Chapter XVIII

; Champignon, “Etudes Physiques,” etc., Paris, 1843; “Archives du Magn. Animal,” published by M. Le Baron d’Hénin de Cuvillers, Paris, 1820–1823; “Report on Animal Magnetism” made by Charles Poyen Saint Sauveur, 1836; Dupotet’s “Manuel,” etc., Paris, 1868; Hale’s “Franklin in France,” 1888, Part II. chap. v. alluding to an interesting manuscript of T. Auguste Thouret now in the collection of the American Philosophical Society.

=A.D. 1772.=--Henley (William T.), F.R.S., invents the _quadrant electrometer_, an apparatus with which the quantity of electricity accumulated in a jar or battery can be measured through the amount of repulsion produced by the fluid upon a pith ball suspended from the centre of a graduated arc. It is generally attached to the prime conductor to measure the state of action of the electrical machine.

He is also the inventor of the _universal discharger_, for directing the charge of jars or batteries (Edw. Whitaker Gray--1748–1807--“Observations on manner glass is charged and discharged by the electric fluid” in Hutton’s abridgments, Vol. XVI. p. 407).

In the _Philosophical Transactions_ for 1774, Henley and Nairne give an account of many curious experiments proving the superiority of points over balls as conductors. The same is shown by William Swift in the _Phil. Trans._, Vol. LXVIII. p. 155. (For Wm. Swift consult, besides, the _Phil. Trans._, Vol. LXIX. p. 454, and Hutton’s abridgments, Vol. XIV. pp. 314, 571.) Henley also states that the vapour of water is a conductor of electricity; that when the flame of a candle is introduced into the circuit and a Leyden jar is discharged through it, the flame always inclines toward the negative side; and he proves that electricity cannot effect a passage through glass (_Phil. Trans._, Vol. LXVIII. p. 1049). He likewise makes a number of experiments to determine the relative conducting power of the different metals according to the quantity of a wire, each of a given size, melted by equal electrical shocks passed through them, and finds the metals to hold the order following as conductors: gold, brass, copper silvered, silver, iron. It was also shown by Nairne that copper conducts better than iron, in the _Phil. Trans._ for 1780, Vol. LXX. p. 334.

REFERENCES.--Harris, “Rud. Electricity,” 1853, p. 93, and his “Frictional Electricity,” 1867, p. 23; “The Electrical Researches of the Hon. Hy. Cavendish,” Cambridge, 1879, Nos. 559, 568, 569, 580; Thos. Young, “Nat. Phil.” _passim_; _Phil. Trans._, Vol. LXIV. pp. 133, 389; Vol. LXVI. p. 513; Vol. LXVII. pp. 1, 85; also Hutton’s abridgments, Vol. XIII. pp. 323 (new electrometer), 512, 551, 659; Vol. XIV. pp. 90, 97, 130, 473; _Transactions of the Humane Society_, Vol. I. p. 63; Ronayne and Henley, “Account of Some Observations ...” London, 1772 (_Phil. Trans._, p. 137).

=A.D. 1772.=--Cavendish (Henry), F.R.S., eldest son of Lord Charles Cavendish, and a prominent English scientist, sometime called “The Newton of Chemistry” (“the most severe and cautious of all philosophers”--Farrar, 284), commences investigating the phenomena of electricity, the results of which study were duly communicated to the _Philosophical Transactions_. His papers embrace twenty-seven mathematical propositions upon the action of the electric fluid, and contain the first distinct statement of the difference between common and animal electricity.

Cavendish made many very important experiments upon the relative conducting power of different substances. He found that a solution of one part of salt in one part of water conducts a hundred times better, and that a saturated solution of sea-salt conducts seven hundred and twenty times better than fresh water, also that electricity experiences as much resistance in passing through a column of water one inch long as it does in passing through an iron wire of the same diameter four hundred million inches long, whence he concludes that rain or distilled water conducts four hundred million times less than iron wire.

He decomposed atmospheric air by means of the electric spark, and he successfully demonstrated the formation of nitric acid by exploding a combination of seven measures of oxygen with three of nitrogen. The latter he did on the 6th of December, 1787, with the assistance of Mr. George Gilpin, in presence of the English Royal Society. (For George Gilpin, consult “Bibl. Britan.,” Vol. XXXVI, 1807, p. 3; _Phil. Trans._ for 1806.)

He improved upon Priestley’s experiments after studying thoroughly the power of electricity as a chemical agent. In one of his experiments he fired as many as five hundred thousand measures of hydrogen with about two and a half times that quantity of atmospheric air, and having by this means obtained 135 grains of pure water, he was led to the conclusion which Mr. Watt had previously maintained, that water is composed of two gases, viz. oxygen and hydrogen.

He explains why no spark is given by the electrical fishes: the latter may contain sufficient electricity to give a shock without being able to make it traverse the space of air necessary for the production of a spark, as the distance through which the spark flies is inversely (or rather in a greater proportion) as the square root of the number of jars in operation.

For an account of his experiments anticipating Faraday’s discovery of the specific inductive capacity of various substances, see Chap. XI. pp. 69–142 of Gordon’s “Physical Treatise,” etc., London, 1883. See, likewise, J. Clerk Maxwell’s “Electrical Researches,” etc., Cambridge, 1879, pp. liii-lvi, as well as references therein made, more

## particularly at articles Nos. 355–366, 376; also the notes 27, 29 as

per Index at pp. 450 and 453; _Phil. Trans._, Vol. CLXVII (1877), p. 599; Sparks’ edition of Franklin’s “Works,” Vol. V. p. 201.

REFERENCES.--Dr. G. Wilson’s “Life and Works of Hon. Henry Cavendish,” London, 1851; Sturgeon’s _Annals_, Vol. VI. pp. 137, 173, etc.; Noad, “Manual,” etc., pp. 14, 161; Harris, “Electricity,” pp. 136, 140; Harris, “Frictional Electricity,” pp. 23 and 45; Whewell, “Hist. of the Ind. Sciences,” 1859, Vol. II. pp. 203–206, 273–275, 278; C. R. Weld, “Hist. Roy. Soc.,” for Lord Charles Cavendish, Vol. II. pp. 171, 176–185, 221; T. E. Thorpe, “Essays in Historical Chemistry,” London, 1894, pp. 70, 110; Thomas Thomson, “Hist. Roy. Soc.,” London, 1812, pp. 456, 457, 471; Sir William Thomson’s “Works,” 1872, pp. 34, 235; _Phil. Trans._ for 1776, Vol. LXVI. p. 196; Thos. Young, “Lectures,” 1807, Vol. I. pp. 658, 664, 751, and Vol. II. p. 418.

=A.D. 1773.=--Walsh (John), F.R.S., demonstrates the correctness of Dr. Bancroft’s opinion that the shock of the _torpedo_ is of an electrical nature, resembling the discharge from a Leyden jar. In the letter announcing the fact, which he addressed to Franklin, then in London, he says: “He, who predicted and showed that electricity wings the formidable bolt of the atmosphere, will hear with attention that in the deep it speeds a humbler bolt, silent and invisible; he, who analyzed the electric phial, will hear with pleasure that its laws prevail in _animated_ phials; he, who by reason became an electrician, will hear with reverence of an instructive electrician gifted at its birth with a wonderful apparatus, and with skill to use it.”

Mr. Walsh’s experiments were made off Leghorn, in company with Dr. Drummond, as stated in _Phil. Trans._, 1775, p. 1, and were confirmed by Johan Ingen-housz as well as by the Italian naturalist, Lazaro Spallanzani (at A.D. 1780). The last named found the _torpedo_ shocks strongest when it lay upon glass, and that when the animal was dying the shocks were not given at intervals, but resembled a continual battery of small shocks: three hundred and sixteen of them have been felt in seven minutes.

REFERENCES.--Leithead, “Electricity,” p. 135; Gray, “Elements of Natural Philosophy,” 1850, p. 323; “Electrical Researches of Lord Cavendish,” 1879, pp. xxxv, xxxvi and 395–437; Fifth Dissertation of “Encycl. Britannica,” 8th ed. p. 738; _Phil. Trans._ for 1773, 1774, 1775 and 1776; also Hutton’s abridgments, Vol. XIII. p. 469; “Chambers’ Ency.,” 1868, Vol. III. p. 821; “People’s Cyclopædia,” 1883, Vol. I. p. 628; Kaempfer (A.D. 1702); _Sc. American Supplement_, No. 457, pp. 7300, 7301, “Lettera dell’ Abate Spallanzani al Signore Marchese Lucchesini,” Feb. 23, 1783, inserted in the _Gothaische Gelehrte Zeitungen_ for 1783, p. 409. See also the experiments of Dr. Ingram, of Kaempfer and of Borelli, described in Van Swinden’s “Recueil,” etc., La Haye, 1784, Vol. II; Wilkinson’s “Galvanism,” 1804, Vol. I. pp. 318, 324; G. W. Schilling, “Diatribe de morbo,” etc., 1770, and Friedrich von Hahn in the preface to Schilling’s “De Lepra,” etc., 1778, as well as at pp. 436–442, Vol. I and at note, p. 160, Vol. II of Van Swinden’s “Recueil,” already noted; J. B. Leroy and M. Saignette “Sur. l’élect. de la Torpille,” etc. (_Jour. de Phys._, 1774, Vol. IV and for 1776, Vol. VIII); “Annales du Musée d’Hist. Nat.,” p. 392; R. A. F. De Réaumur, “Mém. de l’acad. des Sc. de Paris” for 1714; C. Alibert, “Eloges,” etc., Paris, 1806.

=A.D. 1773.=--Odier (Louis), a well-known Swiss physician, thus addresses a lady upon the subject of an electric telegraph: “I shall amuse you, perhaps, in telling you that I have in my head certain experiments, by which to enter into conversation with the Emperor of Mogol or of China, the English, the French, or any other people of Europe, in a way that, without inconveniencing yourself, you may intercommunicate all that you wish, at a distance of four or five thousand leagues in less than half an hour! Will that suffice you for glory? There is nothing more real. Whatever be the course of those experiments, they must necessarily lead to some grand discovery; but I have not the courage to undertake them this winter. What gave me the idea was a word which I heard spoken casually the other day, at Sir John Pringle’s table, where I had the pleasure of dining with Franklin, Priestley and other great geniuses.”

REFERENCES.--Necrology of Prof. Odier in “Bibl. Britan.,” Vol. IV. N. S., 1817, pp. 317–328; see also allusion to Odier at Schwenter (A.D. 1600), and in the report of Bristol meeting of the British Association, August 25, 1875; also Chambers’ “Papers for the People,” 1851, _El. Com._, p. 6; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. p. 357.

=A.D. 1773.=--Hunter (John), a native of Scotland, “by common consent of all his successors, the greatest man that ever practiced surgery,” gives at p. 481 of the _Phil. Trans._ for 1773 his observations on the anatomical structure of the _raia torpedo_.

The electricity of the animal, he found, is generated by organs on each side of the cranium and gills, somewhat resembling a galvanic pile, and consisting wholly of perpendicular columns reaching from the upper to the under surface of the body. Dr. Walsh gave him for examination a fish about eight inches long, two inches thick and twelve inches broad, and Hunter found in each electrical organ as many as 470 columns; but in a very large fish, four and a half feet long and weighing 73 pounds, he counted as many as 1182 in each organ.

He remarks that there is no part of any animal with which he is acquainted, however strong and constant its natural action, which has so great a proportion of nerves; and he concludes that, if it be probable these nerves are not necessary for the purposes of sensation or action, they are subservient to the formation, collection or management of the electric fluid.

REFERENCES.--_Phil. Trans._ for 1773, p. 461; for 1775, p. 465 (_gymnotus electricus_); for 1776, p. 196; the _Phil. Trans._, Vol. LXIII. p. 481, (torpedo); Vol. LXV. p. 395 (gymnotus); and Hutton’s abridgments, Vol. XIII. pp. 478, 666; also John Davy’s account in _Phil. Trans._ for 1832, p. 259; “Am. Trans.,” Vol. II. p. 166; _Nicholson’s Journal_, Vol. I. p. 355; _Journal de Physique_, Vol. XLIX. p. 69; Becquerel et Brachet, _Comptes Rendus_, III. p. 135; Carlo Matteucci, “Recherches,” Genève, 1837; Delle Chiage, on the organs of the torpedo; Geo. Adams, “Essay on Electricity,” etc., 1785, p. 315; D. J. N. Lud. Roger, “Specimen Physiologicum,” etc., Göttingæ, 1760; Dr. Buniva’s experiments recorded in “Journal de Littér. Médicale,” Tome II. p. 112; Leithead, “Electricity,” Chap. XII; _Scient. Am. Suppl._, No. 457, pp. 7300–7302. See also the account of his having been the first to observe the galvanic sensation of light in the experiment on the eyes, published in “Opuscoli Scelti,” Vol. XXII. p. 364.

=A.D. 1774.=--At p. 16 of the third volume of Dr. Wm. Hooper’s “Rational Recreations,” etc., there is given a fine illustration of the electrical machine made by Dr. Priestley, and mention is made of the fact that, since the publication of the latter’s “History and Present State of Electricity,” he contrived, to be placed on the top of his house, a windmill by which the machine could be occasionally turned.

Much of the remainder of the volume is given to all kinds of experiments in the line of electricity and magnetism.

=A.D. 1774.=--Lesage (Georges Louis, Jr.), a Frenchman living at Geneva, Switzerland, makes in that city the first real attempt to avail of frictional electricity for the transmission of signals between two distant points (see C. M., or Charles Morrison, at A.D. 1753). His apparatus consists of twenty-four metallic wires insulated from each other and communicating with separate electrometers formed of small balls of elder held by threads and each marked with different letters of the alphabet. Whenever the electric current was transmitted, the balls indicated the desired letter.

Lesage was not, however, satisfied with a telegraph upon so small a scale as to be utilized only in one building, and on the 22nd of June 1782 he addressed a letter to M. Pierre Prévost, at Geneva, on the subject of “a ready and swift method of correspondence between two distant places by means of electricity.” This, he says, had occurred to him thirty or thirty-five years before, and had been “then reduced to a simple system, far more practicable than the form with which the new inventor has endowed it.” He employed a subterranean tube of glazed earthenware, divided at every fathom’s length by partitions with twenty-four separate openings intended to hold apart that number of wires, the extremities of the wires being “arranged horizontally, like the keys of a harpsichord, each wire having suspended above it a letter of the alphabet, while immediately underneath, upon a table, are pieces of gold leaf, or other bodies that can be as easily attracted, and are at the same time easily visible.” Upon touching the end of any wire with an excited glass tube, its other extremity would cause the little gold leaf to play under a certain letter, which would form part of the intended message.

Georges Louis Lesage (sen.) wrote a work on “Meteors,” etc., published at Geneva in 1730, and alluded to in _Poggendorff_, Vol. I. p. 1433.

REFERENCES.--Abbé Moigno, “Traité,” etc., 2nd ed. Part II. chap. i. p. 59; Ed. Highton, “The Electric Telegraph,” 1852, p. 38; _Journal des Sçavans_, September 1782, p. 637; Pierre Prévost, “Notice,” etc., 1805, pp. 176–177.

=A.D. 1774.=--Wales (William), English mathematician and the astronomer of Captain Cook during the expeditions of 1772, 1773 and 1774, is the first to make scientific observations relative to the local attraction of a ship upon mariners’ compasses. While on his way from England to the Cape and during his passage through the English Channel he found differences of as much as 19 degrees to 25 degrees in the azimuth compass.

REFERENCES.--Sturmy, at A.D. 1684; also Wales and Bayly’s “Observations on Cook’s Voyages,” p. 49.

=A.D. 1775.=--Gallitzin (Dmitri Alexewitsch Fürst, Prince de), an able Russian diplomat and scientist, carries on at the Hague, between the 4th of June, 1775, and the commencement of the year 1778, a series of experiments upon atmospherical electricity, the results of which he communicates to the St. Petersburg Academy of Sciences in a Memoir entitled “Observations sur l’Electricité naturelle par le moyen d’un cerf-volant.” Therein he states that the presence of electricity was always noticeable whenever he raised his kite, whether in the night or in the daytime, as well as during hot, dry, or damp weather, and he ascertained that electricity is generally positive during calm weather and more frequently negative when the weather is stormy.

He also observed during an extensive course of experiments upon animals that hens’ eggs hatch sooner when they are electrified, thus confirming the previous observations of Koeslin and Senebier, and he gives an account of the effects of battery shocks upon various species. He cites the case of a hen which had sustained the shock of sixty-four jars and appeared dead, but which revived and lived thirty-two days; and he gives the report of the dissection made by M. Munichs, as well as the very curious observations upon it noted at the time by M. Camper.

REFERENCE.--Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 13–14, 66, and Vol. II. p. 48, etc.; “Anc. Mém. de l’acad. Belge,” Vol. III. p. 3, showing preference for the pointed form of electrical conductors; “Mercure de France,” 1774, p. 147; “Biog. Univ.,” Tome XV. p. 425; “Mém. de l’Acad. ... de Bruxelles,” Vol. III. p. 14; _Journal de Physique_, Vols. XXI and XXII for 1782 and 1783; “Opuscoli Scelti,” Vol. II. p. 305.

=A.D. 1775.=--Lorimer (Dr. John), “a gentleman of great knowledge on magnetics” (1732–1795), describes his combined dipping and variation needle for determining the dip at sea, which he calls _universal magnetic needle or observation compass_ in a letter to Sir John Pringle, Bart., copied in _Philosophical Transactions_, Vol. LXV. p. 79. This apparatus is also to be found described in Lorimer’s “Essay on Magnetism,” etc., 1795, as well as at p. 168 of Cavallo’s “Treatise on Magnetism” published in 1787; and, at p. 333 of the latter work, the Doctor endeavours to explain the causes of the variation of the magnetic needle.

REFERENCES.--For Lorimer, consult Hutton’s abridgments, Vol. XIII. p. 593, and, for dipping needles, refer to the same volume of Hutton, p. 613, wherein especial mention is made of those of Thomas Hutchins. The dipping needle of Robert Were Fox is described in the “Annals of Electricity,” as well as at p. 411, Vol. II. of “Abstract of Papers of Roy. Soc.,” and the two dipping needles of Edward Nairne are described in _Phil. Trans._ for 1772, p. 496. Capt. Henry Foster made a report on changes of magnetic intensity ... in dipping and horizontal needles, to be found in _Phil. Trans._ for 1828, p. 303 (“Abstracts Sc. Papers ... Roy. Soc.,” Vol. II. pp. 290–296, 344).

=A.D. 1775.=--Cavallo (Tiberius), a distinguished Italian natural philosopher, publishes in London “Extraordinary Electricity of the Atmosphere at Islington,” which volume was reprinted by Sturgeon, and contains his many experiments and important observations upon the line indicated by Franklin. This work was followed in 1777, 1782, 1787, 1795, 1802 by his “Complete Treatise on Electricity,” etc.; by his “Essay on the Theory and Practice of Medical Electricity” (London, 1780, 1781; Leipzig, 1782, 1785; Naples, 1784); and during 1787 was also published in London the first edition of his “Treatise on Magnetism,” a supplement to which appeared eight years later.

He had made many very remarkable observations during the year 1787 on the phenomena of electricity in glass tubes containing mercury, and he had particularly experimented with various substances floating upon mercury in order to test their magnetism.

Before the year 1795 he contrived what he called a _multiplier of electricity_, a good illustration of which is to be found, more

## particularly, opposite p. 270, Vol. II. of his “Elements,” etc.,

published at Philadelphia in 1825. It consisted of two brass plates insulated upon glass pillars, and of a third plate which could be insulated or uninsulated at will, and which, turning on a pivot, or rather a movable arm, could be made to successively convey electricity from one plate to the other until the desired quantity was accumulated. (For the _multiplier_, see Jean Damel Colladon in “Bibl. Britan.,” Vol. XXIX, N.S. for 1825, p. 316.)

Cavallo also invented a small electroscope and a _condenser of electricity_. The latter consisted of an insulated tin plate between the sides of a wooden frame lined with gilt paper, one edge of the plate being connected with the body containing the electricity, and the condensation making itself observable at the opposite edge by the electroscope.

In the fourth edition of his “Treatise on Electricity” (1795), which, like the previous editions, was freely translated into other languages, will be found at pp. 285–296 of the third volume mention of the possibility of transmitting intelligence by combinations of sparks and pauses. For his experiments he made use of brass wires 250 English feet in length, and his electric alarm was based upon either the explosion of a mixture of hydrogen and of oxygen, or of gunpowder, phosphorus, phosphuretted hydrogen, etc., fired by the Leyden phial (vide Bozolus at A.D. 1767). It is in Vol. I. p. 358 of the afore-named fourth edition that Cavallo explains the mode of action of the charged Leyden jar. His concluding words deserve reproduction: “Which shows that one side of a charged electric may contain a greater quantity of electricity than that which is sufficient to balance the contrary electricity of the opposite side. This redundant electricity should be carefully considered in performing experiments of a delicate nature.” The same is expressed in other words in the 1825 American edition of his “Natural Philosophy,” Chap. IV. Therein he asserts that glass is impervious to the electric fluid, saying: “If the additional electric fluid penetrates a certain way into the substance of the glass, it follows that a plate may be given so thin as to be permeable to the electric fluid, and, of course, incapable of a charge; yet glass balls blown exceedingly thin, viz. about the six-hundredth part of an inch thick, when coated, etc., were found capable of holding a charge.” (Consult Cavendish’s experiments which produced this remarkable discovery, in _Phil. Trans._, Vols. LXXV and LXXVIII.)

An electrical machine used by Cavallo in 1777 had a glass cylinder rotated by means of a cord passing around the neck and the wheel, also a cushion (amalgamated with two parts of mercury, one of tinfoil, some powdered chalk and grease) holding a silk flap and freely moving along a groove, and provided with a prime conductor resting on glass legs and with collecting points.

REFERENCES.--Sturgeon, “Lectures,” London, 1842, p. 12; Young’s “Lectures,” London, 1807, Vol. I. pp. 682, 686, 694, 714; _Nicholson’s Journal_, 1797, Vol. I. p. 394; Du Moncel, “Exposé,” Vol. III; Aikin’s “General Biography,” Vol. X; _Phil. Transactions_, 1776, Vol. LXVI. p. 407; 1777, Vol. LXVII. pp. 48, 388; 1780, Vol. LXX. p. 15; 1786, p. 62; 1787, p. 6; 1788, pp. 1 and 255, and 1793, p. 10 (Volta’s letters); likewise Hutton’s abridgments, Vol. XVI. pp. 57, 170, 354, 449; Vol. XIV. pp. 60, 129, 180, 608; see also “Encycl. Britannica,” art. “Magnetism,” Chap. III. s. 1. for Cavallo’s “Observations on the Magnetism of Metals,” etc.

=A.D. 1775.=--Bolten (Joach. Fred.), a German physician, is the author of “Nachricht von einem mit dem Künstlichen magneten gemachten Versuchein einer Nerven-Krankheit” (Hamburg, 1775), the title of which is here given in full, as the work is not usually found recorded in publications and is considered to be of excessive rarity.

Contrary to the accepted belief of many at the time, Bolten asserts that the application of magnetic plates for the cure of nervous and other affections is not only useless, but has, in many instances, been shown to greatly increase pain. This is proven by M. Fonseca in his _Journal_, which forms part of the above-named work; by Andry and Thouret (“Obs. et Rech sur ... l’Aimant ...” 8, pp. 599, 661), and by J. David Reuss (“Repertorium,” Vol. XII. p. 18), as well as by observations recorded in another very scarce work, translated into Dutch during 1775 by the celebrated physicist, J. R. Deimann, under the title of “Geneeskundige Proefneeming met den door Koast gemaakten Magneet, door den Heere T. C. Unzer.”

REFERENCES.--Magnetical cures by different processes are treated of more particularly by Goclenius R., Jr., “Tract. de Mag. Curatione ...” Marp., 1609; J. Robertus, “Curationis Magneticæ ...” Luxemb., 1621, Coloniæ, 1622; Charlton, “A Ternary of Paradoxes ...” London, 1650; G. Mascuelli, “De Medicina Magnetica,” Franckfort, 1613, translated by W. Maxwell (Maxvellus), 1679–1687; Tentzelius, “Medicina Diastatica ...” 1653; A. Van Leuwenhoeck (_Phil. Trans._, Vol. XIX for 1695–1697, as shown below); J. N. Tetens, “Schreiben ... Magnetcuren,” Bützow and Wismar, 1775; Jacques de Harsu, “Receuil des Effets ...” Geneva, 1783; W. Pigram, “Successful Application ...” (_Phil. Mag._, Vol. XXXII. p. 154); Kloerich, F. W., “Versuche ...” (“Götting. Anzeigen,” 1765), “Von dem Medicin ...” Göttingen, 1766; M. Mouzin, “De l’emploi ... Maladies,” Paris, 1843. See likewise A.D. 450, and Hell at A.D. 1770.

For Anthony Van Leuwenhoeck, consult the _Phil. Trans._ for 1695–1697, Vol. XIX. No. 227, p. 512; Vol. XXXII. p. 72; also the abridgments of Reid and Gray, Vol. VI. p. 170, and of Eames and Martyn, Vol. VI. part. ii. pp. 277–278.

=A.D. 1775.=--Volta (Alessandro), an Italian natural philosopher and Professor at the University of Pavia, who had already, in 1769, addressed to Beccaria a Latin dissertation, “De Vi Attractivâ ignis electrici,” etc., makes known his invention of the _electrophorus_, a sort of perpetual reservoir of electricity. This consists of two circular metallic plates having between them a round disc of resin, which is excited by being struck a number of times with either a silk kerchief or pieces of dry warm fur or flannel. During 1782 he discovered what he called an electrical condenser, wherein the disc of resin is replaced by a plate of marble or of varnished wood. With this he is reported (_Philosophical Transactions_, Vol. LXXII) to have ascertained the existence of negative electricity in the vapour of water, in the smoke of burning coals, and in the gas produced by a solution of iron in weak sulphuric acid. An account of the above named and of other discoveries, as well as of various experiments, appears in letters addressed by him to Prof. Don Bassiano Carminati, of the Pavia Medical University, April 3, 1792, and to Tiberius Cavallo, Sept. 13, and Oct. 25, 1792, as shown in the _Philosophical Transactions_ of the Royal Society, which institution gave him its gold Copley medal.

Volta’s crowning effort lies in the discovery of the development of electricity in metallic bodies and in the production of the justly famous pile which bears his name. The latter consisted of an equal number of zinc and copper discs separated by circular plates of cloth, paper or pasteboard soaked in salt-water or dilute acid, all being suitably connected to develop a large quantity of the electric fluid. Thus, says Dr. Dickerson in his address at Princeton College, Volta gave to the world that new manifestation of electricity called Galvanism. In that form this subtle agent is far more manageable than in the form of static electricity; and by the use of galvanic batteries a current of low tension, but of enormously greater power, can be maintained with little difficulty; whereas static electricity is like lightning, and readily leaps and escapes on the surfaces on which it is confined.

“It was Volta who removed our doubtful knowledge. Such knowledge is the early morning light of every advancing science, and is essential to its development; but the man who is engaged in dispelling that which is deceptive in it, and revealing more clearly that which is true, is as useful in his place and as necessary to the general progress of science as he who first broke through the intellectual darkness and opened a path into knowledge before unknown” (Faraday’s “Researches”).

