to Mr. Barlow that if he could distribute over the surface of an artificial globe a series of galvanic currents in such a way that their tangential power should everywhere give a corresponding direction to the needle, this globe would exhibit, while under electrical induction, all the magnetic phenomena of the earth upon a needle freely suspended above it. Mr. Barlow says ‘he has proved the existence of a force competent to produce all the phenomena without the aid of any body usually called magnetic,’ yet he acknowledges that ‘we have no idea how such a system of currents can have existence on the earth, because, to produce them, we have been obliged to employ a particular arrangement of metals, acids, and conductors.’”

Barlow was the first to test the practicability of Ampère’s suggestion that by sending the galvanic current through long wires connecting two distant stations, the deflections of enclosed magnetic needles would constitute very simple and efficient signals for an instantaneous telegraph (_Ann. de Chimie et de Phys._, 1820, Vol. XV. pp. 72, 73). He has thus stated the result: “In a very early stage of electro-magnetic experiments, it had been suggested (by Laplace, Ampère and others) that an instantaneous telegraph might be established by means of conducting wires and compasses. The details of this contrivance are so obvious, and the principle on which it is founded so well understood, that there was only one question which could render the result doubtful; and this was, is there any diminution of effect by lengthening the conducting wires? It had been said that the electric fluid from a common (tinfoil) electric battery had been transmitted through a wire four miles in length without any sensible diminution of effect, and, to every appearance, instantaneously; and if this should be found to be the case with the galvanic circuit, then no question could be entertained of the practicability and utility of the suggestion above adverted to. I was therefore induced to make the trial; but I found such a sensible diminution with only 200 feet of wire, as at once to convince me of the impracticability of the scheme. It led me, however, to an inquiry as to the cause of the diminution, and the laws by which it is governed.” This passage is quoted in “Smithsonian Report” for 1878, p. 279; Fahie, “Hist. El. Tel.,” p. 306; “Memor. of Jos. Henry,” 1880, pp. 223, 224, the last named containing the following footnote: “On the Laws of Electro-Magnetic Action,” _Edinburgh Philosophical Journal_, Jan., 1825, Vol. XII. pp. 105–113:

“In explanation and justification of this discouraging judgment from so high an authority in magnetics, it must be remembered that both in the galvanometer and in the electro-magnet, the coil best calculated to produce large effects was that of least resistance; which unfortunately was not that best adapted to a long circuit. On the other hand the most efficient magnet or galvanometer was not found to be improved in result by increasing the number of galvanic elements. Barlow in his inquiry as to the law of diminution was led (erroneously) to regard the resistance of the conducting wire as increasing in the ratio of _the square_ root of its length” (pp. 110, 111 of the last-cited “Journal.)”]

Mr. Taylor justly adds that subsequent experiments have proved Ohm’s law (announced three years after Barlow’s) of a simple ratio of resistance to length as approximately correct.

REFERENCES.--G. B. Prescott, “The Speaking Telephone,” 1879, II; _Sci. Am. Supp._, Nos. 405, p. 6466; 453, p. 7235; 547, p. 8735: “Mem. of Jos. Henry,” 1880, pp. 83, 94, 144, 485, 487. See also, Poggendorff, Vol. I. pp. 102, 103; Whewell, “Hist. Ind. Sciences,” 1859, Vol. II. pp. 223, 224, 245, 254, 616; “Lib. Useful Knowledge” (Magnetism), p. 86 and (El. Mag.), pp. 7, 18, 22, 28; Sturgeon’s “Sci. Researches,” Bury, 1850, pp. 26, 29, 31, 298; Humboldt, “Cosmos,” 1849, Vol. I. p. 183; Mrs. Somerville, “On the Earth not a Real Magnet,” in the “Conn. of the Phys. Sci.,”; _Phil. Mag._, Vols. LV. p. 446; LX. pp. 241, 343; LXII. p. 321; Harris, “Rud. Mag.,” Part III. pp. 114–116; “Encycl. Metropol.,” Vol. IV (Elect. Mag.), pp. 1–40; “Abstracts of papers ... Roy. Soc.,” Vol. II. pp. 164, 197, 241, 318; “Cat. Sc. Papers ... Roy. Soc.,” Vol. I. pp. 182–184; “Bibl. Britan.,” Vol. XX, N.S. p. 127; “Edin. Phil. Journal,” 1824, Vol. X. p. 184 (alludes to papers of Barlow and Christie in _Phil. Trans._ for 1823, Part II).

Mr. Wm. Henry Barlow, second son of Peter Barlow, is the author of a treatise, “On the spontaneous electrical currents observed in the wires of the electric telegraph,” which was published in London during 1849 and appeared in Part I of the _Phil. Trans._, for that year. He is also the inventor of a new electrical machine alluded to herein at Hare (A.D. 1819), also at p. 130 of the “Annual of Sc. Disc.,” at pp. 76–77 of Noad’s “Manual,” and at p. 428, Vol. XXXVII of the “Philosophical Magazine.”

=A.D. 1820.=--Laplace (Pierre Simon, Marquis de) (1749–1827), a very distinguished French astronomer and mathematician, suggests for telegraphic purposes the employment of magnetic needles suspended in multipliers of wire, in place of the voltameters of Sömmering, and on the 2nd of October 1820 his theory is thus explained by Ampère in a paper read before the French Academy of Sciences:

“According to the success of the experiment to which Laplace drew my attention, one could, by means of as many pairs of live wires and magnetic needles as there are letters of the alphabet, and by placing each letter on a separate needle, establish, by the aid of a distant pile, and which could be made to communicate by its two extremities with those of each pair of conductors, a sort of telegraph, which would be capable of indicating all the details that one would wish to transmit through any number of obstacles to a distant observer. By adapting to the battery a keyboard whose keys were each marked with the same letters and establishing connection (with the various wires) by their depression, this means of correspondence could be established with great facility, and would only occupy the time necessary for pressing down the keys at the one station and to read off the letters from the deflected needles at the other.”

Laplace is, perhaps, best known by his “Traité de Mécanique Céleste,” the sixteen books and supplements to which are by many considered, next to Newton’s “Principia,” the greatest of astronomical works; a book which has been truly said to have had no predecessor and which has been called the crowning glory of Laplace’s scientific career. His next important work was the “Théorie Analytique des Probabilités,” the most mathematically profound treatise on the subject which had yet appeared, while his “Système du Monde” was called by Arago “one of the most perfect monuments of the French language.” By Prof. Nichols, Laplace is called “the titanic geometer”; by Mr. Airy “the greatest mathematician of the past age”; by Prof. Forbes “a sort of exemplar or type of the highest class of mathematical natural philosophers of this, or rather the immediately preceding age.”

Laplace also wrote, in conjunction with Lavoisier, a treatise “On the Electricity which Bodies Absorb when Reduced to Vapor” (_Mém. de Paris_ for 1781). Prof. Denison Olmstead, treating of the origin of atmospherical electricity (“Introd. to Nat. Phil.,” 1835, pp. 158, 159), says: “Among the known sources of this agent none seems so probable as the evaporation and condensation of watery vapor. We have the authority of two of the most able and accurate philosophers, Lavoisier and Laplace, for stating that bodies in passing from the solid or liquid state to that of vapor, and, conversely, in returning from the aeriform condition to the liquid or solid state, give unequivocal signs of either positive or negative electricity,” and he adds, in a footnote:

“M. Pouillet has lately published a set of experiments, which seems to overturn Volta’s theory of the evolution of electricity by evaporation. He has shown that no electricity is evolved by evaporation unless some chemical combination takes place at the same time ...” (Thomson, “Outlines,” p. 440) ... “But we shall be slow to reject the results of experiments performed by such experimenters as Lavoisier and Laplace, especially when confirmed by the testimony of Volta and Saussure.”

With regard to the origin of meteorites, Laplace has advanced the very bold theory that they may be products of Lunar volcanoes, and Prof. Lockhart Muirhead stated that he would “present the reasoning upon which this extraordinary hypothesis is founded in the popular and perspicuous language of Dr. Hutton, of Woolwich: the respect due to the name of Laplace justifying the length of the extract,” which he gives at pp. 633–635, Vol. XIV of the 1857 “Britannica.”

REFERENCES.--Humboldt, “Cosmos,” London, 1849, Vol. I. pp. 108–109; Young, “Course of Lectures,” London, 1807, Vol. II. p. 501, alluding to “Zach. Mon. Corr.,” VI. p. 276, also to Gilbert, XIII. p. 353, 108, and stating that Olbers had suggested Laplace’s idea in 1795. See “Mem. of the Astronom. Soc. of London,” Vol. III. p. 395: Laplace, “Mem. de l’Institut” for 1809, p. 332; Dr. Young’s “Course of Lectures,” 1807, Vol. I. pp. 249, 250, 522; Vol. II. p. 466; Humboldt, “Cosmos,” London, 1849, Vol. I. pp. 28, 76, 130; Vol. II. p. 712; Lavoisier at A.D. 1781: Biot at A.D. 1803; _Annal. de Ch. et Phys._, Vol. XV. pp. 72, 73, and for Laplace and Lavoisier, see Delaunay, “Manuel ...” 1809, p. 178; “Mem. de l’Acad. des Sc.,” for 1781; “Journal des Savants,” for Feb. 1850 and Nov. 1887; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 184; “Cat. Sc. Pap. Roy. Soc.,” Vol. III. pp. 845–848; Johnson’s “Cyclopædia,” pp. 1647–1650 and the “First Supplement,” p. 62.

For Laplace and Joseph Louis Lagrange, see “Mémoires de l’Institut,” Vol. III. p. 22; also “Pioneers of Science,” by Sir Oliver Lodge, London, 1905, Lecture XI, and for Lagrange, consult “Journal des Savants,” Sept. 1844, May 1869, August 1878, Sept. 1879, Sept. 1888 and Oct. 1892.

M. Cyrille Pierre Théodore Laplace, captain in the French navy, is the author of the “Voyage Autour du Monde ... sur la Corvette _Favorite_ ...” and of “Campagne de Circumnavigation de la Frégate _l’Artémise_ ...” published in Paris during the years 1833, 1839 and 1841.

Baron Jean Baptiste Fourier, celebrated French physicist (1768–1830) who, in 1827, succeeded Laplace as head of the Council of the Ecole Polytechnique (“Biog. Gén.,” Vol. XVIII. p. 346) says of his predecessor:

“Posterity, which has so many particulars to forget, will little care whether Laplace was for a short time minister of a great state. The eternal truths which he has discovered, the immutable laws of the stability of the world, are of importance, and not the rank which he occupied” (C. R. Weld, “Hist. Roy. Soc.,” Vol. II. p. 465). Fourier is the author of “Expériences thermo-électriques” (“Encycl. Brit.,” ninth ed., Vol. IX. p. 490; “Eng. Cycl.,” Biography, Vol. II. p. 977).

=A.D. 1820.=--Dutrochet (René Joachim Henri) (1776–1847) a distinguished French natural philosopher, and likewise medical adviser to the King of Spain, Joseph Bonaparte, publishes an interesting treatise on meteors, in conjunction with Mr. Nathaniel Bowditch, who had already written many very able papers on astronomical subjects and who afterwards translated the “Mécanique Céleste” of Laplace. Eight years later (1828) appeared Dutrochet’s “Nouvelles Recherches ...” wherein he attributes to electricity the direction taken by fluids through animal and vegetable membranes. The passage of a fluid from without inwardly he called _endosmosis_, and the passage of the fluid from within outwardly he termed _exosmosis_.

Of Dutrochet, Dr. John Hutton Balfour, of Edinburgh, makes mention when treating of the temperature of plants. He thus expresses himself: “While the nutritive processes are going on in the plant, there is a certain amount of heat produced. This, however, is speedily carried away by evaporation and other causes, and it is not easily rendered evident. Dutrochet, by means of Becquerel’s thermo-electric needle, showed an evolution of heat in plants. In doing this, he prevented evaporation by putting the plant in a moist atmosphere. In these circumstances the temperature of the active vegetating parts, the roots, the leaves, and the young shoots, indicated a temperature above the air of ½ to ¾ of a degree Fahrenheit. Van Beek and Bergsma, in their experiments on the _Hyacinthus Orientalis_ and the _Entelea Arborescens_, found the proper heat of the active parts of plants about 1·8° F. above that of the air. The vital or proper heat of plants, according to Dutrochet, is found chiefly in the green plants, and it undergoes a quotidian paroxysm, reaching the maximum during the day, and the minimum during the night. When stems become hard and ligneous, they lose this vital heat. Large green cotyledons gave indications of a proper heat. The hour of quotidian maximum varied from 10 a.m. to 3 p.m. in different plants.”

It is stated by Becquerel that in the act of vegetation, the earth acquires continually an excess of positive electricity, while the bark and part of the wood receive an excess of negative electricity. The leaves act like the green part of the parenchyma of the bark--that is to say, the sap which circulates in their tissues is negative with relation to the wood, to the pith, and to the earth, and positive with regard to the cambium. The electric effects observed in vegetables are due to chemico-vital action, and he asserts that the opposite electric states of vegetables and of the earth give reason to think that, from the enormous vegetation in certain parts of the globe, they must exert some influence on the electric phenomena of the atmosphere.

REFERENCES.--Gmelin’s “Chemistry,” Vol. I. p. 447; “Biog. Gén.,” Vol. XV. p. 506; Poggendorff, “Annalen,” Vol. I. p. 663; Larousse, “Dict. Univ.,” Vol. VI. p. 1448; J. W. Ritter, in “Denkschr. d. Münch. Acad.” for 1814, and the eighth ed. of the “Ency. Brit.” Vol. XXI. p. 635, for observations concerning the _mimosa pudica_ and the _mimosa sensitiva_; “Cat. Sc. Papers Roy. Soc.,” Vol. II. pp. 422–425; Vol. VI. p. 646; Vol. VII. p. 584; Poggendorff, Vol. I. p. 633; “Observations on the diurnal variation of the magnetic needle,” in Sturgeon’s “Annals,” Vol. VII. pp. 369–370, and in the _Comptes Rendus_, Vol. XII. p. 298, of Feb. 8, 1841; Burnet, “On the motion of sap in plants. Researches of Dutrochet on Endosmose and Exosmose ...” London, 1829 (“Phil. Mag. or Annals,” Vol. V. p. 389).

=A.D. 1820.=--Fresnel (Augustin Jean) (1788–1827), one of the most distinguished French mathematicians and natural philosophers, communicates a paper detailing his experiments for decomposing water by means of a magnet. He produced a current in an electro-magnetic helix enclosing a bar-magnet covered with silk, and on plunging the ends of the wire in water he observed some very remarkable effects which are set forth in the _Annales de Chimie et de Phys._, series 2, Vol. XV. p. 219.

REFERENCES.--“Eloge de Fresnel,” by Arago, in his “Œuvres,” Vol. I; Account of Fresnel’s life in the “Biog. Univ.;” Whewell, “Hist. of Induc. Sci.,” 1859, Vol. II. pp. 96, 102, 114–117; “Œuvres complètes d’Augustin Fresnel, publiées par les soins du Ministre de l’Instruction Publique,” Paris, 1870, in three vols.

=A.D. 1820.=--Sir Richard Phillips (1778–1851), communicates, July 11, to the _Philosophical Magazine_ (Vol. LVI. pp. 195–200) a very interesting paper entitled “Electricity and Galvanism Explained on the Mechanical Theory of Matter and Motion.” After reviewing the then existing theories, he concludes by saying:

“Electricity is no exception to the mechanical principles of matter and motion, and in regard to the kindred phenomena of galvanism, I will content myself with observing that it is merely _accelerated electricity_, the interposing fluid being palpably decomposed and evolving the electrical powers, each term in the series of plates being a new impulse or power added to the previous one, till the ultimate effect is accelerated, like that of a body falling by the continuous impulses of the earth’s motions, or like a nail heated red-hot by accelerations of atomic motion produced by repeated percussions of a hammer.”

Consult “Bibl. Ital.,” Vol. XXVII. p. 107 for references to the “Annals of Philosophy,” in which he mentions an experiment upon a young poplar, “whereby it would seem that copper was imbibed in the branches, etc., from a solution placed at its roots, and that it was precipitated on a knife used to cut off a branch.”

=A.D. 1820.=--Brewster (Sir David) (1781–1868), a very distinguished English natural philosopher and writer, who had just founded the “Edinburgh Philosophical Journal” in conjunction with Prof. Robert Jameson, announces his discovery of the existence of two poles of greatest cold on opposite sides of the northern pole of the earth. By this he was, like other authors, led to the belief that there might be some connection between the magnetic poles and those of maximum cold, and he remarks (Noad “Manual,” London, 1859, p. 545, and article “Magnetism” in “Encycl. Brit.”): “Imperfect as the analogy is between the isothermal and magnetic centres, it is yet too important to be passed over without notice. Their local coincidence is sufficiently remarkable, and it would be to overstep the limits of philosophical caution to maintain that they have no other connection but that of accidental locality; and if we had as many measures of the mean temperature as we have of the variation of the needle, we might determine whether the isothermal poles were fixed or movable.” Similar opinions entertained by Dr. Dalton, Dr. Traill and Mr. Christie are also mentioned by Noad, who quotes from Oersted’s treatise on “Thermo-Electricity” the statement of the Danish philosopher “that the most efficacious excitation of electricity upon the earth appears to be produced by the sun, causing daily evaporation, deoxidation and heat, all of which excite electrical currents.”

From his able paper in the _Edinburgh Philosophical Transactions_ for 1820, one is led to share Sir David Brewster’s belief “that two meridians of greatest heat and two of greatest cold are called into play, and that the magnetism of our globe depends in great measure upon electro or rather thermo-magnetic currents.” The electro-magnetic hypothesis was, he says, ably supported by Prof. Barlow in his paper “On the probable electric origin of all the phenomena of terrestrial magnetism,” communicated to the _Phil. Trans._ for 1831. Brewster thus locates the two poles of maximum cold: The American pole in N. Lat. 73, and W. Long. 100 from Greenwich, a little to the East of Cape Walker; the Asiatic pole in N. Lat. 73 and E. Long. 80, between Siberia and Cape Matzol, on the Gulf of Oby. Hence the two warm meridians will be in W. Long. 10 and E. Long. 170, and the two cold meridians in W. Long. 100 and E. Long. 80.

As has already been indicated (under A.D. 1717, Leméry), Sir David Brewster was the discoverer of the pyro-electrical condition of the diamond, the garnet, the amethyst, etc. His development of some of Haüy’s experiments led to a similar discovery, attaching to several mineral salts as well as to the plates and powders of the tourmaline, of the scolezite and the melozite; and he likewise experimented with the boracite, mesotype and with the several minerals and artificial crystals detailed at pp. 208–215, Vol. I of the _Edin. Jour. of Science_, London, 1826; and in Chap. II. s. 1, vol. viii of the eighth “Encycl. Brit.,” article on “Electricity.”

At Part I. chap. i. s. 6 of the last-named article will be found Brewster’s observations on the nature and origin of electrical light, his latest researches having been made, like those of Joseph von Fraunhofer (see A.D. 1814–1815), on the dark and on the luminous lines which appear in the spectrum formed from it by a prism.

During the year 1831 appeared Brewster’s “Treatise on Optics,” his “Life of Sir Isaac Newton,” and his “Letters on Natural Magic.” It is in one of the chapters of the last-named work that he treats of automatic talking machines and remarks: “We have no doubt that before another century is completed a talking and a singing machine will be numbered among the conquests of science.”

Brewster’s other scientific treatises are too numerous and cover too wide a range to be enumerated here. The “Catal. of Sci. Papers of the Roy. Soc.” (Vol. I. pp. 612–623) gives the titles of as many as 299 contributions made by him on important subjects, and he has had no less than 76 papers in the first 39 parts of the _North British Review_, 30 in the _Phil. Trans._ and 28 in the _Edin. Review_. They appear, in fact, in all the prominent publications of his time, and have won for him leading honours, more especially from the Edinburgh and Aberdeen Universities and the Scotch, Irish, English and French Societies, the French Academy of Sciences doing him the signal honour of selecting him as one of its eight foreign associates in place of Berzelius, deceased. Conjointly with Davy, Herschel and Charles Babbage, he originated the British Association during 1831, and it was in this same year that he was knighted and decorated by King William IV. He had been made a Fellow of the Royal Society of Edinburgh in 1808, and had during the same year undertaken the editorship of the “Edinburgh Encyclopædia of Sci., Lit. and Art.” This he continued for twenty-two years, after which he edited the _Edin. Jour. of Sci._, and also entered with Taylor and Phillips upon the editorship of the _London and Edin. Phil. Mag. and Journal_. Many of our readers will doubtless be glad to know that the last named was a continuation of the well-known _Philosophical Magazine_ so often quoted in this “Bibliographical History.”

REFERENCES.--The obituary notice contributed by Dr. J. H. Gladstone to the proceedings of the Royal Society; _Chemical News_, Amer. reprint, Vol. II. pp. 198, 233; also p. 293 for accounts given by Sir J. Simpson and Prof. Fraser; J. Robison and Brewster, “A System of Mechan. Phil.,” London and Edin., 1822; Ferguson and Brewster’s “Essays and Treatises on Astr. Elect.,” etc., Edinburgh, 1823; Brewster’s several articles in the “Encycl. Britannica,” 7th and 8th editions, on “Electricity and Magnetism”; _Transactions of the Roy. Soc. of Edinburgh_, Vols. IX. 1821; XX. Part IV; _Edin. Jour. of Sci._, Oct. 1824, No. 2, p. 213; Noad, “Manual,” London, 1859, pp. 31, 32, 636–638; Harris, “Magnetism,” Part III. p. 119; Whewell, “Hist. of Induc. Sci.,” 1859, Vol. II. pp. 75, 81, 331, 332; the lectures delivered by Wm. A. Miller during 1867 before the Royal Institution of Great Britain.

Charles Babbage (1792–1871), a prominent English scientist who is mentioned above and who besides being one of the founders of the Royal Astronomical Society, as has already been stated, was also a founder of the British Association and the originator of the Statistical Society, is the author of valuable papers, exhibiting a wide range of learning and research--mainly on mathematical subjects and relating to magnetical and electrical phenomena--which have been published in the Reports of the Royal and other Societies (“English Cycl.,” Vol. I. p. 457; “Encyl. Brit.,” ninth ed., Vol. III. p. 178; Larousse, “Dict.,” Vol. II. pp. 5–6; account of Babbage’s work in C. R. Weld’s “Hist. Roy. Soc.,” Vol. II. pp. 369–391).

=A.D. 1820.=--Fisher (George) (1794–1873), who two years before had joined Captain David Buchan in his voyage to the Arctic regions, is the first to point out the true cause of the sudden alteration in the rates of chronometers at sea. “He observed,” says Dr. Roget, “that the chronometers on board the ‘Dorothea’ and ‘Trent’ had a different rate of going from that they had on shore, even when these vessels had been frozen in, and therefore when their motion could not have contributed to that variation; ... this effect could be attributed only to the magnetic action exerted by the iron in the ships upon the inner rim of the balance of the chronometers, which is made of steel. A similar influence was perceptible on placing magnets in the neighbourhood of the chronometers. This conclusion was confirmed by experiments made for this purpose by Mr. Barlow, who ascertained that masses of iron devoid of all permanent magnetism occasioned an alteration in the rates of chronometers placed in different positions in their vicinity.”

REFERENCES.--Fisher’s article “On the Errors in Longitude as Determined by Chronometers at Sea, Arising from the Action of the Iron in the Ships upon the Chronometers,” communicated by John Barrow, F.R.S., to the _Phil. Mag._, Vol. LVII. pp. 249–257. See besides, _Edinburgh Jour. Sci._, London, 1826, Vol. V. p. 224; _Phil. Trans._ for 1820, Part. II. p. 196, and the volume for 1833, relative to magnetical experiments; also the “Lib. U. K.” (Magn.), p. 63. For Capt. Buchan, consult Barrow’s “Chronological History of Voyages into the Arctic Regions.”

Mr. George Thomas Fischer (1722–1848) is the author of “A Practical Treatise on Medical Electricity” (Poggendorff, Vol. I. p. 756).

=A.D. 1820.=--Bonnycastle (Charles), Professor of Mathematics in the University of Virginia, treats of the distribution of the magnetic fluids in masses of iron, as well as of the deviations which they produce in compasses placed within their influence, at pp. 446–456, Vol. LV of Tilloch’s _Philosophical Magazine_.