The last mentioned discovery, though made in 1796, was first announced only on the 20th of March, 1800, in a letter written from Como to Sir Joseph Banks, by whom it was communicated to the Royal Society. It was publicly read June 26, 1800 (_Phil. Trans._ for 1800, Part II. p. 408).

At pp. 428–429 of “La Revue Scientifique,” Paris, April 8, 1905, will be found a review of J. Bosscha’s work entitled “La correspondance de A. Volta et de M. Van Marum,” published at Leyden. Bosscha calls especial attention to letters numbered XIII and XIV, dated respectively August 30 and October 11, 1792, wherein Volta describes his construction of the apparatus which, as already stated, was not made known until March 20, 1800. M. Bosscha’s work is also referred to in the “Journal des Savants” for August 1905.

Volta, at about the same period, constructed an electrical battery, which has been named _La Couronne de Tasses_ (the crown of cups), and which consisted of a number of cups arranged in a circle, each cup containing a saline liquid and supporting against its edges a strip of zinc and one of silver. As the upper part of each zinc strip was connected by a wire with a strip of silver in the adjoining cup, the silver strip of the first cup and the zinc strip of the last cup formed the poles of the battery. It is said that twenty such combinations decomposed water, and that thirty gave a distinct shock.

On the 16th, 18th and 20th of November 1800 (Brumaire an. IX), Volta, who had obtained permission of the Italian Government to go to Paris with his colleague Prof. Brugnatelli, delivered lectures and experimented before the French National Institute (Sue, “Histoire du Galvanisme,” Vol. II. p. 267). As a member of the latter body, Bonaparte, the First Consul, who had attended the second lecture and witnessed the electro-chemical decomposition of water, proposed that a gold medal be stuck to commemorate Volta’s discovery, and that a commission be formed to repeat all of Volta’s experiments upon a large scale. The commission embraced such prominent men as Laplace, Coulomb, Hallé, Monge, Fourcroy, Vauquelin, Pelletan, Charles, Brisson, Sabathier, Guyton De Morveau and Biot. Biot, the chairman of the commission, made a report December 11, 1800, which appears in Vol. V of the _Mémoires de l’Institut National de France_, as well as in the _Annales de Chimie_, Vol. XLI. p. 3. In addition to the gold medal, Volta received from Bonaparte the sum of six thousand francs and the cross of the Legion of Honour.

To Volta has been attributed the fact of having, as early as 1777, entertained the idea of an electric telegraph, although nothing more appears to be on record in relation to the matter. Fahie quotes a letter of Sir Francis Ronalds, alluding to an autograph manuscript, dated Como, April 15, 1777, and gives its translation by César Cantu, wherein Volta states that he does not doubt the possibility of exploding his electrical pistol at Milan, through wires supported by posts, whenever he discharges a powerful Leyden jar at Como.

REFERENCES.--Arago, “Eloge Historique de Volta” and “Notices Biographiques,” Tome I. p. 234 (“Raccolta Pratica di Scienze,” etc. for March and April 1835); London _Times_ of January 26, 1860; the eulogies pronounced by Giorn. Fogliani at Como and by G. Zuccala at Bergamo, the year of Volta’s death, 1827; P. Sue, “Histoire du Galvanisme,” Tome II. p. 267; _Journal de Leipzig_, Tome XXXIV; _Scelta d’ Opuscoli_, Vols. VIII. p. 127; IX. p. 91; X. p. 87; XII. p. 94; XIV. p. 84; XXVIII. p. 43; XXXIV. p. 65; _Opuscoli Scelti_, Vols. I. pp. 273, 289; VII. pp. 128, 145; XV. pp. 213, 425; XXI. p. 373; “Mem. dell’ I. R. Istit. Reg. L. V.,” Vol. I. p. 24; “Mem. dell’ Istit. Nazion. Ital.,” Vol. I. p. 125; “Memor. Soc. Ital.,” Vols. II., pp. 662, 900; V. p. 551; “Bibl. Fisica d’Europa” for 1788; “Giornale Fis.-Med.,” Vols. I. p. 66; II. pp. 122, 146, 241, 287; III. p. 35; IV. p. 192; V. p. 63; “Giornale dell’ Ital. Lettera,” etc., Vol. VIII. p. 249; L. V. Brugnatelli, “Annali di Chimica,” etc., Vols. II. p. 161; III. p. 36; V. p. 132; XI. p. 84; XIII. p. 226; XIV. pp. 3, 40; XVI. pp. 3, 27, 42; XVIII. pp. 3, 7; XIX. p. 38; XXI. pp. 79, 100, 163; XXII. pp. 223–249 (Aless. Volta and Pietro Configliachi); Aless. Volta and Angelo Bellani, “Sulla formazione,” etc., Milano, 1824; F. A. C. Gren, _Neues Journal der Physik_, Vols. III and IV for 1796 and 1797; Rozier, _Observ._, Vols. VII, XXII and XXIII for 1776, 1873; J. B. Van Mons, _Journal de Chimie_, No. 2, pp. 129, 167; Sédillot, “Receuil Per. de la Soc. de Méd. de Paris,” IX. pp. 97, 231; _Journal de Phys._, Vols. XXIII. p. 98; XLVIII. p. 336; LI. p. 334; LXIX. p. 343; _Annales de Chimie_, Vols. XXX. p. 276; XLIV. p. 396; _Nicholson’s Journal_, Vol. XV. p. 3; _Phil. Tr._ for 1778, 1782 and 1793; “Soc. Philom.,” An. IX. p. 48, An. X. p. 74; “Bibl. Brit.,” Vol. XIX. p. 274; _Le Correspondant_ for August, 1867, p. 1059, and _Les Mondes_, December 5, 1867, p. 561; Highton, “The Elec. Tel.,” 1852, pp. 13 and 28; Robertson, “Mémoires Récréatifs,” 1840, Vol. I. chaps, x. and xiii.; Miller, “Hist. Philos. Illustrated,” London, 1849, Vol. IV. p. 333, note; Achille Cazin, “Traité théorique et pratique des piles électriques,” Paris, 1881; “Mémoires de l’lnstitut” (Hist.) An. XII. p. 195; Andrew Crosse, “Experiments in Voltaic Electricity,” London, 1815 (_Phil. Mag._, Vol. XLVI. p. 421, and Gilbert’s “Annalen,” Bd. s. 60); “Lettere sulla Meteorol.,” 1783; Theod. A. Von Heller, in Gilb. “Annal.,” Vols. IV and VI, 1800; and _Gren’s Neues Journ._, 1795, 1797; “L’Arc Voltaique,” by M. Paul Janet, in “Revue Générale des Sciences,” May 15, 1902, pp. 416–422; “L’Académie des Sciences,” par Ernest Maindron, Paris, 1888, pp. 245–251; “Philosophical Magazine,” Vol. IV. pp. 59, 163, 306; Vol. XIII. pp. 187–190 [_re_ prize founded by Napoleon); Vol. XXI. p. 289 (electrophorus); Vol. XXVIII. p. 182 (theory of Pierre Hyacinthe Azais), and p. 297 (Paul Erman on “Voltaic Phenomena”); Thomson, “Hist. of Chemistry,” Vol. II. pp. 251–252; “Dict. de Gehler,” Vols. III. p. 665; VI. pp. 475, 484; Thomas Thomson, “Hist. of the Royal Soc.,” London, 1812, p. 451; Young’s “Lectures,” Vol. I. pp. 674, 677, 678, 683; see likewise the “Theory of the Action of the Galvanic Pile,” as given by Dr. Wm. Henry at s. 5 Vol. I. of his “Elements of Experimental Chemistry,” London, 1823; also _Nicholson’s Journal_ for Henry’s essay in Vol. XXXV. p. 259; M. De Luc’s papers in Vol. XXXII. p. 271, and Vol. XXXVI. p. 97; Mr. Singer on the “Electric Column” in Vol. XXXVI. p. 373; Dr. Bostock’s essay in Thomson’s “Annals,” Vol. III. p. 32; Sir H. Davy’s chapter on “Electrical Attraction and Repulsion,” in his “Elements of Chem. Philos.,” p. 125; the first volume of Gay-Lussac and Thénard’s “Recherches”; Johann Mayer, “Abhandlungen ... Galvani, Valli, Carminati u. Volta,” etc., Prague, 1793; _Lehrbuch der Meteor._, von L. F. Kaemtz, Halle, 1832, Vol. II. pp. 398, 400, 418; M. Detienne et M. Rouland in _Jour. de Phys._, Vol. VII. for 1776; J. N. Hallé, “Exposition Abrégée,” etc. (“Bull. des Sc. de la Soc. Philom.,” An. X. No. 58); C. B. Désormes’ very extended observations recorded in the _An. de Ch._, Vol. XXXVII. p. 284; Volta’s letter to Prof. F. A. C. Gren in 1794, and Wilkinson, “El. of Galv.,” Vol. II. pp. 314–325; J. F. Ackerman (“Salz. Mediechirurg,” 1792, p. 287); Cadet (_An. de Ch._, Vol. XXXVII. p. 68); letter written by Volta to M. Dolomieu (“Bull. de la Société Philom.,” No. 55, p. 48); Friedlander’s “Experiments” (_Jour. de Phys._, Pluvoise, An. IX. p. 101); Paul Erman (_Jour. de Phys._, Thermidor, An. IX. p. 121); Gilbert’s “Annalen,” VIII, X, XI, XIV); _Jour. de Phys._, Tome LIII p. 309; _Jour. de Médecine_, Nivose, An. IX. p. 351; P. C. Abilgaard,“Tentamina Electrica”; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 vols. _passim_; A. W. Von Hauch’s Memoir read before the Copenhagen Acad. of Sc. (Sue, “Hist. du Galv.,” 1802, Vol. II. p. 255); Alexander Nicoläus Scherer’s Journal, 31st book; “Abstracts of Papers of Roy. Soc.,” Vol. I. p. 27; also Hutton’s abridgments of the _Phil. Trans._ Vol. XV. p. 263; Vol. XVII. p. 285; Vol. XVIII. pp. 744, 798; _Phil. Magazine_, Vol. IV. pp. 59, 163, 306; “Bibliothèque Britannique,” Genève, 1796, Vol. XV. an. viii. p. 3; Vol. XIX for 1802, pp. 270, 274, 339; Vol. XVI, N.S. for 1821, pp. 270–309; account of the immense electrophorus constructed for the Empress of Russia, in Vol. I. of “Acta Petropolitana” for 1777, pp. 154, etc. In the _Philosophical Transactions_ for 1778, pp. 1027, 1049, will be found Ingen-housz’s paper relating to the then recent invention of Volta’s _electrophorus_ and to Mr. Henley’s experiments. It is said that at about this time (1778), John Jacob Mumenthaler, Swiss mechanic, constructed very effective electrophori and electric machines out of a very peculiar kind of paper. M. F. Vilette also made a paper electrophorus which is alluded to by J. A. Nollet (“Experiments Letters,” Vol. III. pp. 209, etc.). Consult, besides, Carlo Barletti, “Lettera al Volta ...” Milano, 1776; W. L. Krafft, “Tentatem theoriæ ...” Petropol, 1778; J. C. Schäffer, “Abbild. Beschr. d. elek. ...” Regensberg, 1778; Georg Pickel, “Experimenta physico-medica ...” Viceburgi, 1778–1788; J. A. Klindworth, “Kurze Beschr. ...” Gotha, 1781–1785; (Lichtenberg’s “Magazin,” I. 35–45;) while for Klindworth, M. Obert and M. Minkeler, see the “Goth. Mag.,” I. ii. p. 35; V. iii. pp. 96, 110; E. G. Robertson, “Sur l’électrophore résineux et papiracé,” Paris, 1790; (_Journal de Physique_, Vol. XXXVII;) M. Robert on the electrophorus (Rozier, XXXVII. p. 183); S. Woods, “Essay on the phenomena ...” London, 1805; (_Phil. Mag._, Vol. XXI. p. 289;) M. Eynard’s “Mém. sur l’electrophore,” Lyon, 1804; John Phillips, “On a modification of the electrophorus,” London, 1833 (_Phil. Mag._, s. 3, Vol. II); G. Zamboni, “Sulla teoria ...” Verona, 1844 (“Mem. Soc. Ital.,” Vol. XXIII); F. A. Petrina, “Neue theorie d. elect. ...” Prag., 1846.

=A.D. 1776.=--Borda (Jean Charles), French mathematician and astronomer, improves upon the work of Mallet (at A.D. 1769), and is the first to establish accurately the knowledge of the third and most important element of terrestrial magnetism, viz. its _intensity_.

To him is exclusively due the correct determination of the difference of the intensity at different points of the earth’s surface by measuring the vibrations of a vertical needle in the magnetic meridian. This he determined during his expedition to the Canary Islands, and his observations were first confirmed through additional experiments which the companion of the unfortunate La Pérouse, Paul de Lammanon, made during the years 1785–1787, and which were by him communicated from Macao to the Secretary of the French Academy.

REFERENCES.--Borda’s biography in the “Eng. Cycl.,” and in the eighth “Britannica”; Walker, “Magnetism,” p. 182; Humboldt on magnetic poles and magnetic intensity, embracing the observations of Admiral de Rossel, and “Cosmos,” Vol. V. 1859, pp. 58, 61–64, 87–100; also Vol. I. pp. 185–187, notes, for the history of the discovery of the law that the intensity of the force increases with the latitude; Norman (A.D. 1576).

=A.D. 1777.=--Lichtenberg (Georg Christoph), Professor of Experimental Philosophy at the University of Göttingen, reveals the condition of electrified surfaces by dusting them with powder.

The _figures_, which bear his name, are produced by tracing any desired lines upon a cake of resin with the knob of a Leyden jar and by dusting upon the cake a well-triturated mixture of sulphur and of red lead. These substances having been brought by friction into opposite electrical conditions, the sulphur collects upon the positive and the lead upon the negative portions of the cake: positive electricity producing an appearance resembling feathers, and negative electricity an arrangement more like stars.

REFERENCES.--Harris, “Frict. Elect.,” p. 89; eighth “Britannica,” Vol. VIII. p. 606; E. Reitlinger, “Sibven Abh. ...” (Wien Acad.); illustrations in _Sc. Am. Suppl._, No. 207, p. 3297; Noad, “Manual,” p. 132; Erxleben’s “Physikalische Bibliotek,” s. 514; L. F. F. Crell, _Chemische Annalen_ for 1786; “Göttingisches Magazin,” J i., S ii., pp. 216–220; Lichtenberg’s “Math. u. Phys. Schriften,” etc., Vol. I. p. 478. See also Dr. Young’s “Lectures on Nat. Phil.,” London, 1807, Vol. II. pp. 119, 419 for additional references, and p. 426 for Lichtenberg’s “Table of Excitation.”

=A.D. 1777.=--Pringle (Sir John), a man of great scientific attainments--who was physician to the Duke of Cumberland as well as to the Queen’s household, became a baronet in 1766, and afterward received many distinguished honours from foreign learned bodies--resigns the Presidency of the English Royal Society, which he had held since the year 1772. In this, as will be seen at a later date, he was succeeded by Sir Joseph Banks (at A.D. 1820), who continued in the office a period of over forty-two years. The cause which led to his resignation is best given in the following extract from his biography in the English Cyclopedia:

“During the year 1777 a dispute arose among the members of the Royal Society relative to the form which should be given to electrical conductors so as to render them most efficacious in protecting buildings from the destructive effects of lightning. Franklin had previously recommended the use of points, and the propriety of this recommendation had been acknowledged and sanctioned by the Society at large. But, after the breaking out of the American Revolution, Franklin was no longer regarded by many of the members in any other light than an enemy of England, and, as such, it appears to have been repugnant to their feelings to act otherwise than in disparagement of his scientific discoveries. Among this number was their patron George III, who, according to a story current at the time, and of the substantial truth of which there is no doubt, on its being proposed to substitute knobs instead of points, requested that Sir John Pringle would likewise advocate their introduction. The latter hinted that the laws and operations of nature could not be reversed at royal pleasure; whereupon it was intimated to him that a President of the Royal Society entertaining such an opinion ought to resign, and he resigned accordingly.”

In Benjamin Franklin’s letter to Dr. Ingen-housz, dated Passy, Oct. 14, 1777, occurs the following: “The King’s changing his _pointed_ conductors for _blunt_ ones is therefore a matter of small importance to me. If I had a wish about it, it would be that he had rejected them altogether as ineffectual.” It was shortly after the occurrence above alluded to that the following epigram was written by a friend of Dr. Franklin:

“While you Great George, for knowledge hunt, And sharp conductors change for blunt, The nation’s out of joint: Franklin a wiser course pursues, And all your thunder useless views, By keeping to the _point_.”

Thomson informs us (“Hist. Roy. Soc.” pp. 446–447) that the Board of Ordnance having consulted the Royal Society about the best mode of securing the powder magazine, at Purfleet, from the effects of lightning, the Society appointed Mr. Cavendish, Dr. Watson, Dr. Franklin, Mr. Robertson and Mr. Wilson a committee to examine the building and report upon it. These gentlemen went accordingly, and the first four recommended the erecting of pointed conductors in

## particular parts of the building, as a means which they thought

would afford complete security. Mr. Wilson dissented from the other gentlemen, being of the opinion that the conductors ought not to be pointed but blunt, because pointed conductors solicit and draw down the lightning which might otherwise pass by. He published a long paper on the subject, assigning a great variety of reasons for his preference (_Philosophical Transactions_, Vol. LXIII. p. 49). It was this dissent of Mr. Wilson which produced between the electricians of the Royal Society a controversy respecting the comparative merits of pointed and blunt conductors, which continued a number of years, and a variety of papers in support of which made their appearance in the _Philosophical Transactions_. The controversy, in fact, engaged almost the exclusive attention of the writers on electricity for several successive volumes of that work.

REFERENCES.--William Henley, “Experiments ... pointed and blunted rods ...” in _Phil. Trans_, for 1774, p. 133; P. D. Viegeron, “Mémoire sur la force des pointes ...”; Edward Nairne, “Experiments ... advantage of elevated pointed conductors,” in _Phil. Trans._ for 1778, p. 823; Lord Mahon, “Principles ... superior advantages of high and pointed conductors,” London, 1779; Hale’s “Franklin in France,” 1880, Part I. p. 91, and

## Part II. pp. 254–256, 279, for some of his other correspondence

with Dr. Ingen-housz; likewise Part II., pp. ix, 273, 441–451, regarding the first publication of copies of letters written by Franklin to Sir Joseph Banks, which “for some curious reason,” Mr. Hale remarks, were not publicly read and were never included in the _Philosophical Transactions_, as Franklin intended they should be. Consult also Thomas Hopkinson on “The Effects of Points,” etc., in Franklin’s “New Experiments,” etc., London, 1754; Tilloch’s _Philosophical Magazine_ for 1820; Hutton’s abridgments, Vol. XIII. p. 382; “Memoir of Sir J. Pringle” in Weld’s “Hist. of Roy. Soc.,” Vol. II. pp. 58–67, 102; Jared Sparks’ edition of Franklin’s “Works,” and Sir John Pringle’s discourse delivered at the Anniversary Meeting of the Royal Society, Nov. 30, 1774, a translation of the last named appearing at p. 15, Vol. XV of the “Scelta d’ Opuscoli.” J. Clerk Maxwell, “Electrical Researches of the Hon. Henry Cavendish,” 1879, pp. 52–54.

=A.D. 1778.=--Martin (Benjamin), English artist and mathematician, who had already written an “Essay on Electricity” and a prominent supplement thereto (1746–1748), publishes an enlarged edition in three volumes of his “Philosophia Britannica,” originally produced in 1759. At Vol. I. p. 47 of the last-named work, he states that his experiments indicate a magnetic force inversely as the square roots of the cubes of the distances. Noad, treating of the laws of magnetic force, says (“Electricity” p. 579) that Martin and Tobias Mayer both came to the conclusion that the true law of the magnetic force is identical with that of gravitation, and that, in the previous experiments of Hauksbee and others, proper allowance had not been made for the disturbing changes in the magnetic forces so inseparable from the nature of the experiments.

His first Lecture explains all the phenomena of electricity and magnetism, the appendix thereto detailing numerous experiments of Mr. John Canton, and giving many additional facts concerning the manufacture of artificial magnets. From his preface the following extracts will, doubtless, prove interesting: “We are arrived at great dexterity since Sir Isaac Newton’s time; for we can now almost prove the existence of this _aether_ by the phenomena of electricity; and then we find it very easy to prove that electricity is nothing but this very _aether_ condensed and made to shine. But I believe, when we inquire into the nature and properties of this _aether_ and electricity, we shall find them so very different and dissimilar, that we cannot easily conceive how they should thus mutually prove each other.... I see no cause to believe that the matter of electricity is anything like the idea we ought to have of the _spiritus subtilissimus_ of Sir Isaac.... The smell also of _electrical fire_ is so very much like that of _phosphorus_, that we may be easily induced to believe a great part of the composition of both is the same.”

REFERENCES.--“Encycl. Britan.,” 1857, Vol. XIV. p. 320; Antoine Rivoire (Rivière), “Traité sur les aimants ...” Paris, 1752; Nicolaus von Fuss, “Observations ... aimants ...” Petersburg, 1778; Le Noble, “Aimants artificiels ...” Paris, 1772, and “Rapport ... aimants,” 1783 (Mém. de Paris); Wens, “Act. Hill,” Vol. II. p. 264; C. G. Sjoestén (Gilbert, _Annalen der Physik_, Vol. XVII. p. 325); Rozier, IX. p. 454.

=A.D. 1778.=--Toaldo (Giuseppe) Abbé, celebrated Italian physicist, who had in 1762 been made Professor at the Padua University and was the first one to introduce the lightning rod in the Venetian States, makes known the merits of the last-named invention through his “Dei conduttori per preservare gli edifizj,” etc., which work embraces most of his previous treatises on metallic conductors as well as the translation of H. B. de Saussure’s “Exposition abrégée,” etc., Geneva, 1771, and of M. Barbier de Tinan’s “Considérations sur les conducteurs en général.”

The above was followed by many highly interesting memoirs containing valuable meteorological observations, notably those in continuation of the work of J. Poleni, made close up to the time of Toaldo’s sudden death at Padua, Dec. 11, 1798. His complete works, covering the period 1773–1798, were published in Venice through M. Tiato, with the assistance of Vincenzo Chiminello, during the year 1802.

REFERENCES.--In addition to the last-named publication (entitled “Completa Raccolta d’ Opuscoli,” etc.), “Mem. della Soc. Ital.,” Vol. VIII. pt. i. p. 29 (“Elogio ... da A. Fabbroni,” 1799); note at Beccaria, p. 42 of Ronalds’ “Catalogue”; Larousse, “Dict. Universel,” Vol. XV. p. 251; “Biographie Générale,” Vol. XLV. p. 450; “Biografia degli Italiani Illustri,” etc., by E. A. Tipaldo, Vol. VIII; “Padua Accad. Saggi,” Vol. III. p. cv; “Opusc. Scelti,” Vol. VI. p. 265; Vol. VII. p. 35; “Nuovo Giornale Enciclopedico di Vicenza” for 1784; Antonio Maria Lorgna, “Lettera ... parafulmini,” 1778; G. Marzari (Vol. II. p. 73, of “Treviso Athenæum”); Fonda “Sopra la maniera ...” Roma, 1770; G. Marzari e G. Toaldo, “Memoria Descrizione ...” 25 Aprile, 1786; Barbier de Tinan, “Mémoire sur la manière d’armer,” etc., Strasbourg, 1780; F. Maggiotto’s letter to Toaldo upon a new electrical machine; Sestier et Méhu, “De la foudre,” etc., Paris, 1866.

Vincenzo Chiminello, nephew of Giuseppe Toaldo, whom he succeeded at the Padua Observatory and who continued the _Giornale Astro-meteorologico_ after his uncle’s death, is the author of works on the magnetic needle, on lightning conductors, etc., which are treated of in the columns of the _Mem. Soc. Ital._, Vols. VII and IX; the _Giornale Astro-met._ for 1801, 1804, 1806, as well as in the _Saggi ... dell’Accad. di Padova_, _Nuova Scelta d’Opuscoli_, and _Opuscoli Scelti sulle scienze e sulle arti_.

REFERENCES.--Chiminello’s biography, _Giorn. dell’Ital. Lettera_, etc., Serie II. tome xvii. p. 164, and in “Atti della Soc. Ital.,” Modena, 1819.

=A.D. 1778.=--Dupuis (Charles François), eminent French writer who, at the age of twenty-four, became Professor of Rhetoric at the College of Lisieux, constructs a telegraph upon the plan suggested by Amontons (at A.D. 1704). By means of this apparatus he exchanged correspondence with his friend M. Fortin, then residing at Bagneux, until the commencement of the Revolution, when he deemed it prudent to lay it permanently aside (_Encyclopædia Britannica_, 1855, Vol. VIII. p. 263).

=A.D. 1778.=--Brugmans--Brugman (Anton), who was Professor of Philosophy at the University of Francker between 1755 and 1766, publishes his “Magnetismus, seu de affinitatibus magneticis.” He is, besides, the author of several works upon magnetic matter and the magnetic influence, which appeared 1765–1784 and are alluded to by Poggendorff (“Biog.-Liter. Hand.,” Vol. I. p. 316), as well as in the “Vaderlandsche Letter” for 1775 and 1776, and at p. 34, Vol. I of Van Swinden’s “Recueil de Mémoires ...” La Haye, 1784.

It was in this same year, 1778, that Sebald Justin Brugmans--Brugman--son of Anton Brugmans, a distinguished physician, naturalist and author who was the successor of Van Swinden at the Francker University, and became Professor of Botany at Leyden, discovered that cobalt is attracted while bismuth and antimony are repelled by the single pole of a magnet, thus laying _the foundation of the science of diamagnetism_.

Humboldt remarks: “Brugmans, and, after him, Coulomb, who was endowed with higher mathematical powers, entered profoundly into the nature of terrestrial magnetism. Their ingenious physical experiments embraced the magnetic attraction of all matter, the local distribution of force in a magnetic rod of a given form, and the law of its action at a distance. In order to obtain accurate results the vibrations of a horizontal needle suspended by a thread, as well as deflections by a torsion balance, were in turn employed.”

REFERENCES.--“Biographie Générale,” Vol. VII. p. 582; Larousse, “Dict. Univ.,” Vol. II. p. 1334; “Catalogue Sc. Papers Roy. Soc.,” Vol. I. p. 672; W. H. Wollaston, “Magnetism of ... Cobalt and Nickel” (_Edin. Phil. Jour._, Vol. X. p. 183); Kohl on pure cobalt (L. F. F. Crell’s “Neusten Ent.,” Vol. VII. p. 39); Tyndall, “Researches on Dia-Magnetism,” London, 1870, pp. 1, 90, etc.; Appleton’s Encyclopædia, 1870, Vol. IV. p. 10; Humboldt’s “Cosmos,” 1859, Vol. V. p. 61; Augustin Roux, “Expériences nouvelles ...” (_Journal de Médecine_, for November 1773). Consult also, for Sebald J. Brugmans, “Biog. Générale,” Vol. VII. p. 582; Bory de Saint Vincent, in the “Annales Générales de Sciences Physiques,” Vol. II.

=A.D. 1779.=--Lord Mahon, afterward third Earl of Stanhope, an Englishman of great ingenuity and fertility in invention and a pupil of Lesage of Geneva (at A.D. 1774), publishes his “Principles of Electricity,” in which he explains the effects of the _return stroke_ or _lateral shock_ of an electrical discharge which was first observed by Benjamin Wilson (at A.D. 1746).

He imagined that when a large cloud is charged with electricity it displaces much of that fluid from the neighbouring stratum of air, and that when the cloud is discharged the electric matter returns into that portion of the atmosphere whence it had previously been taken. According to Lord Cavendish, the theory developed in the above-named work is that “A positively electrified body surrounded by air will deposit upon all the particles of that air, which shall come successively into contact with it, a proportional part of its _superabundant_ electricity. By which means, the _air_ surrounding the body will also become _positively_ electrified; that is to say, it will form round that positive body an electrical atmosphere, which will likewise be positive.... That the _Density_ of all such atmospheres decreases when the distance from the charged body is increased.”

Tyndall says (Notes on Lecture VII) that Lord Mahon fused metals and produced strong physiological effects by the return stroke.

In 1781, the English scientist, John Turberville Needham (1713–1781), published at Brussels his French translation of Lord Mahon’s work under the title of “Principes de l’Electricité.” Needham was the first of the Catholic clergy elected to a fellowship of the English Royal Society, to whose Transactions he made several contributions. His numerous works include “A letter from Paris concerning some new electrical experiments made there,” London, 1746, also a volume of researches upon the investigations of Spallanzani. The list of his communications to the _Phil. Trans._ and to the “Mém. de l’Acad. de Bruxelles” will be found in Watt’s “Bibliotheca Britannica” and in Namur’s “Bibl. Acad. Belge” (“Dict. Nat. Biog.,” Vol. XL. p. 157; _Phil. Trans._, 1746, p. 247, and Hutton’s abridgments, Vol. IX. p. 263).

REFERENCES.--“Electrical Researches” of Lord Cavendish, pp. xlvi-xlvii; _Phil. Trans._ for 1787, Vol. LXXVII. p. 130; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. I. p. 664; Dr. Thomas Thomson, “History of the Royal Society,” London, 1812, p. 449; Sturgeon, “Researches,” Bury, 1850, p. 398.

=A.D. 1779.=--Ingen-housz (Johan), distinguished English physician and natural philosopher, native of Breda, publishes, _Phil. Trans._, p. 661, an account of the electrical apparatus which is by many believed to have led to the invention of the plate electrical machine, although the same claim has been made in behalf of Jesse Ramsden (at A.D. 1768). Dr. Priestley states that Ingen-housz and Ramsden invented it independently of one another. He describes a circular plate of glass nine inches in diameter turning vertically and rubbing against four cushions, each an inch and a half long and placed at the opposite ends of the vertical diameter. The conductor is a brass tube bearing two horizontal branches extending to within about half an inch of the extremity of the glass, so that each branch takes off the electricity excited by two of the cushions (Dr. Thomas Young, “Course of Lectures,” Vol. II. p. 432).

The plate machine of Dr. Ingen-housz is illustrated at p. 16 of “Electricity” in the “Library of Useful Knowledge.” For other plate machines see, more particularly, Dr. Young’s “Course of Lectures,” Vol. II. p. 431; _Phil. Trans._ 1769, p. 659; Geo. K. Winter’s apparatus with ring conductor and peculiar-shaped rubbers, as well as the great machine at the Royal Polytechnic, and that of Mr. Snow Harris, illustrated and described in Vol. III. p. 787, “Eng. Ency.--Arts and Sciences,” and at pp. 223, 224 of J. H. Pepper’s “Cyclopædic Science,” London, 1869; “Allg. deutsche Biblioth.,” B. XXIV. Anh. 4, Abth., p. 549, 1760 (Poggendorff, Vol. II. p. 465), relative to the machines of Martin Planta, Ingen-housz and Ramsden; Reiser’s plate machine (Lichtenberg and Voigt’s “Magazin für das Neueste aus der Physik,” Vol. VII. St. 3, p. 73); Ferdinando Elice, “Saggio sull’Elettricita,” Genoa, 1824 (for two electricities); J. J. Metzger’s machine (Elice, “Saggio,” second edition, p. 55); Marchese C. Ridolfi, for a description of Novelluccis’ plate electrical machine (“Bibl. Italiana,” Vol. LXIII. p. 268; “Antologia di Firenze,” for August 1824, p. 159); Robert Hare, “Description of an Electrical Plate Machine,” London, 1823 (_Phil. Mag._, Vol. LXII. p. 8). See, besides, the machines of Bertholon (rubber in motion) in Lichtenberg and Voigt’s “Magazin,” Vol. I. p. 92 and Rozier XVI. p. 74; of Brilhac (Rozier, XV. p. 377); of Saint Julien (Rozier, XXXIII. p. 367); of Van Marum (Rozier, XXXVIII. p. 447).

Dr. Ingen-housz also constructed a small magnet, of several laminæ of magnetised steel firmly pressed together, capable of sustaining one hundred and fifty times its own weight, and he found that pastes into the composition of which the powder of the natural magnet entered were much superior to those made with the powder of iron; the natural magnet, he observed, having more coercitive force than iron.

REFERENCES.--_Journal de Physique_ for February 1786, and for May 1788, containing the letters of Dr. Ingen-housz, which show that the vegetation of plants is in no sensible degree either promoted or retarded by common electricity. An account is also given of his experiments in “Versuche mit Plantzen,” Vienna, 1778, in the “Catalogue of the Royal Society,” p. 313, in “Goth. Mag.,” Vol. V. iii. 13; Rozier, XXXII. p. 321; XXXIV. p. 436; XXXV. p. 81; _Journal de Physique_, Vol. XXXV for 1789. See also, _Journal de Physique_, XLV (II), 458; Rozier, XXVIII. p. 81; M. Nuneberg, “Osservazioni ...” Milano, 1776 (“Scelta d’Opuscoli,” XVII. p. 113); Pietro Moscati, “Lettera ...” Milano, 1781 (“Opus Scelti,” IV. p. 410); H. B. de Saussure (_Journal de Physique_, Vol. XXV for 1784); G. da San Martino, “Memoria ...” Vicenza, 1785; M. Schwenkenhardt, “Von dem Einfluss ...” (Rozier, XXVII. p. 462; _Journal de Physique_ for 1786, Vol. I); A. M. Vassalli-Eandi in the “Mem. della Soc. Agr. di Torino,” Vol. I for 1786, particularly regarding the experiments of Ingen-housz and Schwenkenhardt; also in the “Giornale Sc. d’una Soc. Fil. di Torino,” Vol. III; N. Rouland, “Elec. appliquée aux vegétaux” (_Journal de Physique_, 1789–1790); Ingen-housz, Rouland, Dormoy, Bertholon and Derozières (Rozier, XXXV. pp. 3, 161, 401; XXXVIII. pp. 351, 427, and in _Journal de Physique_, Vols. XXXII, XXXV, XXXVIII); M. Carmoy, on the effects of electricity upon vegetation, in Rozier, XXXIII. p. 339; _Jour. de Physique_ 1788, Vol. XXXIII; M. Féburier, “Mémoire sur quelques propriétés ...”; G. R. Treviranus, “Einfluss ...” Kiel, 1800 (Gilbert’s _Annalen_, Vol. VII for 1801 and “Nordisches Arch. f. Nat. u. Arzneiw.,” 1st Band, 2tes Stück); C. G. Rafn (“Mag. Encyclopédique,” No. 19, Ventose An. X. p. 370), Paris, 1802; J. P. Gasc, “Mémoire sur l’influence ...” Paris, 1823; E. Solly, “On the influence ...” London, 1845 (“Journ. of the Hortic. Society,” Vol. I. part ii.); E. Romershausen, “Galv. El. ... Vegetation,” Marburg, 1851; M. Menon, “Influence de l’électricité sur la végétation,” and his letters to R. A. F. de Réaumur. Consult likewise J. Browning’s letter to H. Baker, Dec. 11, 1746 (_Phil. Trans._ for 1747, Vol. XLIV. p. 373); G. Wallerius, “Versuch ...” Hamb. and Leipzig, 1754; (“K. Schwed. Akad. Abh.,” XVI. p. 257; also “Vetensk Acad. Handl.,” 1754;) L. F. Kamtz (Kaemtz), “Über d. Elek ...” Nürnberg, 1829; (Schweigger’s _Journal f. Chemie u. Physik_, Vol. LVI;) Bartolomeo Zanon, “Intorno un punto ...” Belluno, 1840; Francesco Zantedeschi “Dell influsso ...” Venezia, 1843; (“Mem. dell Instit. Veneto,” I. p. 269;) E. F. Wartmann, “Note sur les courants ...” Genève, 1850; (“Bibl. Univ. de Genève,” for Dec. 1850;) T. Pine, “Connection between Electricity and Vegetation,” London, 1840; (“Annals of Electricity,” Vol. IV. p. 421.) For the effects of galvanism on plants, see Giulio in “Bibl. Ital.,” Vol. I. p. 28; also E. J. Schmuck “On the Action of Galvanic Electricity on the _Mimosa Pudica_,” and M. Rinklake, as well as Johann W. Ritter, “Elektrische versuche an der _Mimosa Pudica_.” For an account of M. P. Poggioli’s observations on the influence of the _magnetic_ rays on vegetation, and the reply of F. Orioli thereto, see Vol. I of the “Nuova collezione d’opuscoli scientifici ...” Bologna, 1817. Dr. Thomas Young’s “Course of Lectures,” Vol. II. pp. 432–433; N. K. Molitor’s “John Ingen-housz. Anfangsgrunde ...” 1781; Geo. Adams, “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. I. pp. 512–515; John Senebier, “Expériences,” etc., 1st and 2nd Memoirs, Genève and Paris, 1788; Becquerel in the _Comptes Rendus_ for November 1850, also Tome XXXI. p. 633; M. Buff (_Phil. Mag._ N. S. Vol. VII. p. 122); Priestley’s “History ...” 1775, p. 487; Walsh at A.D. 1773; Cavallo’s “Exper. Philosophy,” 1803, Vol. III. p. 357; Pouillet (Poggendorff’s _Annalen_, Vol. XI. p. 430); Reiss, in Poggendorff’s _Annalen_, Vol. LXXIX. p. 288; G. F. Gardini, “De inflvxu ...” s. 7, p. 10; _Philosophical Transactions_ for 1775, 1778, p. 1022; 1779, p. 537; _Journal de Physique_, Vol. XVI for 1780; “Erxleben’s phys. bibliothek,” s. 530; papers relative to the effects of electricity upon vegetation alluded to in “Le Moniteur Scientifique,” more particularly at pp. 904, 907, 1026, Vol. XX for 1878, and at p. 23, Vol. XXI for 1879.

=A.D. 1780.=--Spallanzani (Lazaro), celebrated Italian naturalist, to whom the French Republic vainly offered the Professorship of Natural History at the Paris _Jardin des Plantes_, and who has been already particularly alluded to in connection with John Walsh, at A.D. 1773, writes a second treatise upon the operations of Charles Bonnet, of Geneva, as regards the effects of electricity upon nerves and muscles. He is also the author of works upon electrical fishes as well as upon meteors, etc., which will be found detailed in Vol. VII of the “Biographie Médicale,” as well as at Vol. XLIII. p. 246, of the “Biographie Universelle.”

REFERENCES.--Alibert’s Eloge in Vol. III of the “Mém. de la Soc. Médicale d’Emulation”; “Catal. Roy. Soc. Sc. Papers,” Vol. V. p. 767; “Opus. Scelti,” Vols. VII. pp. 340, 361; VIII. p. 3; XIV. pp. 145, 296; Brugnatelli, “Ann. di chimica” for 1793 and 1795; “Mem. Soc. Ital.,” Vols. II. p. 11; IV. p. 476.

=A.D. 1780–1781.=--Bertholon de Saint Lazare (Pierre), French physician and Professor of Natural Philosophy, and a great friend of Dr. Franklin, publishes at Paris his “Electricité du Corps Humain ...” in which he relates more particularly his general observations upon atmospheric electricity as affecting the human body while in a healthy state and while in a diseased condition. He likewise treats of the effects of electricity upon animals, and details very interesting experiments upon the _torpedo_, which latter, he remarks, establishes the closest possible resemblance to the Leyden phial.

He is also the author of “Electricité des Végétaux” (1783), as well as of “Electricité des Météores” (1787), and of a volume entitled “Electricité des Métaux.” J. C. Poggendorff says (“Biog.-Lit. Handw. ...” Vol. II. p. 102) that J. Ferd. Meidinger (1726–1777) had previously written concerning the action of electric fire upon metals and minerals. Johann Jacob Hemmer published, at Mannheim in 1780, “Sur l’Electricité des Métaux” (“Ob. sur la Physique,” July 1780, p. 50), and A. A. De La Rive wrote in 1853 “De l’Elect. Développée ...” (“Bibl. Univ.,” Vol. LIX).

REFERENCES.--Young’s “Course of Lectures,” Vol. II. p. 431; Ingen-housz at A.D. 1779; _Journal de Physique_, Vol. XXXV; “Biographie Universelle,” Vol. IV. p. 149; “Biographie Générale,” Vol. V. p. 722; Larousse, “Dict. Univ.,” Vol. II. p. 618; “La Grande Encyclopédie,” Vol. VI. p. 450. See also Bertholon’s “Nouvelles Preuves ...” pp. 18–19; Arago, “Notices Scientifiques,” Vol. I. pp. 338–340, 386; “Mercure de France,” 1782, No. 52, p. 188; Abbé d’Everlange de Wittry, “Mém. sur l’Elec. ... dans les végétaux et le corps humain,” read June 24, 1773--“Anc. Mém. de l’Acad. Belge,” Vol. I. p. 181; Vassalli-Eandi, “Esame della Elett. delle Meteore del Bertholon,” Torino, 1787; account of the experiments to ascertain the effects of electricity on vegetation, made in France during the summer of 1878 by MM. Grandeau, Celi and Leclerc; and a curious publication, “Les Animaux et les Métaux deviennent ils Electriques par communication,” by L. Béraud (Bérault), alluded to in Poggendorff, Vol. I. p. 146.

=A.D. 1780–1783.=--Prof. Samuel Williams, at Cambridge, Mass., makes the earliest known observations of the magnetic dip in the United States, and publishes them in the “Memoirs of the American Academy of Arts,” Vol. I. pp. 62, 68. According to this authority, the dip in 1783 was 69° 41’. The next dip observations are those made during Long’s expedition to the Rocky Mountains in 1819.

REFERENCES.--“American Journal of Science,” Vol. XLIII. pp. 93, 94; “Trans. Amer. Phil. Soc.,” O. S., Vol. III. p. 115.

=A.D. 1780–1794.=--Le Père Amyot (Amiot), learned French Jesuit, who was sent in 1751 as a missionary to Pekin, where he resided till his decease in 1794, writes, on the 26th of July 1780, and also on the 20th of October 1782 that, as a result of a great number of observations, he finds no change in the variation of the magnetic needle, _i. e._ that “the point which indicates the north declines westerly from 2 to 2½ degrees, rarely more than 4½ degrees, and never less than 2 degrees.”

REFERENCES.--“Mémoires concernant l’histoire,” etc., Saillant et Nyon, Vol. X. p. 142; Davis, “The Chinese,” Vol. III. p. 13.

=A.D. 1781.=--The so-called compass plant (_Silphium lancinatum_) is first introduced from America into Europe by M. Thouin and blooms for the first time in the Botanic Gardens of Upsala, Sweden.

In the “Scientific American” of February 26, 1881, reference is made to the interesting account of this plant given by Sir J. D. Hooker in Curtis’ “Botanical Magazine,” as well as to the following extract from Prof. Asa Gray’s report concerning it: “The first announcement of the tendency of the leaves of the compass plant to direct their edges to the north and south was made by General (then Lieutenant) Alvord, of the U.S. Army, during the year 1842, and again in 1844, in communications to the American Association for the Advancement of Science.... The lines in “Evangeline” (familiar to many readers):

“Look at this delicate plant that lifts its head from the meadow, See how its leaves all point to the north as true as the magnet; It is the compass plant that the finger of God has suspended, Here on its fragile stalk, to direct the traveller’s journey, Over the sealike, pathless, limitless waste of the desert----”

were inspired through a personal communication made by General Alvord to the poet Longfellow.

In this connection, the following article, headed “A Wonderful Magnetic Plant,” translated from _La Nature_ by the London _Court Journal_, will prove interesting: “There has been discovered in the forests of India a strange plant (_Philotacea electrica_) which possesses to a very high degree astonishing magnetic power. The hand which breaks a leaf from it receives immediately a shock equal to that which is produced by the conductor of an induction coil. At a distance of six metres a magnetic needle is affected by it, and it will be quite deranged if brought near. The energy of this singular influence varies with the hours of the day. All powerful about two o’clock in the afternoon, it is absolutely annulled during the night. At times of storm its intensity augments to striking proportions. While it rains the plant seems to succumb: it bends its head during a thunder-shower and remains without force or virtue even if one should shelter it with an umbrella. No shock is felt at that time in breaking the leaves, and the needle is unaffected by it. One never by any chance sees a bird or insect alight on this electric plant; an instinct seems to warn them that in so doing they would find sudden death. It is also important to remark that where it grows none of the magnetic metals are found, neither iron, nor cobalt, nor nickel--an undeniable proof that the electric force belongs exclusively to the plant. Light and heat, phosphorescence, magnetism, electricity, how many mysteries and botanical problems does this wondrous Indian plant conceal within its leaf and flower!”

The results of some interesting researches on plant-electricity have been reported by A. D. Waller, who finds that whenever a plant is wounded, a positive electric current is established between the wounded part and the intact parts. This may start with an electromotive force of 0·1 volt, but it afterward diminishes. He writes further:

“Actual wounding is not necessary to obtain this manifestation; an electro-positive current is set up when there is mechanical excitation, but it is much weaker (0·02 volt). And light acts like mechanical excitation with certain plants, such as the leaves of the iris, of tobacco, of the begonia, etc. From the illuminated to the darkened part flows a positive electric current that may be as strong as 0·02 volt. A similar reaction in the petals is not always observed. There is a certain correlation between the vigour of a plant and the electric reaction. The more vigorous the plant is, the stronger the current. Plants grown from fresh seeds give a more powerful current than those from old seeds. A bean a year old gave a current of 0·0170 volt; one five years old, a current of 0·0014; and the reaction is inversely and regularly proportional to the age of the seed from which the plant springs. There is observed in vegetable tissues, subjected to an excitation of the same intensity at regular intervals, the characteristic changes of reaction that are present in animal tissues--fatigue, recuperation, etc. Temperature plays a part in all these phenomena; below -4° to -6° C. [+° to + 25° F.] and above 40° C. [108° F.] there is no reaction.”

=A.D. 1781.=--Lavoisier (Antoine Laurent), an eminent French natural philosopher, the chief founder of modern chemistry as well as of the prevailing system of chemical nomenclature which ended in the expulsion of the phlogistic theory, demonstrates by experiments made in conjunction with Volta and Laplace that electricity is developed when solid or fluid bodies pass into the gaseous state. Sir David Brewster says that the bodies to be evaporated or dissolved were placed upon an insulating stand and were made to communicate by a chain or wire with a Cavallo electrometer, or with Volta’s condenser, when it was suspected that the electricity increased gradually. When sulphuric acid, diluted with three parts of water, was poured upon iron filings, inflammable air was disengaged with a brisk effervescence; and, at the end of a few minutes, the condenser was so highly charged as to yield a strong spark of negative electricity. Similar results were obtained when charcoal was burnt on a chafing dish, or when fixed air or nitrous gas was generated from powdered chalk by means of the sulphuric and nitrous acids.

The phlogistic theory alluded to above, which was so named by George Ernest Stahl in 1697 after Johann Joachim Beccher (1635–1682) had pointed out its principle in 1669, had for its most energetic defender the editor of the _Journal de Physique_, M. J. C. De La Méthérie, who is entered at A.D. 1785, and it was in order to offset the influence which this gave him that the antiphlogistians established the _Annales de Chimie_, so frequently mentioned in these pages.[52]

REFERENCES.--George Adams’ “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. I. pp. 575–587, wherein Lavoisier’s system is confuted by the German chemist Wieglib, whose views are endorsed by Mr. Green, while for Stahl and Beccher, refer to Sir H. Davy, “Bakerian Lectures,” London, 1840, p. 102, note, to “Biog. Gén.,” Vol. V. pp. 85–87; “Meyer’s Konvers. Lexikon,” Vol. II. p. 654, and to Thomson’s “Hist. of Roy. Soc.,” London, 1812, p. 467. See also J. M. G. Beseke, “Ueber elementärfeuer ...” Leipzig, 1786; G. A. Kohlreif, “Sollte die elektricität ...” Weimar, 1787; Lavoisier and Laplace, in the “Mém. de l’Acad. Roy. des Sciences” for 1781, p. 292; Lavoisier’s “Opuscules ...” 1774, and his “Rapport ... mag. animal.,” Paris, 1784; Dr. Thomas Thomson, “Hist. Roy. Soc.,” pp. 479–486; Herschel’s “Nat. Phil.,” concerning the third age of chemistry; Grégoire, “Dict. d’hist.,” etc., p. 1171; Miller’s “Hist. Phil. Illus.,” London, 1849, Vol. IV. pp. 332–333, notes. Chap. IV of the “History of Chemistry,” Ernst Van Meyer, tr. by George McGowan, London, 1898, entitled “History of the Period of the Phlogiston Theory from Boyle to Lavoisier,” will prove interesting. “La chimie constituée par Lavoisier,” Jacob Volhard, in “Le Moniteur Scientifique,” du Dr. Quesneville, Vol. XIV for 1872, pp. 50–71; “Nouveau Larousse,” Vol. V. p. 608; “La Révolution chimique,” M. Berthelot, Paris, 1890; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 87, 110; “Journal des Savants” for Nov. 1859 and Feb. 1890; “Lives of Men of Letters and Science,” by Henry, Lord Brougham, Philadelphia, 1846, pp. 140–166.

=A.D. 1781.=--Achard (Franz Carl), able chemist and experimental philosopher, born in Prussia but of French extraction, communicates to the “Mém. de Berlin” a report of many very interesting experiments made by him, which are reviewed by Prince Dmitri Alexewitsch Fürst Gallitzin, in Vol. XXII of the _Journal de Physique_.

He had previously published essays upon the electricity of ice and the electricity developed on the surface of bodies, as well as upon terrestrial magnetism, the electrophorus, etc. He made many notable investigations to prove that fermentation is checked by electricity and that putrefaction is hastened both in electrified meats and in animals killed by the electric shock.

One of his experiments illustrating galvanic irritation so greatly interested Humboldt that the latter repeated it with different animals, not doubting but small birds might in many cases be brought back to life when they fall into a state somewhat resembling death. On one occasion, he took a linnet about to expire and, having established the necessary communication, perceived, the moment the contact took place, that the linnet opened its eyes, stood erect upon its feet and fluttered its wings; it breathed, he says, during six or eight minutes and then expired tranquilly.

It was a namesake of Achard who invented the electro-magnetic brake which will be found described and illustrated in articles from the London _Engineer_ and _Engineering_, reproduced through the _Scientific American Supplements_, No. 111, p. 1760, and No. 312, p. 4974.

REFERENCES.--Poggendorff, “Biog.-Lit. Hand. ...” Vol. I. p. 7; “Biographie Générale,” Vol. I. p. 176; “Cat. Roy. Soc. Sc. Papers,” Vol. I. p. 9; “Opus. Scelt.,” Vols. III. p. 313; V. p. 351; VI. p. 199; Reuss, _Repertorium_, Vol. IV. p. 351; Dr. G. Gregory, “Economy of Nature,” London, 1804, Vol. I. p. 317; Van Swinden, “Recueil ...” La Haye, 1784, Vol. I. p. 24; “Biographie Universelle,” Vol. I. p. 114; “Journal Lit. de Berlin,” for 1776; Cavallo, London, 1777, p. 403; “Mém. de Berlin” for 1776–1780, 1786, 1790–1791; Sturgeon, “Lectures,” London, 1842, p. 12; Geo. Adams, “Essay on Electricity,” etc., London, 1785, pp. 214–220, 277; “Gött. Mag.,” Vol. II. ii. 139; Rozier, VIII. p. 364; XV. p. 117; XIX. p. 417; XXII. p. 245; XXIII. p. 282; XXV. p. 429; XXVI. p. 378; _Phil. Mag._, Vol. III. p. 51.

=A.D. 1781.=--Kirwan (Richard), LL.D., F.R.S., an Irish chemical philosopher of great eminence, who became President of the Dublin Society and of the Royal Irish Academy, receives from the English Royal Society its gold Copley medal for the many valuable scientific papers communicated by him to the latter body. These papers embrace his “Thoughts on Magnetism,” wherein he treats at length of attraction, repulsion, polarity, etc., as shown in the review given at pp. 346–353 of the eighth volume of Sturgeon’s “Annals of Electricity,” etc.

It is said that Kirwan first suggested the notion of molecular magnets, but, according to Dr. J. G. M’Kendrick, it was not till a definite form was given thereto by Weber that it acquired any importance.

REFERENCES.--_Transactions Royal Irish Academy_, Vol. VI; Ninth “Encycl. Britannica,” Vol. XV. p. 276; _Phil. Mag._, Vol. XXXIV. p. 247; Thomson, “Hist. of the Roy. Soc.,” p. 483; “Bibl. Britan.,” An. VII. vol. xii. p. 105.

=A.D. 1781.=--Mauduyt (Antoine René) (1731–1815), Professor at the Collège de France, publishes several observations from which he concludes that the application of electricity is favourable in cases of paralysis. He was in the habit of placing the patient upon an insulated stool, in communication with the conductor of an electrical machine. De La Rive, who mentions the fact (“Electricity,” Chap. III. pp. 586, 587), observes that the effect, if any, could only proceed from the escape of electricity into the air.

REFERENCES.--Bertholon, _Elec. du Corps. Humain_, 1786, Vol. I. pp. 275–276, 302, 439, 447, etc., and Vol. II. pp. 7 and 296; “Mémoire sur les différentes manières d’administrer l’électricité,” etc., Paris, 1784; “Recueil sur l’électricité médicale,” etc., containing articles by G. F. Bianchini, De Lassoné, Deshais (_see_ Sauvages), Dufay, Jallabert, Pivati, Quellmalz, Veratti, Zetzell, etc.; K. G. Kuhn’s works published at Leipzig, 1783–1797; E. Ducretet in “Le Cosmos,” Paris, Oct. 3, 1891, pp. 269–272; P. Sue, aîné, “Hist. du Galvan,” Paris, An. X-XIII, 1802, Vol. I. p. 40; and Vol. II. p. 382; “Grande Encyclop.,” Vol. XXIII. p. 415.

=A.D. 1781–1783.=--Don Gauthey--Gauthier or Gualtier--a monk of the Order of Citeaux, improved upon the invention of Dupuis (at A.D. 1778) and constructed a telegraph, which he submitted at the Académie des Sciences to Dr. Franklin as well as to Condorcet and De Milly, by whom it was recommended to the French Government. In his prospectus, published during 1783, he relates that he has discovered a new mode of rapid transmission enabling him to convey intelligence and sound, by means of water pipes, a distance of fifty leagues in fifty minutes. Ternant, who states this at pp. 33 and 34 of _Le Télégraphe_, Paris, 1881, adds that, as no action was taken at the time upon the prospectus, it doubtless still lies in the archives of the Academy.