He refers to the then recent publication of Peter Barlow’s “Essay on Magnetic Attractions,” containing the results of many experiments, made principally upon spheres of iron, as well as to Dr. Young’s views of the subject, which were printed by order of the Board of Longitude, and he says that the principle upon which he intends establishing his inquiry “is an extension of the law that regulates the action of electrified bodies upon conductors; which was first given by M. Poisson in the Memoirs of the Institute for 1811, and employed by him to determine the development of the electric fluids in spheres that mutually act on each other.”

The afore-named dissertation, at the time, called forth a rejoinder from a correspondent and a further communication from Mr. Bonnycastle, both of which appear at pp. 346–350, Vol. LVI of the same publication.

REFERENCES.--Silliman’s _Journal_, Vol. XL. p. 32; “Sketch of the Life of Chas. Bonnycastle,” by Thomas Thomson; Poggendorff, Vol. I. pp. 234, 235; article “Magnetism,” p. 9, Vol. XIV of the eighth “Britannica.”

=A.D. 1820.=--Harris (Wm. Snow), member of the College of Surgeons, and a very distinguished English scientist (1791–1867), proposes to the Board of the Admiralty his system of lightning conductors, of which an account appears at p. 231, Vol. LX of the _Phil. Mag._, as well as in a separate work published at London during 1822. This is followed by his “Observations on the Effects of Lightning ...” 1823, and by papers relative to the defence of ships and buildings from lightning, which were published, more particularly, in several numbers of the _Nautical Magazine_, the _Phil. Mag._, the _Annals of Electricity_, and in the _Proc. Lond. Elec. Soc._ for 1842, as well as in his “Record of Phil. Papers,” and under separate heads during many years between 1827 and 1854. One of his biographers remarks:

“His researches have gone far to remove certain popular errors as to what have been called ‘conductors’ and ‘non-conductors’ of electricity, and to show the inutility of the old form of lightning rod in the majority of cases; it being necessary, in place of such rod form, to link into one great chain all the metallic bodies employed in the construction of a building, thus providing a connection with these conductors between the highest parts and the ground, the single conductor, in one highest part, being possibly insufficient to divert the course of the fluid and protect the whole fabric. These general principles have been largely applied to the protection of the ships of the Royal Navy during the last five and twenty years, under his advice and direction; and, laying aside the opinions which had been commonly received, the masts themselves of a ship have all been rendered perfectly conducting by incorporating with the spars capacious plates of copper, whilst all the large metallic masses in the hull have been tied, as it were, into a general conducting chain, communicating with the great conducting channels in the masts, and with the sea. This may be considered as the greatest experiment ever made by any country in the employment of metallic conductors for ships, and the result has been to secure the navy from a destructive agent, and to throw new light upon an interesting department of science” (Whewell, “Hist. of Induc. Sci.,” Vol. II. pp. 199, 200; _Phil. Mag._ for March 1841; eighth “Encycl. Britannica,” Vols. VIII. pp. 535, 610, 611, and XX. p. 24; “Edin. Review” for Oct. 1844, Vol. LXXX. pp. 444–473).

Harris was the first, says Brewster, who introduced accurate quantitative measures into the investigation of the laws of statical electricity--the unit measure by which quantity is minutely estimated--and also the hydro-electrometer and scale-beam balance by which its intensity and the laws of attractive forces at all distances are demonstrated. Of not less value is the thermo-electrometer, by which the heating effects of given quantities of electricity are measured and rendered comparable with the varying conditions of quantity and intensity. Besides these instruments, we owe to Harris the discovery of a new reactive force, through which repulsion and other small physical forces are investigated and determined by means of his bifilar balance, founded upon the reactive force of two vertically suspended parallel threads when twined upon each other at a given angle, and acted upon by a suspended weight. With the aid of these instruments he has carried on a variety of important inquiries into the laws of electrical forces, and the laws and operations of electrical accumulation (eighth “Brit.,” Vol. VIII. p. 535). His papers on the subject appeared in 1825 and 1828, and a _résumé_ of them is given by Noad (“Manual” 1859, pp. 35, 137–140), as well as in the “Electricity” article of the “Britannica,” both of which contain descriptions and illustrations of Harris’ unit jar and electro-thermometer.

During the year 1827 Mr. Harris published in the _Trans. Roy. Soc. of Edinburgh_ his memoir entitled “Experimental Inquiries Concerning the Laws of Magnetic Forces,” which experiments were made by means of a new and very accurate apparatus invented by him for examining the phenomena of induced magnetism. The above was followed by two other memoirs, published in the _Phil. Trans._ for 1831, “On the Influence of Screens in Arresting the Progress of Magnetic Action ...” and “On the Power of Masses of Iron to Control the Attractive Force of a Magnet,” which are discoursed of in the “Britannica” article on “Magnetism,” wherein special treatment is also given more particularly to Mr. Harris’ researches concerning artificial magnets as well as the magnetic charge, the development of magnetism by rotation and the phenomena of periodical variations (“Rudim. Mag.,” Part III. p. 60; Fahie’s “Hist, of Elec. Tel.,” pp. 283, 284).

Besides additional apparatus named in the subjoined references Mr. Harris invented a very effective steering compass, of which an account is given in Part III. pp. 148–153, of his “Rudimentary Magnetism,” as well as at p. 594 of Noad’s “Manual,” at p. 105 of the “English Cyclopædia” (Arts and Sciences), Vol. III, and at p. 80, Vol. VIII, 1857, “Encycl. Britannica,” and he has also devised a magnetometer for the measurement of electric forces, of which the description and illustrations appear in the last-named publication as transcribed from Mr. Harris’ work already mentioned.

Mr. Harris was made a F. R. S. in 1831, and received the Copley medal four years later. It was in 1843 he published his well-known work “On the Nature of Thunderstorms,” the plans he advocated being adopted in 1847, when he received the order of knighthood as well as a large money grant from the English Government in acknowledgment of his scientific services. The following appears in the obituary notice of Sir Wm. Snow Harris, contributed by Mr. Charles Tomlinson to the _Proceedings of the Roy. Soc._ (XVI, 1868):

“Harris’ sympathies were with the Bennetts, the Cavendishes, the Singers, the Voltas of a past age. Frictional electricity was his _forte_ and the source of his triumphs. He was bewildered and dazzled by the electrical development of the present day, and almost shut his eyes to it. He was attached too closely and exclusively to the old school of science to recognize the broad and sweeping advance of the new. He was not conscious even of being behind his age when he presented to the Royal Society in 1861 an elaborate paper on an improved form of Bennett’s discharger, and still less in 1864, when he discussed the laws of electrical distribution, and yet relied upon the Leyden jar and the unit jar.”

REFERENCES.--_Trans. of the Plymouth Institution_, also _Trans. of the Roy. Soc._ for 1834, 1836, 1839; “Eng. Encycl.” (“Common Electricity”), Vol. III. p. 801; W. A. Miller, “Elem. of Chem.,” 1864, p. 32. For descriptions of his bifilar balance see the eighth “Britannica,” Vol. VIII. p. 623; Harris, “Rud. Elec.,” p. 99, and “Rud. Magn.,” pp. 119, 120; Noad, “Manual,” pp. 26, 27, 37, 40, 41, 63, 580; C. Stahelin, “Die Lehre ...” 1852; P. Volpicelli, “Ricerche analitiche ...” Roma, 1865, while, for his balance electroscope and electrometers, see “Edin. Phil. Trans.,” Dec. 1831; eighth “Britannica,” Vol. VIII. pp. 540, 590, 620 622, 624; Harris, “Rud. Elec.,” pp. 99, etc.; the “Bakerian Lecture”; the “Report of British Association,” Dundee, 1867, for an able account of electrometers by Sir William Thomson. His electrical machine is described at pp. 74–76 of Noad’s “Manual,” as well as at p. 604, Vol. VIII of the 8th “Britannica,” the latter also giving, at p. 550, Harris’ experiments on the electrical attraction of spheres and planes. “Catal. Sc. Papers Roy. Soc.,” Vol. III. pp. 191–192; Lippincott’s “Biog. Dict.,” 1886, p. 1230; Biography in Harris’ “Frictional Electricity”; “Abstracts of Papers ... Phil. Trans., 1800–1830,” Vol. II. p. 298; _Lumière Electrique_ for Oct. 3, 1891, p. 49; reprint of Sir Wm. Thomson’s “Mathematical Papers,” 1872; “Brit. Asso. Reports” for 1832, 1835, 1836; _Edin. Phil. Trans._ for 1834; Fahie’s “History,” p. 321; _Edin. and London and Edin. Phil. Mag._ for 1840; _Phil. Trans._, 1842; _Phil. Mag._ for 1856–1857, and Harris’ “Manuals of Electricity, Galvanism and Magnetism,” published in John Weale’s Rudimentary Series.

=A.D. 1820.=--Mitscherlich (Eilardt--Eilhert), Professor of Chemistry at the Berlin University, discovers what is called _Isomorphism_ (_isos_, equal; _morphe_, form), showing that bodies containing very different electro-positive elements could not well be distinguished from each other; it was impossible therefore to put them in distant portions of the classification, and thus, remarks Whewell, the first system of Berzelius crumbled to pieces.

In other words, Mitscherlich was the first to draw attention to the fact that two bodies having the same composition could assume different forms; to this law Berzelius gave the name of _Isomerism_ (_isos_, equal; _meros_, part).

Sir John Herschel makes particular mention (“Treatise on Light,” s. 1, 113) of Mitscherlich’s remarkable experiment with sulphate of lime--the alteration in the tints of which by heat, it is said, was first observed by Fresnel. This experiment was repeated by Sir David Brewster, and he discovered still more curious properties in _glauberite_, all of which are detailed in Vol. I. p. 417 of the _London and Edinburgh Phil. Mag._ for Dec. 1832.

REFERENCES.--“Cat. Sci. Papers Roy. Soc.,” Vol. IV. pp. 413–416; “Library Useful Knowledge” (Pol. of Light), p. 63; Poggendorff, Vol. II. pp. 160, 161; the very able treatise of Mr. J. Beete Jukes on “Mineralogical Science”; also Poggendorff’s _Annalen_, Vol. XV. p. 630, for Mitscherlich on the chemical origin of iron glance in volcanic masses.

=A.D. 1820.=--Ampère (André Marie) (1775–1836), one of the most distinguished philosophers of the century, Professor of Mathematical Analysis in the French Ecole Polytechnique (1809), afterwards Professor of Physics at the Collège de France, reads before the Académie Royale des Sciences, Sept. 18, 25, Oct. 9, 13, and Nov. 6, 1820, papers containing a complete exposition of the phenomena of electro-dynamics. His investigations were subsequently embodied in the “Recueil d’Observations ...” Paris, 1822, and were still further developed during 1824 and 1826, as shown through both his “Précis de la théorie ...” and “Théorie des Phénomènes Electro-Dynamiques.”

The news of Oersted’s discovery of the relation existing between the electric current and the magnet--the fundamental fact of electro-magnetism--was made known in July 1820, and the inquiry was at once taken up more particularly by Ampère, Arago, Biot, and Félix Savary in France, as well as by Berzelius, Davy, De la Rive, Cumming, Faraday, Joseph Henry, Schweigger, Seebeck, Sturgeon, Nobili and others throughout Europe and elsewhere. Of all these scientists, Ampère proved the most energetic, and, within three months of the announcement of Oersted’s discovery, his first memoir on the subject was publicly read in Paris.

In this first paper, Sept. 18, he explains the law determining the position of the magnetic needle in relation to the electric current, and he also makes known his intended experiments with spiral or helical wires, which he predicts will acquire and retain the properties of magnets so long as the electrical current flows through them. He likewise explains his theory of magnets, saying that if we assume a magnet to consist of an assemblage of minute currents of electricity whirling all with the same direction of rotation around the steel molecules and in planes at right angles to the axis of the bar, we will have an hypothesis which will account for all the known properties of a magnet. He constructed his spirals and helices, and to the astonishment of all, he produced magnets formed only of spools of copper wire traversed by electric currents. We can readily imagine, adds Prof. A. M. Mayer, the intense interest awakened by this discovery, a discovery which caused Arago to exclaim, “What would Newton, Halley, Dufay, Æpinus, Franklin and Coulomb have said if one had told them that the day would come when a navigator would be able to lay the course of his vessel without a magnetic needle and solely by means of electric currents?” “The vast field of physical science,” says Arago, “perhaps never presented so brilliant a discovery, conceived, verified and completed with such rapidity.” Thus Ampère became the author of a beautiful generalization, which not only included the phenomena exhibited by the new combinations of Oersted, but also disclosed forces existing in arrangements already familiar, although they were never detected till it was thus pointed out how they were to be looked for. His electro-dynamic theory of the action of currents and of magnets has been thought worthy of a place near the Principia of Newton ... it deservedly gained for him the title of the Newton of electro-dynamics, as he did for this branch of science even more than Coulomb had previously done for electro-statics (Profs. A. M. Mayer and W. B. Rogers, “Memorial of Jos. Henry,” 1880, pp. 81, 476; Lardner, “Lectures,” 1859, Vol. II. p. 120; Fahie, “Hist. Tel.,” p. 276).

The experiments of Oersted and Ampère were at once greatly extended by many scientists, among whom may be especially mentioned MM. Yelin, Bœckmann, Van Beek, De la Rive, Moll, Nobili, Barlow and Cumming. The last named apparently gave the earliest notice of the increased effects of a convolution of wire around the magnetic needle, and constructed the first astatic needle galvanometer (_Trans. Camb. Soc._, Vol. I. p. 279). The Chevalier Julius Konrad Yelin (1771–1826), German mathematician, ascertained that the electricity of an ordinary machine when passed along a helix, either in simple electrical sparks or by discharges from a battery, has the effect of rendering an included needle magnetic. According to Dr. Henry, M. Bœckmann found in varying these experiments that no modification of the effect is produced by altering the diameter of the helix from half an inch to thirteen inches. With a helix of thirty-four inches diameter, and a coated surface of 300 square inches, much less magnetism was, however, imparted; and with one of eighty-four inches it was scarcely perceptible. It was found that a needle outside of the helix was magnetized as much as one within; that after being once fully magnetized a continuation of the discharges diminished its power; and that five jars, each of 300 square inches, did not produce, by repeated discharges, much more effect than one of them (Poggendorff, Vol. II. p. 1382; Gilbert’s _Annalen_ for 1820–1823).

In his second paper, Sept. 25 (_Ann. de Chim. et de Phys._, Vol. XV. pp. 59–170), Ampère makes known the results of his experiments on the mutual attractions and repulsions of electrical currents, showing conclusively that when the voltaic current is passed in the same direction through two parallel wires, so placed as to move freely, they attract each other, and that they are repelled if the currents are passed in opposite directions. Thus he establishes the second fundamental law of electro-magnetism, the first law, instituted as we have seen by Oersted, being that the magnetical effect of the electrical current is a circular motion around the current. In the last-named paper he also proposes the hypothesis of currents of electricity circulating from east to west around the terrestrial globe in planes at right angles to the direction of the dipping needle, to account for the phenomena of terrestrial magnetism (Roget, “Electro-Magn.,” p. 47).

In his third paper, Oct. 9, Ampère investigates the properties of currents transmitted through wires forming closed curves (_courbes fermées_) or complete geometrical figures, an inquiry also alluded to in another memoir read Oct. 30, 1820.

These papers were immediately followed by others, which engaged nearly all the sittings of the Academy between Dec. 4, 1820, and Jan. 15, 1821. In these he brings forth new confirmations of his theories, and reduces the phenomena of electro-magnetism to mathematical analysis.

Mr. Samuel Prime remarks (“Life of Morse,” 1875, p. 266) that the discovery of the action of the spiral coil upon the magnetic needle seems to have been independently made by Ampère in 1821:

“I showed that the current which is in the pile acts on the magnetic needle by the conjunctive wire. I described the instrument, which I proposed to construct, and, among others, the galvanic spiral. I read a note upon the electro-chemical effects of a spiral of iron wire, subjected to the action of the earth, directing an electric current as well as a magnet. I announced the new fact of the attraction and repulsion of two electric currents, without the intermediation of any magnet, a fact which I had observed in conductors twisted spirally (Tilloch’s _Journal of Science_, Vol. LVII. p. 47, 1821).

One of his biographers, Professor Chrystal says: “Scarcely had the news of Oersted’s discovery reached France, when a French philosopher, Ampère, set to work to develop the important consequences which it involved. Physicists had long been looking for the connection between magnetism and electricity, and had, perhaps, inclined to the view that electricity was somehow to be explained as a magnetic phenomenon. It was, in fact, under the influence of such ideas, that Oersted was led to his discovery. Ampère showed that the explanation was to be found in an opposite direction. He discovered the ponderomotive action of one electric current on another, and, by a series of well-chosen experiments, he established the elementary laws of electro-dynamic

## action, starting from which, by a brilliant train of mathematical

analysis, he not only evolved the complete explanation of all the electro-magnetic phenomena observed before him, but predicted many hitherto unknown. The results of his researches may be summarized in the statement that an electric current, in a linear circuit of any form, is equivalent in its action, whether on magnets or other circuits, to a magnetic shell bounded by the circuit, whose strength at every point is constant and proportional to the strength of the current. By his beautiful theory of molecular currents, he gave a theoretical explanation of that connection between electricity and magnetism which had been the dream of previous investigators. _If we except the discovery of the laws of the induction of electric currents_, made about ten years later by Faraday, _no advance in the science of electricity can compare for completeness and brilliancy with the work of Ampère_. Our admiration is equally great, whether we contemplate the clearness and power of his mathematical investigations, the aptness and skill of his experiments, or the wonderful rapidity with which he elucidated his discovery when he had once found the clew.”

“Oersted,” remarks M. Babinet, “was the Christopher Columbus of magnetism; Ampère became its Pizarro and its Fernand Cortez.”

Of Ampère’s _astatic_ needles, a description, taken from one of his memoirs (_Ann. de Ch. et de Ph._, Vol. XVIII. p. 320), appears at pp. 280–281 of Fahie’s “History” (Knight’s “Mech. Dict.,” 1874, Vol. I. p. 171, and Vol. II. p. 1181). For this greatly perfected form of galvanometer the credit has erroneously been given to Prof. Cumming, who first suggested the idea of neutralizing the directive force of the needle arising from the earth’s magnetism, which he did by placing a magnetized needle immediately beneath the movable or index needle. Fahie adds, in a footnote: “In Prof. Cumming’s paper ‘On the Connection of Galvanism and Magnetism,’ read before the Cambridge Philosophical Society, April 2, 1821, he described a near approach to the astatic needle. In order to neutralize the terrestrial magnetism he placed a small magnetized needle under the galvanometer needle” (_Trans. Cam. Phil. Soc._, Vol. I. p. 279). The credit of Ampère’s discovery is sometimes given to Nobili, as in Noad’s “Manual of Electricity,” London, 1859, p. 327; also Roget’s “Electro-Magnetism” in “Library of Useful Knowledge,” London, 1832, p. 42.

As has been already shown (Laplace, A.D. 1820), the first proposal to apply Oersted’s discovery to telegraphic purposes by substituting the deflection of the magnetic needle through electric currents for the divergence of the pith balls of the electroscope, was made by Ampère, in his Memoir of Oct. 2, 1820, which appears in the _Comptes Rendus_, and at p. 72, Vol. XV of the _Annales de Chimie et de Physique_. His plan, remarks Sabine, was, however, doomed to the same fate as that of Sömmering, of never coming into practice, and for the same reasons, principally the number of line wires. Had Ampère combined his system, or rather the one of Laplace, with that which Schweigger proposed of reducing Sömmering’s telegraph to two wires, or with any other using a code of signals, the problem of the electric telegraph would have been solved from the year 1820. Ampère makes no mention of surrounding the needles with _coils of wire_, as is so frequently stated by writers on the telegraph. Indeed he could not then have even heard of the galvanometer; for, although Schweigger’s paper on the subject was read at Halle on the 16th of September 1820, it was not published until the November following.

M. Jean Jacques Antoine Ampère (1800–1864), son of André Marie Ampère, was an accomplished scholar who succeeded François Andrieux as professor at the Collège de France and became a member of the French Academy in 1847.

REFERENCES.--For accounts of Ampère’s rotary magnet, electro-dynamic cylinders, revolving battery, and of his electripeter employed to alter rapidly the direction of the electric current in voltaic batteries, consult pp. 639, 640, 643, Vol. VIII of the eighth “Britannica.” Fahie, “Hist. of El. Tel.,” p. 303. See “Catal. Sci. Papers Roy. Soc.,” Vol. I. pp. 58, 61; Messrs. Sainte-Beuve et Littré’s account of his life and labours in the _Revue des Deux Mondes_ for Feb. 15, 1837; “Notice sur M. Ampère,” _par_ M. E. Littré, Paris, 1843; Arago’s “Eulogy on Ampère,” translated, at pp. 111–171 of the “Report of the Smithsonian Institution” for 1872. Consult also “Report Smiths. Instit.” for 1857, pp. 100–107; Ampère’s biography in the _Sci. Am. Suppl._, No. 674, p. 10760; also Ampère’s “Journal et Correspondance,” Poggendorff, Vol. I. pp. 39, 40; Address of His Royal Highness the Duke of Sussex to the Eng. Roy. Soc., 1836; Barlow on “Magnetic Attractions”: _Comptes Rendus_ for 1838, Vol. VII. p. 81; _Bibl. Univ._, XX; _Phil. Mag._, Vols. LVI. p. 308; LVII. pp. 40–47, “On the Electro-Magnetic Experiments of Oersted and Ampère,” by Mr. Hatchett, and pp. 47–49; _Ann. de Phys. de Bruxelles_, Vol. VII; _Ann. de Ch. et de Phys._, XXIX; Du Moncel, Vol. III. p. 7; “Acad. de Paris,” Sept. 12, 1825; _La Lum. Elect._ for Oct. 31, 1891, p. 202; Roch, in “Zeitschr. f. Mathém.” 1859, p. 295; Roget on Ampère’s theory of Mag.; K. W. Knochenhauer, _Pogg. Annal._, XXXIV. p. 481; J. Marsh, “On a Particular Construction of M. Ampère’s Rotating Cylinder,” _Phil. Mag._, LIX. p. 433, 1822; Henn, “De Amperi principiis ...”; “Memorial of Joseph Henry,” 1880, pp. 59, 81; “Lib. of Use. Know.” (El. Mag.), pp. 24, 28, 83–92; Harris, “Rud. Elec.,” pp. 170, 171, and “Rud. Mag.,” p. 130; Noad, “Manual,” pp. 661–662, 861–864; “Encycl. Metrop.” (El. Mag.), Vol. IV. pp. 5–8; Highton, “Elec. Teleg.,” p. 39; Gmelin’s “Chemistry,” Vol. I. p. 317; Mrs. Somerville, “Conn. Phys. Sci.,” 1846, pp. 320, 321; Dr. Lardner, “Lectures,” Vol. II. p. 125; J. F. W. Herschel, “Prelim. Dis. Nat. Phil.,” 1855, p. 243; Whewell, “Hist. Induc. Sc.,” 1859, Vol. II. pp. 242, 246, 619; “Ann. of Sc. Disc.” for 1850, p. 129, and for 1865, p. 125; “Smithsonian Report” for 1878, p. 273; Sturgeon, “Sci. Researches,” Bury, 1850, pp. 12, 16, 29; _Jour. Frankl. Inst._ for 1851, Vol. XXII. p. 59; Turnbull, “El. Mag. Tel.,” 1853, pp. 55 and 221; (Vail’s “History,” pp. 133, 134; Prof. Henry’s Evid., 85a, record; Doct. Channing’s Ev., 47a, record; Hibbard, Ev., 31_a_. ...) See also Humboldt’s “Cosmos,” articles “Aurora Borealis,” “Volcanoes,” “Earthquakes”; Ampère et Babinet, “Exposé des Nouv. Déc. ... de Oersted, Arago, Ampère, Davy, Biot, Erman, Schweigger, De la Rive,” etc., Paris, 1822, translated into German “Darstellung der neuen ... dem Französischen,” Leipzig, 1822, and alluded to in _Lumière Electrique_ for July 18, 1891, pp. 148, 149; Hachette et Ampère, “Sur les Expériences de Oersted et Ampère”: _Journal de Physique_ for September 1820. _Annales de Chimie_ for 1825; “Journal des Savants,” for June 1872; “Dict. Génér. de Biogr. et d’Histoire,” Paris, 2^e ed., pp. 85–86; “Collection de Mémoires relatifs à la Physique,” Paris 1885, 1887, Vols. II and III _passim_, as per indexes; “Amer. Journ. of Psychology,” Vol. IV. pp. 6–7.