REFERENCES.--Laurencin, _Le Télégraphe_, p. 9; Eng. Cycl., “Arts and Sciences,” Vol. VIII. p. 65; “Penny Cycl.,” 1842, Vol. IV. p. 146.

=A.D. 1782.=--Nairne (Edward), an English mathematical instrument maker, publishes papers on electricity describing his invention of a cylinder machine which is illustrated and described at p. 15 of the chapter on “Electricity” in “Library of Useful Knowledge,” 1829. In this, as has been truly said, are seen all the essential parts of the frictional apparatus now in use.

This machine, according to Cuthbertson, was originally constructed in 1774, and was far more powerful than any before made. Nairne also constructed the largest battery known up to that time. It contained 50 square feet of coated surface, and it could be given so high a charge as to ignite 45 inches of iron wire ¹⁄₁₅₀ of an inch diameter, which up to that period was the greatest length of wire ever ignited. Nairne, while improving upon some of Priestley’s experiments, found that a piece of hard drawn iron wire, ten inches long and one-hundredth of an inch diameter, after receiving successively the discharge of 26 feet of coated glass (nine jars), was shortened three-fortieths of an inch by such discharge. Dr. Priestley had previously observed that a chain 28 inches long was shortened one quarter of an inch after having had transmitted through it a charge of 64 square feet of coated glass, and Brooke Taylor found that by passing a charge of nine bottles of 16 feet of coated surface nine times in succession through a steel wire 12 inches long and one one-hundredth of an inch diameter, the wire was shortened one and one-half inches, or one-eighth its entire length.

To Nairne was granted the third English patent in the Class of Electricity and Magnetism, the first having been issued to Gowin Knight in 1766 (see A.D. 1746) and the second to Gabriel Wright, June 25, 1779, for “a new constructed azimuth and amplitude compass.” Knight subsequently covered other similar inventions, July 5, 1791, and Jan. 19, 1796. Nairne’s patent bears date Feb. 5, 1782, No. 1318, and is for what he calls “The Insulated Medical Electrical Machine,” the conductors of which are so arranged as to readily give either shocks or sparks. He says that “by means of the conductors and jointed tubes, the human body can be in any part affected with either kind of electricity in any convenient manner.”

REFERENCES.--_Philosophical Transactions_ for 1772, 1774, 1778, 1780, 1783, Vol. LXIV. p. 79; Vol. LXVIII. p. 823; Vol. LXX. p. 334; also Hutton’s abridgments, Vol. XIII. pp. 360 (dipping needle), 498; Vol. XIV. pp. 427–446, 688; Vol. XV. p. 388; “General Biog. Dict.,” London, 1833, by John Gorton, Vol. I. (n. p.); Cuthbertson, “Practical Electricity,” London, 1807, pp. 165–168; article “Electricity,” in the “Encycl. Britannica”; “Description of ... Nairne’s ... Machine,” London, 1783 and 1787; Caullet de Veaumorel, “Description de la machine électrique négative et positive de Mr. Nairne,” Paris, 1784; Delaunay’s “Manuel,” etc., Paris, 1809, pp. 7, 12–14.

=A.D. 1782–1783.=--Linguet (Simon, Nicolas, Henri), French advocate (1736–1794), who was an associate of Mallet du Pan in the preparation of the _Annales Politiques_ and who was later on committed to the Bastille in consequence of a visit which he imprudently made to Paris, writes a letter to the French Ministry proposing a novel method of transmitting messages of any length or description by means of some kind of a telegraph, “nearly as rapidly as the imagination can conceive them.” He adds, “I am persuaded that in time it will become the most useful instrument of commerce for all correspondence of that kind; just as electricity will be the most powerful agent of medicine; and as the fire-pump will be the principle of all mechanic processes which require, or are to communicate, great force.”

To Linguet has been attributed the authorship of the anonymous letter which appeared in the _Journal de Paris_ of May 30, 1782, and in _Le Mercure de France_ of June 8, 1782, wherein it is proposed to employ twenty-four pairs of gilt wires, placed underground in separate wooden tubes filled with resin and bearing a knob at each extremity. Between each pair of knobs was to be placed a letter of the alphabet, which would become discernible whenever the electric spark was passed through the wire by means of the Leyden phial.

REFERENCES.--Ternant, _Le Télégraphe_, Paris, 1881, p. 11; Linguet, “Mém. manuscrit ... signaux par la lumière,” Paris, 1782; all about the “Mercure de France,” in “Bulletin du Bibliophile” No. 7 of July 15, 1902; “Biog. Dict.,” Alex Chalmers, 1815, Vol. XX. p. 290; “Nouv. Biog. Gén.” (Hœfer), Paris, 1860, Vol. XXXI. p. 279; “Biog. Univ.” (Michaud), Vol. XXIV. p. 565.

=A.D. 1782–1791.=--Cassini (Jean Jacques Dominique, Comte de), son of Cassini de Thury, eminent astronomer, makes the very important announcement that, besides the _secular_ variation of the declination, the magnetic needle is subject to an _annual_ periodical fluctuation depending on the position of the sun in reference to the equinoctial and solstitial points.

Cassini’s discovery is contained in a Memoir consisting of two parts, the first part being a letter addressed to L’Abbé Rosier and published by him in the _Journal de Physique_, while the second part, composed at request of the Académie des Sciences, is that which specially treats of the _annual variation in declination_.

Besides the last named, we have thus far learned of the _secular_ variation discovered by Gellibrand (Hellibrand) in 1635, as well as of the _diurnal_ and _horary_ variations, first accurately observed by George Graham during the year 1722, and we have likewise been informed of the earliest observations of _the dip or inclination_, made independently by both Georg Hartmann (A.D. 1543–1544) and by Robert Norman (A.D. 1576), as well as of the determination of the intensity of the inclination by J. C. Borda (at A.D. 1776). For accounts of the _secular_ and _annual_, as well as of the _diurnal_ and _horary_ variations of the dip, the reader should consult the First Section of Humboldt’s “Cosmos” treating of telluric phenomena and some of the very numerous references therein given.

Speaking of the influence of the sun’s position upon the manifestation of the magnetic force of the earth, Humboldt remarks that the most distinct intimation of this relation was afforded by the discovery of _horary_ variations, although it had been obscurely perceived by Kepler, who surmised that all the axes of the planets were magnetically directed toward one portion of the universe. He says that the sun may be a magnetic body, and that on that account the force which impels the planets may be centred in the sun (Kepler, in “Stella Martis,” pp. 32–34--compare with it his treatise, “Mysterium Cosmogr.,” cap. 20, p. 71). He further observes that the _horary_ variations of the declination, which, although dependent upon true time are apparently governed by the sun as long as it remains above the horizon, diminish in angular value with the magnetic latitude of place. Near the equator, for instance, in the island of Rawak, they scarcely amount to three or four minutes, whilst the variations are from thirteen to fourteen minutes in the middle of Europe. As in the whole northern hemisphere the north point of the needle moves from east to west on an average from 8½ in the morning until 1½ at midday, in the southern hemisphere the same north point moves from west to east (Arago, _Annuaire_, 1836, p. 284, and 1840, pp. 330–358). Attention has been drawn, with much justice, to the fact that there must be a region of the earth, between the terrestrial and the magnetic equator, where no horary deviations in the declination are to be observed. This fourth curve (in contradistinction to the _isodynamic_, _isoclinic_ and _isogonic_ lines, or those respectively of equal force, equal inclination and equal declination), which might be called the _curve of no motion_, or rather _the line of no variation of horary declination_, has not yet been discovered. No point has hitherto been found at which the needle does not exhibit a _horary_ motion, and, since the erection of magnetic stations, the important and very unexpected fact has been evolved that there are places in the southern magnetic hemisphere at which the _horary_ variations of the dipping needle alternately participate in the phenomena (types) of the hemispheres.

Humboldt also alludes, in the article on “Magnetic Variation,” to his recognition of the “four motions of the needle, constituting, as it were, four periods of magnetic ebbing and flowing, analogous to the barometrical periods,” which will be found recorded in Hansteen’s “Magnetismus der Erde,” 1819, s. 459, and he likewise refers to the long-disregarded _nocturnal_ alterations of variation, for which he calls attention to Faraday “On the Night Episode,” ss. 3012–3024. (See also, Poggendorff’s _Annalen der Physik_, Bd. XV. s. 330, and Bd. XIX. s. 373.)

The _Phil. Trans._ for 1738, p. 395, contain the description of a new compass for ascertaining the variation “with greater ease and exactness than any ever yet contrived for that purpose.” This was devised by Capt. Christopher Middleton, whose many interesting observations are to be found in the same volume of the _Phil. Trans._, p. 310, as well as in the volumes for 1726, p. 73; 1731–1732, 1733–1734, p. 127; 1742, p. 157, and in John Martyn’s abridgment, Vol. VIII. part i. p. 374. Reference should also be made to the volumes for 1754 (p. 875) and 1757 (p. 329), giving the reports of W. Mountaine and J. Dodson upon the magnetic chart and tables of 50,000 observations, likewise to the volume for 1766 containing the report of W. Mountaine on Robert Douglass’ observation, as well as for the record of investigations of the variation made by David Ross on board the ship “Montagu” during the years 1760–1762.

REFERENCES.--Sabine, “On the Annual and Diurnal Variations” in Vol. II of “Observations made ... at Toronto,” pp. xvii-xx, also his Memoir “On the Annual Variation of the Magnetic Needle at Different Periods of the Day,” in _Phil. Trans._ for 1851, Part II. p. 635, as well as the Introduction to his “Observations ... at Hobart Town,” Vol. I. pp. xxxiv-xxxvi, and his Report to the British Association at Liverpool, 1854, p. 11--_Phil. Trans._ for 1857, Art. 1, pp. 6, 7--relative to the _lunar diurnal magnetic variation_. See likewise C. Wolf, “Histoire de l’observatoire depuis sa fondation à 1793”; Houzeau et Lancaster, “Bibl. Gen.,” Vol. II. p. 102; “Mém. de Paris,” Vol. II. p. 74, and Vol. VII. pp. 503, 530; Walker, “Ter. and Cos. Magn.,” Chap. III; Mme. J. Le Breton, “Histoire et Applic.,” etc., Paris, 1884, p. 17; Robison, “Mech. Phil.,” Vol. IV. p. 356; Thos. Young, “Nat. Phil.,” 1845, p. 583.

CASSINI FAMILY

This celebrated family, to which allusion was made under A.D. 1700, deserves here additional notice.

Giovanni Domenico Cassini (1625–1712), the first and greatest of the name, succeeded Buonaventura Cavaliéri in the astronomical chair of the Bologna University in 1650, and remained there until given the directorship of the Paris Royal Observatory upon its completion in 1670. Partly with the assistance of his learned nephew, James Philip Maraldi, Cassini made many important discoveries, among which may be signalled the finding of the first, second, third and fifth satellites of Saturn, as well as the dual character of that planet’s ring, the determination of the rotation of Jupiter, Mars and Venus, and the laws of the moon’s axial rotation. (See Thomson, “Hist. of the Roy. Soc.,” p. 331; “Anc. Mém. de Paris,” I, VIII, X; Thos. Morrell, “Elem. of the Hist. of Phil. and Sc.,” London, 1827, pp. 377–379.)

Jacques (James) Cassini (1677–1756), the only son of the preceding, became director of the Paris Observatory upon the death of his father, made many very important astronomical observations, and wrote several treatises upon electricity, etc. In one of his works, “De la Grandeur et de la Figure de la Terre,” Paris, 1720, he gives an account of the continuation of the measurement of Picard’s arc of the meridian from Paris northward, begun by Domenico Cassini and La Hire in 1680, and recommenced by Domenico and Jacques Cassini in 1700. (See “Mém. de Paris,” Vol. VII. pp. 455, 456, 508, 572; and for years 1705, pp. 8, 80; 1708, pp. 173, 292; 1729, Hist. I., Mem. 321.)

Cesar François Cassini de Thury (1714–1784), son of Jacques, whom he in turn succeeded at the Observatory, was, as above stated, the father of Jean Dominique Cassini (1747–1845). He made numerous researches while in the Director’s Chair, his most remarkable work being the large triangulation of France published in 1744, under the title of “La Méridienne,” etc. (See “Hist. de l’Acad. des Sciences de Paris” pour 1752, p. 10.)

=A.D. 1783.=--Robespierre (François-Maximilien-Joseph-Isidore de), who afterward became leader of the famous French Jacobin Club, and was at the time practising law in his native town of Arras, distinguishes himself by successfully defending the cause of the Sieur de Vissery de Boisvalé, a landed proprietor of that place, who had erected a lightning conductor on his house, “much to the scandal of the discreet citizens” of the locality--“Deistical philosophy; away with it!” (Eighth “Britannica,” Vol. XIX. p. 233).

Mr. de Boisvalé’s case was an appeal from a judgment delivered by the sheriff of Saint-Omer, ordering the destruction of the lightning conductor, and its printed report bears the following epigraph:

“L’usage appuyé sur les temps Et les préjugés indociles. Ne se retire qu’à pas lents Devant les vérités utiles.”

Jean Paul Marat, docteur en médecine et médecin des Gardes de corps de M. le Comte d’Artois, who, like Robespierre, was a member of the French National Convention as well as a declared enemy of the Girondins, and who was killed by Charlotte Corday, July 13, 1793, made many electrical experiments. These greatly interested Benjamin Franklin, who used to visit him (Ninth “Encycl. Brit.,” Vol. XV. p. 526). He was the author of many electrical works during the years 1779–1784, notably “Découvertes sur le feu, l’électricité et la lumière,” “Recherches Physiques,” and a memoir on medical electricity (“Œuvres de Marat,” Paris, 1788; A. Bougeart, “Marat, l’ami du peuple,” 1864; F. Chevremont, “Jean Paul Marat,” 1881).

REFERENCES.--Ronalds’ “Catalogue,” p. 434; _La Lumière Electrique_ for Sept. 5, 1891; the _Electrician_, London, Sept. 11, 1891.

=A.D. 1783.=--Wilkinson (C. H.), Scotch physician, publishes at Edinburgh his “Tentamen Philosophico-medicum de Electricitate,” which is followed, during 1798 and 1799, by other works upon electricity, wherein he cites a number of marvellous cures of intermittent fevers similar to those made by Cavallo, also of amaurosis (_goutte sereine_) and of quinsy (_squinancie_) like those performed by Lovet, Becket and Mauduyt.

During the year 1804 appeared the first edition, in two volumes, of his “Elements of Galvanism in Theory and Practice,” containing a very comprehensive review of the discovery from the time of Galvani’s early experiments. In this last-named work, however, he shows that incipient amaurosis and the completely formed gutta serena have not yielded to his own treatment by galvanic influence as had been the case with Dr. C. J. C. Grapengieser, who published many accounts of surprising cures (Grapengieser, “Versuche den Galvanismus ...” Berlin, 1801 and 1802, or Brewer and Delaroche, “Essai ...” Paris, 1802). The whole of Chap. XXXVI is devoted to the application of galvanism to medicine, whereto allusion had already been made in the first chapter of the same work.

Wilkinson refers also to the electricity of the _torpedo_, and to the observations made thereon by Hippocrates, Plato, Theophrastus, Pliny and Ælian, also by Belon, Rondelet, Salviana and Gesner, as well as by Musschenbroek, Redi, Réaumur, Walsh, Hunter, Spallanzani, ’Sgravesande, Steno, Borelli, Galvani and others. Much space is likewise given to the observations recorded on animal electricity, notably by Fontana, De La Méthérie, Berlinghieri, Vassali-Eandi, Humboldt, Pfaff, Lehot, Hallé, Aldini, and to the experiments of Valli as they were repeated before the French Academy of Sciences and before the Royal Society of Medicine of Paris, in presence of M. Mauduyt. When treating of the powers of galvanism as a chemical agent, reference is made to the decomposition of water, thus first effected in 1795 by Creve, the discoverer of metallic irritation, and to the operations of Nicholson and Carlisle, Dr. Henry, Cruikshanks, Haldane, Henry Moyes, Richter, Gibbes, etc.

REFERENCES.--J. J. Hemmer, “Commentat Palatinæ,” VI, Phys., p. 47; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 314, 330, 483, and Vol. II. p. 299; “Bibl. Britan.,” 1808, Vol. XXXVIII. p. 270 (_Phil. Mag._, No. 105); _Annales de Chimie_, Vol. LXXVIII. p. 247; _Phil. Mag._, Vol. XXIX. p. 243, and Vol. XLIX. p. 299; F. Buzzi, “Osservazione ... amaurosi ... elettricita,” Milano, 1783 (“Opus. Scelti,” Vol. VI. p. 359); _Nicholson’s Journal_, Vol. VIII. pp. 1, 70, 206; also Vol. X. pp. 30–32, for letter relative to certain erroneous observations of Mr. Wilkinson respecting galvanism, by Mr. Ra. Thicknesse, who also wrote in Vol. IX. pp. 120–122, explaining the production of the electric fluid by the galvanic pile.

=A.D. 1783.=--Saussure (Horace-Benedict de), Professor of Physics at the University of Geneva and founder of the Society for the Advancement of the Arts in the same city, is the inventor of an electrometer designed to ascertain the electrical state of the atmosphere, which will be found described in Vol. VIII. p. 619 of the 1855 “Encycl. Britannica.”

He observed that electricity is strongest in the open-air, that it is weak in streets, under trees, etc., and that during the summer and winter, by night as well as by day, when the atmosphere is free from clouds, the electricity of the air is always positive. In contradistinction, Mr. T. Ronayne found in Ireland that the electricity of the atmosphere is positive in winter when the air is clear, but that it diminishes in frosty or foggy weather and that he could detect no electricity in the air during summer except on the approach of fogs, when the electricity proved to be positive. During the year 1785, M. de Saussure observed at Geneva that, during the winter, the intensity of atmospherical electricity attained its first maximum at 9 a.m., diminishing from that hour until it reached its minimum at 6 p.m., after which it began to increase until attaining its second maximum at 8 p.m., diminishing gradually thereafter till it recorded its second minimum at 6 a.m. During the summer he found the electricity increasing from sunrise till between 3 and 4 p.m., when it would reach its maximum; after that it appeared to diminish till the dew fell, when it again became stronger, but was scarcely sensible during the night.

Sir David Brewster informs us in his able article on “Electricity” in the “Britannica” that De Saussure made a number of elaborate experiments on the electricity of evaporation and combustion. He observed at first that the electricity was sometimes positive and sometimes negative when water was evaporated from a heated crucible, but in his subsequent trials he found it to be always positive in an iron and in a copper crucible. In a silver, also in a porcelain crucible, the electricity was negative and the evaporation of both alcohol and of ether in a silver crucible also gave negative electricity. M. de Saussure made many fruitless attempts to obtain electricity from combustion, and he likewise failed in his efforts to procure it from evaporation without ebullition.

To De Saussure is often erroneously attributed the authorship of Lullin’s “Dissertatio physica de electricitate,” alluded to at A.D. 1766.

REFERENCES.--De Saussure’s “Dissertatio de Igne,” “Exposition abrégée,” etc. (translated by Giuseppe Toaldo, in both his “Della maniera,” etc., and “Dei conduttori,” etc., Venezia, 1772 and 1778), “Voyage dans les Alpes,” all published at Geneva, 1759, 1771, 1779, also the important 1786 Neuchatel edition of the last-named work, more particularly at pp. 194, 197, 203, 205, 206, 211, 212, 216, 218, 219, 228, 252, 254 of Vol. II, and at pp. 197, 257 of Vol. IV; likewise his Memoirs relative to the electricity of the atmosphere, of vegetables, of microscopic animals, etc., etc., alluded to in _Journal de Physique_ for 1773, 1784, 1788; in _Journal de Paris_ for 1784, 1785; in Vol. I of Lazaro Spallanzani’s “Opuscoli di fisica,” etc., for 1776; in Vol. III of the “Opuscoli Scelti di Milano,” and in the _Philosophical Transactions_. See also Jean Senebier, “Mémoire historique,” etc., Genève, 1801; Louis Cotte in his “Traité,” etc., “Mémoires,” etc., “Observation,” etc., Paris, 1762, 1769, 1772; in the “Mémoires de Paris,” Année 1769, “Hist.,” p. 19; Année 1772, “Hist.,” p. 16, and in the _Journal de Physique_ for 1783, Vol. XXIII; the experiments of MM. Becquerel and Brachet in Becquerel’s “Traité d’El. et de Magn.,” Paris, 1836, Vol. IV. p. 110; Theodor Ægidius von Heller, “Beobach d. Atmosphär. Elektricität.” (F. A. C. Gren, “Neues Journal der Physik” for 1797, Vol. IV); Faujas de St. Fond, “Description,” etc., Vol. II. p. 271, as per George Adams’ “Essay on Electricity,” London, 1799, p. 419; Noad, “Manual,” etc., London, 1859, p. 16; Poggendorff, Vol. II. p. 755; Rozier, XXXI. pp. 317, 374; XXXIV. p. 161; articles “Meteorology and Electricity” in the “Encyclopædia Britannica”; Thomas Young, “Course of Lectures,” etc., London, 1807, Vol. II. pp. 447, 466–471.

=A.D. 1784.=--Swinden (Jan Hendrik Van) (1746–1823), who had been made Professor in the University of Franequer at the early age of twenty (1767), and was at this time occupying the Chair of Natural Philosophy and Mathematics at Amsterdam, publishes in three volumes, at La Haye, his “Recueil de Mémoires sur l’Analogie de l’Electricité et du Magnétisme,” etc. (“De Analogia ...” in Vol. II of the “Neue Abhandl. der Baierischen Akad. Phil.”). The latter contains all the essays sent to the Electoral Academy of Bavaria on the subject--“Is There a Real and Physical Analogy Between Electric and Magnetic Forces; and, if Such Analogy Exist, in What Manner Do These Forces Act Upon the Animal Body?”

Van Swinden’s essay, which gained him one of the prizes, shows that, in his opinion, the similarity between electricity and magnetism amounts merely to an apparent resemblance, and does not constitute a real physical analogy. He infers from this that these two powers are essentially different and distinct from one another, but the contrary opinion was maintained by Profs. Steiglehuer and Hubner, who contended that so close an analogy as that exhibited by these two classes of phenomena indicated the effects of a single agent, varied only in consequence of a diversity of circumstances.

The eminent professor, Gerard Moll, of Utrecht, has communicated to the Edinburgh _Journal of Science_ (1826, Vol. I. part ii. pp. 197–208) a biographical notice of Van Swinden, wherein he gives a list of the latter’s principal works and there speaks of one of his best-known productions in following manner: “The _Positiones Physicæ_ (Opusc. Scelti, X. 7), as far as they are published (Harderovici, 1786, Vol. I and Vol. II. part i.), are allowed to rank among the best elements of natural philosophy, and have been found by actual experience to belong to the best sources from which the young student could draw his information on those parts of natural philosophy, and its general principles, as are contained in the first volume and part of the second, which is all that was published. The work itself is on a most extensive plan; and the multifarious avocations which crowded on Van Swinden in Amsterdam delayed the publications, and made him afterward abandon all thoughts of completing a work which would have done the greatest honour to its author, and which even now, unfinished as it is, is celebrated as an excellent specimen of sound reasoning and profound learning.”

Van Swinden was the first President of the Royal Institute of the Netherlands. He entered with ardour into all the new discoveries of his day and kept up an extensive correspondence with many of the leading scientific characters of the time, notably with the Swiss philosopher, Charles Bonnet (whose “Contemplations de la Nature” he annotated extensively); with Dr. Matthew Maty (who became secretary of the Royal Society upon the resignation of Dr. Birch in 1765, and who was appointed, by the king, principal librarian of the British Museum upon the death of Dr. Gowin Knight, 1772); with the eminent French physician, Michel-Augustin Thouret, Dean of the Paris “Faculté de Médecine”; as well as with Delambre, Euler, De Saussure, and many others who have been named elsewhere in this “Bibliographical History.”

The following is further extracted from Prof. Moll’s interesting paper: “Mr. Biot, in his treatise on Natural Philosophy (Tome III. p. 143) asserts that we are indebted to Cassini IV. (see Jean Dominique, Comte de Cassini, at A.D. 1782–1791) for much of what we know even about the diurnal variation of the needle. This, I think, is not fair. We do not mean to undervalue Mr. Cassini’s observations, but it is unquestionable that long before the publication of that philosopher’s work, Mr. Van Swinden had observed and published (‘Recherches sur les aiguilles aimantées et leurs variations’--Mémoires présentés à l’Académie des Sciences de Paris, Tome VIII--prize essay 1777) that which Mr. Biot less accurately is pleased to ascribe to his countryman. In this respect, however, Mr. Van Swinden was treated with more justice by other eminent philosophers, such as Haüy, Halley and Burkhardt.” (Consult also the “Acta Acad. Petrop.” for 1780, Part I. Hist. p. 10.)

In the afore-named very meritorious work, “Recueil de Mémoires,” etc., crowned by the Bavarian Academy, Van Swinden has treated fully of the then current theories relative to electrical and magnetical phenomena, reviewing the entire field of their application. In so doing he has necessarily made numerous references to discoverers and experimenters of all countries, the names of many of which appear in the present compilation, and while it is, of course, useless here to quote these anew, it has been thought best, for a record, to specify such as are infrequently met with, and which appear in many of his most important articles, even at the risk of being accused of diffuseness or prolixity. They are as follows:

REFERENCES.--John T. Needham (Vol. IV, Mem. Brussels Acad. for 1783); _Phil. Trans._, 1746, p. 247; J. G. Lehmann (“Abhandlung von Phosph.”; “Von Magnet Theilen im Sande,” “Novi Com. Acad. Petrop.,” Vol. XII. p. 368, etc.); M. De La Cépède, “Essai sur l’El. nat et artif.”; C. E. Gellert (“Com. Acad. Petrop.,” Vol. XIII. p. 382, Exp. 15, 16); J. F. Henckel, “Pyritologia,” etc.; J. E. Von Herbert, “Theor. Phæn. Elect.,” cap. 4, prop. 8; C. F. M. Déchales, “Mundus Mathematicus,” lib. 1, _Quartus Exper. Ordo._, exp. 16, Tome II. p. 488, ed. 2, etc.; M. Marcel’s Dissertation on powdered magnets, which appears in the Dutch “Uitgezogte Verhandelingen,” Vol. I. p. 261, etc.; Jean M. Cadet (“Nova Acta. Physico. Med. Acad. Natur. Curios.,” Tome III); Abbé Giraud-Soulavie (“Comment. ... Œuvres de Mr. Hamilton,” note 4, p. 303); J. B. Le Roy (“Mém. de l’Acad. de Paris,” for 1753, p. 447; for 1772, p. 499; _Jour. de Phys._, Vol. II); Rudolph Richard (“Magazin d. Hamb.,” IV. p. 681); Gilles A. Bazin, “Descrip. des Cour, Mag.,” Plates 14, 16–18; J. F. Gross, “Elektrische Pausen,” Leipzig, 1776; _Jour. de Phys._, Vol. X. p. 235; Niccolo Bammacaro, “Tentamen de vi Electrica,” etc., s. 6; Samuel Colepress (_Phil. Trans._, 1667, No. 27, Vol. I. p. 502); E. F. Du Tour, “Discours sur l’aimant,” s. 27; “Recueil des Prix de l’Acad. de Paris,” Tome V. mém. ii. p. 49; “Mém. Math, et Phys.”; Mr. Calendrin, at Van Swinden’s, Vol. I. pp. 233, etc.; M. Blondeau (“Mém. de l’Acad. de Marine,” Brest., Tome I. s. 46, pp. 401–431, 438); J. A. Braun, “Observations,” etc.; “Novi. Comment. Acad. Petrop.,” Vol. VII. pp. 388, 407; M. Antheaulme (“Mém. sur les aimants artif.” (prize essay), 1760; “Mém. de l’Acad. Roy.,” 1761, p. 211; Van Swinden, 1784, Vol. II. pp. 95, 170); J. N. Reichenberger, “Directorium magneticum magneticis,” etc., and “Hydrotica,” as at Van Swinden, 1784, Vol. II. pp. 272–273; Geo. C. Schmidt, “Beschr., einer Elektrisir Masch.,” etc., 1778; M. De la Folie (_Jour, de Phys._, 1774, Vol. III. p. 9); Cölestin Steiglehner, “Obs. phaenom. elect.,” “Ueber die Annal der Elek. und des Magn.”; Lorenz Hubner, “Abh. u. d. Annal. u. mag. Kraft”; Jos. Thad. Klinkosch, “Schreiben,” etc., “Beschreib. d. Volta ... Elektrophors.” Reference should also be made to Noad, “Manual,” etc., p. 641; Encycl. Brit., 1857, Vol. XIV. p. 6; “Messager des Sciences et des Arts,” Gand, 1823, pp. 185–201, detailing all of Van Swinden’s works; Antoine Thillaye’s treatise presented to the Ecole de Médecine le 15 Floréal, An. XI; Butet (“Bull, des Sc. de la Soc. Philom.,” No. 43, Vendémiaire, An. IX).

=A.D. 1784.=--Cotugno (Domenico), Professor of Anatomy at Naples, thus addresses Le Chevalier G. Vivenzio under date October 2, 1784: “The observation which I mentioned some days ago, when we were discoursing together of the electrical animals, upon which I said I believed the mouse to be one of that number, is the following: Toward the latter end of March, I was sitting with a table before me and observing something to move about my foot, which drew my attention. Looking toward the floor I saw a small domestic mouse, which, as its coat indicated, must have been very young. As the little animal could not move very quick, I easily laid hold of it by the skin of the back and turned it upside down; then with a small knife that laid by me, I intended to dissect it. When I first made the incision into the epigastric region, the mouse was situated between the thumb and finger of my left hand, and its tail was got between the last two fingers. I had hardly cut through part of the skin of that region, when the mouse vibrated its tail between the fingers, and was so violently agitated against the third finger that, to my great astonishment, I felt a shock through my left arm as far as the neck, attended with an internal tremor, a painful sensation in the muscles of the arm, and such giddiness of the head, that, being affrighted, I dropped the mouse. The stupor of the arm lasted upward of a quarter of an hour, nor could I afterwards think of the incident without emotion. I had no idea that such an animal was electrical; but in this I had the positive proof of experience.” (See G. Vivenzio, “Teoria e pratica della elettricità med.” ... Napoli, 1784.)

Cotugno’s observations attracted much attention throughout Italy and gave rise to many experiments, notably by Vassalli, who, however, merely concluded from them that the animal’s body could retain accumulated electricity in some unaccountable manner.

REFERENCES.--_Essai sur l’histoire_, etc., J. B. Biot, p. 9; _Journal de Physique_, XLI. p. 57; _Mémoires Récréatifs_, etc., par Robertson, Paris, 1840, Vol. I. p. 233; Cavallo, _Electricity_, London, 1795, Vol. III. p. 6; Izarn, _Manuel_, Paris, 1804, p. 4; _Journal Encyclopédique de Bologne_, 1786, No. 8; Poggendorff, Vol. I. p. 417; Sue, aîné “Hist. du Galv.,” Vol. I. pp. 1–2.

=A.D. 1785.=--Coulomb (Charles Augustin de), the founder of _electro-statics_ and of the school of experimental physics in France, invents the torsion balance, with which he discovers the true law of electric and magnetic attractions and repulsions. Some have asserted that Lord Stanhope had previously established the law with regard to electricity, but it has not been seriously questioned that its extension to magnetism belongs exclusively to Coulomb. Johann Lamont (“Handbuch ...” p. 427) gives the credit of the latter discovery to Giovannantonio Della Bella, of Padua, who is mentioned by Poggendorff (“Biog.-Liter. Handwörterbuch,” Vol. I. p. 139) as the author of several works on electricity and magnetism, but the claim does not appear to be established upon any satisfactory foundation.

With his torsion balance, or rather electrometer, Coulomb measured the force by the amount of twist it gave to a long silken thread carrying a horizontal needle, constructed, preferably, of a filament of gum-lac or of straw covered with sealing-wax. From his experiments he concluded: That the attractive force of two small globes, one electrified positively and the other negatively, is in the inverse ratio of the squares of the distances of their centres, and that the repulsive force of two small globes, charged either with positive or negative electricity, is inversely as the squares of the distances of the centres of the globes (“Mém. de l’Acad. Roy. des Sciences,” 1784, 1785).

In one of his three memoirs to the French Academy during 1785, he states that a balance used by him was so delicate that each degree of the circle of torsion expressed a force of only one hundred-thousandth of an English grain, that another, suspended by a single fibre of silk four inches long, made a complete revolution with a force of one seventy-thousandth of a grain, and turned to the extent of a right angle when a stick of sealing-wax, which had been rubbed, was presented to it at the distance of a yard. It is said that a similar electrometer has been constructed in which the movement of one degree recorded a force not exceeding twenty-one million six-hundred-thousandths of a grain.

The many valuable experiments made by Coulomb on the dissipation of electricity and upon the distribution of electricity upon the surfaces of bodies are fully recorded in the able article of Sir David Brewster in the “Encyclopædia Britannica” (F. C. Achard, “Mém. de Berlin,” 1780, p. 47); M. Vernier, “De la dist. ... conducteurs,” Paris, 1824; J. L. F. Bertrand, “Programme d’une thèse ...” Paris, 1839; D. Bourdonnay, “Sur la dist. ... conducteurs,” Paris, 1840; Ed. A. Roche in “Montp. Acad. Sect. Sciences,” Vol. II. p. 115).

He discovered that shellac is the most perfect of all insulators, also that a thread of gum-lac insulates ten times better than a dry silken thread of the same length and diameter: and he established the law that the densities of electricity insulated by different lengths of fine cylindrical fibres, such as those of gum-lac, hair, silk, etc., vary as the square root of the lengths of the fibre.

Besides the communications above alluded to, Coulomb sent to the French Academy, during the years 1786, 1787, 1788 and 1789, many papers upon Electricity and Magnetism, and, up to within two years of his death (1806), he made many notable experiments, especially in magnetism, of which full accounts are given in several of the Mémoires noted at foot. The theory of the two magnetic fluids appeared in his 1789 paper. It is also in this same paper that Coulomb describes his improved method of making artificial magnets by employing compound magnets as first made use of by Gowin Knight and as explained at A.D. 1746. Still further improvements in these were brought about more particularly by the young Flemish scientist, Etienne Jean Van Geuns (1767–1795), by Jean Baptiste Biot (see A.D. 1803), and by the Rev. Dr. Scoresby during the year 1836.

Coulomb found that a steel wire is, by twisting, rendered capable of being nine times more strongly magnetized; that the magnetic power dwells on the surface of iron bodies and is independent of their mass; that the directive force of a magnetized bar reached its maximum when tempered to a bright cherry-red heat at 900 degrees, and that every substance is susceptible of magnetism to a degree of actual measurement. This last important research was communicated by him to the French Institute during the year 1802. His experiments proved that a grain of iron could communicate sensible magnetism to twenty pounds’ weight of another substance, and that when even beeswax had incorporated with it a portion of iron filings equal only to the one hundred-and-thirty-thousandth part of its weight it was yet sensibly affected by the magnet.

According to Dr. Thomas Young, Coulomb’s improvements in the theory of electricity may be considered as having immediately prepared the way for the elegant inventions of Volta and for the still more marvellous discoveries of Davy. Dr. Young gives reports of some of Coulomb’s experiments at p. 439, Vol. II of his “Course of Lectures” London, 1807 (“Journal of the Royal Institution” Vol. I. p. 134; “Décade Philosophique,” No. 21).

REFERENCES.--“Mém. de l’Acad. Royale des Sciences,” Paris, 1784, p. 266; 1785, pp. 560, 569, 578, 612; 1786, p. 67; 1787, p. 421; 1788, p. 617; 1789, p. 455; “Mém. de l’Institut,” Vol. III. p. 176; Vol. IV. p. 565, and Vol. VI. for 1806; “Mém. de Math. et de Phys.” Vols. VIII and IX; “Mémoires de Coulomb,” Vol. I of the “Collection de Mémoires relatifs à la Physique,” Paris, 1884; “Cat. of Sc. Papers Roy. Soc.,” Vol. III. p. 73; “Abstracts of Papers of Roy. Soc.,” Vol. II. p. 402; “Bull. de la Soc. Philom.,” Nos. 3, 31, 61, 63, and for 1795, 1802; _Journal de Physique_, Vols. XLV (II), pp. 235, 448; LIV. pp. 240, 267, 454; LV. p. 450 (for Carradori’s report); Ch. N. A. De Haldat du Lys (“Mém. de Nancy” for 1841); _Phil. Magazine_, Vols. XI. p. 183; XII. p. 278; XIII. p. 401; XV. p. 186; Rozier, XXVII. p. 116; XLIII. p. 247; Gilbert, XI. pp. 254, 367; XII. p. 194; Dr. Young, “Course of Lectures,” London, 1807, Vol. I. pp. 682, 685, 686; “Royal Society Cat. of Sc. Papers,” Vol. II. p. 73; Eighth “Britannica,” Vol. XIV. pp. 37–38; Humboldt, “Cosmos,” 1859, Vol. V. p. 61; Schaffner, “Manual,” 1859, p. 56; Biot’s article in the “Biographie Universelle” and Biot’s “Traité de Physique,” Paris, 1816, Vols. II, III; Dr. Thomas Thomson, “Outline of the Sciences,” etc., London, 1830, pp. 350, 351, 379–422; Harris, “Rudim. Magn.,” Parts I, II. p. 56. See also description of the electrometer of Colardeau and the electro-micrometer of Delaunay, in the latter’s “Manuel,” etc., Paris, 1809, pp. 66, 76–80, and Plate V. fig. 61, as well as Libes’ “Dict. de Phys.,” Vol. I. p. 406.

=A.D. 1785.=--The Canon Gottoin de Coma, friend of Alessandro Volta, observes that an iron wire about thirty feet in length will give a sound under certain conditions of the atmosphere when stretched in the open air. The circumstances that accompany, as well as those that favour the production of the phenomenon, says Prescott, demonstrate that it must be attributed to the transmission of atmospheric electricity. This transmission does not occur in a continuous manner, like that of a current, but is observable by a series of discharges.

REFERENCES.--Knight’s _Mechanical Dictionary_, 1876, Vol. III. p. 2515; Prescott’s “The Speaking Telephone,” etc., 1879, p. 122; _Encyl. Britannica_, 1860, Vol. XXI. p. 631.

=A.D. 1785.=--Marum (Martin Van), a Dutch electrician who had in 1776 taken the degree of M.D. at the Academy of Gröningen, constructs for the Teylerian Society at Haarlem, with the assistance of John Cuthbertson, an electrical machine said to be the most powerful theretofore made. According to Cavallo (_Nat. Phil._, 1825, Vol. II. p. 194) it consisted of two circular plates of French glass, each sixty-five inches in diameter, parallel with each other on a common axis, and about seven and a half inches apart. Each plate was excited by four rubbers, the prime conductor being divided into two branches which entered between the plates and, by means of points, collected the electric fluid from their inner surfaces only.

In Van Marum’s machine, the positive and negative electricity could only be obtained in succession, but Dr. Hare, of the University of Pennsylvania, remedied this by causing the plates to revolve horizontally. It is said the machine was so powerful that bodies at a distance of forty feet were sensibly affected; a single spark from it melted a leaf of gold and fired various kinds of combustibles; a thread became attracted at the distance of thirty-eight feet, and a pointed wire was tipped with a star of light at a distance of twenty-eight feet from the conductor.

Descriptions of his machines are given by Dr. Van Marum in letters to the Chevalier Marsiglio Landriani and to Dr. Ingen-housz, both printed in Haarlem during 1789 and 1791. The first quarto volume of _Nicholson’s Journal_ also contains a reference thereto and gives (p. 83) the extract from a letter read June 24, 1773 (_Phil. Trans._, Vol. LXIII. pp. 333–339), addressed to Dr. Franklin, F.R.S., by John Merwin Nooth, M.D., who describes improvements by which machines are rendered effective in all kinds of weather. Nooth was the inventor of the silk flap, of which mention was made in the description of Cavallo’s machine (under A.D. 1775).

Van Marum also constructed a powerful battery, the metallic coatings of which were equal to 225 square feet, enabling him to give polarity to steel bars nine inches long, nearly half an inch wide and one-twelfth of an inch thick, as well as to sever a piece of boxwood four inches diameter and four inches long, and to melt three hundred inches of iron wire one hundred-and-fiftieth of an inch in diameter, or ten inches of one-fortieth of an inch in diameter. It is said that, during these experiments, the report was so loud as to stun the ears, and the flash so bright as to dazzle the sight.

Dr. Van Marum likewise made experiments upon the electricity developed during the melting and cooling of resinous bodies, which are detailed in the article “Electricity” 8th Edit. “Encyclopædia Britannica,” Vol. VIII. p. 565, and also upon the effects of electricity on animals and vegetables, which are given at pp. 49–51 of the article “Electricity” in the “Library of Useful Knowledge,” as well as in the 1855 Edit. “Encyclopædia Britannica,” Vol. VIII. pp. 602, 603.

In 1785 again Van Marum discovered that electric sparks, on passing through oxygen gas, gave rise to a peculiar sulphurous or electrical odour, which Cavallo called “electrified air,” and the presence of which Dr. John Davy, brother of Sir Humphry Davy, found the means of detecting.

During the month of October 1801 Volta wrote a letter to Van Marum asking him to make, in concert with Prof. C. H. Pfaff, of Kiel, several experiments on the electricity of the pile with the very powerful apparatus of the Teylerian Society. The extended researches of these two scientists are embodied in the _Phil. Mag._, Vol. XII. p. 161, as well as in the “Lettre à Volta” etc., published at Haarlem during 1802, and are likewise treated of in a very complete manner throughout Chaps. XVI and XXXII of Wilkinson’s well-known work on galvanism. Their united observations confirm the doctrine of Volta as to the identity of the current of the fluid put in motion by the voltaic pile and that to which an impulsion is given by an electrical machine. Thus is answered the question asked during May 1801 by the Haarlem Society of Sciences, viz. “Can the voltaic pile be explained in a satisfactory manner by the known laws and properties of electricity; or is it necessary to conclude the existence of a particular fluid, distinct from the one which is denominated electrical?” They also demonstrated that the current put in motion by the voltaic pile has an enormous celerity “which surpasses all that the imagination can conceive.” With a pile of one hundred and ten pairs of very large copper and zinc plates, they made experiments on the fusion of iron wires and ascertained the causes of the more considerable effects of large piles in the fusion and oxidation of metals, proving, among other facts, as Biot and Cuvier had already done, that a part of the oxygen is absorbed whether the operation be carried on in the open air or _in vacuo_ (Biot and Cuvier, _Soc. Philomathique_, An. IX. p. 40; _Annales de Chimie_, Vol. XXXIX. p. 247).

Another of Van Marum’s experiments is related in a letter to M. Berthollet, wherein he says: “... I have succeeded in the decomposition of water, by means of the current of the electrical machine, provided with a plate of thirty-one inches diameter, constructed by me on a new plan (see the _Journal de Physique_ for June, 1795).... I took a thermometrical tube, of the kind employed in making the most sensitive thermometers of Crawford and Hunter, for which purpose I had procured several of these tubes some time before in London. Its diameter interiorly was not more than the one-hundredth part of an inch; and I introduced into it an iron wire of the diameter of about the three-hundredth part of an inch, to the depth of about twelve inches. I now closed the end of my thermometrical tube with sealing wax in such a way that the extremity of the iron wire should scarcely project, and I placed the tube itself, by means of a cork, within a larger tube containing water. The rest of the apparatus was arranged in the customary manner. By directing the powerful current of the above-mentioned machine to this apparatus, the copper ball belonging to which, placed on the thermometrical tube, was at the distance of about three or four lines from the conductor, I succeeded in decomposing the water with a promptitude nearly equal to that which results from a voltaic pile of a hundred pairs of metallic plates.” This method of decomposing water is a very tedious one, and is in fact the result of an interrupted explosion, while the process of Dr. Wollaston (alluded to at A.D. 1801) is tranquil and progressive.

REFERENCES.--“Biogr. Univ.,” Vol. XLII. p. 600; J. G. Heinze, “Neue elekt. versuche ...” Oldenberg, 1777; Tries’ claim to Van Marum’s machine in Rozier, XL. p. 116; Prieur’s extract in _Annales de Chimie_, Vol. XXV. p. 312; “Verhand. Genootsch. Rott.,” VI for 1781 and VIII for 1787; _Journal de Physique_, XXXI, 1787; XXXIII, 1788 (Marum en Troostwyk); XXXIV, 1789; XXXVIII, 1791; XL, 1792; “Journal du Galvanisme,” XI, Cahier, p. 187; “Journal des Savants” for August 1905; “Revue Scientifique,” Paris, April 8, 1905, pp. 428–429; _Nicholson’s Journal_ for March 1799, Vol. II. p. 527; Harris, “Electricity,” pp. 62, 90, 171; Cuthbertson, “Practical Electricity,” London, 1807, pp. 166, 172, 197, 225; Cavallo, “Electricity,” 4th ed., Vol. II. p. 273; “Lib. of Useful Knowledge,” “Electricity,” p. 45; Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 106–128, 384; “Teyler’s Tweede Genootschap”; Gilbert, _Annalen_, I. pp. 239, 256; X. p. 121; Rozier, XXVII. pp. 148–155; XXXI. p. 343; XXXIV. p. 274; XXXVIII. pp. 109, 447; XL. p. 270; “Opus. Scelti,” IX. p. 41; XIV. p. 210.

=A.D. 1785.=--Sigaud de la Fond, Professor at the Collège d’Harcourt in Paris, publishes in the latter city his “Précis historique et expérimental des phénomènes electriques,” wherein he states having, as far back as 1756, made use of a circular plate machine provided with cushions and similar in shape to that which many claim to have originated with Ingen-housz and with Ramsden. (See A.D. 1779 and A.D. 1768.)

Sigaud de la Fond is also the author of “Description d’un Cabinet de Physique” (1784), “Cours de Physique,” etc. (1786), “Examen.,” etc. (1803) and of several treatises on medical electricity.

REFERENCES.--“Journal de Physique,” Vol. II. 1773; Figuier, “Exposition et Histoire,” Paris, 1857, pp. 50, 74–76, 178; Poggendorff, Vol. II. p. 927.

=A.D. 1785.=--In the “Nachricht von einer neuen Elektrisirmaschine des Herrn Walkiers von Saint Amand,” the last named gives a description of the electrical machine presented by him in 1784 to the Belgian Academy of Sciences.

It is also described and outlined in Delaunay’s “Manuel” named below, but, although very powerful in its effects, cannot be made readily available in consequence of its huge dimensions. M. Caullet de Veaumorel suggested the feasibility of changing the cylinders from a horizontal to a vertical position.

REFERENCES.--“Lichtenberg’s Mag.,” Vol. III. 1 st. p. 118; Delaunay, “Manuel,” etc., 1809, pp. 14–16.

=A.D. 1785.=--Adams (George), mathematical instrument maker to his Majesty, writes an enlarged edition of his “Essay on Electricity,” etc., which first appeared the year previous and wherein, as its full title indicates, he endeavours to explain the theory and practice of that science and the mode of applying it to medical purposes. He illustrates many experiments and gives an Essay on Magnetism, in the treatment of which latter he acknowledges the valuable aid of Dr. J. Lorimer.

The fifth and last edition of the “Essay,” which was issued by William Jones in 1799, four years after Adams’ death, contains a communication on the subject of Medical Electricity by John Birch, the author of “Della Forza dell’ Elettricita,” etc., Napoli, 1778.

At p. 86 of the 1799 “Essay,” etc., Adams relates that, while M. Loammi Baldwin (“Memoirs of Amer. Acad.,” Vol. I. p. 257) held the cord of his kite during the approach of a thunderstorm, he “observed himself to be surrounded by a rare medium of fire, which, as the cloud rose nearer the zenith, and the kite rose higher, continued to extend itself with some gentle faint flashes.” At pp. 137, 186 and 222, he alludes to “A. Brook’s Miscellaneous Experiments and Remarks on Electricity,” etc., as well as to the Rev. John Lyon’s “Experiments and Observations of Electricity,” and refers to the “Journal of Natural Philosophy” (Vol. II. p. 438) for Nicholson’s experiments on the _plus_ and _minus_ of electricity.

=A.D. 1785.=--La Méthérie (Jean Claude de), French physicist naturalist, becomes sole editor of the “Journal de Physique, de chimie et d’histoire naturelle,” and publishes in Paris his “Essai Analytique,” etc., wherein amongst other observations he asserts that the electric spark results from the combination of oxygen with hydrogen.

He considers that all bodies exist in an electrical or magnetical condition, that we are only a temporary aggregation of molecules of matter governed in different ways by nature’s laws, and that excitability is produced by galvanic action resulting from the superposition of nervous and muscular fibres.

He is also the author of very interesting treatises on animal electricity communicated to the _Journal de Physique_ (Vol. XLII. pp. 252, 255, 292), and of which an account is given in Sue’s “Histoire du Galvanisme,” Paris, 1802, Vol. I. pp. 64–68. The last-named work also gives, at p. 80, an account of the letter on “Galvanism” sent to M. De La Méthérie by M. Leopold Vacca-Berlinghieri (_Journal de Physique_, Vol. XLI. p. 314).

REFERENCES.--“Biographie Générale,” Vol. XXIX. p. 209; Rozier, XLI. p. 437; Delaunay, “Manuel,” etc., 1809, p. 15, also Delaunay’s letter in _Phil. Mag._, Vol. XXVII. p. 260; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Vol. I. p. 62; Vol. II. p. 9; “Opus. Scelti,” XXI. p. 373; _Journal de Physique et Chimie_ (of which La Méthérie remained editor up to the time of his death, during 1817), Vols. LIII, LIV, Pluviose, An. XI. p. 161; also p. 157 for letter sent him by Giuseppe Izarn; _Ann. di Chim. di Brugnatelli_, Vol. XIX. p. 156; Aubert, “Elektrometische Flasche,” Paris, 1789.

=A.D. 1785.=--According to Prof. Tyndall, George Cadogan Morgan sought to produce the electric spark in the interior of solid bodies. He inserted two wires into wood and caused the spark to pass between them; the wood was illuminated with blood-red light or with yellow light according as the depth at which the spark was produced proved greater or less. The spark shown within an ivory ball, an orange, an apple, or under the thumb, illuminates these bodies throughout. A lemon is especially suited to this experiment, flashing forth, at every spark, as a spheroid of very brilliant golden light, and a row of eggs is also brilliantly illuminated throughout, at the passage of every spark from a Leyden jar. Morgan likewise made several experiments to ascertain the influence of electricity on the animal functions. These are alluded to at p. 602, Vol. VIII of the 1855 “Britannica,” and at p. 49 of “Electricity” in the “Library of Useful Knowledge.”

This George Cadogan Morgan (1754–1798) was an English physician and also a Professor of Natural Philosophy at Hackney, in an establishment founded by his uncle, Dr. Price. His “Lectures on Electricity” appeared in Norwich during the year 1794. In the second volume he describes (pp. 225–236) “the form, noise, colours and devastation of the electric flash,” and treats (pp. 383–397) of the “relation of the electric fluid to vegetation,” alluding more particularly to the experiments of Maimbray, Nollet, Achard, Duvernier, Ingen-housz, Van Breda, Dr. Carmoy and the Abbé d’Ormoy. He likewise gives an account of the northern lights, as well as descriptions of Bennet’s movable doubler and electroscope, and of Lane’s electrometer.

REFERENCES.--Morgan’s biography in Larousse, “Dict. Universel,” Tome XI. p. 562, and in “Biog. Générale,” Tome XXXVI. p. 570; “Bibl. Britan.” An. VII. vol. ii. pp. 129, 223, and Vol. XII. p. 3.

=A.D. 1786.=--Rittenhouse (David), an American physicist and astronomer who afterward became F.R.S. and succeeded Dr. Franklin as President of the Am. Philos. Soc., publishes his theory of magnetism in a letter to John Page at Williamsburg, which is reproduced at folio 178 of Vol. II, old series, of the Transactions of the above-named Society.

“Were we called upon,” says Renwick, “to assign him a rank among the philosophers whom America has produced, we should place him, in point of scientific merit, as second to Franklin alone.”

REFERENCES.--“Trans. Am. Phil. Soc.,” Vol. II, O.S., pp. 173, 175, for Page and Rittenhouse, and Vol. III. for Rittenhouse and Jones, as well as Rittenhouse and Hopkinson, upon “Meteors and Lightning.”

=A.D. 1786.=--Galvani (Aloysio or Luigi), an Italian physician, who, at the age of twenty-five, was Professor of Anatomy at the University of Bologna, is led to the discovery of that important branch of electricity which bears his name. The manuscript giving the result of his experiments upon the Electricity of Metals is dated Sept. 20, 1786.

From papers in the “Bolognese Transactions” noted below, it would appear that he had, even before the year 1780, made many observations on the muscular contraction of frogs by electrical agency. Upon one occasion his wife happened to be holding a scalpel against the dissected legs and parts of the spine of a frog, which lay in close proximity to the conductor of an electrical machine recently charged by one of Galvani’s pupils. She noticed that whenever the dissecting knife touched the muscles they were violently convulsed, and, upon communicating the fact to her husband, he repeated and extended the experiment and found it necessary to pass the electric fluid through a metallic substance in order to develop the result originally observed. At first the frogs had been hung upon a copper hook fastened to an iron railing, but he afterward substituted an arc composed of both metals and with which he could readily produce the same results as were obtainable with an electrical machine.

Galvani also made experiments to ascertain the effect of atmospheric electricity upon the nerves of frogs. He connected the latter with rods leading to lightning conductors erected upon the roof of his house, attaching also ground wires to the legs of the animals, and found that the same convulsions appeared whenever lightning was seen and likewise when heavy storm clouds passed over the house.

The results of his many interesting observations were first made public in the celebrated work entitled “Aloysii Galvani de viribus electricitatis in motu musculari. Commentarius: cum Aldini dissertatione et notis,” which appeared during 1791–1792. Therein, he expresses the belief that the bodies of animals possess a peculiar kind of electricity by which motion is communicated through both nerve and muscle, positive electricity going to the nerve, while negative electricity goes to the muscle, and that the muscles represent the exterior and the nerves the interior of the Leyden jar, the discharge being similarly produced by the metal which communicates with both.