For William Ritchie (1790–1837), the author of an able paper, “On electro-magnetism, and Ampère’s proposal of telegraphic communication by means of this power,” consult _Phil. Trans._ for 1833, p. 313; “Abstracts of Papers ... Roy. Soc.,” Vol. II. pp. 350, 382; _Phil. Mag._ or _Annals_, Vol. VII, 1830, p. 212; _Phil. Mag. and Journal of Science_, Vol. III, 1833, pp. 37, 122, 124, 145.

For Leopoldo Nobili (1784–1835), frequently mentioned above, consult “Bibl. Univ.,” Bruxelles, 1834 (Sc. et Arts), Tome LVI. pp. 82–89, 150–168; “Edin. Trans.” Vol. XII and _Phil. Mag._ Vol. XI, 1832, p. 359, for the account of experiments made by James David Forbes, similar to those of Nobili, wherein an electric spark was elicited from a natural magnet. For J. D. Forbes, see also _Phil. Mag._, 1832, Vol. XI. p. 359. For Nobili and Antinori, consult _Phil. Mag._, Vol. XI, 1832, pp. 401, 466; “Bibl. Britan.,” Vol. XXV, 1824, N.S. p. 38; Vol. XXIX, 1825, N.S. p. 119. For Antinori and Marchese Cosimo Ridolfi, consult “Bibl. Britan.” Vol. XVI, N.S., 1821, pp. 72–75, 101–118.

For Prof. James Cumming (1777–1861), also frequently named in above article, consult _Phil. Mag._, Vol. LX, 1822, p. 253; “Bibl. Britan.,” Vol. XXV, N.S., 1824, p. 104, for experiments of Cumming, Trail and Marsh; the investigations in the same line of Mr. Thos. Stuart being especially reported on in “Bibl. Britan.,” Vol. XXVII, N.S., 1824, pp. 199–206; “Dict. of Nat. Biog.,” Vol XIII. p. 296; “Edin. Phil. Journal,” 1824, Vol. X. p. 185; “Cat. Sc. Papers Roy. Soc.,” Vol. I. pp. 58–61; Vol. VI. p. 565; Vol. VII. p. 29; “Bibl. Britan.,” Vol. XVI, N.S. p. 309; Vol. XVII, N.S. p. 16; Vol. XIX. p. 244; Vol. XX. pp. 173, 258; Vol. XXIV. p. 109.

For Le Chevalier Julius Konrad von Yelin (1771–1826), consult “Bibl. Britan.,” Vol. XXIII, N.S., 1823, p. 38; Vol. XXIV, N.S., 1823, p. 253, and, especially, the important tract on the discovery of thermo-magnetism at p. 31 of his “Die Akademie der Wissenschaften und ihre Gegner,” Munich, 1822.

=A.D. 1820.=--Arago (Dominique François Jean), famous French astronomer, physicist and statesman (1786–1853), who at the early age of twenty-three had, besides being Assistant Astronomer to the Observatory, become the successor both of Lalande in the Academy of Sciences and of Monge in the chair of analytical mathematics at the Polytechnic School, and who, conjointly with Gay-Lussac, had founded the highly valued _Annales de Chimie et de Physique_ in 1816, communicates to the French Institute, on the 25th of September 1820, his discovery that the electric current has the power of developing magnetism in iron and steel. Into the axis of a galvanic conductor made in the form of a coil, or helix, he placed a needle, the extremities of the wire coil being connected to the poles of a battery, and with this he proved that the wire not only acted on bodies already magnetized, but that it could develop magnetism in such as did not already possess the power. When soft iron was used, the magnetism given was only temporary, but on repeating the experiment, M. Arago succeeded completely in permanently magnetizing small steel needles. Arago’s paper on the subject appears at p. 94, Vol. XV of the _Ann. de Ch. et de Ph._, and it is said that at about the same time Dr. Thos. J. Seebeck (1770–1831), and Georg Friedrich Pohl (1788–1849) laid similar results before the Berlin Academy, also that Sir Humphry Davy independently made a like discovery, of which he advised Dr. Wollaston, Nov. 12, 1820. Reference to this fact has already been made at Davy, under date A.D. 1801, wherein it was stated that the latter had found iron filings to so adhere to the connecting wire as to form a mass ten or twelve times the thickness of the wire. This was also the case in the experiments of M. Arago, who, upon observing that the filings rose before coming in contact with the conjugate wire, drew the conclusion that each small piece of iron was converted into a temporary magnet. Thus was Arago led to the discovery of what is called magnetic induction by electric currents, or, in other words, that an electrical current passing through a conductor will induce magnetic action in such bodies near it as are capable of being magnetized (_Phil. Trans._ for 1821, p. 9; Tilloch’s _Jour. of Sci._, Vol. LVII. p. 42, 1821; eighth “Britannica,” Vol. VIII. p. 532 and Vol. XIV. p. 640; Thomas Thomson, “Outline of the Sciences,” p. 563).

A fact worth noting in connection with the development of Oersted’s discovery by both Arago and Ampère, is that in order “to prevent the communication of the electricity laterally in the folds of the coil, the wire was insulated by varnish in the first instance and afterward by winding silk or cotton around it” (F. C. Bakewell, “Elec. Sci.,” London, 1853, p. 37).

On the 22nd of November 1824, Arago announced to the French Academy of Sciences the remarkable discovery made by him of a new source of magnetism in rotatory motion. He was led to this by observing that when a magnetic needle was oscillating above or close by any body, such as water or a plate of metal, it gradually oscillated in arcs of less and less amplitude, as if it were standing in a resisting medium, and, besides, that the oscillations performed in a given time were the same in number (Humboldt’s “Cosmos,” “Magnetic Observations,” 1825). He caused a circular copper plate to revolve immediately beneath a magnetic needle or magnet, freely suspended so that the latter might rotate in a plane parallel to that of the copper plate, and he found that the needle tends to follow the circumvolution of the plate; that it will deviate from its true direction, and that by increasing the velocity of the plate the deviation will increase till the needle passes the opposite point, when it will continue to revolve, and at last with such rapidity that the eye will be unable to distinguish it. This, says Mrs. Somerville, is quite independent of the motion of the air, since it is the same if a pane of glass be interposed between the magnet and the copper. When the magnet and the plate are at rest, not the smallest effect, attractive, repulsive, or of any kind, can be perceived between them. In describing this phenomenon Arago states that it takes place not only with metals, but with all substances, although the intensity depends upon the kind of substance in motion.

Arago’s experiments were repeated in London, March 7, 1825. His valuable discovery, which obtained for him the Copley medal, and which confirms the doctrine of the universal prevalence of magnetism in all bodies, is recorded in Arago’s “Sur les Déviations ... aiguille aimantée” (_An. de Ch. et de Ph._, Vol. XXXIII, and _Phil. Trans._, p. 467 for 1825), and a solution of the phenomena is given by Faraday in _Phil. Trans._ for 1832, p. 146, by Sir John Leslie in the Fifth Dissertation of the eighth “Britannica,” p. 746, as well as in the article “Magnetism” of the latter publication, and in Mrs. Somerville’s “Conn. of Phys. Sc.,” pp. 325–327. (See also the observations recorded in Humboldt’s “Cosmos,” 1849, Vol. I. pp. 172, 173; in Dr. Thomson’s “Outline of the Sciences,” pp. 556–558; Fahie, pp. 282, 283, 321; Dr. Whewell, Vol. II. pp. 254–256; Brewster’s _Edin. Jour. of Sci._, 1826, Vol. III. p. 179; “Dict. Gén. de Biogr. et d’Histoire,” Paris, 2^e ed. p. 126.)

In Brewster’s _Edinburgh Journal of Science_ (Vol. V. p. 325), notice is given of Arago’s then recent researches on the influence which bodies considered not magnetic have on the motions of the magnetic needle, and reference is made to a new communication transmitted by Arago to the Académie des Sciences, as well as to a report of additional experiments in the same line given at meetings held July 3 and 10, 1826. Arago satisfactorily meets the denials made by Leopoldo Nobili and another Italian natural philosopher (Liberato Giovanni Bacelli) that substances not metallic have any influence on the magnetic oscillations, and he announces as a result of his investigations that, for certain positions of a vertical needle, and for velocities of rotation sufficiently rapid, the repulsive force which is exerted in the direction of the radius is as great as the force perpendicular to the radius, of which the effects are observed upon a horizontal needle.

Poisson having stated in his memoir “On the Theory of Magnetism” in motion (see Poisson at A.D. 1811) that Coulomb had recognized the magnetic virtue in all bodies, independently of the iron which they contain, Arago remarked that the idea of Coulomb was quite different from his, Coulomb having been of opinion that a quantity of iron, although too small for chemical analysis even to appreciate, was sufficient to produce in bodies which contained it appreciable magnetic effects. MM. Thénard and La Place confirmed this remark. Brewster adds that, in justice to Coulomb, it is necessary to state that he is the undoubted author of the discovery that _all bodies, whether organic or inorganic, are sensible to the influence of magnetism_. M. Biot has remarked that there are two ways of explaining this, _either all substances in nature are susceptible of magnetism, or they all contain portions of iron, or other magnetic metals, which communicate to them this property_. This last explanation, though adopted by Coulomb, by no means affects his claim to the discovery of the general fact that all bodies, whether organic or inorganic, are susceptible of becoming magnetic. Prof. Hansteen has drawn from numerous experiments and observations the important conclusion that _every vertical object, of whatever material it is composed, has a magnetic south pole above, and a north pole below_ (_Edin. Phil. Journal_ for January-April 1821).

M. Arago made many valuable investigations concerning the influence of the aurora borealis on the needle, on the variations of the latter, upon the nature of meteors, lightning, the zodiacal light, magnetic storms, etc. etc., which are admirably recorded more particularly in the great work of Alex. von Humboldt. The latter remarks that Arago has left behind him a treasury of magnetical observations (upward of 52,600 in number) carried on from 1818 to 1835, which have been carefully edited by M. Fédor Thoman, and published in the “Œuvres Complètes de François Arago” (Vol. IV. p. 493). Much could be said, especially regarding Arago’s paper, presented by him to the Academy of Sciences in 1811, which is considered to have established the foundation of chromatic polarization. Mention must at any rate be made of the fact that in Humboldt’s estimation the discovery of the two kinds of polarization of light may be considered the most brilliant of the century. They, unquestionably, rank among the most splendid of optical phenomena.

Etienne Louis Malus, a distinguished French philosopher (Fifth Dissert. of “Encycl. Brit.”), discovered in 1808 polarization by reflection from polished surfaces, and Arago, during 1811, made the discovery of coloured polarization. A world of wonder, remarks Humboldt, composed of manifold modified waves of light having new properties was now revealed. A ray of light which reaches our eyes, after traversing millions of miles from the remotest regions of heaven, announces of itself in Arago’s polariscope (consisting of a plate of quartz cut across the axis placed in one end of a tube, at the other end of which is a doubly refracting prism) whether it is reflected or refracted, whether it emanates from a solid or fluid, or gaseous body, even announcing the degree of its intensity (Delambre, “Histoire de l’Astronomie,” p. 652; Humboldt, “Cosmos,” 1849, Vol. I. p. 33; Vol. II. p. 715).

In 1818, Arago was elected a F.R.S.; he became a member of the Royal Astronomical Society and also member of the Bureau des Longitudes during 1822, was made Perpetual Secretary of the Academy and Director of the Paris Observatory eight years later, and received the Rumford medal in 1850. The Copley medal given him in 1825 had never before been conferred upon a Frenchman of science. It was upon his urgent request that the “Annuaire du Bureau des Longitudes” and “Les Comptes Rendus hebdomadaires” were commenced by the Academy, 1828–1835.

In a letter to Schumacher, Humboldt speaks of Arago as “one gifted with the noblest of natures, equally distinguished for intellectual power and for moral excellence.” In conjunction with Gay-Lussac, Arago was, for almost half a century, Humboldt’s most intimate friend, and their ever-increasing intimacy became such as to lead to a perfect unity of thought on scientific subjects. It cannot, therefore, be considered an exaggerated expression of feeling when, in a letter to Geoffroy St. Hilaire, dated Berlin, June 24, 1829, Humboldt should conclude with the words: “Pray remember me to MM. Valenciennes, Deleuze and Cuvier, but especially to him whom I hold dearest in this life, to M. Arago.”

REFERENCES.--Poggendorff, Vol. I. pp. 53, 54, and the several biographies named at p. 202, Vol. I of “Johnson’s New Univ. Cycl.,” 1877; J. A. Barral, “Œuvres de F. Arago,” 1854–1855; Faria E. De e Arago, “Breve compendio ...” Lisbon, 1800; Arago’s “Notices Scientifiques,” “Cat. Sc. Papers Roy. Soc.,” Vol. I. pp. 80–84; Vol. IV. pp. 697–701; Vol. VI. pp. 567, 736–737; Vol. VIII. p. 537; “Encycl. Metropol.,” Vol IV (Magnetism), pp. 6, 7; J. F. W. Herschel, “Nat. Phil.,” 1855, pp. 117, 244, and his account of the repetition of M. Arago’s experiments on rotatory magnetism in _Phil. Trans._ for 1825; Whewell, “Hist. Induc. Sci.,” 1859, Vol. II. p. 226; _Phil. Mag._, Vols. LIX. p. 233; LVII. pp. 40–49; LVIII. p. 50; LXI, p. 134; “Lib. Useful Knowledge’” (Magnetism), p. 91; Noad, “Manual,” pp. 204, 534; “Ann. of Sci. Disc.” for 1850, p. 124; Harris, “Rud. Magn.,” Parts I, II. pp. 58–61 and _Phil. Trans._ for 1831,

## Part I; Prime’s “Life of Morse,” pp. 168, 265, 266; Gmelin’s

“Chemistry,” Vol. I. p. 317; _Comptes Rendus_ for 1836, Vol. II. p. 212; Dredge, “Electr. Illum.,” Vol. II. p. 122; Sturgeon, “Scient. Res.,” Bury, 1850, pp. 13, 37, 216, etc.; Appleton, “New Am. Cycl.,” Vol. XI. p. 71; _Sci. Am. Suppl._, No. 204, p. 3254; _La Lumière Electrique_ for Oct. 31, p. 202; “Reports of the Smithsonian Institution” for 1857, pp. 102, 107; for 1862, pp. 132–143, and p. 127 of last named for Malus’ discovery. Houzeau et Lancaster, “Bibl. Générale,” Vol. I. part. i. pp. 676–677 detailing the contents of Arago’s “Œuvres Complètes,” published in thirteen volumes under the direction of J. A. Barral, also Vol. II. p. 76; _Cornhill Magazine_, Vol. XVII. p. 727; Pierre Prévost, “Tentative,” Genève, 1822 (Poggendorff, Vol. II. p. 525); _Phil. Mag._, Vol. LVIII. p. 50; Vol. LXI. p. 134; “Abstracts of Papers ... Roy. Soc.,” Vol. II. p. 249.

=A.D. 1821.=--Ridolfi (Marquis Cosimo di), an Italian agriculturist, is the author of several treatises on _fenomeni elettro-magnetici_, published in Florence, wherein he expresses the belief that “because electricity produces both magnetic and calorific phenomena, the elements giving these separately may possibly be so compounded together as to produce electricity; which infers that electricity is a compound of magnetism and caloric.”

REFERENCES.--“Antologia di Firenze,” 1824, p. 159, and “Biblio. Ital.,” Vol. LXIII. p. 268 for Ridolfi’s description of the electric plate machine of Novellucci; also “Annales de Chimie et de Physique,” Vol. X. p. 287; Sturgeon, “Scientific Researches,” 1850, Sec. I. p. 29; “Bibliothèque Universelle” for Feb. 1821.

=A.D. 1821.=--Scoresby (Dr. William) (1789–1857), English master-mariner, and author of numerous scientific and other treatises, first publishes, in the “Trans. of the Edinburgh Society,” accounts of his magnetometer--magnetimeter--and of his electro-magnetic experiments. These were duly followed up by full reports of his many interesting investigations relative, more particularly, to the development of magnetic properties of metals by percussion, as well as to magnetic induction, and regarding the uniform permeability of all known substances to the magnet’s influence.

REFERENCES.--“Abstracts of Papers ... Roy. Soc.,” London 1832–1833, Vol. II. pp. 108, 168, 210; “Dict. of Nat. Biog.,” London, 1897, Vol. LI. p. 6; _Phil. Trans._ for 1822–1824; “Trans. Edin. Soc.,” Vol. IX. pp. 243–258, 353, 465; Vol. XI for 1824; Vol. XII for 1831; Vol. XIII for 1832, and Vol. XIV for 1833; “Brewster’s Jour. of Sc.,” Vol. VIII for 1828; “Bibliothèque Britannique,” Genève, 1796, N.S., Vol. XXIX for 1825, p. 185; “Edin. Phil. Jour.” for 1823, Vol. IX. p. 45.

=A.D. 1821.=--Babinet (Jacques) (1794–1872), French scientist, is the author of a very valuable treatise, published in Paris, upon the magnetical discoveries of Oersted, Ampère, Arago, Davy and others. This was followed by his “Résumé complet de la physique,” etc., and by a companion work treating of the relations of ponderable and imponderable bodies to the phenomena of magnetism and electricity, also, during the year 1829, by his Memoir upon the determination of terrestrial magnetism.

He succeeded Savary as Professor at the Collège de France in 1838, and, two years later, took the place of Dulong in the section of General Physics at the Académie des Sciences, becoming not long after the Assistant Astronomer at the Paris Observatory for Meteorology.

His numerous scientific treatises are to be found throughout the “Mémoires de la Société Philomathique,” the “Annales de Physique,” the “Comptes Rendus,” the “Revue des Deux-Mondes” and other prominent publications of the day.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. II. p. 10; “Eng. Cycl.,” London, 1872, Supplement, p. 143; “Biog. Gén.,” Vol. IV. p. 21; Mme. Blavatsky, “Isis Unveiled,” Vol. I. p. 202; and Ronalds’ “Catalogue,” pp. 10–11, for the joint works of Ampère and Babinet.

=A.D. 1821.=--Pfaff (Christian Heinrich) (1773–1852), who became Professor of Medicine, Physics, etc., at the Kiel University, and was one of the most energetic followers of Volta, sends an unusually interesting communication to Gilbert’s “Annalen der Physik” and to Schweigger’s “Journal für Chemie und Physik,” wherein he very ably supports the views of the Pavia physicist.

Pfaff had, long before that, become favourably known through numerous scientific papers, which were translated into the leading foreign journals, the ones entitled “Dissertatio inauguralis ...” published at Stuttgart, and “Über thierische Elektricität,” published at Leipzig, having brought him special distinction. He had also written, more

## particularly, upon the experiments made by Alex. von Humboldt as well

as relative to Pacchiani’s “Formation of Muriatic Acid by Galvanism,” alluded to at the A.D. 1805 entry, and it was by reason of the investigations made by Pfaff and Van Marum that the use of the voltaic column was generally abandoned. These scientists had constructed very strong piles consisting, in some instances, of as many as seventy large separate discs, when they found that the lower layers of wet cloth or of pasteboard were so seriously compressed by the discs above them as to neutralize their effect.

REFERENCES.--Johann Samuel T. Gehler’s “Phys. Wörterbuch,” Vol. VI. pp. 507, 517–518; “Roy. Soc. Cat. Sc. Papers,” Vol. IV. pp. 866–871; “Ann. der Chemie,” Vol. XXXIV. p. 307; Vol. LX. p. 314; “Annales de Chimie et de Physique,” Vol. XLI. pp. 236–247; Sturgeon, “Annals,” Vol. VIII. pp. 80, 146; Noad, “Manual,” p. 558; Wilkinson, “Elements,” Vol. I. pp. 1–8, 18, 22, 196, 326, 407; Vol. II. p. 106; “Encycl. Brit.” ninth ed., Vol. XVIII. p. 725; “Soc. Philom.,” Vol. II. p. 181; _Phil. Mag._, Vol. XXVII. p. 338.

=A.D. 1821.=--Faraday (Michael), a very distinguished English chemist and natural philosopher (1791–1867), who probably did more for the development of the study of electrical science than any other investigator, publishes his “History of the Progress of Electro-Magnetism” and succeeds, on the morning of Christmas (December 25), 1821, both in causing a magnetic needle to rotate round a wire carrying an electric current and in making the wire rotate around the needle, thus rendering possible the production of continuous mechanical motion by electricity.

The apparatus with which he produced this result is described in nearly all works treating of natural philosophy. Premising his reference to this discovery of Mr. Faraday, whose original papers thereon appear in the _Quarterly Journal of Sciences and the Arts_, Vol. XII. pp. 75, 186, 283 and 416 (the first bearing date September 11, 1821), Dr. Whewell says that on attempting to analyze the electro-magnetic phenomena observed by Oersted and others into their simplest forms, they appeared, at least at first sight, to be different from any mechanical actions which had yet been observed. It seemed as if the conducting wire exerted on the pole of the magnet a force which was not attractive or repulsive, but _transverse_; not tending to draw the point acted on nearer, or to push it further off, in the line which reached from the acting point, but urging it to move at right angles to this line. The forces appeared to be such as Kepler had dreamt of in the infancy of mechanical conceptions, rather than such as those of which Newton had established the presence in the solar system, and such as he, and all his successors, had supposed to be the only kinds of force which exist in nature. The north pole of the needle moved as if it were impelled by a vortex revolving round the wire in one direction, while the south pole seemed to be driven by an opposite vortex (called by Wollaston _vertiginous magnetism_ and considered by Mr. Barlow as the result of _tangential action_). The case seemed novel, and almost paradoxical. It was soon established by experiments, made in a great variety of forms, that the mechanical action was really of this transverse kind. And a curious result was obtained, which a little while before would have been considered as altogether incredible: that this force would cause a constant and rapid revolution of either of the bodies about the other--of the conducting wire about the magnet, or of the magnet about the conducting wire (Vol. XII of the “Journal of the Royal Institution”; Watkins, “Popular Sketch of Electro-Magnetism; or Electro-Dynamics,” London, 1828; Mrs. Somerville, “Connection of Phys. Sciences,” 1846, p. 315).

Passing over many of Faraday’s important scientific investigations in other lines, we come to his second great discovery, that of _magneto-electric induction_, which is the converse of Oersted’s (developed by Ampère and Arago), the production of electricity by magnetism. This is recorded in the first series of “Experimental Researches in Electricity,” read November 24, 1831 before the Royal Society, of which body Faraday had become a Fellow during 1824, and it is published at p. 125 of the _Phil. Trans._ for 1832.

It appears that upon observing certain phenomena, which he described as _Volta-electric_, he concluded before long that magnetism in motion ought to produce an electric current just as electricity was made to imitate all the effects of magnetism. He carried on many experiments, and after the announcements made by Arago to the French Academy, November 22, 1824, he endeavoured to make the conducting wire of the voltaic circuit excite electricity in a neighbouring wire by induction, just as the conductor charged with common electricity would have done, but he obtained no satisfactory results until August 29, 1831 (_Annales de Chimie_, Vol. XLVIII. p. 402). He remarks: “Certain effects of the induction of electrical currents have already been recognized and described; as those of magnetism; Ampère’s experiments of bringing a copper disc near to a flat spiral; his repetition, with electro-magnets, of Arago’s extraordinary experiments, and perhaps a few others. Still it appeared unlikely that these could be all the effects which induction by currents could produce.... These considerations, with their consequence, the hope of obtaining electricity from ordinary magnetism, have stimulated me at various times to investigate experimentally the inductive effects of electric currents. I lately arrived at positive results, and not only had my hopes fulfilled, but obtained a theory which appeared to me to open out a full explanation of Arago’s magnetic phenomena, and also to discover a new state which may probably have great influence in some of the most important effects of electric currents.” His very important conclusion was finally verified, October 1–17, in the following manner. He had taken a helix, or spool of copper wire, which latter, Prof. Brande tells us, was covered with silk as in his former experiments and which was connected by its extremities with a galvanometer, the deflection of which would of course announce a current of electricity in the spiral and wires connected with it, and he found that while in the act of introducing the pole of a powerful bar-magnet within the coils of the spiral, a deflection of the galvanometer took place in one direction, and that when in the act of withdrawing, it took place in the opposite direction; so that each time the conducting wire cut the magnetic curves, a current of electricity was, for the moment, produced in it. Dr. Whewell’s account of the discovery is so well interspersed with references that it deserves repetition here:

“In 1831, Faraday again sought for electro-dynamical induction, and, after some futile trials, at last found it in a form different from that in which he had looked for it. It was then seen, that at the precise time of making or breaking the contact which closed the galvanic circuit, a momentary effect was induced in a neighbouring wire, but disappeared instantly (_Phil Trans._, 1832, p. 127, 1st ser., Art. 10). Once in possession of this fact, Mr. Faraday ran rapidly up the ladder of discovery, to the general point of view. Instead of suddenly making or breaking the contact of the inducing circuit, a similar effect was produced by removing the inducible wire nearer to or further from the circuit (Art. 18)--the effects were increased by the proximity of soft iron (Art. 28)--when the soft iron was affected by an ordinary magnet, instead of the voltaic wire, the same effect still recurred (Art. 37)--and thus it appeared, that by making and breaking magnetic contact, a momentary electric current was produced. It was produced also by moving the magnet (Art. 39)--or by moving the wire with reference to the magnet (Art. 53). Finally, it was found that the earth might supply the place of a magnet in this as in other experiments (2nd ser., _Phil. Trans._, p. 163) and the mere motion of a wire, under proper circumstances, produced in it, it appeared, a momentary electric current (Art. 141). These facts were curiously confirmed by the results in special cases. They explained Arago’s experiments: for the momentary effect became permanent by the revolution of the plate. And without using the magnet, a revolving plate became an electrical machine (Art. 150), a revolving globe exhibited electro-magnetic action (Art. 164), the circuit being complete in the globe itself without the addition of any wire; and a mere motion of the wire of a galvanometer produced an electro-dynamic effect upon its needle (Art. 171).... And thus he was enabled, at the end of his second series of ‘Researches’ (December 1831), to give, in general terms, the law of nature to which may be referred the extraordinary number of new and curious experiments which he has stated (Arts. 256–264), namely, that if a wire move so as to cut a magnetic curve, a power is called into action which tends to urge a magnetic current through the wire; and that if a mass move so that its parts do not move in the same direction across the magnetic curves, and with the same angular velocity, electrical currents are called into play in the mass. And here might properly be added the experimental distinction between a helix and a magnet, which Faraday subsequently pointed out (‘Exper. Res.,’ Art. 3273): ‘Whereas an unchangeable magnet can never raise up a piece of soft iron to a state more than equal to its own, as measured by the moving wire, a helix carrying a current can develop in an iron core magnetic lines of force of a hundred or more times as much power as that possessed by itself when measured by the same means.’”

An article on the reduction of Mr. Faraday’s discoveries in magneto-electric induction to a general law appeared in the “Philosophical Transactions of the Royal Society” Vol. III. p. 37, and at Vol. IV. p. 11, new series, of the _Philosophical Magazine_ (see Faraday’s first two Memoirs in the _Phil. Trans._, Book XIII. chaps. v and viii; letter to Gay-Lussac in _Annales de Chimie_, Vol. LI. 1832, pp. 404–434; _Phil. Mag._, Vol. XVII. pp. 281, 356); while, in the _Phil. Trans._ for 1832, p. 132, is the Report of his production of the electric spark through a modified arrangement in which the electric current was induced by an electro-magnet, as shown in his subsequent work published in London during 1834. This is alluded to in Vol. V. pp. 349–354 of the _Phil. Mag._ for latter year, and in Poggendorff’s _Annalen_, Vol. XXXIV. pp. 292–301 for 1835. (See also Bakewell, “Elect. Science,” pp. 39, 140, 144.)

“Around the magnet, Faraday Is sure that Volta’s lightnings play; But how to draw them from the wire? He took a lesson from the heart ’Tis when we meet--’tis when we part, Breaks forth the electric fire.”

HERBERT MAYO, in _Blackwood_.

In Prof. Alfred M. Mayer’s address, delivered before the American Association at Boston, August 26, 1880, we read: “It is not generally known or appreciated that Henry and Faraday independently discovered the means of producing the electric current and the electric spark from a magnet. Tyndall, in speaking of this great discovery of Faraday, says: ‘I cannot help thinking while I dwell upon them, that this discovery of magneto-electricity is the greatest experimental result ever obtained by an investigator. It is the Mont Blanc of Faraday’s own achievements. He always worked at great elevations, but higher than this he never subsequently attained.’ And it is this same physicist who further remarks (‘Johnson’s Cycl.,’ Vol. II. pp. 26–27) that all our induction coils, our medical machines, and the electric light so far as it has been applied to lighthouses, are the direct progeny of Faraday’s discovery. In the paper here referred to (Nov. 24, 1831) he for the first time calls the ‘magnetic curves,’ formed when iron-filings are strewn around a magnet, ‘lines of magnetic force.’ All his subsequent researches upon magnetism were made with reference to those lines. They enabled him to play like a magician with the magnetic force, guiding him securely through mazes of phenomena which would have been perfectly bewildering without their aid. The spark of the _extra current_, which I believe was noticed for the first time by Prof. Joseph Henry, had been noticed independently by Mr. William Jenkin. Faraday at once brought this observation under the yoke of his discovery, proving that the augmented spark was the product of a secondary current evoked by the reaction of the primary upon its own wire.” The phenomenon of the spark from the _extra current_ here alluded to was first announced by Henry in July 1832. He had observed that when the poles of a battery are united by means of a short wire of low resistance, no spark or at least a very faint one is produced, but when the poles of the battery are connected by a long copper wire and mercury cups, a brilliant spark is obtained at the moment the circuit is broken by raising one end of the wire out of its cup of mercury and also that the longer the wire and the greater the number of its helical convolutions, the more powerful would be the effect (Silliman, “Am. Jour. of Sc.,” Vol. XXII). The results of Faraday’s investigation of the _extra current_ first appeared in the _Phil. Mag._ for November 1834.

The references already named give an account of many other important results attained by Faraday during 1831 and up to the date of the publication of the third series of his “Experimental Researches” (p. 76), wherein he recognizes the “Identity of Electricities derived from different sources”[60] (Vol. I. par. 265 and 360), after investigating the electricities of the machine, the pile, and of the electrical fishes, and after employing as conductors the entire plant of the metallic gas pipes and water pipes of the city of London (_Phil. Trans._ for 1833, p. 23; Poggendorff, _Annalen_, Vol. XXIX, 1833, pp. 274, 365).

In the fourth series, relating to “A New law of electric conduction” (Vol. I. par. 380, 381, 394, 410), he demonstrates the influence of what is called “the state of aggregation” upon the transmission of the current. He found that although the latter was conveyed through water it did not pass through ice. This he subsequently explained by saying that the liquid condition enables the molecule of water to turn round so as to place itself in the proper line of polarization, which the rigidity of ice prevents. This polar arrangement must precede decomposition, and decomposition is an accompaniment of conduction (_Phil. Trans._ for 1833, p. 507; Poggendorff, _Annalen_, Vol. XXXI, 1834, p. 225; also _Phil. Mag._, Vol. X. p. 98; “Royal Inst. Proc.,” Vol. II. p. 123; Silliman’s _Journal_, Vol. XXI. p. 368).

Other series (pars. 309, 450, 453–454, 472, 477, 661–662, 669, etc.) treat of “Electro-chemical or electrolytic decomposition.” The experiments of Wollaston in this line have been given under the A.D. 1801 date, where Prof. Faraday’s opinion of them is also expressed. Faraday was successful in the employment of Wollaston’s apparatus for the decomposition of water, and he afterwards devised an arrangement enabling him to effect true electro-chemical decompositions by common electricity as well as by the voltaic pile. For this, it is said, he used an electric battery consisting of fifteen jars and a plate machine having two sets of rubbers and a glass disc fifty inches in diameter, the whole presenting a surface of 1422 inches. One revolution of the plate could be made to give ten or twelve sparks, each one inch long, while the conductors afforded sparks ten to fourteen inches in length. He also devised a _discharging train_, to instantaneously carry off electricity of the feeblest tension by connecting a thick wire as he had previously done with the London gas and water pipes. A good description of the methods by which he succeeded with the latter apparatus in establishing the analogy between ordinary and voltaic electricity is given in the eighth “Britannica,” Vol. VIII. pp. 596–597. He had shown, at paragraph 371 and p. 105 of his “Researches,” that as a measure of quantity, a voltaic group of two small wires of platinum and zinc, placed near each other, and immersed in dilute acid for three seconds, yields as much electricity as the electrical battery, charged by thirty turns of a large machine; a fact that was established both by its momentary electro-magnetic effect, and by the amount of its chemical action, but, in order to enable him to establish a principle of definite measurement, he devised a _voltameter_ or _volta-electrometer_ as mentioned at paragraph No. 739 (Noad, “Manual,” p. 365). By means of this apparatus he calculated that a single grain of water in a voltaic cell will require for its decomposition a quantity of electricity equal to that liberated in 800,000 discharges of the great Leyden battery of the Royal Institution (“Researches,” par. 861). Also, that the decomposition of a single grain of water by four grains of zinc in the active cell of the voltaic circle, produces as great an amount of polarization and decomposition in the cell of decomposition, as 950,000 charges of a large Leyden battery, of several square feet of coated surface; an enormous quantity of power, equal to a most destructive thunderstorm. Tyndall remarks (“Notes on Electricity,” No. 118, also “Faraday as a Discoverer,” 1868, p. 44) that Weber and Kohlrausch ascertained that the quantity of electricity associated with one milligramme of hydrogen in water, if diffused over a cloud 1000 metres above the earth, would exert, upon an equal quantity of the opposite electricity at the earth’s surface, an attractive force of 2,268,000 kilogrammes.[61]

Faraday introduced new terms to express more specifically the circumstances attending electro-chemical decomposition. Objections had long been made to the designation _poles_--one _positive_, the other _negative_--on the ground that such did not convey a correct idea of the effects produced. These designations had been given under erroneous supposition that the poles exerted an attractive and repulsive energy towards the elements of the decomposing liquid, much as the poles of the magnet act towards iron. When connecting the extremities of a battery, the electricity simply makes a circuit; the current passes _through_ the substance to be decomposed and the elements remain in operation until the connection is broken. Since the poles merely act as a path to the current he calls them electrodes (_electron_, electricity, _odos_, a way); that part of the surface of the decomposing matter which the current enters--immediately touching the positive pole--he designates as _anode_ (_ana_, upward) and the part of the matter which the current leaves--next to the negative pole--_cathode_ (_kata_, downward). He names _electrolyte_ (_luo_, to set free) the fluid decomposed directly by electricity passing through it; the term _electrolyzed_ meaning electro-chemically decomposed. The elements of an _electrolyte_ are named _ions_ (_ion_, going), the _anion_ being the body (in sulphate of copper solution, the acid) which _goes up_ to the positive pole, to the _anode_ of the decomposing body, whilst the _cation_ is that (in sulphate of copper solution, the metal) which _goes down_ to the negative pole, to the _cathode_ of the decomposing body.

The many tests which he made with his voltameter led him to the conclusion “that under every variety of circumstance, the decompositions of the voltaic current are as definite in their character as those chemical combinations which gave birth to the atomic theory” (_Phil. Trans._ for 1833, p. 675; for 1834, p. 77; Poggendorff, _Annalen_, Vols. XXXII. p. 401; XXXIII. pp. 301, 433, 481; Bakewell, “Electric Science,” p. 124; “Brit. Assoc. Report” for 1833, p. 393; Henry’s “Memoirs of Dalton,” p. 106).

The eighth series of his “Researches” (Vol. I. pars. 875, etc.) treats of the “electricity of the voltaic pile,” a further investigation of which is shown through the papers constituting his sixteenth and seventeenth series as per Index of Vol. II. p. 302. Faraday establishes by very simple experiments the most powerful known refutation of Volta’s contact theory and shows conclusively that the current in the pile results from the mutual chemical action of its elements, just as Fabbroni and Wollaston had stated before him. An extract from the conclusion of his very elaborate defence of the chemical theory reads as follows: “... the contact theory assumes, that a force which is able to overcome powerful resistance ... can arise out of nothing: that, without any change in the acting matter, or the consumption of any generating force, a current can be produced, which shall go on for ever against a constant resistance, or only be stopped as in the voltaic trough, by the ruins which its exertion has heaped upon its own course.... The chemical theory sets out with a power, the existence of which is pre-proved, and then follows its variations, rarely assuming anything which is not supported by some corresponding simple chemical fact. The contact theory sets out with an assumption to which it adds others, as the cases require, until at last the contact force, instead of being the firm unchangeable thing at first supposed by Volta, is as variable as chemical force itself. Were it otherwise than it is, and were the contact theory true, the equality of cause and effect must be denied. Then would perpetual motion also be true; and it would not be at all difficult, upon the first given case of an electric current by contact alone, to produce an electro-magnetic arrangement, which, as to its principle, would go on producing mechanical effects for ever” (“Exp. Res.,” pars. 2071–2073, Vol. II. pp. 103–104; _Phil. Trans._ for 1834, p. 425; for 1840, pp. 61, 93; Poggendorff, _Annalen_, Vols. XXXV. pp. 1, 222; LII. pp. 149, 547; LIII. pp. 316, 479, 548. Auguste Arthur De la Rive, “Archives de l’Elect.,” Genève, 1841–1845, Vol. I. pp. 93, 342; Graham, “Elem. of Chem.,” London, 1850, Vol. I. pp. 242, etc.; Faraday and Sturgeon, “Ann. of Elec.,” Vol. IV. pp. 229, 231; Daniell, “Intro. to Study of Chem. Phil.”; Liebig, _Annal._, Vol. XXXVI. p. 137; Figuier, “Expos. et Hist.,” 1857, Vol. IV. p. 434. Also De la Rive’s “Treatise,” Vol. I. pp. 393–402; “Exper. Researches,” Vol. I. pp. 322–323--induction of galvanic current upon itself).

Faraday’s theory of induction offers nothing new as to the nature of the electric forces--it simply indicates the manner of their distribution and the laws by which they are affected. His experiments show that electrization by influence is possible only by means of continuous particles of air or other non-conducting medium (dielectric), that no electric action occurs at a distance greater than the interval existing between two adjacent molecules of such medium, in which latter a true polarization of the particles takes place, and that it is by means of this polarization that electric force is transferred to a distance. Induction only takes place through insulators: induction is insulation, it being the action of a charged body upon insulating matter, of which latter the particles communicate to each other in a very minute degree the electric forces whereby they become polarized and are enabled to transmit an equal amount of the opposite force to a distance. The latter property is termed _inductive force_ or _specific inductive capacity_, and Faraday discovered that the intensity of electric induction varies in different insulating media; for instance, the induction through shell-lac (the first substance he experimented with) being twice as great as through a like thickness of air. It was while experimenting with shell-lac that he first observed the singular phenomenon of the _return_ or _residual charge_, i. e. the charge which would of itself gradually reappear in the apparatus after the latter had been suddenly and perfectly discharged. This, he considered due to the penetration, into the substance of the dielectric, of a portion of the charge by conduction. The inductive capacity of all gases he found to be the same as that of air, and this property does not alter with variations in their density.

His discovery of the specific inductive capacity of various substances has been already alluded to (A.D. 1772, Cavendish). Faraday’s biographer in the ninth “Britannica” says: “It appears, from hitherto unpublished papers, that Henry Cavendish had, before 1773, not only discovered that glass, wax, rosin and shell-lac have higher specific inductive capacities than air but had actually determined the numerical ratios of these capacities. This, of course, was not known to Faraday or other electricians of his time.” It was on the 30th of November, 1837, Faraday communicated to the Royal Society the paper on Induction wherein he announces the re-discovery of _specific inductive capacity_. One of its most important results to-day, remarks John Tyndall, “is the establishment of the specific inductive capacity of insulators--a subject of supreme importance in connection with submarine cables. As a striking illustration of Faraday’s insight, it may be mentioned that as early as 1838 he had virtually foreseen and predicted the retardation produced by the inductive action between the wires of submarine cables and the surrounding sea-water” (Tyndall’s “Notes on Electricity,” 1871, pp. 160–161; “Exper. Researches,” Index Vol. I.; “Faraday as a Discoverer,” new edition, p. 89). Consult, also, the references entered at Cavendish, A.D. 1772; J. E. H. Gordon, “Phys. Treatise on Elect. ...” London, 1883, Vol. I. chap. xi. par. 81–83, which alludes to “Exper. Researches,” 1161, Vol. I. p. 360 as well as to the investigations of specific inductive capacities made by Boltzmann, Romich and Fajdiga, Romich and Nomak, Schiller, Silow, Wüllner, Dr. Hopkinson, J. E. H. Gordon, Ayrton and Perry, and gives the “General Table of Specific Inductive Capacities,” detailing the observations of Cavendish, Faraday and all the others named above. See, besides, “Reprint of Papers ...” Sir Wm. Thomson, 1872 to 1884, 2nd ed., paragraphs 36, 46, 50; _Phil. Trans._, 1838, pp. 1, 79, 83, 125; 1842, p. 170; Poggendorff, _Annalen_, Vols. XLVI. pp. 1, 537; XLVII. pp. 33, 271, 529; XLVIII. pp. 269, 424, 513; XCVI. p. 488; XCVII. p. 415; _Phil. Mag._, Vols. IX. p. 61; XI. p. 10; XIII. pp. 281, 355, 412; “Bibl. Univ.,” Vol. XVII. p. 178 and “Archives des Sc. Phys.,” Vol. XXXI. p. 48; “Journal de Pharm.,” Vol. XXVII. p. 60; W. S. Harris, “Specific Inductive Capacities ...” (_Phil. Trans._, 1842).

In the fifteenth series of his “Exper. Researches” (Vol. II. pars. 1749–1795), Faraday gives the results of his experiments proving the identity of the power of the _gymnotus_ or the _torpedo_ with common electricity. He concludes that “a single medium discharge of the fish is at least equal to the electricity of a Leyden battery of fifteen jars, containing 3500 square inches of glass coated on both sides, charged to its highest degree” (p. 8); “all the water and all the conducting matter around the fish, through which a discharge circuit can in any way be completed, is filled at the moment with circulating electric power and this state might be easily represented generally in a diagram by drawing the lines of inductive action upon it. In the case of a _gymnotus_ surrounded equally in all directions by water, these would resemble generally in disposition the magnetic curves of a magnet having the same straight or curved shape as the animal, that is, provided he in such cases employed, as may be expected, his four electric organs at once” (p. 12) (C. Matteucci, “Traité des phénom. ...” Paris, 1844, pp. 188–192).

Then follow in due course, Faraday’s remarkable papers relating to the magnetization of light and the illumination of magnetic lines of force, the polar and other condition of diamagnetic bodies, etc. These communications, which he made to the Royal Society in November and December 1845, contain the particulars of what many consider to be his most brilliant discoveries. He first shows that when a ray of polarized light passes through a piece of silicated borate of lead glass placed between the poles of a natural (or preferably an electro-) magnet, so that the line of magnetic force shall pass through its length, the polarized ray will experience a rotation. The law is thus expressed: “If a magnetic line of force be _going_ from a North pole or coming from a South pole, along the path of a polarized ray, _coming_ to the observer, it will rotate that ray to the right hand, or if such a line of force be coming from a North pole or going from a South pole it will rotate such a ray to the left hand” (_Phil. Trans._ for 1846 and 1856; Poggendorff, _Annalen_, Vol. C. pp. 111, 439; Noad, “Manual,” pp. 804–805; Harris, “Rud. Mag.,” Parts I and II. p. 71; Whewell, “Hist. of the Inductive Sciences,” Vol. II. pp. III, 133; Gmelin’s “Chemistry,” Vol. I. pp. 168–169). At the Faraday Centenary Celebration held in London, June 18, 1891, Lord Rayleigh observed that “the full significance of the last-named discovery was not yet realized. A large step towards realizing it, however, was contained in the observation of Sir William Thomson, that the rotation of the plane of polarization proved that something in the nature of rotation must be going on within the medium when subjected to the magnetizing force, but the precise nature of the rotation was a matter for further speculation, and perhaps might not be known for some time to come.”

Through Faraday’s other communication, is made known the discovery of _diamagnetism_. Therein he shows, as the result of his customary careful experimental explorations that the magnetism of every known substance (even tissues of the human frame) is manifested in one of two ways. Either the body is, like iron, attracted by the magnet, taking a position coincident with the magnetic forces which he calls _paramagnetic_ (_para_ beside or near, _magnetes_, _magnes_, magnet) or bodies--like bismuth, for instance--are repelled by the poles and should therefore be called _diamagnetic_ (_dia_, across) for they set themselves across, equatorially, or at right angles to the magnetic lines. As far back as 1788, the repulsion by bismuth was first observed by Brugmans, while M. Becquerel, during 1827, confirmed the observation, said to have been made by Coulomb, that a needle of wood could be made to point across the magnetic curves, and stated that he had found such a needle place itself parallel to the wires of a galvanometer. Yet, neither M. Becquerel nor M. Lebaillif, who (after Saigy and Seebeck) had called attention to the repulsion of both bismuth and antimony by the magnet, made a distinction of the diamagnetic force from the paramagnetic as Faraday did. Amongst other results, this English scientist found that phosphorus is at the head of all diamagnetic substances, bismuth taking the lead amongst the metals, whilst, of many gases and vapours, oxygen proved to be the least diamagnetic, in fact, the only one which is paramagnetic (“Lond., Edin., and Dub. Phil. Mag.” for December 1850). All the facts set forth in Mr. Faraday’s paper are, according to Brande, resolvable by induction into the general law; that while every particle of a magnetic body is attracted, every particle of a diamagnetic body is repelled by either pole of a magnet: these forces continue as long as the magnetic power is sustained, and cease on the cessation of that power, standing therefore in the same general antithetical relation to each other as the positive and negative conditions of electricity, the northern and southern polarities of ordinary magnetism, or the lines of electric and magnetic force in magneto-electricity. (_Phil. Trans._ for 1846–1851; _Phil. Mag._, Vols. XXVIII. pp. 294, 396, 455; XXIX. pp. 153, 249; XXXVI. p. 88; _Annales de Chimie_, Vol. XVII. p. 359; Poggendorff, _Annalen_, Vols. LXVIII. p. 105; LXX. p. 283; LXXXII. pp. 75, 232; “Bibl. Univ. Archives,” Vols. I. p. 385; III. p. 338; XVI. p. 89; Ludwig F. von Froriep, “Notizen,” Vols. XXXVII. cols. 6–8; XXXIX. col. 257; Erdmann, “Jour. Prak. Chem.,” Vol. XXXVIII. p. 256; Liebig, _Annal._, Vol. LVII. p. 261; Napoli, “Rendiconto,” Vol. VI. p. 227; Silliman’s “Journal,” Vols. II. p. 233; X. p. 188; Walker, “Elect. Mag.,” Vol. II. p. 259; John Tyndall, “Researches on Diamagnetism and Magne-crystallic Action,” London, 1870, pp. 1, 38, 89, 90, 137; Whewell, “Hist. of Ind. Sc.,” 1859, Vol. II. p. 620; “Athenæum” for January 31, 1846; Plücker’s paper “On the relation of Magnetism and Diamagnetism,” dated September 8, 1847, in Poggendorff’s _Annalen_ and in Taylor’s “Scientific Memoirs,” Vol. V. part ix. p. 376; Edmond Becquerel’s “Memoir on Diamagnetism” in _An. de Ch. et de Ph._, Vol. XXXII. p. 112; “Practical Mech. and Engin. Mag.,” 1846, p. 117; for “Coexistence of Paramagnetism and Diamagnetism in same Crystal,” _see_ “Jour. of Chem. Soc.,” London, February 1906, p. 69, taken from _Les Comptes Rendus_).

During the course of Faraday’s experiments to ascertain the effects of magnetism on crystals some very curious results were obtained with bismuth. Having suspended four bars of the metal horizontally between the poles of the electro-magnet, the first pointed _axially_; the second _equatorially_; another _equatorial_ in one position, and _obliquely equatorial_ if turned round on its axis fifty or sixty degrees; the fourth _equatorially and axially_ under the same treatment; whilst all of them were repelled by a single magnetic pole, thus showing their strong and well-marked diamagnetic character. These variations were attributed to the regularly crystalline condition of the bars. He then chose carefully selected crystals and, after describing their peculiar action between the poles, he says that “the results are altogether very different from those produced by diamagnetic action. They are equally distinct from those dependent on ordinary magnetic action. They are also distinct from those discovered and described by Plücker, in his beautiful researches into the relation of the optic axis to magnetic action; for there the force is equatorial, whereas here it is axial. So they appear to present to us a new force, or a new form of force in the molecules of matter, which, for convenience’ sake, I will conventionally designate by a new word, as the _magne-crystallic force_.” Prof. A. M. Mayer justly observes (“Johnson’s Cycl.,” I. 1342) that the above-named facts “received their full explanation at the hands of Tyndall, whose subtile examination or lucid explanation of these phenomena--though not popularly known--we think form his greatest claim to illustrious distinction as a man of science.” For an extract from the last-named work relative to M. Poisson’s remarkable theoretic prediction of magne-crystallic action, see the article concerning that scientist at A.D. 1811. (Consult _Phil. Trans._ for 1849, pp. 4, 22; _Phil. Mag._, Vol. XXIV. p. 77 and s. 4, Vol. II. p. 178; De la Rive, “Treatise,” Vol. I. pp. 482–497; “Athenæum,” No. 1103, p. 1266; Gmelin’s “Chemistry,” Vol. I. pp. 514–519.)