Galvani’s singular experiments naturally attracted everywhere the attention of philosophers, by whom they were repeated and varied, but by none were they more assiduously prosecuted than by Volta, who was then a Professor at the Pavia University, and who, as already indicated, was led by them to the discovery of the voltaic pile and of voltaic or galvanic electricity.

The announcement of Galvani’s observations was made in Germany, notably by J. F. Ackermann (“Medicinisch-chirurgische Zeitung”), by M. Er (“Physiologische Darstellung der Lebenskräfte”), by M. Smuck (“Beiträge zur weiteren Kenntniss,” etc.), and by F. A. C. Gren (“Journal der Physik,” Vols. VI, VII and VIII), while experiments were continued upon an extensive scale by the Italians F. Fontana, Carlo Francesco Bellingeri, M. Giulio and F. Rossi, as well as by Samuel T. Von Sömmering, by Wilhelm Behrends and by Karl Friedrich Kielmayer (Kielmaier), Professor of Medicine at the Tübingen University (Poggendorff, Vol. I. p. 1253). For the curious galvanic experiments of the celebrated French physician Larrey, and of Stark, Richerand, Dupuytren and Dumas, see “Bulletin des Sciences de la Société Philomathique,” 1793, Nos. 23, 24, and “Principes de Physiologie,” Vol. II. p. 312.

REFERENCES.--C. Alibert, “Eloges Historiques de Galvani, Spallanzani, Roussel et Bichat ...” Paris and Bologna, 1802–1806 (“Mém. de la Soc. d’Emul. de Paris,” Vol. IV; S. Gherardi, “Rapporto sui Manoscrotti,” Bologna, 1840, p. 19); Poggendorff, Vol. I. p. 839; Thomas Thomson, “History of the Royal Society,” London, 1812, pp. 450, etc.; Thomas Young, “Course of Lectures,” London, 1807, Vol. II; “Bolognese Transactions” for papers dated April 9, 1772, April 22, 1773 and Jan. 20, 1774; Sabine, “El. Tel.,” 1872, pp. 16–18; Knight’s “Mech. Dict.,” Vol. II. pp. 936, 937, for extract from report of Nat. Inst. of France, July 4, 1798; “Johnson’s Encyclop.,” 1877, Vol. I. p. 1510; Bakewell’s “Electricity,” p. 26; “Encyclop. Britannica,” 1855, Vol. VIII. p. 530, and Vol. XXI. pp. 609, etc.; Fahie’s “History,” etc., 1884, pp. 180–185; _Phil. Trans._, 1793; Miller, “History Philos. Illustrated,” London, 1849, Vol. IV. p. 333; Thomson, “Hist. of Chemistry,” Vol. II. pp. 251, 252; Matteucci, “Traité des phénomènes,” etc., Part I. p. 7; the Address of M. Gavarret made in 1848 before the Paris Medical Faculty; J. C. I. A. Creve’s treatise on Galvanism (“Jour. de la Soc. de Méd.,” Vol. XVIII. p. 216); “Mém. de la Soc. Méd. d’Emul.,” Vol. I. p. 236); Biot et Cuvier (_Ann. de Ch._, Vol. XXXIX. p. 247); A. Richerand (“Mém. de la Soc. Méd. d’Em.” Vol. III. p. 311); “Opus. Scelt.,” Vol. XV. p. 113; “Giornale Fis. Med.,” Vol. II. pp. 115, 131 (letter of B. Carminati); Marsiglio Landriani, “Lettera,” etc., 1776; Lettre d’un ami au Comte Prosper Albo (“Bibl. de Turin,” 1792, Vol. I. p. 261; _Jour. de Phys._, Tome XLI. P. 57); “Comment Bonon. Scient.,” Vol. VII. p. 363; account of the experiments made by MM. Cortambert and Gaillard, reported in “Mém. de la Soc. Méd. d’Em.,” Vol. I. pp. 232, 235; G. Klein’s “Dissert. de Métal,” etc., Maintz, 1794; Ostwald’s _Klassiker_, No. 52, p. 4; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 Vols. _passim_; Wm. C. Wells, “Obs. on the Influence,” etc. (_Phil. Trans._, 1795, Pt. XI. p. 246); E. G. Robertson (_An. de Ch._, 1801, Vol. XXXVII. p. 132; _Jour. de Paris_, 10, 15 and 17 Fructidor de l’An. VIII); Paul Louis Simon, “Beschreibung neuengalvanisch,” etc., “Resultate,” etc., and “Versuche,” etc., all published in 1801 (L. W. Gilbert’s _Annalen_, 1801, Book V, _An. de Chimie_, No. 121, p. 106); L. W. Gilbert’s Book VI of the _Annalen_, containing the “Memoirs on Galvanism,” by J. L. Boeckmann, L. A. von Arnim, Paul Erman, M. Gruner and C. H. Pfaff; C. Dupuytren, “Faits Particuliers,” etc., 1801; J. B. Trommsdorff, “Expér. Galv.,” 1801; M. Rouppe’s letter of Aug. 28, 1801, in Van Mons’ _Jour. de Ch._, Vol. I. pp. 106, 108; M. Bichat (Sue, “Hist. du Galv.,” II. p. 216); A. M. Vassalli-Eandi (_Jour. de Phys._, Frimaire, An. X. p. 476); C. F. Hellwag and M. Jacobi fils, “Erfahrungen,” etc., 1802; M. le Comte de Pusckin’s experiments on Galvanism, made Sept. and Dec. 1801, with a _colonne tournante_ (Sue, “Hist. du Galv.,” Vol. II. pp. 257, 258); Al. Volta, in _Jour. de Leipzig_, and in “Comment ... Med. gestis,” 1792; Johann Mayer, “Abh. ... Galvani, Valli, Carminati u. Volta ...” Prag, 1793); Junoblowiskiana Society (“Comment ... Med. gestis,” 1793); “Imperial Dictionary of Universal Biography,” Wm. McKenzie London, n. d., Vol. II. p. 546; M. Cortambert (“Mém ... Soc. ... d’Emul.,” I. p. 232); M. Payssé (“Jour. de la Soc. des Pharm.,” first year, p. 100); Geo. Couvier (_Jour. de Physique_, Vol. VII. p. 318; “Mém. des Soc. Sav. et Lit.,” Vol. I. p. 132), 1801; C. Mathieu (“Rec. de la Soc. d’Agr. ... d’Autun,” An. X. p. 21), 1802; Ponton d’Amécourt, “Exposé du Galvanisme,” Paris, 1803; Joseph Weber’s works, published in 1802–1803, 1815, 1816, and those of J. K. F. Hauff, Marburg and Leipzig, 1803, 1804; M. Curtet (_Jour. de Van Mons._, No. VI. p. 272; _Jour. de Physique_, An. XI. p. 54), 1803; William Meade (“On the origin and progress of Galvanism”), Dublin, 1805; J. C. Reil (_Jour. de Van Mons._, No. IV. p. 104; Sue, “Hist. du Galv.,” Vol. IV. p. 26); J. A. Heidmann (_Phil. Mag._, Vol. XXVIII. p. 97), 1807; Sir Richard Phillips, “Electricity and Galvanism explained ...” (_Phil. Mag._, Vol. LVI. p. 195), London, 1820; B. G. Sage, “Recherches ... Galvanisme”; Leopold Nobili, “Sur le courant....” Genève, 1827.

=A.D. 1786.=--Hemmer (J. J.), celebrated physician and secretary of the Meteor. Society of Mannheim, gives, in the “Transactions of the Electoral Society,” an account of what have been pronounced the most complete series of experiments ever made upon the electricity of the human body. They absolutely show that the human subject possesses no species of electrical organs which are under the regulation of the will. Of his many observations, the following are worth recording: He found that the electricity of the body is common to all ages and sexes; that its intensity and character often vary in the same body (in 2422 experiments, it was 1252 times positive, 771 times negative and 399 times imperceptible); that the electricity of the body is naturally positive, it being always so when subject to no violent exertion, and that when the body is subjected to sudden or violent motion the electricity becomes negative, the case also when the body experiences either cold or extreme lassitude.

REFERENCES.--“Encycl. Brit.,” Vol. VIII, 1855, p. 571; “Rheinische Beiträgen zur Gelehrsamkeit” for 1781, Fifth Book, pp. 428–466; Van Swinden, “Recueil,” etc., La Haye, 1784, Vols. I and II _passim_; “Observ. sur la Phys.,” July, 1780; _Phil. Mag._, 1799, Vol. V. pp. 1, 140; “Comment. Acad. Theod.-Palat.,” Vols. IV, V and VI of _Phys._; “Mém. de l’Acad. de Mannheim,” Vol. IV; “Pfalzbayr. Beiträge” for 1782.

=A.D. 1787.=--Lomond--Lomont--(Claude Jean-Baptiste), a very capable French machinist, and “one who has a genius for invention,” is the first to introduce a successful electric telegraph consisting of but one wire. Of this the following account appears under date Oct. 16, 1787, in Arthur Young’s “Voyage Agronomique en France” (“Travels”), fourth edition, Vol. I. p. 79: “You write two or three words on a paper; he takes it with him into an adjoining room and turns a machine in a cylinder case, on the top of which is an electrometer having a pretty little ball of pith of a quill suspended by a silk thread; a brass wire connects it to a similar cylinder and electrometer in a distant apartment, and his wife, on observing the movements of the corresponding ball, writes the words which it indicates. From this it appears that he (Lomond) has made an alphabet of motions. As the length of the brass wire makes no difference in the effect, you could correspond with it at a great distance, as, for example, with a besieged city or for objects of much more importance. Whatever be the use that shall be made of it, the discovery is an admirable one.”

REFERENCES.--Ed. Highton, “Elec. Tel.,” 1852, p. 38; Sabine, “Elec. Tel.,” pp. 10–11; Shaffner, “Manual,” pp. 132, 133; Vail’s “History,” etc., p. 121; “Appleton’s Encycl.,” 1871, Vol. XV. p. 335.

=A.D. 1787.=--Brard (Cyprien Prosper), French mineralogist, first observes that some crystals of axinite (consisting mainly of silica, alumina, lime and peroxide of iron) become electric by heat.

REFERENCES.--Gmelin, article “Electricity,” etc., Vol. I. p. 319; Larousse, “Dict. Univ.,” Vol. II. p. 1205; Thomas, “Dict. of Biog.,” Vol. I. p. 429; “Enc. Brit.,” 8th ed., Vol. VIII. p. 530; Brard, “Manuel du Minéralogiste,” etc., Bordeaux Academy of Sciences Report for 1829, p. 39, and for 1838, p. 84--the latter containing M. Hatchett’s observations on one of M. Brard’s meteorolites.

=A.D. 1787.=--Haüy (Le Père René Just), native of Picardie and member of the Académie Royale des Sciences, publishes an abridgment of the doctrines of Æpinus (at A.D. 1759) under the title of “Exposition raisonnée de la Théorie de l’Électricité et du Magnétisme.” He was doubtless the first to observe that in all minerals the pyro-electric state has an important connection with the want of symmetry of the crystals, and no proof of the extent to which he directed his investigations in that line can more readily be had than by consulting general “Encyclopædia” articles relative to the pyro-electricity of boracite (borate of magnesia), of prehnite (silica, alumina and lime), of mesotype (hydrated silicate of alumina and of lime or of soda), of sphene (silica, titanic acid and lime), calamine (silicate of zinc) and of Siberian topaz.

At pp. 480, 481 of his “Outline of the Sciences,” etc., London, 1830, Dr. Thomas Thomson states:

“There is a hill of sulphate of lime, called Kalkberg, situated near Lunebourg, in the duchy of Brunswick, in which small cubic crystals are found. These cubes are white, have a specific gravity of 2·566, and are composed of two atoms of boracic acid combined with one atom of magnesia. They are distinguished among mineralogists by the name of _boracite_. If we examine the cubic crystals of boracite, we shall find that only four of the solid angles are complete, constituting alternate angles placed at the extremity of two opposite diagonals at the upper and lower surface of the cube. The other four solid angles are replaced by small equilateral triangles. When the boracite is heated all the perfect solid angles become charged with _negative_ electricity, while all the angles replaced by equilateral triangles become charged with _positive_ electricity. So that the boracite has eight poles: four positive and four negative. Those are obviously the extremities of four diagonals connecting the solid angles with each other. One extremity of each of these diagonals is charged with positive and the other extremity with negative electricity. In general, the electricity of boracite is not so strong as that of the _tourmaline_.” This curious law of the excitability of the boracite and of its eight poles was discovered by Haüy in 1791 (Haüy’s “Minéralogie,” 260, second edition).

_Axinite_, _mesotype_, and the _silicate of zinc_ are also minerals which become electric when heated, and which, like the _tourmaline_, exhibit two opposite poles, the one positive, the other negative. It is not every crystal of axinite and mesotype which possesses this property, but such only as are unsymmetrical, that is to say, such as have extremities of different shapes. No doubt this remark applies also to the silicate of zinc; though as the crystals of that mineral are usually acicular it is not so easy to determine by observation the degree of symmetry which they may possess.

The _topaz_, _prehnite_, and the titaniferous mineral called _sphene_ are also capable of being excited by heat, and have two opposite poles like those already mentioned.

Haüy also made the most extensive and accurate observations known upon the development of electricity in minerals by friction. Detailed lists of the different classes of minerals, as well as the conclusions arrived at through various experiments, are given in the “Encyclopedia Britannica,” Vol. VIII, 1855, pp. 538, 539, while at pp. 529 and 558 of the same work are to be found accounts of his observations on the electricity of the _tourmaline_, as well as a description of the different electroscopes employed in his many experiments.

REFERENCES.--Priestley, “History of Electricity,” 1767, pp. 314–326; Gmelin’s “Chemistry,” Vol. I. p. 319; Noad, “Manual,” pp. 27–31; also article “Electricity” in “Library Useful Knowledge,” pp. 3, 54, 56; M. Lister, “Collection Académique,” Tome VI; “Société Philomathique,” An. V. p. 34; An. XII. p. 191; “Mém. du Museum d’Hist. Nat.,” Vol. III; “Mém. de l’lnstitut,” An. IV. tome i., “Sciences Math. et Phys.” p. 49; “Mém. de l’Académie,” 1785, Mem. p. 206; _Philosophical Magazine_, Vols. XX. p. 120; XXXVIII. p. 81; Thomas Thomson, “Hist. of the Roy. Soc.,” London, 1812, pp. 180, etc.; Young’s “Lectures,” London, 1807, Vol. II; Haüy, “Traité Élémentaire de Physique,” Chap VII, “Magnetism”; Experiments of J. L. Treméry (author of “Observations sur les Aimants Elliptiques,” recorded in _Journal des Mines_, Vol. VI for 1797, also in _Jour. de Phys._, Vols. XLVIII and LIV) and of M. De Nelis, some of whose observations are given in the _Phil. Mag._, Vol. XLVIII. p. 127, and in the _Jour. de Phys._, Vols. LXI. p. 45; LXII. p. 150; LXIII. p. 147; LXIV. p. 130; LXVI. pp. 336, 456, as shown and illustrated at pp. 153–162 of Delaunay’s “Manuel,” etc., of 1809; “Séances de l’Acad. de Bordeaux” for 1835, giving M. Vallot’s report on the difference existing between the chalcedony and the tourmaline. Regarding the latter, consult S. Rinmann (“K. Schwed. Akad. Abh.,” XXVIII. pp. 46, 114); C. Rammelsberg, “Die Zuzam ... und Feldspaths”; Mr. Magellan’s edition of Cronstedt’s Mineralogy for Steigliz’s tourmaline; Cesare G. Pozzi, on the tourmaline; H. Von Meyer (“Archiv. ... Ges. Natural,” XIV. 3, p. 342); M. Lechman (Berlin Academy Reports); Carl Von Linné (Linnæus), “Flora Zeylanica,” Stockholm, 1747; M. Leymerie (Toulouse Acad. Reports); Brewster, “Journal” I. p. 208; J. K. Wilcke (“Vetensk. Akad. Handl.,” 1766 and 1768); Jos. Muller, “Schreiben ... Tourmaline,” Wien, 1773; F. J. Muller von Reichenstein, “Nachr. ... an Born,” Wien, 1778; H. B. de Saussure (“Jour. de Paris”), 1784; Louis Delaunay’s letter on the tourmaline, 1782; D. G. Fischer’s works, published at Mosk, 1813, 1818; J. D. Forbes (“Edin. Trans.,” Vol. XIII), 1834.

=A.D. 1787.=--Charles (Jacques Alexandre César), a singularly able French physicist and experimentalist, who became the Secretary of the Académie des Sciences, relates many of his electrical experiments in the thirtieth volume of the _Journal de Physique_.

He was one of the first to study and develop the theories of Franklin, who, in company with Volta, frequently attended the brilliant lectures which Charles was enabled to give in what was then considered the most complete philosophical laboratory of Europe. In many of his experiments on atmospherical electricity, Charles has been known to produce thousands of sparks, beams or flashes, which exceeded 12 feet in length and which made reports similar to those of fire-arms. The French Academy endorsed the opinion given the Minister of War by Charles to the effect that “a conductor will effectually protect a circular space whose radius is twice the length of the rod.”

Charles invented the megascope and was the first to make an ascension in a hydrogen balloon, which he did in company with M. Robert on the 1st of December (not on the 2nd of August) 1783, ten days after the first trip made by Pilatre de Rozier and Comte d’Arlandes in a Montgolfière from the Paris Bois de Boulogne.

REFERENCES.--“Biographie Générale,” Vol. IX. pp. 929–933; Larousse, “Dict. Univ.,” Vol. III. p. 1020; _Journal de Physique_ for 1791, p. 63; “Mémoires de l’Acad. des Sciences” for 1828; George Adams, “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. III. pp. 462–464; Edin. Encycl., 1813, article “Aeronautics,” Vol. I. p. 160, “Franklin in France,” 1888, Part II. pp. 256, 270, 276–280; M. Veau Delaunay, Introduction to his “Manuel,” etc., Paris, 1809, pp. 19, 25 and 61–63; also pp. 23, 68, 92, 96, 122, 176 and 214.

=A.D. 1787.=--Mann (Théodore Augustin), Abbé, Flemish writer and antiquary, becomes perpetual secretary of the Brussels Academy of Sciences ten years after leaving the Nieuport Monastery (1777), and is charged with the duty of making meteorological observations, which are regularly transmitted to the Mannheim Academy officials, who receive similar reports regularly from different parts of Europe and publish them under the title of “Ephémérides Météorologiques.”

His many investigations made with electrical machines are embraced in the last-named publication and are also alluded to in his “Marées Aériennes,” etc., which appeared in Brussels during the year 1792.

REFERENCES.--“Biog. Générale,” Tome XXXIII. p. 231; Larousse, “Dict. Universel,” Tome X. p. 1085; _Phil. Mag._, Vol. IV. p. 337; “Comm. Ac. Theod. Pal.,” 1790, Vol. VI. p. 82.

=A.D. 1787.=--Bennet (Rev. Abraham), F.R.S., first describes in the _Philosophical Transactions_ for this year, pp. 26–32, the gold-leaf electroscope which bears his name and which is considered the most sensitive and the most important of all known instruments for detecting the presence of electricity. It consists of a glass cylinder which is covered with a projecting brass cap, made flat in order to receive upon it whatever article or substance is to be electrified, and having an opening for the insertion of wires and of a metallic point to collect the electricity of the atmosphere. The interior of the cap holds a tube which carries two strips of gold leaf in lieu of the customary wires or threads, and upon two opposite sides of the interior of the cylinder are pasted two pieces of tinfoil directly facing the gold-leaf strips. The cap is turned around until the strips hang parallel to the pieces of tinfoil, so that any electricity present will cause the strips to diverge and make them strike the tinfoil, which will carry the electricity through the support of the cylinder to the ground.

This electroscope, says Wilkinson, possesses great sensibility, and through the movable coatings introduced by Mr. Pepys, very small portions of electricity are discernible. Another very excellent electroscope is formed with either extremely fine silver thread, prepared after the manner of Mr. Read, or with the minutest thread found in a bundle of very fine flax, having a little isinglass glue applied gently over it with the finger and thumb.

Of the numerous observations made by Bennet, the following interesting extract relative to the phenomenon of evaporation is taken from the _Philosophical Transactions_ for the year 1787. “If a metal cup with a red hot coal in it be placed upon the cap of a gold leaf electroscope, a spoonful of water thrown in electrifies the cup resinously; and if a bent wire be placed in the cup with a piece of paper fastened to it to increase its surface, the vitreous electricity of the ascending column of vapour may be seen by introducing the paper into it. The experiments on the evaporation of water may be tried with more ease and certainty of success by heating the small end of a tobacco pipe and pouring water into the head, which, running down to the heated part, is suddenly expanded, and will show its electricity when projected upon the cap of the electrometer more sensibly than any other way that I have tried. If the pipe be fixed in a cloven stick and placed in the cup of one electrometer while the steam is projected upon another, it produces both electricities at once.”

Some of Mr. Bennet’s experiments with the electroscope on the electricity of sifted powders, upon the electricity of the atmosphere, etc., are recorded at pp. 564 and 566 of the “Britannica,” Vol. VIII, and at p. 56 of “Library of Useful Knowledge.”

Mr. Bennet also invented the _electrical doubler_, designed to increase small quantities of electricity by continually doubling them until visible in sparks or until the common electrometer indicates their presence and quality (_Phil. Trans._ for 1787, p. 288). It consists of three plates of brass, illustrated and explained at Fig. 9, p. 20, Vol. I of Prescott’s “Electricity and the Electric Telegraph,” 1885 edition, wherein it is stated that in forty seconds the electricity can thus, by continual duplication, be augmented five hundred thousand times. (See, for doublers, C. B. Désormes and J. N. P. Hachette, in _Annales de Chimie_, Vol. XLIX for 1804; J. Read (_Phil. Trans._ for 1794, p. 266); Sir Francis Ronalds (Edin. “Phil. Journal,” Vol. IX. pp. 323–325).)

At p. 105 of his “Rudim. Magnetism,” Snow Harris mentions the fact that, in some of his experiments, Mr. Bennet employed a magnetic needle suspended by filaments of a spider’s web as a magnetometer. In this connection, it may be said that, in the _Philosophical Transactions_ for 1792, the assertion is made that a fine, and weakly magnetic steel wire suspended from a spider’s thread of three inches in length will admit of being twisted around eighteen thousand times and yet continue to point accurately in the meridian, so little is the thread sensible of torsion (Young’s “Course of Lectures,” 1807, Vol. II. p. 445). The use of the spider’s line had, during the year 1775, been recommended as a substitute for wires by Gregorio Fontana, who, it is said, obtained threads as fine as the eight-thousandth part of a line. In a lecture delivered at Boston, Mass., during the year 1884, Prof. Wood alluded to spiders’ threads estimated to be one two-millionths of a hair in thickness.

REFERENCES.--Bennet, “New Experiments on Electricity,” etc., Derby, 1789, and “A New Suspension of the Magnetic Needle,” etc., London, 1792; Introduction to “Electrical Researches,” by Lord Henry Cavendish; _Sc. Am. Supplement_, No. 647, pp. 10, 327; Noad, “Manual,” p. 27; Cavallo, “Nat. Phil.,” 1825, Vol. II. pp. 199, 216; _Phil. Trans._, Vol. LXXVII. pp. 26–31, 32–34, 288–296; also the abridgments by Hutton, Vol. XVI. pp. 173, 176, 282 and Vol. XVII. p. 142; _Sc. American_, Vol. LI. p. 19; _Annales de Chimie_, Vol. XLIX. p. 45; Ezekiel Walker, _Phil. Mag._ for 1813, Vol. XLI. p. 415 and Vol. XLII. pp. 161, 215, 217, 371, 476, 485; also Vol. XLIII. p. 364.

=A.D. 1788.=--Barthélémy (Jean Jacques), who, after completing his studies in a French seminary of Jesuits, succeeded Gros de Boze as keeper of the king’s cabinet of medals, publishes in four volumes, at Paris, the first edition of his “Voyage du Jeune Anacharsis.” In this well-known work, begun by him in 1757, and translated into English under the title “Travels of Anacharsis the Younger in Greece,” Barthélémy alludes to the possibility of telegraphing by means of clocks (_pendules_, not _horloges_), having hands similarly magnetized in conjunction with artificial magnets. These were “presumed to be so far improved that they could convey their directive power to a distance, thus, by the sympathetic movements of the hands or needles in connection with a dial alphabet, communications between distant friends could be carried on.”

Writing to Mme. du Deffand in 1772, he observes:

“It is said that with two timepieces the hands of which are magnetic, it is enough to move one of these hands to make the other take the same direction, so that by causing one to strike twelve the other will strike the same hour. Let us suppose that artificial magnets were improved to the point that their virtue could communicate itself from here to Paris; you have one of these timepieces, we another of them; instead of hours we find the letters of the alphabet on the dial. Every day at a certain hour we turn the hand, and M. Wiard [Mme. du Deffand’s secretary] puts together the letters and reads.... This idea pleases me immensely. It would soon be corrupted by applying it to spying in armies and in politics, but it would be very agreeable in commerce and in friendship.”

REFERENCES.--“Correspondance inédite de Mad. Du Deffand,” Vol. II. p. 99; letter of J. MacGregor in _Journal Society of Arts_, May 20, 1859, pp. 472, 473.

=A.D. 1789.=--Adriaan Paets Van Troostwÿk and Jean Rodolphe Deimann, Dutch chemists, associated for the purpose of scientific research, complete the experiments of Lord Cavendish and announce, in the _Journal de Physique_, their discovery of the decomposition of water through the electric spark, which latter is conveyed by means of very fine gold wires. As is now well known, water is by this means resolved into its two elements of oxygen and hydrogen, both of which assume their gaseous form.

The electric machine they employed was a very powerful double-plate one, of the Teylerian mode of construction, causing the Leyden jar to discharge itself twenty-five times in fifteen revolutions.

REFERENCES.--“Mém. de la Soc. de Phys. Exp. Rotterdam,” Tome VIII; _Journal de Physique_, Vol. XXXIII; Noad, “Manual,” p. 161; “Encyl. Brit.,” Vol. VIII, 1855, pp. 530, 565; “Biog. Universelle,” Vol. X. p. 282; De La Rive, “Electricity,” Vol. II. p. 443; Wm. Henry, “Elements of Experimental Chemistry,” London, 1823, Vol. I. pp. 251, 252; Delaunay’s “Manuel,” etc., 1809, pp. 180–183; “Verhandl. van het Genootsch te Rotterdam” (“Mém. de la Soc. de Phys. Exp. de Rotterdam”) Vol. VIII; Poggendorff, Vol. I. p. 1555; Dove, p. 243; G. Carradori (Brugnatelli’s _Annali di chimica_, Vol. I. p. 1); John Cuthbertson, “Beschreibung einer Elekt. ...” Leipzig, 1790.

=A.D. 1790.=--Reveroni--Saint-Cyr (Jacques Antoine, Baron de), French Colonel and author, best known by his very interesting work, “Mécanismes de la Guerre,” proposes an electric telegraph for the purpose of announcing the drawings of lottery numbers; no satisfactory information as to its construction, however, appears obtainable.

REFERENCES.--Fahie, “History,” etc., London, 1884, p. 96; Etenaud, “La Télégraphie Electrique,” 1872, Vol. I. p. 27; _Sc. Am. Supp._, No. 384, pp. 6, 126.