The remarkable discoveries we have named were succeeded by many others of a very high order, the references to which occupy as many as 158 separate entries through pp. 555–560, Vol. II. of the “Catal. of Sci. Papers of the Royal Society.” Among those may be singled out his additional investigations regarding the magnetism of gases and the magnetic relations of flames and gases, the lines of magnetic force, subterraneous electro-telegraphic wires (_Phil. Mag._ s. 4, Vol. VII. 1854), the relation of gravity to electricity, atmospheric magnetism, likewise his recorded observations on hydro-electricity, magneto-electric light for lighthouses, pyro-electricity, the electrophorus, Wheatstone’s telegraph, etc. (“Roy. Inst. Proc.” for 1854–1858, pp. 555–560). It was in 1848 he wrote of the powerful insulating properties of gutta-percha (Gmelin’s “Chemistry,” Vol. I. p. 313; “Lond. and Edin. Phil. Mag.,” Vol. XXXII. p. 165), and he not long after constructed a very singular apparatus to a Leyden jar consisting of a wire 140 miles long, perfectly insulated with gutta-percha, one end of which communicated with an insulated pile of 360 elements of zinc and copper charged with acidulated water, as described in the “Britannica.” The results of his inquiries concerning the Leyden jar charge of buried electric conducting wires were, according to Whitehouse’s pamphlet on the Atl. Tel. (p. 5) communicated to the Roy. Inst. during the year 1854.

The life of Michael Faraday is an admirable example of extraordinary successes achieved through patient endeavour and constancy of purpose over unusual obstacles of birth and education. M. Dumas, in the sixteenth volume of the London “Chemical News,” tells us he was the only man in England who raised himself to the first rank in science, whose every attribute can be fearlessly held up as a model. He had none of the “ambition, eternal pining after rank or hauteur” of Davy, nor “the secretiveness and coldness” of Wollaston. “Faraday’s intellect, while it burnt as brightly as Davy’s, was as deep searching as Wollaston’s, and as reverent as Newton’s, yet it had nothing in it which could repel us, chill us, or forbid our affection.” The son of a blacksmith, he was first placed in a bookseller’s shop, then apprenticed to a bookbinder, but his tastes were averse to the trade and he was led to seek instruction in another line, more particularly after attending the evening lectures of Mr. Tatum, yet, as already stated (see Dr. George Gregory, A.D. 1796), it was while in M. Riebau’s (the bookbinder’s) employ that chance threw in his way the works which led him to enter the channels in which he subsequently became so distinguished. To a friend, he writes:

“Your subject interested me deeply every way; for Mrs. Marcet was a good friend to me, as she must have been to many of the human race. I entered the shop of a bookseller and bookbinder at the age of thirteen, in the year 1804, remaining there eight years, and during the chief part of the time bound books. Now it was in those books, in the hours after work, that I found the beginning of my philosophy. There were two that especially helped me, the ‘Encyclopædia Britannica,’ from which I gained my first notions of electricity, and Mrs. Marcet’s ‘Conversations on Chemistry,’ which gave me my foundation in that science. Do not suppose that I was a very deep thinker, or was marked as a precocious person ... but facts were important to me and saved me. I could trust a fact and always cross-examined an assertion. So when I questioned Mrs. Marcet’s book by such little experiments as I could find means to perform, and found it true to the facts as I could understand them, I felt that I had got hold of an anchor in chemical knowledge, and clung fast to it....” (“Faraday as a Discoverer,” by John Tyndall, 1868, pp. 6–7).

Think of the startling, not to say marvellous, achievements growing out of Faraday’s subsequent first experiments with an electrical machine made out of an old bottle and by the aid of a Leyden jar constructed with a medicine phial!

In 1812, he was taken by Mr. Dance to the lectures of Sir Humphry Davy, whose chemical assistant he became the following year and in whose company, as we have already seen (A.D. 1801), he travelled on the Continent until 1815. Mr. Davies Gilbert, to whom is due Davy’s introduction to the Royal Institution, has said of the last-named illustrious philosopher that the greatest of all his discoveries was the discovery of Faraday. In 1816, Michael Faraday was placed by Mr. Brande in charge of the “Quarterly Journal of Science,” and, during 1823, he was elected corresponding Member of the French Academy, becoming F.R.S. the ensuing year through the influence of his friend Richard Phillips. It was during 1825–1826 he published in the _Phil. Trans._ the chemical papers wherein he announces the discovery of benzole (called by him bicarburet of hydrogen) to which, says Hoffmann, “we virtually owe our supply of aniline, with all its magnificent progeny of colours.” In 1827, Faraday succeeded Davy as lecturer at the Royal Institution, and, from 1829 to 1842, he occupied the post of chemical lecturer at the Royal Military Academy, Woolwich. The “Experimental Researches,” to which we have so often alluded, first appeared in the 1831 _Phil. Trans._, and were afterwards collected in three volumes, which were published respectively during 1839, 1844, 1855. Faraday was made D.C.L. in 1832 by Oxford University, and, one year later, he received the Fullerian professorship of chemistry in the Royal Institution, which he held till his death. A pension was given him by the English Government in 1835, and he also received the Royal Medal, which latter was again conferred upon him, together with the Rumford Medal, during 1846. Ten years before (1836) he had become a member of the Senate of the London University, and during the year 1858 the Queen allotted him the residence in Hampton Court where he died in 1867. “Taking him for all in all,” says Tyndall, “it will, I think, be conceded that Faraday was the greatest experimental philosopher that the world has ever seen; and I would hazard the opinion that the progress of future research will tend not to diminish but to enhance the labours of this mighty explorer.”

REFERENCES.--“Life of Faraday,” by Dr. H. Bence Jones (Sec. R.I.); “Michael Faraday,” by Dr. J. H. Gladstone, 1872; “Faraday as a Discoverer,” by John Tyndall; the biographical sketch by Prof. Joseph Lovering; “Michael Faraday, his Life and Work,” by Silv. P. Thompson, New York, 1898; “The Chemical News” (Am. Rep.), Vol. I. pp. 246, 250, 276, and Vol. II. pp. 98, 202; Report of the Faraday Centenary celebration at the London Roy. Inst., June 17, 1891; Poggendorff, Vol. I. pp. 719–722; Larousse, “Dict. Univ.,” 1872, Vol. VIII. p. 99; “Biog. Gén.,” Vol. XVII. pp. 90–93; “Men of the Time,” London, 1856; Reports on Faraday’s Lectures delivered before the Roy. Inst. (taken from the “London Mining Journal,” Nos. 714, 717–722), at pp. 319–324, 387–393; Vol. XVIII for 1849 of “Jour. of Frankl. Inst.”; Gmelin’s “Chemistry,” Vol. I. pp. 424, etc., 435–436, 514–519; Poggendorff, _Annalen_, Vols. LXXXVIII. p. 557; Ergänz, Vol. I. pp. 1, 28, 64, 73, 108, 187, 481–545; Gustav Wiedemann, “Die Lehre von Galv.,” 1863 and “Die Lehre von der Elektricität,” 1883; W. H. Uhland, “Die Elektrische Licht,” 1884, p. 62; An. Sc. Dis. for 1850, pp. 129, 131, 132; for 1851, p. 133, and for 1852, p. 110 on “Atmospheric Magnetism,” taken from “Jameson’s Journal,” July 1851; for 1853, p. 132; for 1856, p. 161; for 1858, p. 177, Faraday, “On the Conservatism of Force”; for 1860, p. 125, Faraday on “Static Induction”; for 1863, p. 108, “Elec. Lamp in Lighthouses”; for 1868, p. 169; for 1870, p. 10; for 1874, p. 174, on “Dielectric Absorption”; Robison, “Mechan. Phil.”; Leslie, “Geomet. Anal.”; “Jour. Roy. Inst.” for February 1831, Vol. I. p. 311 (Electrif. of ray of light); eighth “Britannica,” Vols. I, sixth dissertation; VIII. pp. 532–533, 539, 542, 544, 552, 601, 607, 617; XIV. pp. 68, 663; XXI. pp. 612, 622, 628, 630; ninth “Britannica,” Vol. IX. pp. 29–31; Brockhaus, “Conversations-Lexikon,” Vol. VI. pp. 565–566; “Lond. and Edin. Ph. Mag.,” Vol. I. p. 161 for letter of Faraday of July 27, 1832, enclosing one signed P. M., “in which _chemical decomposition is for the first time obtained by the induced magnetic current_”; Faraday and Schönbein (“London and Edin. Mag.,” July-August 1836; “Roy. Instit. Proc.,” III. 70–71); Faraday and Riess, “On the action of non-conducting bodies in electric induction,” 1856; Sturgeon, “Sc. Res.,” 1850, pp. 20, 475; “Practical Mechanic,” Vols. II. pp. 318, 408; III. p. 197; “Libr. of Useful Knowledge” (Elec. Mag.), pp. 18, 99; Humboldt, “Cosmos,” Vol. I. pp. 182, 188; Harris, “Rud. Magn.,” 1852, I and II, pp. 61–69, etc., 199; III. 122–128 and “Rud. Elec.,” 1st ed., pp. 33–34; “Edin. Jour. Sc.,” 1826, Vol. III. p. 373; “Edin. new Ph. Jour.,” Vol. LI. p. 61; Golding Bird’s “Nat. Phil.,” p. 227; James Johnstone, “The Ether Theory of 1839,” pp. 26, 37; Noad, “Manual,” pp. 59, 236, 692, 805, 866; “Am. Jour. Sc.” for April 1871, relative to lines of magnetic force; “Ann. of Phil.” for 1832; “Bibl. Univ. Archives,” Vol. XVI. p. 129; “Roy. Instit. Proc.,” Vol. I, 1851–1854, pp. 56, 105, 216, 229; _Phil. Trans._, 1832, p. 163; 1851, pp. 29, 85; 1852, pp. 25, 137; _Phil. Mag._, Vol. III, 1852, p. 401; Dredge, “Elect. Illum.,” Vol. I. pp. 46, 91, 95; “New Eng. Mag.” for March 1891; Silliman’s _Journal_, Vol. XII. p. 69; “Sc. Am. Suppl.,” Nos. 198, p. 3148; 206, p. 3284; 526, p. 8404; 547, p. 8733; 652, p. 10416; _La Lum. Electrique_ for October 31, 1891, pp. 202–203; Marcel Joubert, “Leçons,” 1882, Vol. I. pp. 495, 559; 576; Th. du Moncel, “Exposé des App. de l’Elec.,” 1872, Vols. I and II; G. B. Prescott, “Electricity,” 1885, Vol. I. pp. 105–112; “Reports of the Smithsonian Institution” for 1857, pp. 372–380; for 1862, p. 204; for 1889, p. 444; Richard Mansill, “New Syst. of Univ. Nat. Science,” 1887, pp. 180–185; “Faraday’s Researches on Electrostatical Induction,” also “Faraday’s Law of Attractions and Repulsions,” at pp. 26–30, and 647–664 of “Reprint of Papers on Electro-statics and Magnetism,” by Sir Wm. Thomson, London, 1884; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, p. 142; “Life and Letters of Thomas Henry Huxley,” by Leonard Huxley, New York, 1901, as per Index at pp. 513–514; “Fragments of Science,” by John Tyndall, New York, 1901, Vol. I. pp. 420–443; “Jnl. of Psychological Medicine,” by Dr. William A. Hammond, New York, 1870, pp. 555–569; “Cat. Sc. Papers ... Roy. Soc.,” Vol. II. pp. 555–561; Vol. VI. p. 653; Vol. VII. p. 638; “Bibl. Britan.,” Vol. XVIII, N.S. for 1821, p. 269; “Phil. Mag. and Jour. of Science,” 1833, Vol. III. pp. 18, 37, 38, 161, 253, 353, 460, 469, and Vol. XI, 1838, pp. 206, 358, 426, 430, 538.

APPENDIX I

ACCOUNTS OF EARLY WRITERS, NAVIGATORS AND OTHERS ALLUDED TO BY GILBERT AND NOT ALREADY DISPOSED OF THROUGHOUT THIS “BIBLIOGRAPHICAL HISTORY”

=Abano=, Pietro di--Petrus Aponus, Apponensis or Apianus--called “the Reconciler” (1250–1316), was Professor of Medicine at Padua and wrote several works of importance on different subjects. The best known is “Conciliator differentiarum philosophorum ac Medicorum,” which is devoted to the reconciliation of the various medical and philosophical schools, and in which reference is made to the loadstone, as is also the case in his “Tractatus de Venenis,” published during 1490.

REFERENCES.--Larousse (Pierre), “Dict. Universel,” Vol. I. p. 11; “Biographie Générale,” Vol. I. pp. 29–31; G. A. Pritzel, “Thesaurus Literaturæ Botanicæ,” Lipsiæ, 1851, p. 226; N. F. J. Eloy, “Dict. hist. de la médecine,” Mons, 1778, Art. _Apono_; Ludovico Hain, “Repertorium Bibliographicorum,” Art. _Abano_; Mazzuchelli (Frederigo), “Raccolta d’Opuscoli ...” Venetia, 1741; Pellechet (Marie), “Catalogue général des incunables,” 1897, pp. 1–4; Gilbert, _De Magnete_, Book I. chap. i.

=Agricola=, Georgius--Bauer--Landmann--(1494–1555), is called by Dr. Thomas Thomson one of the most extraordinary men as well as one of the greatest promoters of chemistry that have ever existed, and he pronounces Agricola’s “De Re Metallica,” which was published in 1546, 1556, 1558, 1561, as, beyond comparison, the most valuable chemical work produced in the sixteenth century. Agricola is also the author of “De Natura eorum,” of “De Natura fossilium” and of “De veteribus et novis metallis,” all published at Basle in 1657.

Gilbert mentions Agricola in his _De Magnete_ (Book I. chaps, i. ii. vii. viii.; Book II. chap. xxxviii.) and, in connection with him, alludes more particularly to Gilgil, the Mauretanian, and also to Christoph--Entzelt--Encelius, author of a book bearing the same name as Agricola’s chief work, “De Re Metallica,” published at Frankfort, 1551. Attention may as well be called here to additional authors, whose works, in the same line, are of great variety and but little known: (1) Cæsalpinus (Andreas) (1519–1603), “De Metallicis,” Romæ, 1596; (2) Morieni (Romani), who, in his “De Re Metallica,” Parisiis, 1559, treats (as does also John Joachim Beccher, 1635–1682: “Hutton’s Abridgments” Vol. I. p. 620) of the transmutation of metals and of the occult, much in same manner as Robertus Vallensis in his “De veritate et antiquitate artis chemicæ ...” 1593, 1612; (3) Bernardo Pèrez de Vargas, who, in his “De Re Metallica, en el qual se tratan de muchos diversos secretos ...” Madrid, 1569, tells how to find different kinds of minerals and metals and how to treat them to the best advantage in various industries; (4) J. Charles Faniani, “De Arte Metallicæ” 1576.

Cuvier says of Agricola: “He was the first mineralogist who appeared after the _renaissance_ of the sciences in Europe: he was to mineralogy what Conrad Gesner was to zoology.”

REFERENCES.--“Biog. Générale,” Vol. I. pp. 410–411; Larousse (Pierre), “Dict. Univ.,” Vol. I. p. 141; “Dict. hist. de la médecine” (N. F. J. Eloy), Mons, 1778, Vol. I. pp. 50–52.

=Agrippa=, Heinricus Cornelius--ab Netiesheyem, Nettesheim--(1486–1535), German Doctor of Medicine, also a Doctor of Divinity, a soldier--knighted for valour on the battle-field of Ravenna--a diplomatist, an astrologer, etc. He was in turns, ambassador at Paris and London, historiographer to Emperor Charles V, professor at the university of Pavia, town physician in Friburg, private practitioner at Geneva, court physician to Louise of Savoy, chief magistrate of Metz, theological delegate to the schismatic council of Pisa, etc., and for three years was engaged in a military expedition to Catalonia. He is the author of several important works, the full collection of which was published at Lyons in 1550. The one by which he is best known is “De occulta philosophia,” which was translated in French by Levasseur.

REFERENCES.--Morley (Henry), “The Life of H. Corn. Agrippa,” London, 1856; Bayle (Pierre), “Dict. Hist.”; Jos. Ennemoser, “History of Magic,” London, 1854, Vol. II. pp. 253–256; G. Naudé, “Apologie”; Larousse (Pierre), “Dict. Univ.,” Vol. I. pp. 143–144; Bolton (H. C.), “Chr. Hist. of Chem.,” p. 946; Gilbert, _De Magnete_, Book I. chap. i.

=Albategnius=--Machometes Aractensis, Muhammad Ibn Jabir--Al-Battani--(_d._ A.D. 929), is considered by Lalande one of the twenty greatest known astronomers. His principal work, “De scientia stellarum,” was published in 1537.

REFERENCES.--Delambre (J. B), “Hist. de l’astron. moderne,” pp. 10–62; Houzeau et Lancaster, “Bibl. Générale,” Vol. I. part. i. p. 467; Vol. II. p. 71; Gilbert, _De Magnete_, Book VI. chap. ix.; “Engl. Cycl.” Vol. I. p. 84.

=Alexander Aphrodisæus=--Aphrodisiensis--a celebrated Greek scientist and the oldest commentator on Aristotle, who lived at about the close of the second century after Christ, and whose works were so highly esteemed by the Arabs that they translated most of them (Casiri, “Bibl. Arab. Hisp. Escur.,” Vol. I). The list of all of his publications appears in “Biog. Générale,” Vol. I. pp. 911–914.

REFERENCES.--Fabricius (Johann Albert), “Bibliotheca Græca,” Vol. V. p. 650; Ritter (Dr. Heinrich), “Geschichte der Philosophie,” Vol. IV. p. 24; Gilbert, _De Magnete_, Book I. chap. i. and Book II. chaps. ii. xxv.

=Amatus Lusitanus.= _See_ Lusitanus Amatus.

=Anaxagoras=, born at Clazomenæ, one of the Greek towns of Ionia, in 500 B.C., three years before the death of Pythagoras, was a very eminent philosopher of the Ionic school, wherein he succeeded Anaximenes as a leader, and numbered among his many hearers and pupils Diogenes of Apollonia, Pericles, Euripides, Socrates and Archelaus. A very good analysis of Anaxagoras’ philosophical opinions is to be found in the “Biographical Dictionary of the Society of Useful Knowledge.” Gilbert alludes to him (_De Magnete_, Book II. chap. iii. and Book V. chap. xiii.) as believing that the loadstone was endowed with a sort of life, because it possessed the power of moving and attracting iron, and as declaring in fact that the entire world is endowed with a soul.

Anaxagoras is accused, by Pliny and other early writers, of having predicted the fall of aerolites from the sun, and of regarding all bodies in the universe “as fragments of rocks, which the fiery ether, in the force of its gyratory motion, has torn from the earth and converted into stars” (Humboldt, “Cosmos” 1859–1860, Vol. I. pp. 133–135, note; Vol. II. p. 309; Vol. III. pp. 11–12; Vol. IV. pp. 206–207).

Aristotle also attacks Anaxagoras for not properly etymologizing the word _aether_, from αιθεἲν, to burn, and on this account using it for fire. He shows that _aether_, which signifies to run perpetually, implies that a perpetual motion and perpetuity of subsistence belongs to the heavenly bodies (“Treatises of Aristotle,” by Thos. Taylor, London, 1807, p. 43, note).

According to Anaximenes, named above (born at Miletus about 528 B.C.), the primal principle was Aer, of which all things are formed and into which all things are resolved. He belonged to the branch called the dynamical, whose doctrines as to the heavenly bodies were opposed to those of mechanical philosophers such as Anaxagoras, Empedocles and Anaximander of Miletus (“Engl. Cycl.,” Biography, 1866, Vol. I, p. 201).

REFERENCES.--Houzeau et Lancaster, “Bibl. Gén.,” Vol. I. part i. pp. 401–402, and Vol. II. p. 74; “Plato,” by George Grote, London, 1865, Vol. I. pp. 49–62; “Essai théorique et pratique sur la génération des connaissances humaines,” par Guillaume Tiberghien, Bruxelles, 1844, Vol. I. pp. 181–182; Dr. Heinrich Ritter, “History of Ancient Philosophy,” London, 1846, Vol. I. pp. 281–318; Chas. Rollin, “Ancient History,” London, 1845, Vol. I. p. 376; Paul Tannery, “Pour l’histoire de la Science Hellène,” Paris, 1887, Chap. XII; Theod. Gomperz, “Greek Thinkers,” transl. of L. Magnus, London, 1901, Chap. IV. pp. 556–558, 597; Ueberweg, “Hist. of Philosophy,” transl. of Geo. S. Morris, New York, 1885, Vol. I. pp. 63–67; Alf. Weber, “Hist. of Phil.,” transl. of Frank Thilly, New York, 1896, pp. 48–53.

=Aquinas=--St. Thomas--also called Doctor Angelicus (born at Aquino in Naples, A.D. 1225)--“the most successful organizer of knowledge the world has known since Aristotle”--was a famous schoolman and is considered by many the greatest of Christian philosophers. He is well worthy the profound respect and high admiration in which he is held always by Gilbert, who alludes to him in Book I. chap. i. and in Book II. chap. iii. of his _De Magnete_. The chief work of St. Thomas Aquinas is the “Summa Theologiæ,” to which he devoted the last nine years of his life and which by many has been called the supreme monument of the thirteenth century. The first part of the “Summa Theologiæ” is said to have been originally published in 1465 and the second part in 1471, the completed work first appearing during the year 1485.[62]

One of his critics remarks that those wishing to thoroughly comprehend the peculiar character of metaphysical thought in the Middle Ages should study Aquinas, in whose writings it is seen with the greatest consistency. He is thus spoken of in Dr. Wm. Turner’s “History of Philosophy,” published by Ginn & Co., 1903: “He had a comprehensiveness of purpose which, in these modern times, seems nothing short of stupendous. It is only when, as we study the history of later scholasticism and the history of the philosophy of modern times, we shall look back to the thirteenth century through the perspective of ages of less successful attempts at philosophical synthesis, that we shall begin to realize the true grandeur of the most commanding figure in the history of mediæval thought.”

Aquinas died at the Cistercian Monastery in 1274, and was canonized forty-nine years later by Pope John XXII.

REFERENCES.--Carle (P. J.), “Hist. de la vie ... de Th. d’Aq.,” 1846; Maffei (Francesco Scipione), “Vita ...” 1842; B. Hauréau, “De la Phil. Schol.,” Paris, 1850, Vol. II. pp. 104, 213; G. Tiberghien, “Essai historique ... des con. hum.,” Bruxelles, 1844, Vol. I. pp. 374–378; Dr. Fried. Ueberweg, “Hist. of Phil.,” transl. of Geo. S. Morris, New York, 1885, Vol. I. pp. 440–452; “Thomæ Aquinatis Opera Theologica,” Venice, 1745–1760, 28 vols. quarto, edited by Bernardo M. de Rossi-Rubeis; “Petri de Bergamo, Super Omnia Opera D. Thomæ Aquinatis,” Bononiæ, 1473; “Biogr. Gén.,” Vol. XLV. pp. 208–218; “Siger de Brabant et l’Averroïsme au 13^e siècle,” par Pierre Maudonnet, Friburg, 1899, Chap. IV _passim_; “Albert the Great,” by Dr. Joachim Sighart, transl. of Rev. Fr. T. A. Dixon, London, 1876, Chap. VI. p. 63; “The Great Schoolmen of the Middle Ages,” by W. J. Townsend, London, 1881, pp. 199–241; Alfred Weber, “Hist. of Phil.,” transl. of Frank Thilly, New York, 1896, pp. 241–246; Dr. W. Windelband, “Hist. of Phil.,” authorized transl. by Jas. H. Tufts, New York, 1893, pp. 313–314; Paola Antonia (Novelli), “De D. Th. Aquin.”; A. Hunaci, “Oratio,” Venice, 1507; likewise Veen (Otto van), Etiro (Partenio), Rodericus de Arriaga, Frigerio (Paolo) and Thouron (V. C.) in their works on Aquinas, 1610, 1630, 1648, 1688 and 1737–1740; Henry Hart Milman, “History of Latin Christianity,” London, 1857, Vol. VI. pp. 273–278, 281–286; Pellechet (Marie), “Catal. Gén. des Incunables,” 1897, pp. 210–249; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 264; “Le Journal des Savants” for May 1851, pp. 278, 281–298 _passim_, and also in the issue of December 1905.

=Aristarchus of Samos=, one of the earliest astronomers of the Alexandrian School, who lived in the third century B.C., is referred to in Gilbert’s _De Magnete_, at Chaps. III and IX of book vi. Vitruvius ascribes to him the invention of a concave sundial which he calls _scaphe_ and which is described by Martianus Mineus Capella (cited by Weidler); and Censorinus says that Aristarchus was the author of an extensive work called “Annus Magnus,” covering a period of 2484 years.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. I. p. 623; Montucla (J. F.), “Hist. des Math.,” Vol. I. p. 721; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 77; “Engl. Cycl.,” Vol. I. p. 314.

=Arnaldus de Villa Nova=--Arnaldus Novicomensis--Arnaud de Villeneuve, dit de Bachuone (1235–1312), who assumed the name of Magrinus when on his way from France to Sicily, was an eminent physician, the master of Raymond Lully, who taught medicine as well as alchemy at Barcelona and whose numerous treatises upon the virtues of plants, etc., are analyzed in M. F. Hœfer’s “Histoire de la Chimie,” Vol. I. p. 385. The first edition of his works appeared at Lyons in 1504.

REFERENCES.----Campegius (Laurentius), “Arnaldi Vita”; “Nouvelle Biographie Générale” (Hœfer), Vol. III. pp. 279–282; Boulay (H. de), “Hist. de l’Univ. de Padoue,” Vol. IV; Freind (John), “Hist. de la Médecine,” Vol. III; N. F. J. Eloy, “Dict. Hist. de la Médecine,” Mons, 1778, Tome III. p. 131; Astruc (Jean), “Hist, de la fac. de méd. de Montpellier”; “Journal des Savants” for June 1896, p. 342, “Testaments d’Amand de Villeneuve et de Raimond Lulle,” “L’Alchimie et les Alchimistes”; Figuier (Louis), Paris, 1860, p. 172; Gilbert, _De Magnete_, Book I. chap. i.

=Barbarus=, Hermolaus--Barbaro Ermoleo--(1454–1495)--(Barbari Hermolai, Aquileiensis Pontificis), whose name alone Gilbert mentions, was a well-known Italian savant, Professor of Philosophy at the Padua University, and the author of many works, of which the most popular are: (1) “Castigationes Plinianæ,” Rome, 1492, wherein he boasts of having made more than five thousand corrections in Pliny’s “Natural History”; (2) “Castigationes Secundæ,” Venice, 1480; (3) “Castigationes in Pomponium Melam,” Antwerp, 1582; (4) “Compendium scientiæ naturalis ex Aristotele,” Venice, 1545.

REFERENCES.--Paul Jove, “Elogia”; Boissardus (Joannes Jacobus), “Icones ... virorum illustrium”; “Giornale de’ letterati d’ Italia,” Vol. XXXVIII; “Theosaurus Litteraturæ Botanicæ,” Lipsiæ, 1851, p. 333; “Biogr. Générale,” Vol. IV. pp. 418–419.

=Becanus.= _See_ Goropius.

=Benedictus=--Benedetti--Joannes Baptista (1530–1590), Italian mathematician, who was considered a prodigy at the age of eighteen, and who, five years later, published in Venice a remarkable work on the solution of most of Euclid’s problems. He is also the author of treatises on navigation, astronomy, music, etc., and can justly be placed in the first rank of savants of the sixteenth century.

REFERENCES.--“La Grande Encyclopédie,” Vol. VI. pp. 132–133; “Biog. Générale,” Vol. V. pp. 340–342; Libri (Guillaume), “Hist. des Sciences Mathém.,” Vol. III. pp. 121–133; Montucla (J. F.), “Hist. des Mathém.,” Vol. I. pp. 572, 693, 729; Marie (J. F.), “Hist. des Sc. Math.,” Vol. II. p. 307; Houzeau et Lancaster, “Bibliographie Générale,” Vol. II. p. 83; Gilbert, _De Magnete_, Chap. IX of book iv.

=Brasavolus=, Antonius Musæ (1500–1570), alluded to by Gilbert in

## Book I. chap. i., was a very eminent Italian physician and the author

of “Examen omnium simplicium medicamentorum,” Rome, 1536, as well as of “In octo libros Aphorism. Hippocratis Comment. et Annot.,” Basle, 1541, and of several other works, including a very complete index of all the notable features of the works of Galen.

REFERENCES.--Ginguené (Pierre Louis), “Histoire Litéraire d’Italie”; Baruffaldi (Girolamo), “Commentario istorico all’ inserizione ...,” Ferrara, 1704; “Biog. Générale,” Vol. VII. p. 269; “Storia della Medicina in Italia” (Salvatore de Renzi), Napoli, 1848, in Vol. III _passim_ as per Index, Vol. V. p. 987; Pritzel (G. A.), “Thesaur. Lit. Botan.,” 1851, p. 31.

=Calaber=, Hannibal Rosetius. Of all the authors cited by Gilbert, this is the only one, who, thus far, cannot satisfactorily be identified, although exhaustive efforts to this end have been made by the authors of both the English translations of _De Magnete_. One interpretation (Hannibal, of Roseto in Calabria, shown on map at end of Vol. I. of “Briefe uber Kalabrien und Sizilien,” Göttingen, 1791), has as yet found no endorsement.

=Calcagninus=, Cælius, Italian philosopher and astronomer (1479–1541) is the author of “Quomodo Cœlum stet, terra moveatur ...” wherein he asserts that the earth turns around the sun, also of “De Re Nautica,” containing a good account of ancient ceremonies and observations, as well as of a Commentary on Aristotle, and of many creditable poetical effusions published 1533. His complete works appeared at Basle during the year 1544, and a list of them, fifty-six in all, is given by Jean Pierre Nicéron in his “Mémoires pour servir à l’histoire des hommes illustres,” Paris, 1727–1745.

REFERENCES.--Calcagnini (T. G.), “Della vita ... C. Calcag”; Ginguené (Pierre Louis), “Histoire Litéraire d’Italie,” Vols. IV, VI and VII; Paul Jove--Jovius--Giovio (_b._ 1483, d. 1552), “Eloges”; Borsetti, Ferranti Bolani (Ferrante Giovanni), “Historia almi Ferrariæ Gymnasii,” 1735; “Biog. Gén.,” Vol. VIII. pp. 159–161; Larousse, “Dict. Univ.,” Vol. III. p. 109; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 98; Gilbert, _De Magnete_, Book I. chap. i.

=Cardanus=, Hieronymus (1501–1576), who is so very frequently mentioned by Gilbert, throughout Books I, II, III and IV, was an Italian physicist whose writings are extremely numerous and are well reviewed in the best edition of his works published at Lyons during 1663. Those by which he is best known are the “Ars Magna,” “De Rerum Varietate, Libri XVII,” and the “De Subtilitate, Libri XXI,” which may be considered the exponent of all his scientific knowledge and a notably good translation of which, in French, by Richard Leblanc was published in Paris, 1556.

REFERENCES.--Morley (H.), “Life of Cardan,” 1854, wherein, Vol. II. pp. 56–70, will be found a long account more particularly of the contents of “De Subtilitate”; Larousse, “Dict. Univ.,” Vol. III. pp. 376–377; Dr. Fr. Ueberweg, “Hist. of Philosophy,” tr. of Geo. S. Morris, 1885, Vol. II. p. 25; Walton and Cotton, “Complete Angler,” New York and London, 1847, Part I. p. 142; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 101.

=Copernicus=, Nicolaus--Koppernik--Zepernic--celebrated astronomer, native of Poland (1472–1543), whose studies led him to reject the Ptolemaic system of the universe, and who proposed the one now bearing his name, is the author of “De revolutionibus orbium cœlestium,” which was published May 24, 1543, a few days before his death. He is alluded to by Gilbert (_De Magnete_, Chaps. II, III, VI, IX, of book vi.), who calls him “the restorer of astronomy” and “a man most worthy of the praise of scholarship.” The life and labours of Copernicus are fully detailed, in chapter treating of “Discoveries in the celestial spaces” of the “Cosmos” by Von Humboldt, who, in relation to a passage in “De Revolutionibus,” makes the following very curious note: “It very singularly happens that in an otherwise instructive memoir” (Czynski, “Kopernik et ses travaux,” 1847, p. 102), “the _Electra_ of Sophocles is confounded with electric currents. The passage of Copernicus (quoted in Latin) is thus rendered: ‘If we take the sun for the torch of the universe, for its spirit and its guide--if Trismegistes call it a God, and if Sophocles consider it to be an electrical power which animates and contemplates all that is contained in creation....’

“Four men, Gutenberg, Columbus, Luther and Copernicus, stand at the dividing line of the Middle Ages, and serve as boundary stones marking the entrance of mankind into a higher and finer epoch of its development” (Kapp (Friedrich), _Geschichte_, etc., I).

REFERENCES.--Westphal (E. J.), “Nikolaus Kopernikus” (“Biographie des Copernicus”); Delambre (J. B. J.), “Histoire de l’astronomie Moderne”; “Journal des Savants” for February 1864 and for December 1895; Larousse, “Dict. Univ.,” Vol. V. pp. 66–67; Edw. S. Holden in “Pop. Sc. Monthly” for June 1904, pp. 109–131; _Phil. Magazine_, Vol. XIX. p. 302; Gassendi (Pierre), in “Nicolai Copernici Vita,” appended to his biography of Tycho (“Tychonis Brahei Vita,” 1655, Hagæ Comitum, p. 320); W. Whewell, “Hist. of the Ind. Sciences,” New York, 1858, Vol. I. pp. 257–290; the article at pp. 378–382, “Engl. Cycl.,” which abounds in references; Rheticus, “Narrat. prima”; Kepler (Johann), “De Temporis”; Horrebow (at A.D. 1725--the luminous process of the sun, a perpetual northern light); Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 109–113, for an extended list of authorities, and also pp. 1571–1572; Joachimus (Georgius) surnamed Rhecticus, who quotes many works on Copernicus.

=Cordus=, Valerius--Eberwein--celebrated German botanist (1515–1544), who is alluded to by Gilbert, Book I. chap ii. wrote a Commentary on Dioscorides, published by Egénolphe in 1549, as well as an extensive history of plants, which is to be found in the Strasburg editions of his works, issued during 1562 and 1569.

REFERENCES.--“Biog. Générale” (Hœfer), Vol. XI. pp. 804–807; Larousse (Pierre), “Grand Dictionnaire Universel,” Vol. V. p. 133; Adam (Melchior), “Vitæ med. Germ.”; “Lindenius renovatus”--“Thesaur. Lit. Botan.,” 1851, pp. 52, 334; Camerarius, “Vita Melanchthon”; Linden (Joannes Antonides van der), “De Scriptis Medicis,” 1651, pp. 572–573; “Dict. Historique de la Médecine,” par N. F. J. Eloy, Mons, 1778, pp. 705–707, Vol. I.

=Cortesius=, Martinus, celebrated Spanish geographer who died about 1580, is the author of the well-known and extremely scarce work, “Breve compendio de la esfera, y de la arte de navegar,” Cadiz, 1546 1551, and Seville, 1556, which was translated by Richard Eden, 1561, 1589, 1609. Of the 1556 issue, Salva remarks (II, 3763): “2e édition aussi rare que la première. C’est cet ouvrage qui a revolutionné la science nautique et qui fut le premier à indiquer la déclinaison de l’aiguille. Les instructions pour construire des mappemondes ne sont la partie la moins intéressante du texte et pourraient être utiles à tous ceux qui sont incapables de comprendre le principe des roses de vents et des loxodromes, qui couvrent la surface des cartes hydrographiques anciennes. Mais c’est justement ici que l’intelligence pénétrante de Cortez a indiqué les défauts de la projection longtemps avant Mercator.”

For a reproduction of the title page and of the twelve-page text of Martin Cortez’s “Breve Compendio,” see G. Hellmann, “Neudrucke,” 1898, No. 10.

REFERENCES.--Fernandez de Navarrete, “Disertacion sobre la historia de la nautica y de las mathematicas,” Madrid, 1846; “La Grande Encyclopédie,” Vol. XII. p. 1114; “Biographie Générale,” Vol. XI. p. 964; Gilbert, _De Magnete_, Book I. chap. i.; Book III. chap. i. and Book IV. chap. i.

=Costæus=, Joannes--Giovanni Costeo--of Lodi, who died at Bologna in 1603, was an Italian physician teaching medicine at the Universities of Turin and of Bologna and the author of several valuable works, notably the “Tractatus de universali stirpium natura,” Turin, 1578; the “Disquisitionum physiol. ... Avicennæ sectionem,” Bologna, 1589; the “Annot. in Avicennæ canonem ...” Venetia, 1595; and the “De igneis medicinæ ...” published also at Venice in the last-named year.

Gilbert, who speaks of him (_De Magnete_, Book I. chap. i.; Book II. chap. iii.; Book VI. chap. v.) gives this as the theory propounded by Costæus regarding the powers of amber and loadstone: “There is work on both sides, result on both sides, and therefore the motion is produced in part by the loadstone’s attraction and in part by the iron’s spontaneous movement; for, as we say that the vapours given out by the loadstone do by their own nature haste to attract the iron, so, too, do we say that the air impelled by the vapours, while seeking a place for itself, is turned back, and when turned back impels and transfers the iron, which is picked up, as it were, by it, and which, besides, is exerted on its own account. In this way, there is found a certain composite movement, resulting from the attraction, the spontaneous motion and the impulsion; which composite motion, however, is rightly to be referred to attraction, because the beginning of this motion is invariably from one term, and its end is there too; and that is precisely the distinguishing character of attraction.”

REFERENCES.--Eloy (N. F. J.), “Dict. historique de la Médecine”; Larousse, “Dict. Univ.,” Vol. V. p. 245.

=Cusanus=--Nicolas Khrypffs or Krebs, Cardinal de Cusa (1401–1464), an eminent German scholar, who, abandoning the study of law, entered the Church, became Archdeacon of Liége, member of the Council of Basle, and was raised, in 1448, to the dignity of Cardinal. His biographer in the ninth “Encycl. Britan.” (Vol. VI. pp. 728–729) says: “As in religion he is entitled to be called one of the _Reformers before the Reformation_, so, in philosophy, he was one of those who broke with scholasticism while it was still the orthodox system.” His works were published in complete form by H. Petri, 1565.

REFERENCES.--Hartzheim (Josephus), “Vita N. de C.,” Trèves, 1730; Deux (M.), “Life of C. Cusa,” 1847; Scharpff (Franz Anton), “Der Cardinal und Bischof Nic. von Cusa ...” Tübingen, 1871; Dr. W. Windelband, “History of Philosophy,” auth. tr. by Jas. H. Tufts, New York, 1893, pp. 345–347; Humboldt, “Cosmos,” 1860, Vol. II; Libri (G.), “Hist. des Sciences Mathém.,” Vol. III. p. 99; Dr. F. Ueberweg, “History of Philosophy,” tr. by Geo. S. Morris, 1885, Vol. II. pp. 23–24; Ritter (Dr. Heinrich), “Geschichte der Phil.,” Vol. IX. p. 142; Gilbert, _De Magnete_,

## Book I. chap. i. and Book II. chaps, iii. xxxvi.; “Journal des

Savants” for January 1894; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 115; Larousse, “Dict. Univ.,” Vol. V. p. 687; “Biogr. Gén.,” Vol. XII. pp. 651–657.

=Dominicus=, Maria Ferrariensis--“Novara”--Italian savant (1464–1514), taught astronomy at Bologna, Rome and elsewhere, and had for one of his pupils the celebrated Copernicus, who, later on, became an associate in his investigations. None of his writings have reached us.

Gilbert thus alludes to Dominicus as well as to Stadius at Chap. II. book vi. of his _De Magnete_: “According to Dominicus Maria’s observations, the north pole is raised higher and the latitudes of places are greater now than in the past: from this he infers a change of latitudes. But Stadius, holding the directly opposite opinion, proves by observations, that the latitudes have grown less. ‘The latitude of Rome,’ says he, ‘is given in the _Geographia_ of Ptolemy as 41⅔°; and lest any one should say that some error has crept into the text of Ptolemy, Pliny relates, and Vitruvius in his ninth book testifies, that at Rome on the day of the equinox the ninth part of the gnomon’s shadow is lacking. But recent observation (as Erasmus Rheinhold states) gives the latitude of Rome in our age as 41⅙°; so that you are in doubt whether one-half of a degree has been lost (_decrevisse_) in the centre of the world, or whether it is the result of an obliquation of the earth.’”

REFERENCES.--Borsetti (Ferrante Giovanni), “Hist. Gymn. Ferrar.,” Vol. II. p. 50; Tiraboschi (Girolamo), “Storia della Letteratura Italiana,” Vol. XIV. p. 296; Montucla (J. F.), “Hist. des Math.,” Vol. I. p. 549; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 215–216; “Biog. Gén.,” Vol. XXXVIII. p. 336.

=Dupuis.= _See_ Putaneus.

=Empedocles=, whom Gilbert merely names in Book V. chap. xii. of _De Magnete_, was a native of Sicily, distinguished as a philosopher as well as for his knowledge of medicine and of natural history.

Empedocles flourished about the year 442 or 460 B.C., and was pupil of Pythagoras or Anaxagoras, and, as others say, of Parmenides (“The Metaphysics of Aristotle” by the Rev. John H. McMahon, London, 1857, pp. 19–20, 34, 118).

“Rien n’est engendré, disait Empédocle, rien ne périt de la mort funeste. Il n’y a que mélange ou séparation de parties.... L’éclair, c’est le feu s’échappant du nuage où le soleil l’avait lancé. La foudre n’est qu’une plus grande quantité de feu. Le tonnerre, c’est ce même feu qui s’éteint dans le nuage humide.... Les phénomènes magnétiques viennent de la convenance parfaite des pores et des effluves de l’aimant et du fer. Dès que les effluves de l’aimant out chassé l’air que contenaient les pores du fer, le courant des effluves de fer devient si fort que la masse entière est entrainée” (“Dict. des Sc. Philos.,” Paris, 1852, Vol. II. pp. 206–214).

REFERENCES.--Karsten, “Emped. Agrig. Carmin. Reliq.” in Vol. II of “Phil. Graec. vet. relig.,” Amst., 1838; and the extensive list of authorities cited in Larousse, “Dict. Univ.,” Vol. VII. pp. 457–458; Houzeau et Lancaster, “Bibl. Gén.,” Vol. I. part i. p. 401; Ueberweg, “Hist. of Philos.” (Morris), 1885, Vol. I. pp. 60–63; “The Works of George Berkeley,” by A. C. Fraser, Oxford, 1901, Vol. III. pp. 205, 247, 254, 290; Paul Tannery, “Pour l’histoire de la Science Hellène,” Paris, 1887, Chap. XIII. pp. 304–339; “Greek Thinkers,” by Theodor Gomperz, tr. of L. Magnus, London, 1901, Chap. V. pp. 558–562, 601; “A History of Classical Greek Literature,” by Rev. John P. Mahaffy, New York, 1880, Vol. I. pp. 123–128; Vol. II. pp. 48, 73, 77; “Essai Théorique et Historique sur la génération des connaissances humaines,” par Guillaume Tiberghien, Bruxelles, 1844, Vol. I. pp. 185–187.

We are told by Alex. Aphr. (Quæst. Nat., II. 23, p. 137, Speng) that, like Empedocles, Democritus sought to explain the attractive power of the magnet, upon which the latter wrote a treatise (according to Diog. IX. 47).

Democritus was born at Abdera in Thrace about 470 or 460 B.C., and, according to Thrasyllus, the grammarian, he died 357 B.C.--the same year as Hippocrates. He was considered, by far, the most learned thinker of his age, and, according to Carl Snyder, who dedicates “The World Machine,” 1907, to Democritus, he was justly esteemed by Bacon as the mightiest of the ancients, for he wrote illuminatively upon almost every branch of natural knowledge.

The following note to “The Atomistic Philosophy” appears at p. 230, Vol. II of Dr. E. Zeller’s “History of Greek Philosophy,” translation of S. F. Alleyne, London, 1881:

“Leucippus and Democritus derive all action and suffering from contact. One thing suffers from another, if parts of the latter penetrate the empty interspaces of the former.... Democritus thought that the magnet and the iron consist of atoms of similar nature but which are less closely packed together in the magnet. As, on the one hand, like draws like, and, on the other, all moves in the Void, the emanations of the magnet penetrate the iron, and pass out a part of its atoms, which, on their side, strain towards the magnet, and penetrate its empty interspaces. The iron itself follows this movement, while the magnet does not move towards the iron, because the iron has fewer spaces for receiving the effluences.”

The attraction of the magnet, as explained by Diogenes of Appollonia, is thus given by Alex. Aphr. (Quæst. Nat., II. 23, p. 138, Speng): “Empedocles supposed that, after the emanations of the magnet have penetrated into the pores of the iron, and the air which choked them has been expelled, powerful emanations from the iron pass into the symmetrical pores of the magnet, which draw the iron to itself and hold it fast.”

It may be added that the Atomic Doctrine of Leucippus and Democritus was opposed to the Homoiomeria of Anaxagoras of Clazomenæ--the last great philosopher of the Ionian School.

REFERENCES.--Ueberweg (Fr.), “History of Philosophy,” trans. of G. S. Morris, New York, 1885, Vol. I. pp. 67–71; Larousse (Pierre), “Dict. Univ. du XIX^e siècle,” Paris, 1870, Tome VI. pp. 409–410; “La Grande Encyclopédie,” Paris, Tome XIV. pp. 66–69; “Nouvelle Biographie Générale” (Hœfer), Paris, 1855, Vol. XIII. pp. 566–574; Franck (Ad.), “Fragments qui subsistent de Démocrite,” in the “Mém. de la Société Royale de Nancy,” 1836; Beazley (C. Raymond), “The Dawn of Modem Geography,” Oxford, 1906, Vol. I. p. 254 (the use by Democritus of magnetic stones, mentioned by Solinus); Snyder (Carl), “The World Machine,” 1907, p. 133 (work on the magnet); Zeller (Eduard), “Philosophie der Griechen”; Ritter and Preller, “Historia Philosophiæ Græcæ” (7th ed., Gotha, 1888); Mulloch (F. G. A.), “Democriti Abderitæ operum fragmenta,” Berlin, 1843.

=Erasmus=, Reinholdus (1511–1553), a German savant, who taught astronomy and mathematics at Wittemberg, has left us “Commentarius Theoricæ Novæ Planetarum,” 1542, 1558, a work which, Delambre says, supplies the omissions of Purbacchius and must have cleared many of the passages of Ptolemy’s syntax. He also wrote “Almageste,” 1549;[63] made up the Prutenic (Prussian) astronomical tables (“Prutenicæ tabulæ cœlestium motuum,” 1551), from the observations of Copernicus, Hipparchus and Ptolemy, and he is believed to be the author of the anonymous work entitled “Hypotyposes orbium cœlestium ...” which appeared during the year 1568.

Gilbert’s reference to Erasmus has already been given in connection with Dominicus.

REFERENCES.--Vossius (G.), “De Scientiis Mathem.,” Chap. XXXVI. p. 14; Delambre (J. B. J.), “Hist. de l’astronomie moderne,” Vol. I. pp. 142, 146, 164; Zedler (Johann Hch.); Mädler--Mædler (Johann Henrich von), Vol. I. p. 168; Bailly (Jean Sylvain), “Histoire de l’astronomie moderne ...” Vol. I. p. 366 and Vol. II. p. 71; Jöcher (Johann Friedrich), “Bibliogr. Astronom.”; Weidler (Christian Gottlieb), p. 353; “Biogr. Générale,” Vol. XLI. pp. 928–929.

=Erastus=, Thomas--Thomas Lieber--(1524–1583) was a native of Switzerland, notable in medicine and famous in ecclesiastical polemics, who furiously combated the medical views of Paracelsus, notably in his “Disputationum de Medicina,” Basileæ, 1572–1573. Gilbert mentions him (_De Magnete_, Book I. chaps. i. and vii.), merely saying that, knowing naught of the nature of the loadstone, Erastus draws from it weak arguments against Paracelsus.

His numerous works are detailed in the “Biographisches Lexikon,” Vienna und Leipzig, 1885, Vol. II. pp. 292, etc., and a very complete account thereof is to be found at pp. 561–564 of “De Scriptis Medicis,” by Joannes Antonides Van Der Linden, Amstel., 1651.