=A.D. 1790.=--Mr. Downie, master of his Majesty’s ship “Glory,” makes a report on local attraction wherein he observes “that in all latitudes, at any distance from the magnetic equator, the upper ends of iron bolts acquire an opposite polarity to that of the latitude,” an observation, Harris remarks, which accords with Marcel’s experiment (at A.D. 1702).

“I am convinced,” says Mr. Downie, “that the quantity and vicinity of iron, in most ships, has an effect in attracting the needle; for it is found by experience that the needle will not always point in the same direction when placed in different parts of a ship; also, it is very easily found that two ships, steering the same course by their respective compasses, will not go exactly parallel to each other; yet when their compasses are on board the same ship they will agree exactly.”

REFERENCES.--William Walker, “The Magnetism of Ships,” London, 1853, p. 20; J. Farrar, “Elements,” p. 376; Harris, “Rudim. Magn.,” 1852, Part III. p. 161.

=A.D. 1790.=--Tralles (Johann Georg), a German scientist, is the first to make known the negative electricity of cascades. This he communicates through his “Uber d. Elektricität d. Staubbachs,” published at Leipzig.

In the Report on Atmospheric Electricity of Francis J. F. Duprez, translated from the Memoirs of the Royal Academy of Brussels by Dr. L. D. Gale, we read that one day while in the Alps, opposite the cascade of Staubbach, near Lauterbrunnen, Tralles “presented his atmospheric electrometer, not armed with the metallic wire, to the fine spray which resulted from the dispersion of the water. He immediately obtained very distinct signs of negative electricity. The same effect was exhibited at the cascade of Reichenbach. Volta, a short time after, verified the correctness of this observation, not only above the great cascades, but also wherever a fall of water existed, however small, provided the intervention of the wind caused the dispersion of the drops. The electricity always appeared to him, as it did to Tralles, negative. Schübler repeated the same experiments in his journey to the Alps in 1813. He observed farther, that this negative electricity was very strong, since it became perceptible at a distance of 300 feet from the cascade of Reichenbach; and at a distance of 100 feet his electrometer indicated 400 and even 500 degrees.... Tralles attributed it at first to the friction of the minute drops of water against the air; but soon after he thought, with Volta, that the cause was to be found in the evaporation which the same minute drops experience in falling....”

The Italian physicist, Giuseppe Belli, who published at Milan, during 1836, “Sulla Elettricità negativa delle cascate,” entertains an opinion contrary to that advanced by M. Becquerel, and believes “that the electrical phenomenon of the water of cascades is owing to the development of electricity by the induction which the positive electricity of the atmosphere exercises on the water. The water, he says, is by induction in the negative state, when the atmosphere is, as it is ordinarily, charged with positive electricity. At the moment when this water divides into thousands of minute drops, it cannot fail to carry the electricity with which the electrical induction of the atmosphere has impregnated it to all bodies which it meets.”

REFERENCES.--“Œuvres de Volta,” Vol. II. p. 239; Franz Samuel Wilde, “Expériences sur l’électricité des cascades” (“Mémoires de Lausanne,” Vol. III, “Histoire,” p. 13, 1790); “Bibliographie Universelle,” N. S., 1836, Vol. VI. p. 148; Houzeau et Lancaster, “Bibl. Générale,” Vol. II. p. 265; “Biblio. Ital.,” LXXXIII. p. 32; Schweigger, _Journal f. Chemie u. Physik_, Vol. IX. p. 358; Tralles, “Beyträge zur Lehre von der Electricität”; L. W. Gilbert’s _Annalen der Physik und Chemie_, Vol. XXVIII for 1808; F. A. C. Gren’s _Journal der Physik_, Vol. I. for 1790; Humboldt, “Cosmos,” London, 1849, Vol. I. p. 344, and the reference to Gay-Lussac in _Ann. de chimie et de physique_, Vol. VIII. p. 167.

=A.D. 1790.=--Eandi (Giuseppe Antonio Francesco Geronimo), an able physicist, native of Saluces (1735–1799), reads, May 10, before the Academy of Sciences of Turin, a Memoir upon Electricity _in vacuo_ which is printed in the Collections of that Institution. He studied for the priesthood and entered the Normal College of Turin, where he followed protracted courses of literature under Bartoli and of natural philosophy under Beccaria, becoming the assistant of the latter, whom he finally replaced from 1776 to 1781. He afterward became Professor of Natural Philosophy at the College of Fine Arts, where he gave particular attention to electrical studies, and published several papers on that science, as well as upon natural philosophy generally.

He bequeathed all his possessions to his nephew Vassalli, upon condition of the latter’s taking the name of Eandi.

Besides the above, he wrote: “Memorie istorische,” etc., or “Historical Memoir upon the Studies of Father Beccaria,” Turin, 1783, which is dedicated to Count Balbi and gives the new theories of electricity, also an “Essay upon the Errors of Several Physicists in Regard to Electricity,” Turin, 1788.

REFERENCES.--“Notice sur la vie ... d’ Eandi par Vassalli-Eandi,” Turin, 1804; “Biographie Générale,” Vol. XV. p. 589; Larousse, “Dict. Universel,” Vol. VII. p. 5; the Turin Academy Memoirs for the years 1802–1804; Eandi e Vassalli-Eandi, “Physicæ Experimentalis,” etc., Turin, 1793–1794.

=A.D. 1790.=--Vassalli-Eandi (Antonio Maria), Italian savant (1761–1825), nephew of G. A. F. G. Eandi, who was, like his uncle, a pupil of Beccaria, publishes his views concerning the electricity of bodies and regarding other investigations, as well as a report upon experiments relative to the electricity of water and of ice, which appear respectively in L. V. Brugnatelli’s _Annali di Chimica_, Vol. I. p. 53, in the “Bibl. Fis. d’Europa,” Vol. XVII. p. 144, and in the third volume of “Mem. della Soc. Italiana.”

He was one of the most prolific of Italian writers, his more important essays, which number 160, being written in Italian, Latin and French, and covering almost every leading branch of physical science. One of his biographers tells us, _Il a embrassé, pour ainsi dire, l’ensemble des connaissances humaines_, and that he is one of whom his country may justly be proud.

In his investigations concerning aerolites, which appeared in 1786 (“Memoria ... sopra ... bolidi in generale”), he explains the movements of those bodies much more satisfactorily than had previously been done by any scientist. Essays published by him during the same year, as well as in 1789 and 1791, treat of the effect of electricity upon vegetables; then follow his papers relative to Bertholon’s “Electricité des Météores,” to Haüy’s theories and to the meteorological observations of Senebier, De Saussure, Toaldo and Monge, up to 1792, when Vassalli was made Professor of Natural Philosophy at the Turin University. He had also in the meantime carefully looked into the scientific knowledge possessed by the ancients, and was led to believe, as shown in his “Conghietture sopra l’arte,” etc., that they had the means of attracting and directing thunder and lightning. The latter fact has been alluded to in this “Bibliographical History,” under the B.C. 600 entry. (See J. Bouillet, “De l’état des connaissances,” etc., Saint Etienne, 1862.)

He was after this made perpetual secretary of the Royal Academy of Sciences of Turin, then became Director of the Museum of Natural History, as well as of the Observatory situated in the last-named city, which position he held at the time of his death.

His other essays treat more particularly of animal electricity, the electricity of fishes, the effects of electricity upon recently decapitated bodies, the application of electricity and of galvanism to medicine, and cover very extended observations on meteorology. He was the editor of both the “Memoirs of the Academy of Sciences of Turin, from 1792 to 1809,” and of the “Annals of the Turin Observatory, from 1809 to 1818” (Larousse, “Dictionnaire Universel,” Vol. XV. p. 801); was likewise editor of the “Bibliothèque Italienne,” in conjunction with Giulio Gioberti and Francesco Rossi, and is said to have devised an electrometer superior to that of Volta.

REFERENCES.--Vassalli-Eandi, Giulio (or Julio) e Rossi, “Rapport présenté,” etc., Turin, 1802, or “Transunto del Rapporto,” etc., Milano, 1803 (“Opusc. Scelti,” Vol. XXII. p. 51), translated into English, London, 1803 (_Phil. Mag._, Vol. XV. p. 38); also Vassalli-Eandi, F. Rossi et V. Michelotti, “Précis de nouvelles expériences galvaniques,” Turin, 1809 (“Mém. de Turin,” Années, 1805–1808, p. 160). See likewise, S. Berrutti, “Elogio,” etc., 1839; “Saggio sulla vita ... Vassalli-Eandi,” Torino, 1825; “Notizie biografiche ... Vassalli Eandi” (“Mem. di Torino,” Vol. XXX. p. 19); “Elogio, scritto dal Berrutti” (“Mem. of the Ital. Soc.,” Vol. XXII. p. liv); _Phil. Mag._, Vol. XV. p. 319; _Journal de Physique_, An. VII. p. 336 and Vols. XLIX, L; “Ital. Soc. Mem.,” Vols. VIII. p. 516; X. p. 802; XIII. p. 85; XVII. p. 230; XIX. p. 347; “Mémoires de Turin,” Vols. X-XIII; “Mem. dell’ Acad. di Torino,” Vols. VI, X, XXII, XXIV, XXVI, XXVII, XXIX; “Mem. della Soc. Agrar. di Torino,” Vol. I; “Opuscoli Scelti,” Vols. XIX. pp. 215, etc.; XXII. p. 76; “Nuova Scelta d’Opuscoli,” Vol. I. p. 167; “Opuscoli Scelti di Milano,” quarto, Vol. XIV; “Mem. Soc. Ital.,” Vols. IV. p. 263; X. p. 733; “Biblioteca Oltramontana”; Brugnatelli’s _Annali di Chimica_; “Giornale Scientifico ... di Torino,” Vols. I, III; “Giornale Fis. Med.,” Vol. II. p. 110; “Biblioteca Italiana”--“Bibliothèque Italienne,” Vols. I. p. 128; II. p. 25; “Recueil périodique ... de Sédillot,” Vol. II. p. 266.

=A.D. 1790–1800.=--Morozzo--Morotius--(Carlo Luigi, Comte de), Italian savant, who studied mathematics under Lagrange, and was President of the Turin Academy of Sciences, publishes numerous scientific memoirs in French through the reports of the last-named institution, in one of which he is said to have described an experiment suggesting the electro-magnet.

REFERENCES.--Biography in Larousse, “Dictionnaire Universel,” Tome XI. p. 577, and in the “Biographie Générale,” Tome XXXVI. p. 643.

=A.D. 1791.=--Leslie (Sir John), an able English scientist (April 1766–Nov. 1832), who, upon the death of Prof. John Playfair, was called to the Chair of Natural Philosophy in the University of Edinburgh, writes a very interesting paper entitled “Observations on Electric Theories,” which is read the following year at the meeting of the Royal Society of Edinburgh, and is published at the latter place during 1824.

According to Carnevale Antonio Arella, “Storia dell’ Elettricità,” Alessandria, 1839, Vol. I. p. 130, Sir John Leslie is the author of quite an interesting treatise on the inefficacy of lightning conductors, and the “English Cyclopædia” (Biography), Vol. III. p. 866, gives a list of many of the numerous contributions he made to the leading publications of his day, more particularly in the “Edinburgh Philos. Transactions,” the “Encyclopædia Britannica,” the “Edinburgh Review,” and “Nicholson’s Philos. Journal.” The reviewer adds, what will surprise many readers, that, although some papers by Sir John Leslie treating of physical subjects were also read before the Royal Society of London, none were ever printed in their “Philos. Transactions.”

Professor John Playfair above alluded to (1748–1819), became, during 1785, Joint Professor of Mathematics with Dr. Adam Ferguson in the University of Edinburgh and, in 1805, exchanged this for the Professorship of Natural Philosophy in the same university.

REFERENCES.--Macvey Napier, “Memoir of Sir John Leslie,” 1838, which appeared in seventh edition of “Encycl. Britan.,” Vol. XIII; “Engl. Cycl.” (Biography); Rose, “New Gen. Biogr.”; Hœfer, “Nouv. Biogr. Gen.,” Paris, 1862, Vol. XXX. pp. 949–952 (giving full account of his works); “Encycl. Britan.,” ninth edition, Edinburgh, 1882, Vol. XIV. pp. 476–477; Sidney Lee, “Dict. Nat. Biogr.,” Vol. XXXIII. pp. 105–107 and Vol. XLVIII. pp. 413–414; Pierre Larousse, “Grand Dict. Univ.,” Vol. X. pp. 406–407; “Caledonian Mercury,” article of Prof. Napier summarized in the “Gentleman’s Magazine” for 1833, Vol. I. pp. 85–86. Consult also A.D. 1751 at Adanson; “Dove,” p. 256; _Philosophical Magazine_, Vols. XL and XLII.

=A.D. 1791.=--At p. 353, Chap. III of the first volume of Gmelin’s “Handbook of Chemistry,” it is stated that during 1791 James Keir (Kier) first showed, by immersing iron in a solution of nitrate of silver or fuming nitric acid, that many metals can be made to pass from their ordinary _active_ state into a _passive_ or electro-negative state and lose either wholly or in part their tendency to decompose acids and metallic oxides.

At pp. 167–170, Sixth Memoir, of Wm. Sturgeon’s “Scientific Researches” (Bury, 1850), treating of the application of electro-chemistry to the dissolution of simple metals in fluids, reference is made to the long line of investigations carried on by both Bergman and Keir, the last named having demonstrated that iron “acquires that _altered_ state by the action of nitric acid which Sir John Herschel met with in his experiments, and has called _prepared_ state, and that Schönbein and others call the _peculiar_ or the _inactive_ state” (Noad’s “Manual of Electricity,” London, 1859, p. 534). The iron which is active in nitric acid was called by Keir “fresh iron,” while that which became inactive he designated as “altered iron” (Sturgeon’s “Annals of Electricity,” Vol. V. p. 439).

Some remarkable phenomena in the display of which but one individual piece of metal is used, as first shown by Keir, remain, Sturgeon says, “without even an attempt at explanation by any of the philosophers under whose notice they have appeared.” Sir John Herschel pronounces them as of an “extraordinary character”; Prof. Andrews, after giving some very satisfactory explanations of several phenomena, acknowledges that he “can offer no explanation of most of the particular facts which have been described,” and Professor Schönbein “has not made public any conclusive explanation of them whatever” (_Phil. Mag._ for October 1837, p. 333, and for April 1838, p. 311).

This same James Keir, called by Watt “a mighty chemist” (1735–1820), has strangely by some been confounded with Robert Kerr, also a Scotchman, who was an able scientific writer and lived at about the same period (1755–1813). Kerr made valuable translations from Lavoisier and Linnæus which, during 1805, won for him a fellowship in the Edinburgh Royal Society. (Consult Sidney Lee, “Dict. of Nat. Biogr.,” London, 1892, Vol. XXI. p. 64, also the references therein given; and the article “Faraday” in the “Encycl. Britan.,” ninth edition, Edinburgh, 1879, Vol. IX. p. 30.)

REFERENCES.--Mrs. Amelia Moillet, “Sketch of the Life of James Keir,” 1859; Sidney Lee, “Dict. of Nat. Biog.,” London, 1892, Vol. XXX. pp. 313–314; _Annales de Chimie_ for October 1837; _Phil. Trans._ for 1790, p. 353, as well as Hutton’s abridgment of the same, Vol. XVI. p. 694; Sturgeon’s “Annals of Electricity,” Vol. V. p. 427; Gmelin’s Chemistry, pp. 367, 370.

=A.D. 1791.=--Shaw (George), English naturalist, who became a Fellow of the Royal Society during the year 1789, communicates to the latter body a paper on the _Scolopendra electrica_ and _Scolopendra subterranea_ (“Linn. Soc. Trans.” I. pp. 103–111). This was afterward translated into Italian and appeared in Vol. IX. p. 26, of Brugnatelli’s _Annali di Chimica_. Mr. James Wilson, F.R.S.E., in his “Encycl. Brit.” article on _Myriapoda_, alludes to the _Scolopendra electrica_ as figured by Frisch and described by Geoffroy in his “Histoire des Insectes,” Vol. II. p. 676, n. 5. Shaw also treats of the _Trichiurus Indicus_, which Sir David Brewster believes to be the same as the _trichiurus electricus_, known to inhabit the Indian Seas and to have the power of giving electric shocks.

Five years before the above date (1786), the _Phil. Trans._ contained (p. 382) the description of the _tetraodon electricus_, which Lieutenant William Paterson discovered in the cavities of the coral rocks of one of the Canary Islands and which he found to possess the properties of other electrical fishes. (See Hutton’s abridgments, Vol. XVI. p. 134.)

REFERENCES.--“Biographie Générale,” Vol. XLIII. p. 922; “Gentleman’s Magazine,” Vol. LXXXIII; Poggendorff, Vol. II. p. 918; “Cat. Royal Society Sc. Papers,” Vol. V. p. 674; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. II. p. 436, for the _Trichiurus Indicus_....

Having thus far called attention to the most important varieties of the electrical fishes, notably at the articles Adanson (A.D. 1751), Bancroft (A.D. 1769), Walsh, also Hunter (A.D. 1773), the following original list of additional references will prove interesting:

_Raia Torpedo._--Stephani Lorenzini, “Osservazioni ...” Firenze, 1678; R. A. F. de Réaumur, “Des Effets ...” Paris, 1714; Templeman, in “Nouvelliste,” 1759; Ingen-housz (_Phil. Trans._, 1775); Cavendish (_Phil. Trans._, 1776, Vol. LXI. p. 584, Vol. LXVI. p. 196, also Hutton’s abridgments, Vol. II. p. 485; Vol. XIII. p. 223; Vol. XIV. p. 23); F. Soave (“Scelta di Opuscoli,” Vol. XV), Milano, 1776; J. A. Garn, “De Torpedine ...” Witteb., 1778; R. M. de Termeyer (Raccolta Ferr. di Op. Sc. ... Vol. VIII), Venice, 1781; L. Spallanzani (“Goth. Mag.,” V. i. 41; “Opusc. Scelti,” VI. 73), Milano, 1783; Girardi and Walter (“Mem. Soc. Ital.,” III. 553), Verona, 1786; W. Bryant (“Tr. Amer. Phil. Soc.,” II. 166, O. S.), Philad., 1786; J. W. Linck, “De Raja Torpedine,” Lips., 1788; Vassalli-Eandi (_Journal de Physique_, Vol. XLIX. p. 69); Geoffroy Saint-Hilaire (“Annal. du Mus.,” An. XI. Vol. I., No. 5, and _Phil. Mag._, Vol. XV. p. 126), 1803; J. F. M. Olfers, “Die Gattung Torpedo ...” Berlin, 1831; Linari-Santi in “Bibl. Univ.,” Ser. II., Geneva, 1837–1838, and in “Bibl. Ital.,” Vol. XCII. p. 258, Milan, 1839; C. Matteucci, “Recherches ...” Genève, 1837 (“Royal Soc. Catalogue of Sc. Papers,” Vol. IV. pp. 285–293); also Delle Chiaje, “On the Organs ...” and P. Savi, “Etudes ...” Paris, 1844; G. Pianciani (“Mem. Soc. Ital.,” XXII. 7); F. Zantedeschi (“Bull. Acad. Brux.,” VIII. 1841); A. Fusinieri (“Ann. del Reg. Lomb.-Veneto,” VIII. 239), Padova, 1838; A. F. J. C. Mayer, “Spicilegium ...” Bonnæ, 1843; L. Calamai, “Osservazioni ...” 1845; C. Robin, “Recherches ...” Paris, 1847; Krünitz, “Abhandl.,” XVII; _Nicholson’s Journal_, Vol. I. p. 355; Rozier, IV. p. 205; “Acad. Brux.,” 111; “Phil. Hist. and Mem. of the Roy. Acad. of Sc. Paris,” 1742, Vol. V. pp. 58–73; John Ewing, at A.D. 1795; Dr. Godef. Will. Schilling (in original Latin, also the French translation), “Biblioth. Britannique,” Vol. XL. pp. 263–272; Dr. Jan Ingen-housz in _Phil. Tr._ Vol. LXV. p. 1; Vol. LXVIII. pp. 1022, 1027; Vol. LXIX. pp. 537, 661; also Hutton’s abridgments, Vol. XIII. p. 575; Vol. XIV. pp. 462, 463, 589, 598; “Journal des Sçavans,” Vol. LXXVIII. for January-April, 1726, p. 58; “The System of Natural History, written by M. De Buffon,” Edinburgh, 1800, Vol. II. pp. 24–25.

M. R. A. F. De Réaumur, mentioned above, has communicated the results of his investigations relative to the _torpedo_ in “Mém. de Paris” for 1714, following it up more particularly with another article in the issue for year 1723 on magnetization, which is also alluded to in “Journal des Sçavans,” Vol. LXXXII. for 1727, p. 4.

_Silurus Electricus._--Ranzi, on the discovery of the discharge of this animal; P. Forskal “Beobachtungen ...” 1775; F. Pacini, “Sopra l’ Organo ...” Bologna, 1846; Abd-Allatif, Relation de l’Egypte, p. 167, quoted at p. 250; Note XI. vol. i. of Libri’s “Hist. des Mathém.”; C. Maspero, “The Dawn of Civilization,” New York, 1894, p. 36, wherein it is said that the silurus was the _nârû_ of the ancient Egyptians, as described by Isidore Geoffroy de St. Hilaire in his “Histoire Naturelle des Poissons du Nil.”

_Gymnotus Electricus._--T. Richer, “Observations ...” Paris, 1679 (“Hist. et Mém. de l’Acad. Roy. des Sciences,” Vols. I. p. 116; VII. i. pt. 2, p. 92); “Edinburgh Review,” Vol. XVI. pp. 249–250; John Ewing at A.D. 1795; P. Sue, aîné “Histoire du Galvanisme,” Paris, An. X, 1802, Vol. II. pp. 94–97; A. Van Berkel, “Reise nach Rio ...” Memming, 1789, for the observations made in 1680–1689; J. B. Duhamel (“Hist. Acad. Sc.,” 168); J. N. Allamand, “On the Surinam Eel ... by S’Gravesande,” Haarlem, 1757; Gronov-Gronovius (“Acta Helvetica ...” IV. 26, Basle, 1760; _Phil. Trans._, Vol. LXV. part i. p. 94, 102, and part ii. p. 395); P. V. Musschenbroek (“Hist. et Méms. de l’Acad. des Sc.,” 1760); G. W. Schilling, “Diatribe de Morbo ...” 1770, treating of the torpedo as well as of the _magnetism_ of the Gymnotus (which latter was observed by him in 1764, and is alluded to besides by Jan Ingen-housz in his “Nouv. Exper.,” Paris, 1785); “Mem. of Berlin Acad. of Sc.,” Bonnefoy, “De l’app. de l’élect ...” 1782–1783, p. 48; Ferdinando Elice, “Saggio sull’ Elettricità,” p. 26; H. Williamson, Alexander Garden and John Hunter in the _Phil. Trans._ for 1775, p. 94, 102, 105, 395, and in Hutton’s abridgments, Vol. XIII. pp. 597–600; R. M. de Termeyer (“Opus. Scelti,” IV. 324, for 1781); H. C. Flagg (“Trans. Amer. Phil. Soc.,” O. S., Vol. II. p. 170); Samuel Fahlberg, “Beskrifning ofver elektriska alen Gymnotus electricus,” Stockholm, 1801; (See Fahlberg at A.D. 1769, and in “Vet Acad. Nyr. Handl.”; Gilbert, _Annalen_, XIV. p. 416); Humboldt, “Observations ... anguille elect ...” Paris, 1806; “Versuche ... elec. fische,” Jena, 1806; also in the _Annales de Chimie et de Physique_, Vol. XI for 1819, and at p. 256 of the “Harmonies of Nature,” by Dr. G. Hartwig, London, 1866, will be found a picture showing mode of capture of the Electric Eel; F. S. Guisan, “De Gymnoto ...” Tübingen, 1819, Carl Palmstedt (“Skand. Naturf. motets Forhand,” 1842); H. Letheby (“Proceedings London El. Soc.,” Aug. 16, 1842, and June 17, 1843); M. Vanderlot’s work, alluded to by Humboldt at p. 88 of his “Voyage ...”; F. Steindachner, “Die Gymnotidie ...” Wien, 1868.

Consult likewise, for reputed magnetic powers of the _echeneis_, or sucking-fish, Gaudentius Merula, “Memorabilium,” 1556, p. 209; Fracastorio, “De Sympathia,” lib. 1, cap. 8; W. Charleton, “Physiologia,” 1654, p. 375; Cornelius Gemma, “De Naturæ Divinis,” 1575, lib. 1, cap. 7, p. 123; and, for electrical fishes generally, Rozier, Intr., II. p. 432; Bloch, “Naturgeschichte ...” Berlin, 1786; A. De la Rive, “Traité de l’électricité,” Paris, 1858, Vol. III. pp. 61–82; Rozier, Vol. XXVII. pp. 139–143; “Works of Michael de Montaigne,” by W. Hazlitt, New York, 1872, Vol. II. pp. 158–159; R. J. Haüy, “Traité de Physique,” p. 41; Geoffroy Saint-Hilare (_Journal de Physique_, LVI. 242; _Phil. Mag._ XV. 126–136, 261; “B. Soc. Phil.” N. 70; Gilbert, _Annalen_, XIV. 397; “Ann. du Mus.” for 1803); M. Schultze, “Zur Kentniss ... elect ... fische,” Halle, 1858 and 1859; Jobert (de Lamballe) “Des Appareils ...” Paris, 1858; W. Keferstein and D. Kupffer (Henle u. Pfeuffer’s “Zeitschr. f. rat. Med. Newe Folgc,” III. 1858) and Keferstein’s “Beitrag ... elekt. fische,” Göttingen, 1859; “Annual of Sc. Discovery” for 1863, giving, at pp. 115–116, the views of Sir John Herschel, of Charles Robin and of M. Moreau on the electrical organs of fishes.

=A.D. 1792.=--Berlinghieri (Francesco Vacca, and not Vacca Leopold nor Andrea Vacca), Italian surgeon and anatomical writer, communicates to M. De La Méthérie the result of the extensive experiments made by him in concert with M. Pignotti and his brother. After describing his investigations with frogs, he remarks that the same movements and contractions can be produced on animals with hot blood, but that the latter require a peculiar process. He says that after having dissected the crural or any other considerable nerve, and cut it at a certain height to separate it from its superior part, it should have a piece of tinfoil wrapped around its summit, and the communication should be made in the usual way by touching the coating with one of the extremities of the exciting arc and the muscles in which the nerve is distributed with the other extremity.

Many other investigations of Berlinghieri were, later on, communicated to the Société Philomathique, by whom they were successfully renewed, and, during the year 1810, a translation of his paper on the method of imparting magnetism to a bar of iron without a magnet appeared at p. 157, Vol. XXXV. of the _Philosophical Magazine_.

REFERENCES.--Rozier, XL. p. 133, and XLI. p. 314; “Giorn. di Med. Prac. di Brera,” IX. pp. 171–298; L. B. Phillips, “Dict. of Biog. Ref.,” 1871, p. 137; Tipaldo, “Biografia ...” 1834.