REFERENCES.--Pluquet (François André Adrien), “Diction. des Hérésies”; Moreri (Louis), “Le Grand Dictionnaire Historique”; Wordsworth (Christopher), “Ecclesiastical Biography”; “New Int. Encycl.,” New York, 1903, Vol. VI. p. 828; “Biog. Gén.,” Vol. XXXI. pp. 174–175; “La Grande Encyclopédie,” Vol. XVI. p. 163; Larousse, “Dict. Univ.,” Vol. VII. p. 788; Adam (Melchior), “Vitæ Germanorum Medicorum,” pp. 107–109; Bolton, H. C., “Ch. Hist. of Chem.,” p. 981.

=Evax=--Euace--a Latin naturalist who lived in the time of Tiberius and said to have been King of the Arabs, is the supposed author of “De nominibus et virtutis lapidum qui in artem medicinæ recipiuntur,” treating of gems, of which the MS.--now in the Oxford Library--was used by Marbodeus to make up his own work on precious stones.

Salmasius delivers it as his opinion that, by an error of transcribers, from Cratevas, who in some copies is also named Cratevas, this Evax has arisen. (“Gen. Biog. Dict.” of Alex. Chalmers, London, 1814, Vol. XIII. p. 411.)

REFERENCES.--“Journal des Savants” for June 1891 (“Traditions ... chez les Alchimistes du Moyen Age,” par Marcellin Pierre Eugène Berthelot); Larousse, “Dict. Univ.,” Vol. VII. p. 1153; Gilbert, _De Magnete_, Book II. chap. xxxviii.

=Fallopius=, Gabriellus (1523–1562), was a famous Italian anatomist and one of the three who, according to Cuvier, restored or rather created anatomy during the sixteenth century. The other two were Vassalli and Eustachi. His principal work is “Observationes Anatomicæ,” Venice, 1561; a list of the others--named in “Biog. Gén.,” Vol. XVII. pp. 66–69--embracing “De medicatis ... de metallis sev fossilibus ...” Venice, 1564; “De Simplicibus Medicamentis purgantibus tractatus,” 1566; “De Compositione Medicamentorum,” 1570; “Opera Genuina Omnia,” 1584, 1596, 1606. The collected edition of his complete works was published in Venice, 1584, and at Frankfort, 1600.

REFERENCES.--Tiraboschi (Girolamo), “Biblioteca Modenese,” Vol. II. p. 236; Nicéron (J. P.), “Mémoires,” Vol. IV. p. 396; Gilbert, _De Magnete_, Book I. chaps. i. and xv. also Book II. chap. xxxviii.; Larousse, “Dict. Univ.,” Vol. VIII. p. 67.

=Fernelius=, Joannes Franciscus (1497–1558), celebrated French physician, called the modern Galen, is the author of many works which are cited at pp. 477–483, Vol. XVII of the “Biographie Générale,” the principal ones being “De naturali parte medicinæ,” 1542, “De vacuandi ratione liber,” 1545, and “De Abditis Rerum Causis,” 1548. Gilbert alludes to the last named (_De Magnete_, Book I. chap. i.), saying that Fernel believes there is in the loadstone a hidden and abstruse cause: elsewhere he says this cause is celestial; and he does but explain the unknown by the more unknown. This search after hidden causes, he adds, is something ignorant, beggarly and resultless.

REFERENCES.--Thou (François Auguste de), “Historiarum sui temporis”; Sc. de Sainte Marthe, “Elogia Doct. Gallorum”; Eloy, “Dict. Hist. de la Médecine,” Mons, 1778, Vol. II. pp. 208–221; Larousse, “Dict. Univ.,” Vol. VIII. p. 259.

=Ficino=, Marsilia (1433–1499), was the son of Ficino, the physician of Cosmo de Medici, and was one of the leading scholars of the Renaissance. He was celebrated as the most distinguished translator of Plato and as the reviver of Platonic philosophy in Italy. One of his biographers has said that the most important feature of his philosophy is his claim to harmonizing Platonic idealism with Christian doctrine.

Gilbert says that “Ficinus chews the cud of ancient opinions, and to give the reason of the magnetic direction seeks its cause in the constellation Ursa. Ficinus writes, and Merula copies, that in the loadstone the potency of Ursa prevails, and hence it is transferred into the iron” (_De Magnete_, Book. I. chap. i.; Book III., chap. i.; Book IV. chap. i.).

His complete works (published in two volumes, Venice, 1516, Basle, 1561, 1576, Paris, 1641), embrace “Theologiæ Platonicæ,” 1488; “De Vita libri tres,” 1489; “Iamblichus, de mysteriis ...” 1497; “Apologiæ in qua medicina, astrologia ...” 1498.

REFERENCES.--Corsi (Raimondo Maria), “M. Ficini Vita,” Pisa, 1772; Symonds (John Addington), “Remains in Italy,” London, 1875, and “Renaissance in Italy,” New York, 1888, pp. 324–328; “English Cyclop.” (Biography), Vol. II. p. 908; “The Rise of Intellectual Liberty from Thales to Copernicus,” by Frederic May Holland, New York, 1885, pp. 279–280; Larousse, “Dict. Univ.,” Vol. VIII. pp. 331–332; “Journal des Savants” for May 1894; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 131; “Biog. Générale,” Vol. XVII. pp. 634–638; “The Works of Geo. Berkeley,” by A. C. Fraser, Oxford, 1901, Vols. II. p. 268; III. pp. 216–217, 221–223, 260, 296–297; “Dict. of Philos. and Psych.,” by J. M. Baldwin, New York, 1901, Vol. I. p. 381.

=Fracastorio=, Hieronymo (1483–1553), Italian physician and one of the most learned men of his day, is said to have been made Professor of Logic at the University of Padua when but nineteen years of age. J. B. Ramusio admitted that he owed to Fracastorio the idea and much of the material for his great work “Rac. di Navigazioni e Viaggi,” first published in 1550.

Fracastorio made many important astronomical observations, and it was he and Peter Apian who first made known in Europe the fact that comets’ tails are always turned away from the sun, so that their line of prolongation passes through its centre.

Gilbert alludes to Fracastorio (_De Magnete_, Book I. chap. i.;

## Book II. chaps. ii. iv. xxiv. xxxviii. xxxix.; Book IV. chap. i.),

and to his “De Sympathia,” of which the first edition is Venet., 1546. This, says Libri, is “an important work in which universal attraction, as well as electric and magnetic motion, is attributed to an _imponderable_ principle.”

REFERENCES.--Baillet (Adrien), “Jugement des Savants,” Vol. II; Menken (F. O.), “De Vita,” Leipzig, 1731; Teissier (H. A.), “Eloges des hommes illustres,” tirés de M. De Thou; Libri, “Hist. des. Sc. Mathém.,” Paris, 1838, Vol. III. p. 100; “Biog. Gén.,” Vol. XVIII. pp. 418–420; Humboldt, “Cosmos,” 1849, Vol. I. p. 86; Vol. II. p. 697; Larousse, “Dict. Univ.,” Vol. VIII. pp. 692–693; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 135.

=Garcia d’Orta=--Garzia ab Horto--Garcia del Huerto--Garcie du Jardin--a Portuguese physician and the author of “Coloquios dos simples ... pello douctor Garcia Dorta,” 1563, which was translated into French and united to the works of C. d’Acosta and Nic. Monardes (Christophile de la Coste et M. Nicholas Monard) in 1567, 1574 and 1579. The passage which Gilbert alludes to (in _De Magnete_, Book I. chap. xiv.), is to be found in the abridged Latin translation of Garcia’s work made by Charles de l’Ecluse, Antwerp, 1593, lib. i. cap. 56, pp. 178–179. Hakewill observes (“Apologie,” 1635, lib. ii. p. 165): “Remarkable indeed, that is which Garzias ab Horto writes concerning the loadstone in _Simpl. Indiæ_, lib. i. cap. 47.”

REFERENCES.--“Biog. Gén.,” Vol. XXXVIII. p. 887; Machado (Barb.), “Bibliotheca Lusitana”; Denis (Ferdinand), “Bulletin du Bibliographe”; Pincio (Léon), “Biblioteca Oriental y Occidental”; “Histoire des Drogues par Antoine Collin,” Lyon, 1619; “Thesaur. Lit. Bot.,” 1851, p. 127.

=Gauricus=, Lucas (1476–1558), Italian mathematician and astronomer, one of whose pupils was César Scaliger, is the author of twenty-one different works (“Opera Omnia,” Basle, 1575), of which the best known are “Rerum naturalium et divinarum ...” 1540; “Isagogicus ... in tot am astrologiam prædictivam ...” 1546; “Tractatus Astrologicus,” 1552; “Tabulæ de primo mobili,” 1560.

Gilbert says (_De Magnete_, Book I. chap. i.) the astrologer Lucas Gauricus held that beneath the tail of Ursa Major is a loadstone, and that he assigns the loadstone (as well as the sardonyx and the onyx) not only to the planet Saturn, but also to Mars (with the diamond, jasper, and ruby), so that the loadstone, according to him, is ruled by two planets. Further, Lucas says that the loadstone belongs to the sign Virgo--and with a veil of mathematical erudition he covers many similar disgraceful stupidities.

REFERENCES.--Ughelli (Ferdinando), “Italia Sacra,” Venetiis 1717–1722; Nicodemo (Francesco), “Biblioteca Napoletana”; “Chronicum Mathematicorum,” which prefaces the Almagest of Riccioli; “Biog. Gén.,” Vol. XIX. pp. 681–683; “La Grande Encycl.,” Vol. XVIII. p. 617; Larousse, “Dict. Univ.,” Vol. VIII. p. 1087.

=Geber=--Yeber--Djaber--Abū-Mūsa-Jābir--Ibn Haiyān--Al-Tarsūsi--who, according to Aboulwefa (Michaud, “Dict.,” Vol. XVI. p. 100) lived in the eighth century A.D., is the earliest of the Great Arabian chemists or alchemists. Rhazès and Avicenna call him “the master of masters,” and, by the author of “The Lives of Alchemystical Philosophers,” he is designated as “the prince of those alchemical adepts who have appeared during the Christian Era.” As many as five hundred different alchemical works have been attributed to him, and a complete list of the most important will be found in M. F. Hœfer, “Histoire de la Chimie,” Paris, 1842.

REFERENCES.--“Journal des Savants,” for May 1851, February 1892, pp. 118–128 _passim_, and for May 1892 (“Geber et ses œuvres alchimiques”), pp. 318–329; Larousse, “Dict. Univ.,” Vol. VIII. pp. 1114–1115; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 147; Bolton (H. C.), “Chron. Hist. of Chem.,” pp. 985–986; “La Grande Encyclopédie,” Vol. XVIII. pp. 680–682; Gilbert, _De Magnete_, Book I. chap. vii.

=Gemma=, D. Cornelius, a well-known physician of Louvain (1535–1597) and son of the celebrated mathematician Gemma Frisius, is the author of the several works named at p. 854, Vol. XIX of the “Biographie Générale.” Of these, the most important is the “Cosmocritice, seu de naturæ divinis ... proprietatibus rerum” published at Antwerp in 1575.

REFERENCES.--Foppens, “Bibliotheca Belgica”--“Biog. Médicale”; Linden (Joannes Antonides van der), “De scriptis medicis,” Amst., 1651, pp. 147–148; Gilbert, _De Magnete_, Book II. chap. iii.

=Gemma=, Frisius--Rainer--(1508–1555), above alluded to, besides being a mathematician was a medical practitioner. He wrote “De Principiis Astronomiæ et Cosmographiæ ...” Antwerp, 1530 (now of excessive scarcity and Chapters XXX-XXXI of which deal with America), as well as several other similar works published notably in 1539, 1545, 1548. These are standards of the Netherlands geographical schools, whose most brilliant representative was the well-known geographer, Gerard Mercator (1512–1594).

REFERENCES.--“Biog. Générale,” Vol. XIX. p. 854; “La Grande Encycl.,” Vol. XVIII. p. 702; Houzeau et Lancaster, “Bibl. Gén.,” Vol. L. part i. p. 1405 and Vol. II. p. 148.

=Goropius=, Henricus Becanus--Jean Bécan--Jean Van Gorp (1518–1572), a Belgian savant who practised medicine at Antwerp and who attempted to prove, in his “Indo-Scythica,” that Adam’s language was the German or Teutonic. We are told by Gilbert, in the first book of _De Magnete_, that Goropius ascribes the invention of the compass to the Cimbri or Teutons, on the ground that the thirty-two names of the winds thereon inscribed are pronounced in German by all mariners, whether they be British or Spaniards, or Frenchmen.

REFERENCES.--“Opera Joannis Goropii Becani,” Antwerp, 1570; Larousse, “Dict. Univ.,” Vol. II. p. 457; “Biog. Générale,” Vol. V. pp. 70–71; and, for additional citations, as well as for mention of all his works, the “Grande Encyclopédie,” Vol. XIX.

=Grotius=, Hugo, the latinized form of the Dutch _De Groot_--a great theologian and jurist (1583–1645). His singular precocity attracted Joseph J. Scaliger, who undertook to direct his studies at the Leyden University, where it is said he achieved brilliant success in all studies.

One of his biographers remarks that, in the annals of precocious genius, there is no greater prodigy on record than Hugo Grotius, who was able to write good Latin verses at nine (1592), was ripe for the University at twelve (1595), and at the age of fifteen (1598), edited the Encyclopædic work of Martianus Capella--a writer of the fifth century--with the aid of his father, Jan de Groot, the Delft burgomaster. It might be added that, in 1597, he had delivered public discourses on mathematics, philosophy and jurisprudence; in 1598, he was so highly sought for everywhere, that he was asked to, and did, accompany Count Justin of Nassau and Olden Barneveldt on their special embassy to the French Court, and that, in 1599, he not only took his degree of doctor of law and pleaded his first cases before the Hague Courts, but was able, through his superior knowledge of mathematics, to translate into Latin Simon Stevin’s work on navigation. Later on, 1603, he was appointed historiographer of the United Provinces, becoming fiscal general in 1607 (also Council Pensionary at Rotterdam six years later), and during 1609, he published his first work “De Mare Liberum,” which was a treatise against the claims of the English to exclusive right over certain seas. This was followed in 1610 by “De Antiq. Reipub. Batavæ,” and some years afterwards by his chief work, “De Jure Belli et Pacis,” considered the basis of international law and freely translated into all the principal languages. Grotius is twice mentioned in Book IV. chap. ix. of _De Magnete_.

REFERENCES.--Brandt et Cattenbuch, “Histoire de Hugo de Groot,” 1727; Burigny (J. Levêque de), “Vie de Grotius,” 1752; Cras (Hendrik Constantijn), “Laudatio Hugonis Grotii,” 1796; Dr. Fried. Ueberweg, “Hist. of Phil.,” (Morris tr., 1885, Vol. II. p. 31); Rogge (H. C.), “Bibliotheca Grotiana,” 1883; Kœnen (Hendrik Jakob), “Hugo Grotius,” 1837; “Chambers’s Encycl.,” Vol. V. pp. 431–432; “La Grande Encycl.,” Vol. XIX. pp. 451–452; “Biographisch Woordenbock,” J. G. Frederiko en F. J. Van den Branden, Amsterdam, pp. 301–302; Larousse (Pierre), “Dict. Univ.,” Vol. VIII. p. 1556, giving list of his many works; Butler (C.), “Life of Grotius,” London, 1826; Creuzer (Georg Friedrich), “Luther und Grotius,” Heidelberg, 1846; “Biog. Générale,” Vol. XXII. pp. 197–216 for a complete record of all his works.

=Hali Abas=--‘Ali Ibn Al-‘Abbás--Al Majusí--celebrated Arabian physician, whose death occurred about A.D. 995, is author of “Ketab-el-Maleki,” _i.e._ the “Royal Book”--_Liber Regius_--in which he pretends to give all that was then known concerning medicine. Mr. Adams explains (Appendix, “Barker’s Lemprière,” London, 1838), that he considers the “Royal Book” as the most complete ancient treatise that has reached us on medicine, and the sciences generally, with exception of the _Synopsis_ of Paulus Ægenita. The Latin translation of this work, given in 1127 by Stephanus Antiochenus, was first printed in Venice, 1492, then at Lyons in 1523.

REFERENCES.--Casiri (Michael), “Bibliotheca Arabico-hispana Escur.,” Vol. I. pp. 260, 273; Hœfer, “Nouv. Biogr. Univ.,” Vol. II. pp. 96–97; Michaud, “Biog. Univ.,” Paris, 1843, Vol. I. p. 468; Gilbert, _De Magnete_, Book I. chap. i.; Freind (John), “History of Physick”; Choulant (Johann Ludwig), “Handbuch der Bücherkunde ...”; Wüstenfeld (H. F.), “Geschichte d’ Arab. Ærzte,” p. 59; “Biog. Gén.,” Vol. II. pp. 96–97.

=Harriot=, Thomas (1560–1621), one of the learned Englishmen alluded to by Gilbert, at the end of the first chapter, Book I of _De Magnete_, as having on long sea voyages observed the differences of magnetic variation, was a mathematician and astronomer, whose miscellaneous works, noted at pp. 437–439, Vol. XXIV of the “Dict. of Nat. Biog.,” embrace treatises on magnetism, mechanics, etc. The account he has given of his voyage to Virginia was printed in Hakluyt’s “Principal Navigations,” Vol. III and is pronounced “one of the earliest and best examples of a statistical survey made upon a large scale,” at p. 11, Vol. LXXI of the “Edinburgh Review.”

=Heraclides= of Pontus and Ecphantus, was a Greek historian and philosopher who died about 330 B.C. Diogenes Laertius attributes to him many works that have not reached us, and we have nothing of him but fragments of his treatise on the constitutions of the different States which have been printed with the works of Elien. Gilbert commences the third chapter of his sixth book by saying that Heraclides, as well as the Pythagoreans Nicetas of Syracuse and Aristarchus of Samos, and, as it seems, many others, held that the earth moves, that the stars set through the interposition of the earth, and that they rise through the earth’s giving way: they do give the earth motion, and the earth being, like a wheel, supported on its axis, rotates upon it from west to east.

REFERENCES.--Rowles (S.), “De Vita et Scriptis,” 1824, Vol. VIII; Deswert (Eugenius), “Dissert de Heraclide Pontico,” 1830; Krische (August Bernhard), “Forschungen ...” p. 325; “La Grande Encyclopédie,” Vol. XIX. p. 1131; Dr. F. Ueberweg, “History of Philosophy,” tr. by Geo. S. Morris, New York, 1885, Vol. I. pp. 38–42; Humboldt, “Cosmos,” 1860, Vol. II. p. 309; “Essai théorique ... des connaissances humaines,” par G. Tiberghien, Bruxelles, 1844, Vol. I. pp. 182–185; Larousse, “Dict. Univ.,” Vol. IX. p. 200.

=Hermes Trismegistus= (or “thrice great”) is the supposed author of many Greek works that have reached us and which constitute an encyclopædia of Egyptian wisdom in that they treat of astronomy, medicine, and other sciences. As one of his biographers has it, the principal tenets of the Hermetic Books are that the Creator made the Cosmos by his word out of fluid ... that death and life are only changes and that nothing is destructible ... that passion or suffering is the result of motion.... Gilbert only refers to him in Book V. chap. xii. by saying that Hermes, Zoroaster and Orpheus recognize a universal soul. Clemens Alexandrinus, who has given an account and catalogue of his writings, makes him the author of six books of physic and of thirty-six books of divinity and philosophy.

REFERENCES.--“The Works of George Berkeley,” by A. C. Fraser, Oxford, 1901, Vol. III. pp. 209, 253–255, 261, 267, 280; Baumgarten--Crusius (Ludwig Friedrich Otto), “... de librorum Hermeticorum ...” 1827; “Dict. of Philos. and Psychol.,” by J. M. Baldwin, New York, 1901, Vol. I. p. 475; “Hermes Trismegistus,” by Scheible (J.), 1855; Alex. Chalmers, “Gen. Biog. Dict.,” London, 1814, Vol. XVII. p. 396; “Hermes Trismegistus,” by Parthey (Gustav Friedrich Constantin), 1854; Houzeau et Lancaster, “Bibl. Gén.,” Vol. I. part i. pp. 427–428, 691–694; Larousse, “Dict. Univ.,” Vol. IX. p. 228; and the long list of citations in “Biog. Générale,” Vol. XXIV. pp. 377–382.

=Hero=--Heron--of Alexandria, a Greek mathematician, pupil of the celebrated Ctesibius who flourished in the third century before Christ and to whom have been attributed many ancient writings upon different technical subjects. Allusion is made by Gilbert (_De Magnete_, Book II. chap. ii.), to Hero’s “Spiritualia,” which is his most valuable known work and which has been often translated, notably into Latin, 1575, 1680, 1683, into Italian, 1547, 1589, 1592, 1605; and into German, 1687, 1688.

REFERENCES.--Hultsch (Friedrich), “Heronis Alex.,” 1864–1874; Montucla (J. F.), “Hist. des Mathém.,” Vol. I. p. 267; “Abhandlungen zur Geschichte der Mathematik,” Vol. VIII. pp. 175–214; Martin, “Sur la vie et les ouvrages d’Héron d’Alexandrie”--Mém. de l’Acad. des Ins. B. L., Paris, 1854, ss. 438–439; Arago (François), “Eloge de Watt” (_Œuvres_, Vol. I); Fabricius (Johann Albert), “Bibliotheca Græca,” Vol. IV. p. 234; Figuier (Louis), “Hist. des principales découvertes,” Vol. I. p. 42; “A short history of Greek Mathematics,” Jas. Gow, Cambridge, 1884, pp. 276–286; Larousse, “Dict. Univ.,” Vol. IX. p. 241; “Chambers’s Encyclopædia,” Vol. V. p. 689; ninth “Encycl. Britan.,” Vol. XI. p. 760; “La Grande Encyclopédie,” Vol. XIX. p. 1200; “Journal des Savants” for March 1903, p. 147, and for April 1903, p. 203; “Biogr. Générale,” Vol. XXIV. pp. 447–449; Th. Martin (“Mém. Ac. des Inscr.,” 1854); also two papers by Boncompagni and Vincent in “Bulletino di Bibliog.,” Vol. IV.

=Hipparchus= the Rhodian, “le plus grand astronome de l’antiquité”--born, according to Strabo, at Nicæa in Bithynia, 160–145 B.C.--is the inventor of the astrolabe[64] and discoverer of “the precession of the equinoxes.” He is mentioned by Gilbert five times in Book VI. chaps, ii. viii. ix. of _De Magnete_, and is extensively treated of in the “Journal des Savants” for November 1828, January 1829, August and September 1831, October 1843, August and September 1848, July 1859; also by the Rev. H. M. Close, in “Proc. of Roy. Irish Acad.,” Series III. vol. vi. No. 3, in Larousse, “Dict. Univ.,” Vol. IX. p. 286, in the “Historical Account of Astronomy,” by John Narrien, London, 1833, pp. 219–244, and in the “Astronomy” article of the “Encyclopædia Britannica.”

By Humboldt, Hipparchus is called the founder of scientific astronomy and the greatest astronomical observer of antiquity. He was the actual originator of astronomical tables amongst the Greeks and, in the new map of the world which he constructed and founded upon that of Eratosthenes, the geographical degrees of latitude and longitude were based on lunar observations, and on the measurement of shadows, wherever such an application of astronomy was admissible (“Cosmos,” London, 1849, Vol. II. p. 545; Ideler, “Handbuch der Chronologie,” Vol. I. ss. 212, 329).

The mathematician Eratosthenes, alluded to above, was a native of Cyrene, and pronounced the most celebrated of the Alexandrian librarians. He is reported to have made the earliest attempt at measurement of an arc of the meridian. The next measurement of record is that of the astronomers of Almamon in the plains of Mesopotamia (“Encycl. Brit.,” ninth edition, Edinburgh, 1876, Vol. X. p. 177). The first arc of the meridian measured in modern times with an accuracy any way corresponding to the difficulty of the problem was by Snellius, who has given an account of it in his most remarkable work called “Eratosthenes Batavus,” published at Leyden in 1617 (“Ency. Brit.,” ninth edition, Vol. VII. pp. 597, 606, also eighth edition, Vol. I. pp. 617–618; “Cosmos,” London, 1849, Vol. II. p. 544, and Chasles, “Recherches sur l’astronomie ...” in the _Comptes Rendus_, Vol. XXIII, 1846, p. 851). The biographers of Snellius--Snell van Roijen (Willebrood)--state that he was a very celebrated Dutch astronomer (1591–1626), the discoverer of the law of refraction generally attributed to Descartes (Humboldt, “Cosmos,” 1849, Vol. II. p. 699), the author of a treatise on navigation (“Tiphys Batavus,” Leyde, 1624) after the plan of Edward Wright, and that the method he employed (with imperfect instruments), for measuring an arc of the meridian has since been followed by all scientists (“La Grande Encyclopédie,” Vol. XXX. p. 115; “Nouv. Biog. Gén.,” de Hœfer, Vol. XLIV. p. 83; Montucla, “Hist. des Mathém.,” Vol. II; Larousse, “Dist. Univ.,” Vol. XVI. p. 795; Delambre, “Hist. de l’astronomie moderne,” Vol. II. pp. 92–119; “Ency. Brit.,” Akron, Ohio, 1905, Vol. XXII. p. 211).

REFERENCES.--Theodor Gomperz, “Greek Thinkers,” translation of L. Magnus, London, 1901, p. 544; Houzeau et Lancaster, “Bibl. Gén.,” Vol. I. part i. pp. 413–414, and Vol. II. p. 164; “Geographical Journal” for October 1904, p. 411; Wm. Whewell, “Hist. of the Ind. Sc.,” New York, 1858, Vol. I. pp. 145–156; “Journal des Savants” for 1828, 1831, 1843; Alex. Chalmers, “Gen. Biog. Dict.,” London, 1814, Vol. XVII. pp. 505–506.

=Hues=--Hood--Robert (1553(?)-1632), another of the English sea voyagers named by Gilbert at the end of his first book, was a mathematician and geographer who sailed around the world with Thomas Cavendish and is the author of “Tractatus de Globis ... et eorum usu,” 1593, 1594, 1627, which was written for the especial purpose of being used in connection with a set of globes by Emery Molyneux. This work was shortly afterwards followed by another in the same line entitled “Breviarum totius orbis”--“Breviarum orbis terrarum” (“Dict. of Nat. Biog.,” Vol. XXVIII. p. 156).

=Kendall=--Kendel--Abram, who has already been mentioned (Gama, A.D. 1497; Norman, A.D. 1576), is called by Gilbert “the expert English navigator.” He was sailing master of the “Bear,” a ship belonging to Sir Robert Dudley (1573–1649), on the voyage which is referred to in Vol. IV of Hakluyt’s “Collection of the early voyages, travels and discoveries,” London, 1811. Therein, at pp. 57 and 58, mention is made of Kendall, who is also favourably alluded to in the very attractive and justly prominent work of Sir Robt. Dudley, published in three volumes at Florence, 1646–1647, 1661, and entitled “Dell Arcano del Mare di Roberto Dudleio, Duca di Nortumbria e Conte di Warwick.”

REFERENCES.--“Dict. of Nat. Biogr.,” Vol. XVI. p. 125; also Libri’s “Catalogues,” 1859, Vol. I. p. 160, and 1861, Vol. I. p. 268; Vol. II. p. 573, wherein it is said that amongst the _Portulani_ are those of Abraham Kendall and John Diez for the coasts of America and the West Indies.

Kendall is said to have joined, during the year 1595, the last expedition of Francis Drake and to have died the year following. Drake is alluded to in the address by Edward Wright in connection with Thomas Candish (Cavendish), and they are both also mentioned together (_De Magnete_, Book III. chap. i.), where Gilbert calls Drake “our most illustrious Neptune,” and Cavendish “that other world-explorer.”

REFERENCES.--David Hume, “History of England,” London, 1822, Vol. V; “Lives of Drake, Candish and Dampier,” Edin., 1831; “Collection of Voyages and Discoveries,” Glasgow, 1792; “English Seamen of the Sixteenth Century,” by James Anthony Froude, New York, 1896, pp. 75–103, detailing Drake’s voyage around the world; “Life of Sir Francis Drake and Account of his Family,” reprinted from the “Biog. Britannica,” 1828; “The Works of John Locke,” London, 1812, Vol. X. pp. 359–512, for the “History of Navigation from its Origin to this Time” (1704), prefixed to “Churchill’s Collection of Voyages,” and embracing the voyages of Stephen Burrough, Sebastian Cabot, Sir Thos. Candish, Christopher Columbus, Sir Francis Drake and Vasco da Gama, as well as the discoveries attributed to Gioia and others; making, for the polarity of needle, special mention of Bochart’s “Geog. Sacra,” p. 716, Purchas’ “Pilgrims,” p. 26 and Fuller’s “Miscellanies,” lib. iv. cap. 19; Franciscus Drakus, 1581, is Epig. 39, Liber Secundus, p. 28 of 1747, Amsterodami ed. of “Epigrammatum Ioan Oweni” (John Owen, 1560–1622, “Dict. of Nat. Biog.,” Vol. XLII. pp. 420–421). At pp. 437 and 444, Vol. I. of “The History of No’ America,” by Alfred Brittain, Philadelphia, 1903, will be found a plate portrait of Sir Francis Drake and the reproduction of a page from “Sir Francis Drake Revived,” originally published in 1626. The latter is “a true relation of foure severall voyages ... collected out of the notes of Sir Francis Drake, Philip Nichols and Francis Fletcher ...”; “The Voyages of the Cabots,” in “Narrative and Critical History of America,” by Justin Winsor, Boston, 1889, Vol. III. pp. 1–59–84 for Drake, Hawkins and Cavendish. “Life of Sir Rob. Dudley ...” by John Temple Leader, Florence, 1895. For Sir Francis Drake and Thos. Candish, consult also Vols. XV and XVI, as per Index, p. 412 of Richard Hakluyt, “The Principal Navigations ...” Edinburgh, 1889; “General Biog. Dict.,” Alex. Chalmers, London, 1813, Vol. XII. p. 305 for Sir Francis Drake and pp. 414–418 for Sir Rob. Dudley.

=Lactantius=--Lucius Cœlius Firmianus--celebrated orator of Italian descent, called “the Christian Cicero,” died about 325–326 A.D. He was a teacher of rhetoric in Nicomedia, Bithynia, was entrusted by Constantine the Great with the education of his son Crispus Cæsar (“History of Christianity,” Rev. Hy. Hart Milman, London, 1840, Vol. II. p. 384), and became a very extensive writer. Dufresnoy enumerates as many as eighty-six editions of his entire works, besides separate publications of his different treatises, appearing between the years 1461–1465 and 1739; the best editions being given in Vols. X-XI of the “Bibliotheca Patrum Ecclesiasticorum Latinorum ...” by Gersdorf (Ephraim Gotthelf), Leipzig, 1842–1844 and in Migne (Jacques Paul) “Patrologiæ,” Vols. VI-VII, 1844. His principal work is the “Divinarum Institutionum,” the third book of which (“De falsa sapientia”) is referred to by Gilbert (_De Magnete_, Chap. III), when he says that Lactantius, like the most unlearned of the vulgar, or like an uncultured bumpkin, treats with ridicule the mention of antipodes and of a round globe of earth.

Geo. Hakewill, who has already appeared in this “Bibliographical History,” at A.D. 1627, alludes to the above (“Apologie,” Oxford, 1635, lib. iii. p. 281), in manner following: “Yet that which to me seemeth more strange is that those two learned Clearkes, Lactantius (_Divin. Inst._, lib. iii. cap. 24), and Augustine (_De Civitate Dei_, I. lib. xvi. cap. 9), should with that earnestnesse deny the being of any antipodes.... Zachary, Bishop of Rome, and Boniface, Bishop of Mentz, led (as it seems), by the authority of these Fathers, went farther herein, condemning one Vergilius, a Bishop of Saltzburg, as an heretique, only for holding that there were antipodes.” Madame Blavatsky (“Isis Unveiled,” Vol. I. p. 526) says: “In 317 A.D. we find Lactantius teaching his pupil Crispus Cæsar, that the earth is a plane surrounded by the sky, which is composed of fire and water, and warning him against the heretical doctrine of the earth’s globular form!”

The following notes concerning the antipodes are likely to prove interesting:

“Pythagoras left no writings--Aristotle speaks only of his school--but Diogenes Laertius in one passage (‘Vitæ,’ VIII. I. Pythag. 25), quotes an authority to the effect that Pythagoras asserted the earth to be spherical and inhabited all over, so that there were antipodes, to whom that is _over_ which to us is _under_.... Plato makes Socrates say that he took up the work of Anaxagoras, hoping to learn whether the earth was round or flat (‘Phædo,’ 46, Stallb. I, 176).” In Plutarch’s essay, “On the face appearing in the orb of the moon,” one of the characters is lavish in his ridicule of the sphericity of the earth and of the theory of antipodes. (Justin Winsor, “Narrative and Critical History,” Boston, 1889, Vol. I. pp. 3–5, notes; Lucretius, “De Rerum,” V. pp. 1052, etc., and vi. p. 630; Virgil (Publius V. Maro), “Georgics,” I. p. 247; Tacitus (Publius Cornelius), “Germania,” p. 45.)

Speaking of the lower hemisphere or antipodes, as well as of islands of magnetic power drawing vessels on their rocks, Albertus Magnus says, in the book “De Natura Locorum,” contained in his “Philosophus Philosophorum Princeps”: “Perhaps also some magnetic power in that region draws human stones, even as the magnet draws iron.” See the Legends, in Reisch’s--Reysch’s--“Map of the World,” Rome, 1508 (“Christ. Colombus,” by J. B. Thatcher, New York, 1903, Vol. I. pp. 165–166).

At the beginning of the fourteenth century, the roundness of the earth and the antipodes were generally recognized. Mention thereof is to be found in the “Trésor” of Brunetto Latini, in the “Divina Commedia,” in the “Convito” (Dante, Opere Minori, Vol. I. p. 93), and in the “Acerba” of Francesco degli Stabili (Cecco d’Ascoli), at ff. 8–11, lib. i. cap. 3; as well as in most cosmographical treatises of the fourteenth century (Libri, Vol. II. p. 197, note).

[Illustration: Cecco D’Ascoli. Last page of the earliest known edition of his “Acerba” Venetia 1476. Printed nineteen times up to and including the edition of 1546. Now in the Bibliothèque Sainte Geneviève, Paris.]

[Illustration: Lactantius. “De Divinis Institutionibus.” Page taken from the 1465 edition. In the Bibliothèque Ste. Geneviève, Paris.]

The passage in Lactantius (lib. iii. cap. 24), begins _Ineptum credere_. In the 1570 edition, it commences at Chap. XXIII, “_Aut est_ ...” p. 178. In the “Works of Lactantius,” Edinburgh, 1871, Vol. I. chap. xxiv. pp. 196–197, the translator, Wm. Fletcher, says that he thus ridicules the antipodes and the roundness of the earth: “... the rotundity of the earth leads, in addition, to the invention of those suspended antipodes,” whilst, at Vol. II. chap. xxxix. p. 122, Lactantius says again that “about the antipodes, also, one can neither hear nor speak without laughter.”

In “Christian Schools and Scholars,” Augusta Th. Drane, London, 1867, p. 70, Albertus describes the antipodes and the countries they embrace.

Robert Steele, in his “Mediæval Lore,” London, 1893, p. 75, has it: “And fables tell, that there, beyond the antipodes be men that have their feet against our feet.”

At p. 200 of André Pezzani’s “La Pluralité des Existences de l’Ame,” Paris, 1866, he mentions that Cardinal Nicolas De Cusa admits the roundness of the earth, the plurality of worlds, etc.

For antipodes and roundness of the earth see, likewise: Libri, “Hist. des Sc. Mathém.,” Vol. II. pp. 178, 182, note; Ch. W. Shields, “The Final Philosophy,” New York, 1877, p. 46; “Le Journal des Sçavans,” Vol. XXXVI for 1707, p. 510, wherein it is said that Plutarch denied the antipodes, as did both Lactantius and Saint Augustine. Consult, also, the volumes of “Le Journal des Sçavans” for the years 1710 and 1721.

REFERENCES.--Dupin (André M. J. J.), “Biblioth. des Auteurs Eccles.,” Vol. I. p. 295; Celier (Léonce), “Hist. des Auteurs Sacrés,” Vol. III. p. 387; Schöll (Carl), “Hist. de la Lit. Romaine,” Vol. IV. p. 26; “Biog. Gén.,” Vol. XXVIII. pp. 611–620; ninth “Encycl. Brit.,” Vol. XIV. pp. 195–196; Lenain de Tillemont, “Hist. Eccles.,” Vol. VI; Fleury (Claude), “Historia Ecclesiastica” (“The Eccles. History from A.D. 400 to A.D. 456”), Vol. I; “History of the Decline and Fall of the Roman Empire,” by Edward Gibbon (Milman), Philad. 1880, Vol. II. p. 248 note; “Anti-Nicene Christian Library,” edited by Drs. Roberts and Donaldson.

=Lusitanus=, Amatus--Joan Rodrigo Amato--Portuguese physician (1511–1568), is author of several medical essays wherein he advocates the views of Galen and of the Arabian School. His most important work is “Curationum medicinalium centuriæ septem,” and is so named because it is divided into seven parts, each containing a hundred different observations and reports on medical cures, etc. In _De Magnete_,

## Book I. chap. i., Gilbert names him amongst authors, like Antonius

Musae Brasavolus and Joannes Baptista Montanus, who tell of the efficacy of the loadstone in medicine.

REFERENCES.--“Thesaurus Literaturæ Botanicæ,” Lipsiæ, 1851, pp. 334–335; Larousse, “Dict. Univ.,” Vol. X. p. 796; “Dict. Hist. de la Médecine,” par N. F. J. Eloy, Mons, 1778, Vol. I. pp. 106–107.

=Lynschoten=--Linschooten--Jan Huygan van--who, with Richard Hakluyt, we find mentioned by Edward Wright in his Address “to the most learned Mr. William Gilbert,” was a celebrated Dutch navigator (1563–1611) who accompanied Vicente Fonseca, Archbishop of Goa, upon his Eastern trip and first published a relation thereof during the year 1601. He is the author, also, of “Itinerario Voyage ofte Schipvært,” Amsterdam, 1596, 1604, 1605, 1623, and “Itinerarium, ofte Schipvært,” Amsterdam, 1614.

REFERENCES.--Lautz (G.), “Biog. de J. H. Van L.,” Amst., 1845; Du Boys (Pierre), “Vies des Gouverneurs,” p. 4; “La Grande Encycl.,” Vol. XXII. p. 299; Larousse, “Dict. Univ.,” Vol. X. p. 542; “Biog. Générale,” Vol. XXXI. p. 303.

=Machometes Aractensis.= _See_ Albategnius.

=Marbodeus Gallus=, surnamed Pelliciarius, who is briefly mentioned twice by Gilbert in _De Magnete_, Book I. chap. i., was a French writer, son of a merchant (Marbode, Marbœuf) who finally became Bishop of Rennes in 1081, and died at Angers in 1123–1125. He is best known by his poetical works, which were first published in 1524. As has already been said, Marbodeus is supposed to have used the manuscript of Evax-Euace--to make up his own book on precious stones. The latter work is alluded to by J. B. Hauréau in the second of his articles on the Latin MSS. of the Palatine--“Codices Palatini Bibliothecæ Vaticanæ”--wherein the first line is quoted:

“_Evax, rex Arabum, fertur scripisse Neroni_”

(“Journal des Savants,” Sept. 1887, p. 565, June 1891, p. 372; “Hildeb. et Marbod. Opera,” Col. 1637).

Bertelli quotes, at p. 96 of his “Pietro Peregrino” Memoir, four of the Latin lines, as well as those of Hildeberti, which can be translated as follows:

“The magnet stone is found amongst the Troglodites, The same stone which India, its mother, sends; This one is known to be of ferruginous colour And its nature is to draw iron when near it.”

REFERENCES.--“The Lapidarium of Marbodus” (with translation of the sixty-one chapters) at pp. 389–417 of “Antique Gems,” by Rev. C. W. King, London, 1866; “Gallia Christiana,” XIV. col. 746; “Hist. Lit. de la France,” Vol. X. p. 343; “La Grande Encycl.,” Vol. XXIII. p. 15; Larousse, “Dict. Univ.,” Vol. X^2. p. 1126; “Biographie Générale,” Vol. XXXIII. pp. 366–367.

=Marco Polo.= _See_ A.D. 1271–1295, p. 55.

=Matthæus= Silvaticus. _See_ Silvaticus.

=Matthiolus=, Petrus Andreas--Pierre André Mattiole--(1500–1577), Italian naturalist and physician, is best known by his Commentary originally published at Venice under the title “Il Dioscoride con gli suoi discorsi” and translated into Latin, 1554, which is said to contain all that was known of medicine and botany up to that time (Larousse, “Dict. Univ.,” Vol. X. p. 1349; Eloy, “Dict. Hist. de Médecine,” Mons, 1778, Vol. III. pp. 190–193.)

Gilbert tells, in Book I. chap. i. of _De Magnete_, that Matthiolus, the translator of Dioscorides, “furbishes again the garlic and diamond story, in connection with the loadstone, that he also brings in the fable of Mahomet’s shrine having an arched roof of magnets so that the people might be fooled by the trick of the coffin suspended in air, as though ’twere some divine miracle, and, furthermore, that he compares the attractive virtues of the loadstone, which pass through iron, to the mischief of the _torpedo_, whose poison passes through bodies and spreads in an occult way.”

=Maurolycus=--Marulle--Franciscus (1494–1575) was Abbot of Messina and a celebrated geometer. His well-known “Opuscula Mathematica,” Venice, 1575, containing treatises on the sphere, astronomical instruments, etc., was preceded by his great book on Cosmography published during 1543, and he also wrote many other works which will be found enumerated in the Catalogue so ably made up by the Abbé Scina (Larousse, “Dict. Univ.,” Vol. X. p. 1365; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 201).

Gilbert mentions Franciscus Maurolycus (_De Magnete_, Book I. chaps. i. and xvii., also Book IV. chaps. i. and xviii.), regarding the variation in the Mediterranean Sea and says that he discusses a few problems regarding the loadstone, adopting the current opinion of others, and that he believes the variation is caused by a certain magnetic island mentioned by Olaus Magnus.

REFERENCES.--Libri, “Hist. des Sc. Mathém.,” Paris, 1838, Vol III. p. 102; “Nouv. Biog. Gén.” (Hœfer), Vol. XXXIV. p. 428; “Vita del Abate. Maurolico,” Messine, 1613; Nicéron, “Mémoires,” Vol. XXXVII; “Biog. Univ.” (Michaud), Vol. XXVII. p. 352; Tessier (H. A.), “Eloges des hommes Illustres”; “Dict. Univ. du XIX^e siècle” (Larousse), Vol. X. p. 1365.

=Menelaus= (called also Mileus, Milieus, by Apian and by Mersenne), was a celebrated Alexandrian, living end of first century A.D., who, in his brilliant treatment especially of spherical geometry, went considerably beyond all his predecessors. The only work of his, however, that has reached us is a treatise on the sphere in three books, of which the translation was made by Maurolycus and inserted by P. Mersenne in his “Univ. Geometriæ Synopsis,” 1644.

Menelaus is mentioned by Gilbert (_De Magnete_, Book VI. chaps. viii. and ix.) together with Ptolemy and Machometes Aractensis, who, says he, have held in their writings that the fixed stars and the whole firmament have a forward movement, for they contemplated the heavens and not the earth and knew nothing of magnetic inclination.

REFERENCES.--Montucla, J. F., “Hist. des Mathém.,” Vol. I. p. 291; Delambre, J. B. J., “Hist. de l’Astron. Moderne,” Vol. II. p. 243.

=Merula=, Gaudentius, was an Italian savant living early in the sixteenth century, author of “De Gallorum ... antiquitate,” 1536, 1538, 1592, of “Memorabilium” 1546, 1550, 1551, 1556, and of several general histories, etc. Gilbert says (_De Magnete_, Book I. chap. i.) Merula advises that on a loadstone be graven the image of a bear, when the moon looks to the north, so that, being suspended by an iron thread, it may win the virtue of the celestial Bear.

REFERENCES.--Cotta (Lazaro Agostino), “Musæo Novarese,” p. 133; Philippo Argellati, “Bibliotheca ... Mediol. ...” Vol. II. pp. 2131–2134; “La Grande Encycl.” Vol. XXIII. p. 732; “Biog. Gén.,” Vol. XXXV. p. 127.

=Montagnana=, Bartholommeo, who is briefly alluded to at the end of Book I. chap. xv. of _De Magnete_, was the head of a well-known family of Italian physicians. He was born about 1400, practised medicine at Bologna and Padua, and wrote “Consilia Medica, edita Paduæ anno 1436,” also “De Balneis Patav.; de compositione et dosi medicamentorum,” the latter appearing at Padua in 1556.

REFERENCES.--Papadopoli (Nicolaus Comnenus), “Historia Gymnasii Patavavini,” I; Manget (Jean Jacques), “Bibliotheca Scriptorum Medicorum”; “Biog. Générale,” Vol. XXXVI. p. 34.

=Montanus=, Arias--Benedictus (1527–1598), eminent Spanish Catholic divine and orientalist, member of the Council of Trent, is best known by his Polyglott Bible--_Biblia Regia_ or _Biblia Plantiniana_--though he is the author of many works, mostly religious, published during the years 1569, 1571, 1572, 1574 and 1593. Upon completing the last of the eight folio volumes of the _Biblia_, he was offered, but declined, a bishopric by King Philip II, at whose request he had undertaken the work and who, later on, rewarded him with a liberal pension and other emoluments.

He is but briefly referred to by Gilbert, _De Magnete_, Book I. chap. i.

REFERENCES.--Antonio (Nicolas), “Bibl. Hisp. Nova”; D. Nicol. M. Serrano, “Appendice al Dicc. Univ.,” Madrid, 1881, Vol. XIV. p. 407; “Diccionario Enciclopedico Hispano-Americano,” Barcelona, 1887, Vol. II. p. 596; Loumyer (C.), “Vie de B. A. Montano,” 1842; “Biog. Gén.,” Vol. III. pp. 145–146; Rosenmüeller (Ernst Friedrich Carl), “Handbuch für die Literatur,” Vol. III. p. 296; Colomiès (Paul), “Italia et Hispania Orientalis,” p. 241.

=Montanus=--Da Monte--Joannes Baptista (1488–1551), already mentioned in connection with Lusitanus, was a Professor of Medicine at the Padua University and regarded as one of the most celebrated physicians of his day. He is the author of many valuable works, including “Metaphrasis Summaria,” 1551, “De Differentiis Medicamentorum,” 1551; “In Nonum librum; Rhazès ad Almansorem Expositio,” 1554, 1562.

REFERENCES.--Tiraboschi (Girolamo), “Storia della Letteratura Italiana”; Facciolati (Jacopo), “Fasti Gymnasii Patavini,” par. III; Gilbert, _De Magnete_, Book I. chap. i.; “Biog. Générale,” Vol. XXXVI. pp. 108–109.

=Myrepsus=--Myrepsius--Nicolaus, Greek physician, living in the thirteenth century, became very prominent in Rome as a great student of the Arabic writers. He is the author, more particularly, of a medical treatise, divided into forty-eight sections containing as many as two thousand six hundred and fifty-six formulæ, which was translated by Leonard Fuchs under the title “Nic. Myr. Alex. medicamentorum opus,” Basle, 1549, and frequently reprinted, whilst another translation was made by Nicolas de Reggio, who, like Matthæus Silvaticus, was a physician at Salerno and who called it “Nic. Alex. liber de compositione medicamentorum,” Ingoldstadt, 1541. The last-named work has, by some, been confounded with the “Antidotarium” of Nicolas Præpositas.

Myrepsus is spoken of by Gilbert, Book I, at end of chap. xiv. _De Magnete_ treating of the medicinal virtue of the loadstone. Nicolaus, says he, puts into his “divine plaster” a good deal of loadstone, as do the Augsburg doctors in their “black plaster” for fresh wounds and stabs; because of the exsiccating effect of the loadstone without corrosion, it becomes an efficacious and useful remedy. Paracelsus, in like manner, and for the same end, makes loadstone an ingredient of his plaster for stab wounds.

REFERENCES.--Fabricius (Johann Albert), “Bibliotheca Græca,” Vol. X. p. 292; Vol. XII. pp. 4, 346; Kastner (Christian Wilhelm), “Medicin. Gelehrten-Lexikon,” p. 577; Freind (John), “Hist. of Physic,” Vol. I. p. 464; Hœfer (M. F.), “Hist. de la Chimie,” Vol. I; Sprengel (Kurt Polycarp Joachim), “Geschichte der Arzneikunde,” Vol. II. p. 334; Larousse, “Dict. Univ.,” Vol. XI. p. 744; “Biog. Générale,” Vol. XXXVII. p. 92.

=Nicander of Colophon=, whom Gilbert mentions twice in his first book,