=A.D. 1792.=--Lalande (Joseph Jérome le Français de), a distinguished scientist, and, doubtless, the best known of all French astronomers, who had previously communicated (1761) observations on the loadstone to the “Mémoires de Paris,” and had likewise written upon meteoric displays (1771), addresses to the _Journal des Sçavans_ of Nov. 1792 a treatise entitled “Une Notice sur la découverte du Galvanisme,” justifying his claim to being the first introducer of galvanism into France, which he had before made through the columns of the _Journal de Paris_ of the 17 Pluviôse, An. VII.

REFERENCES.--Lalande, “Abrégé de l’Astronomie,” pp. 101, etc.; “Biog. Générale,” Vol. XXVIII. p. 948; “Biog. Universelle,” Vol. XXII. pp. 603–613; Ninth “Enc. Britannica,” Vol. XIV. p. 225; P. Sue, aîné, “Hist. du Galv.,” Paris, An. X (1802), Vol. I. p. 1.

=A.D. 1792.=--Chappe (Claude), a French mechanician (1763–1805), introduces the _sémaphore_, which he at first called a _tachygraphe_, from two Greek words meaning to write fast, but to which M. Miot, chief of one of the divisions of the War Department, gave the name of telegraph during the year 1793. Chappe had not long before devised a contrivance somewhat like that alluded to by Barthélémy (A.D. 1788), but it was not apparently brought into use.

His _sémaphore_ consisted of a vertical wooden pillar 15 feet or 16 feet high, bearing a transverse beam 11 feet or 12 feet long, which turned upon its centre and held at each extremity pivoted arms so worked by cords or levers as to admit of 256 distinct signals. The semaphores were placed upon high towers, about four miles apart, on level ground, and even as much as ten miles apart upon intervening elevations. This system of signals was presented by Chappe to the Assemblée Législative, and was originally erected during the month of August 1794 upon stations between Paris and Lille (Lisle), a distance of about 148 miles. One of the first sentences conveyed between the two places by the Committee of Public Safety consumed 13 minutes and 40 seconds, but it was not long before dispatches could be conveyed in two minutes’ time, and it was through Chappe’s apparatus that the news of the recapture of the city of Condé was conveyed to the Assembly shortly after the entry of the troops of the Republic.

It is not now believed that Claude Chappe was acquainted with the devices of either Robert Hooke (at A.D. 1684) or of Guillaume Amontons (at A.D. 1704), as was at the time claimed by many of his jealous contemporaries. No doubt exists that he is justly entitled to the credit of having, with the assistance of other members of his family, developed an entirely new system of signals as well as the mechanism by which they were operated. The histories of telegraphy written by I. U. J. Chappe (Paris, 1824; Le Mans, 1840) review Claude Chappe’s investigations and the difficulties he encountered, besides making reference to the false magnetic telegraphs of A. T. Paracelsus (A.D. 1490–1541), William Maxwell (A.D. 1679), and F. Santanelli (“Philosophiæ reconditæ ...” Coloniæ, 1723) alluded to in the “Dictionnaire des Sciences Médicales.”

Claude Chappe’s uncle, L’Abbé Jean Chappe d’Auteroche (1722–1769), French astronomer, who succeeded N. L. de la Caille at the Paris Observatory as assistant to Cassini de Thury and edited a translation of the works of Dr. Halley, is the author of several memoirs upon the declination and inclination and upon lightning, meteors, etc., alluded to in J. B. J. Delambre’s “Hist. de l’Astron. au 18^e siècle,” in J. C. Poggendorff’s “Biog.-Liter. Hand.,” Vol. I. p. 420, and in the “Mém. de Paris,” 1767, _Mém._ p. 344.

REFERENCES.--English Encycl., “Arts and Sciences,” Vol. VIII. p. 65; “Johnson’s Encycl.,” Vol. IV. p. 757; “Penny Ency.,” Vol. XXIV. p. 146; Shaffner, “Manual,” pp. 27, 45 and 48; “Le Cosmos,” Paris, Feb. 4, 1905, p. 128; Nicholson’s “Journ. of Nat. Phil.,” Vol. VIII. p. 164, note; _Sc. American Supplement_, No. 475, p. 7579; “Emporium of Arts and Sciences,” Vol. I. p. 292; Rozier, XXXIV. p. 370, and XL. p. 329; “Bull. des Sc. de la Société Philomathique,” March 1793, No. 21, for an account of the experiments of Galvani and of Valli repeated for the Society by C. Chappe, M. Robillard and A. F. de Silvestre.

=A.D. 1792.=--Valli (Eusebius), Italian physician of Pisa, corresponding member of the Royal Academy of Sciences at Turin, publishes his “Experiments on Animal Electricity” the results of which were communicated to the French Academy of Sciences and found to be of such great importance that a committee composed of Messrs. Le Roy, Vicq d’Azyr, Coulomb and Fourcroy, was directed to repeat them. The most important were repeated in Fourcroy’s laboratory on the 12th of July 1792.

Valli was the first to demonstrate that when an arc of two metals, plumber’s lead and silver, is employed upon an animal, the most violent contractions are produced while the lead is applied to the nerves and the silver to the muscles. He also showed that of all metals, zinc, when applied to the nerves, has the most remarkable power of exciting contractions; and he found that when a frog had lost its sensibility to the passage of a current, it regained it by repose.

These experiments were also repeated before the French Royal Society of Medicine. M. Mauduyt, who was present, deduced from the results obtained by Valli that the metals were charged with a different quantity of the electric fluid, in so much that when they were brought in contact with each other a discharge ensued. And, secondly, that the animal body, by which the electric fluid is rendered perceptible, is a more delicate electrometer than any one heretofore discovered.

Many new and very interesting investigations were afterward made by Valli upon different animals, the results of which were given to the public through the columns of the _Journal de Physique_ as shown below. These embrace thirteen experiments upon animals rendered insensible by means of opium and powdered tobacco, showing electricity to be independent of their vitality, as well as others to show that the electric fluid is necessary to man and animals. He fully established the identity of the nervous and the electric fluids, and proved that the convulsions took place by merely bringing the muscles themselves into contact with the nerves, without the intervention of any metal whatever. In answer to the inquiry of M. Vicq d’Azyr, member of the late French Academy of Sciences, he supported by nineteen experiments the assertion that however the blood vessels may be, as they assuredly are, conductors of electricity, the nerves alone prove capable of exciting muscular movements in consequence of the mode in which they are disposed.

REFERENCES.--Brugnatelli, _Annali di Chimica_, Vol. VII. pp. 40, 213, 228 (and pp. 138, 159, 186, 208 for Caldani); also the “Giornale Fis. Med. di Brugnatelli,” Vol. I. p. 264; Sue, “Histoire du Galvanisme,” Paris, An. X-1802, Vol. I. p. 45; “Société Philomathique,” Vol. I. pp. 27, 31, 43; _Journal de Physique_, Vol. XLI. pp. 66, 72, 185, 189, 193, 197, 200, 435; Vol. XLII. pp. 74, 238, the last named containing the “Lettre sur l’Electricité Animale” (“De animalis electricæ theoriæ ...” Mutinæ, 1792) sent by Valli to MM. De La Méthérie and Desgenettes; Report of MM. Chappe, Robillard and Silvestre on Valli’s and Galvani’s experiments (“Soc. Phil.” for March 1793, No. 21); Report of Messrs. Le Roy, Vicq d’Azyr and Coulomb in “Médecine éclairée par les Sciences Physiques,” Tome IV. p. 66; “Epitome of Electricity and Magnetism,” Philad., 1809, p. 133; “Versuche ... animal, electricität” of Karl Friedrich Kielmayer (Kielmaier) of the Tübingen University (Poggendorff, Vol. I. p. 1253; F. A. C. Gren, _Journal der Physik_, Vol. VIII for 1794); Floriano Caldani’s works, 1792–1795, and those of Leopoldo Marc-Antonio Caldani, 1757–1823; Junoblowiskiana Society, 1793–1795.

=A.D. 1793.=--Fontana (Felice), distinguished Italian experimental philosopher and physiologist, gives in his “Lettere sopra l’ Elettricità Animale,” the result of further extensive investigations carried on by him to ascertain more especially all the features of galvanic irritability and the peculiar actions of the several organs in cases of death by electricity. Some of his previous observations in the same line had already been made known through his “Di Moti dell’ Iride,” 1765, and “Richerche filosofiche,” 1775, all which led to an active correspondence in after years with the Italian Giochino Carradori, as will be seen by consulting the volumes of Luigi Valentino Brugnatelli’s well-known “Giomale Fisico-Medico” (Cuvier, in “Biog. Univ.,” Vol. XV. p. 8, par. 1816; “Giornale Fisico-Medico,” Vol. IV. p. 116).

Fontana (Gregorio), younger brother of Felice Fontana, likewise an able natural philosopher, succeeded the celebrated Ruggiero Giuseppe Boscovich in the Chair of Higher Mathematics at the University of Padua, and is the author of “Disquisitiones physico-mathematicæ,” Papiæ, 1780, as well as of many papers in the “Mem. della Soc. It. delle Scienze,” wherein he gives detailed accounts of many very interesting electrical observations. Mention of Gregorio Fontana’s name has already been made under Bennet, A.D. 1787.

REFERENCES.--Houzeau et Lancaster, “Bibl. Gén.,” Vol. I. part i. p. 334, and, for R. G. Boscovich, “The Edinburgh Encyclopædia,” 1830, Vol. III. pp. 744–749.

=A.D. 1793.=--Aldini (Giovanni), nephew of Luigi Galvani and one of the most active members of the National Institute of Italy, who succeeded his former instructor, M. Canterzani, in the Chair of Physics at the Bologna University, established in the last-named Institution a scientific society whose open object was to combat all of Volta’s works and which became very hostile to the organization already formed in the University of Pavia by Felice Fontana, Bassiano Carminati and Gioachino Carradori against the followers of Galvani. Similar societies espousing the cause of Volta were subsequently organized in England, at the suggestion of Cavallo and others, and during five years, the scientists of Europe were divided between the two discoverers, without, however, any material benefit accruing therefrom to either faction.

Aldini proved to be an indefatigable investigator, as shown by the numerous Memoirs sent by him to the publications named below, up to the month of October 1802, when he experimented before the Galvani Society of Paris. An account of these experiments is given in his “Essai théorique,” etc., where, among other results, attention is called to the curious fact that contractions can be excited in a prepared frog by holding it in the hand and plunging its nerves into the interior of a wound made in the muscle of a living animal (Figuier, “Exposition,” etc., Vol. IV. p. 308). His interesting investigations of the artificial piles of muscle and brain, first made by M. La Grave and shown to the French Galvani Society, are alluded to in _Nicholson’s Journal_, Vol. X. p. 30, in the _Journal de Physique_, An. XI. pp. 140, 159, 233, 472, and in Sturgeon’s “Scientific Researches,” Bury, 1850, p. 195.

Nearly all of Aldini’s experiments were successfully repeated in London at Mr. Wilson’s Anatomical Theatre, where Mr. Cuthbertson assisted Prof. Aldini in arranging the apparatus, and where a student, by the name of Hutchins, furnished the anatomical preparations, but the demonstration, of all others, which attracted most attention was doubtless the one made in London on the 17th of January 1803. The murderer Forster had just been executed and, after his body lay for one hour exposed in the cold at Newgate, it was handed over to Mr. Koate, President of the London College of Surgeons, who, with Aldini, made upon it numerous important observations to ascertain the precise effects of galvanism with a voltaic column of one hundred and twenty copper and zinc couples. The extraordinary results obtained, which cannot properly be enumerated here, are to be found in the “Essai Théorique,” etc., already alluded to. They led Aldini to believe he could, by the galvanic agency, bring back those in whom life was not totally extinct, such as in cases of the recently drowned or asphyxiated. (Consult M. Bonnejoy’s method of proving death by ... Faradization, Paris, 1866, and Georgio Anselmo, “Effets du Galvanisme ...” Turin, 1803; S. T. Sömmering, “On the application of Galvanism to ascertain the reality of death,” Ludwig scripter nevrolog., III. 23; Ure, “Exper. on the body of a criminal ...” “Journal of Sc. and Arts,” No. XII; _Phil. Mag._, Vol. LIII. p. 56; Jean Janin de Combe Blanche, “Sur les causes,” etc., Paris, 1773 (hanging); C. W. Hufeland, 1783, for the app. of Elec. in cases of asphyxia; T. Kerner, for the app. of Galv. and Magn. as restoratives, Cannstadt, 1858; Wm. Henley, for electricity as a stimulant ... drowned or ... suffocated, “Trans. of the Humane Society,” Vol. I. p. 63.)

Another of Aldini’s curious experiments was the production of very powerful muscular contractions upon the heads of oxen and other animals recently decapitated, by introducing into one of the ears a wire connecting with one of the battery poles and into the nostrils or tongue a wire communicating with the other pole. Thus were the eyes made repeatedly to open and roll in their orbits while the ears would shake, the tongue move and the nostrils dilate very perceptibly (De la Rive, “A Treatise on Electricity,” 1856, Vol. II. p. 489, and 1858, Vol. III. p. 588; Pepper, “Voltaic Electricity,” 1869, pp. 287, 288). In the experiments which Aldini made during 1804 upon corpses, the body became violently agitated and even raised itself as if about to walk, the arms alternately rose and fell and the forearm was made to hold a weight of several pounds, while the fists clenched and beat violently the table upon which the body lay. Natural respiration was also artificially re-established and, through pressure exerted against the ribs, a lighted candle placed before the mouth was several times extinguished.

For the experiments of the eminent French physiologist and anatomist Marie François Xavier Bichat, of Vassalli-Eandi, Giulio, Rossi, Nysten, Hallé, Mezzini, Klein, Bonnet, Pajot-Laforest, Dudoyon, Berlinghieri, Fontana, Petit-Radel, Alizeau, Lamartillière, Guillotin, Nauche and others upon animals and men recently decapitated, see Bichat’s “Recherches Physiologiques sur la vie et la mort,” Paris, 1805; Francesco Rossi’s “Rapport des expériences,” etc., Turin, 1803; P. H. Nysten’s “Nouvelles Expériences Galvaniques,” etc., Paris, 1811, and also the latter’s “Expériences faites ... le 14 Brumaire, An. XI.” (Consult likewise, J. R. P. Bardenot, “Les Recherches ... refutées,” Paris, 1824, and, for an account of Bichat consult F. R. Buisson, “Précis historique ...” Paris, 1802; Larousse, Vol. II. pp. 703, 704; “Biog. Univ.,” Vol. XI. pp. 2–19.)

In Aldini’s “Account of Galvanism,” printed for Cuthell and Martin, London, 1803, it is said (p. 218) that, on the 27th of February 1803, he transmitted current through a battery of eighty silver and zinc plates from the West Mole of Calais harbour to Fort Rouge, by means of a wire supported on the masts of boats, and made it return through two hundred feet of intervening water.

REFERENCES.--J. B. Van Mons’ treatise on animal electricity in Tome III of the sixth year of the “Magasin Encyclopédique”; Fowler, in “Bibl. Britannica,” May 1796; Giulio e Rossi (“Gior. Fis. Med. di Brugnatelli,” 1793, Vol. I. p. 82); P. Sue, ainé, “Hist. du Galvanisme,” Paris, An. X, 1802, Vol. I. pp. 31, 67, 73; Vol. II. p. 268; Brugnatelli, _Annali di Chimica_, Vols. XIII. p. 135; XIV. p. 174; XIX. pp. 29, 158; “Opuscoli Scelti,” Vols. XVII. p. 231; XIX. p. 217; XX. p. 73; XXI. p. 412; “Mem. Soc. Ital.,” Vol. XIV. p. 239; Poggendorff, Vol. I. p. 27; “Bibl. Britan.,” Vol. XXII. 1803, pp. 249–266; “Galvanische und elektrische ... Körpern,” 4to, Frankfort, 1804; “Bull. des Sc. de la Soc. Philom.,” No. 68; J. C. Carpue, “Bibl. Britannica,” Nos. 207, 208, p. 373; _Phil. Mag._, Vols. XIV. pp. 88, 191, 288, 364; XV. pp. 40, 93; Cassius Larcher, M. Daubancourt et M. Zanetti, ainé (_Ann. de Chimie_, Vol. XLV. p. 195); also Larcher, Daubancourt et M. de Saintiot (Précis succinct, etc., Paris, 1803); W. Sturgeon, “Scientific Researches,” Bury, 1850, p. 194; M. Kilian, “Versuche über restitution ...” Giessen, 1857; Gilbert, IV. 246; J. Tourdes (“Décade Philos.” No. 3, An. X. p. 118); Francesco Rossi (“Bibl. Ital.,” Vol. I. p. 106; _Phil. Mag._, Vol. XVIII. p. 131; and in the “Mémoires de Turin”); J. J. Sue, “Recherches Physiol.,” etc., 1803, p. 77; Vassalli-Eandi (“Expériences sur les décapités ...” Turin, 1802 and “Recueil ... de Sédillot,” Vol. II. p. 266); C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 Vols. _passim_; Report of MM. Chappe, Robillard and Silvestre (“Bull. des Sciences de la Soc. Philom.,” No. 21 for March 1793; also _Jour. de Phys._, Vol. XLII. p. 289); M. Payssé (“Jour. de la Soc. de Pharm.,” first year, p. 100); Dr. Crichton (“Rec. Périod. de Litt. Méd. Etrangère,” Tome II. p. 342); J. Louis Gauthier, “Dissertatio,” etc., Hales, 1793 (“Com. de Leipzig,” Tome XXXVI. p. 473); Gardiner’s “Observ. on the animal œconomy”; Humboldt (“Soc. Philom.,” Vol. I. p. 92); Alex. Monro’s “Experiments,” etc., Edin., 1793, 1794 (“Trans. Edin. Roy. Soc.,” Vol. III); Felice Fontana, “Lettere ...” 1793; Joseph Izarn, “Manuel du Galvanisme,” Paris, An. XII, 1804, pp. 97, 138, 141, 160, 163, 285; Louis Figuier, “Exposition et Histoire,” Vol. IV. pp. 307–308, 358, 360–363, 365, 366, 370, 371.

=A.D. 1793.=--Fowler (Richard), a very ingenious physician, of Salisbury, makes known in Edinburgh his “Experiments and Observations relative to the influence lately discovered by Galvani and commonly called Animal Electricity,” of which a very complete review is made by Dr. G. Gregory at pp. 374–381, Vol. I of his “Economy of Nature,” etc., third edition, published in London during the year 1804.

Dr. Fowler observed that the contractions in a frog are excited by making the metals touch under water even at the distance of an inch from the divided spine of the animal. He succeeded in causing the heart to contract, but could not produce the same effect upon the stomach and intestines. He also found, as did Prof. John Robison, of Edinburgh, at the same period, that the senses of touch and smell are unaffected by the metals, but that when these are applied to the eye, or, what is better, when they are thrust up between the teeth and the lips, and then made to touch, a flash of light is rendered visible. This is the case also when the metals are placed between the gums and the upper and lower lips, as proven by the experiments of Dr. Rutherford and of Mr. George Hunter, of York. Fowler likewise observed that all pure metals prove excellent conductors of the galvanic influence and that living vegetables afford it a ready passage, but that stones and oils seem to be possessed of no conducting power whatsoever.

In conjunction with Mr. Alexander Munro, Fowler published a work on animal electricity (translated into German under the title of “Abhandlung ueber thierische elekt.” etc.), while, in the “Bibliotheca Britannica” for May 1796, mention will be found of the observations of Dr. Fowler respecting the muscular irritability excited by electricity, as well as on the reproduction of the nervous substance, on the action of poisons, on the phenomena of muscular contraction, etc. etc.

REFERENCES.--“Essays and Observations,” etc., Edinburgh, 1793, in Library of the Royal Institution; Gilbert Blane’s paper read to the English Royal Society, of which an extract can be found in Bacher’s “Medical Journal,” Vol. XC. p. 127; Figuier, “Exp. et Hist. des Princip. Déc.,” Vol. IV. p. 309; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Chap. VI. _et passim_; eighth “Encyc. Brit.,” Vol. XXI. p. 634.

=A.D. 1793.=--Dalton (John), LL.D., F.R.S. (1766–1844), a very able English natural philosopher and the illustrious author of the “Atomic Theory of Chemistry and of the Constitution of Mixed Gases,” gives in his earliest separate publication, “Meteorological Observations and Essays,” the result of many experiments upon the electricity of the atmosphere, made by him at Kendal and at Keswick during the seven years ending May 1793.

He proved, as Sir David Brewster expresses it, that the aurora exercises an irregular action on the magnetic needle, that the luminous beams of the aurora borealis are parallel to the dipping needle; that the rainbow-like arches cross the magnetic meridian at right angles; that the broad arch of the horizontal light is bisected by the magnetic meridian; and that the boundary of a limited aurora is half the circumference of a great circle crossing the magnetic meridian at right angles, the beams perpendicular to the horizon being only those on the magnetic meridian.

In the eighth “Encyclopædia Britannica” (Vol. IV. p. 246), treating of the height of polar lights, reference is made to the extraordinary aurora borealis observed by Dalton on the 29th of March 1826, and of which a description is given in a paper read before the Royal Society, April 17, 1828 (_Phil. Mag. or Annals_, Vol. IV. p. 418; _Philosophical Transactions_ for 1828, Part II; James Hoy in _Phil. Mag._, Vol. LI. p. 422; J. Farquharson in _Phil. Trans._ for 1839, p. 267). This aurora was seen in places one hundred and seventy miles apart and covered an area of 7000 to 8000 square miles. In Vol. XIV of the same Encyclopædia will be found (p. 15), an account of another aurora observed at Kendal, February 12, 1793, while at p. 12 are given Dalton’s views as to the connection between the heat and magnetism of the earth, and, at p. 66, his conclusions as to the cause of the aurora and its magnetic influence.

REFERENCES.--“Memoirs of Dalton’s Life,” by Dr. W. C. Henry, London, 1854; “Life and Discoveries of Dalton,” in _British Quarterly Review_, No. 1; _Pharmaceutical Journal_, London, October 1841; Thomson’s “History of Chemistry,” Vol. II; Young’s “Course of Lectures,” London, 1807, Vol. I. pp. 706–709, 753, and Vol. II. pp. 466–470; Noad, “Manual,” etc., London, 1859, pp. 226, 269, 534; article, “Aurora Borealis,” immediately following A.D. 1683; Sir H. Davy, “Bakerian Lectures,” London, 1840, pp. 322, 323, 328–330; “Dict. of Nat. Biog.,” Vol. XIII. pp. 428–434, as well as the numerous references therein cited. Consult also, for theories, investigations, observations, records, etc., of the Aurora Borealis: Georg. Kruger, 1700; J. J. Scheuchzer, 1710–1712, 1728–1730; L. Feuillée, 1719; J. L. Rost, 1721; J. C. Spidberg, 1724; W. Derham, 1728, 1729–1730; F. C. Mayer--Meyer, 1726; J. F. Weidler, 1729, 1730, 1735; J. Lulolfs, 1731; M. Kelsch, 1734; F. M. Zanotti, 1737, 1738; also Zanotti and P. Matteucci, 1739; B. Zendrini, J. Poleni, F. M. Serra, E. Sguario and D. Revillas in 1738; G. Bianchi, 1738 and 1740; J. M. Serantoni, 1740; G. C. Cilano de Maternus, 1743; S. von Trienwald, 1744; G. Guadagni, 1744; J. F. Ramus, 1745; C. Nocetus, 1747; P. Matteucci, 1747; Jno. Huxham, 1749–1750; G. W. Krafft, 1750; P. Kahm--Kalm, 1752; G. Reyger, 1756; A. Hellant, 1756, 1777; Jos. Stepling, 1761; H. Hamilton, 1767, 1777; M. A. Pictet, 1769; J. E. Silberschlag, 1770; C. E. Mirus, 1770; J. E. B. Wiedeburg, 1771; Max. Hell, 1776; Mr. Hall, J. H. Helmuth, 1777; E. H. de Ratte, W. L. Krafft, 1778; J. E. Helfenzrieder, 1778; G. S. Poli, 1778–1779; Marcorelle and Darguier, 1782; L. Cotte, 1783; J. A. Cramer, 1785; D. Galizi, in A. Calogera’s “Nuova Raccolta ...” Vol. XXXIX. p. 64; J. L. Boeckmann, in “Mem. de Berlin” for the year 1780; H. Ussher, 1788; G. Savioli, 1789, 1790; J. J. Hemmer, 1790; P. A. Bondoli, 1790, 1792, 1802; A. Prieto, 1794; J. D. Reuss’s works published in Göttingen; Jacopo Penada, 1807–1808; M. Le Prince, “Nouvelle Théorie ...”; W. Dobbie, 1820, 1823; Col. Gustavson, in _Phil. Mag._ for 1821, p. 312; M. Dutertre, 1822; J. L. Späth, 1822; Chr. Hansteen, 1827, 1855; L. F. Kaemtz, 1828, 1831; G. W. Muncke, 1828; J. Farquharson, 1829; D. Angelstrom, Rob. Hare, 1836; Ant. Colla, 1836, 1837; L. Pacinotti, 1837; G. F. Parrot, 1838; J. H. Lefroy, 1850, 1852; Don M. Rico-y-Sinobas, 1853; A. A. de La Rive, 1854; A. Boué (_Katalog_), 1856, 1857; C. J. H. E. Braun, 1858; E. Matzenauer, 1861; F. Dobelli, 1867; F. Denza, 1869.

=A.D. 1793–1797.=--Robison (John), a very distinguished English natural philosopher, completes what are without question the most important of all his scientific publications. These are to be found throughout the eighteen volumes and two supplements to the third “Encyclopædia Britannica,” where they cover such subjects as Physics, Electricity, Magnetism, Thunder, Variation, etc. etc. Taken together, “they exhibited,” according to Dr. Thomas Young, “a more complete view of the modern improvements of physical science than had previously been in the possession of the British public.”

It was after his retirement from the navy that Robison devoted himself to scientific studies, becoming the successor of Dr. Black in the lectureship of chemistry at the University of Glasgow during 1766, and accepting, seven years later (1773), the Professorship of Natural Philosophy at Edinburgh, where he taught all branches of physics and of the higher mathematics. In 1783 he was made Secretary of the Philosophical Society of Edinburgh, received the degree of Doctor of Laws, 1798–1799, and was elected foreign member of the Saint Petersburg Academy of Sciences in 1800. Of him, Mr. James Watt wrote, Feb. 7, 1805: “He was a man of the clearest head and the most science of anybody I have known” (Arago’s “Eloge of Jas. Watt,” London, 1839, p. 81).

It was while acting as midshipman under Admiral Saunders that Robison himself observed the effect of the aurora borealis on the compass, which had been remarked by Hiörter, Wargentin, and Mairan several years before, but which was not then generally known. The aurora borealis, he afterwards wrote, “is observed in Europe to disturb the needle exceedingly, sometimes drawing it several degrees from its position. It is always observed to increase its rate of deviation from the meridian; that is an aurora borealis makes the needle point more westerly. This disturbance sometimes amounts to six or seven degrees, and is generally observed to be greatest when the aurora borealis is most remarkable.... Van Swinden says he seldom or never failed to observe aurora borealis immediately after any anomalous motion of the needle, and concluded that there had been one at the time, though he could not see it.... This should farther incite us to observe the circumstance formerly mentioned, viz., that the South end of the dipping needle points to that part of the heavens where the rays of the aurora borealis appear to converge....”

The experiments of J. H. Lambert (at A.D. 1766–1776) upon the laws of magnetic action were carefully repeated by Robison, who, in 1769 or 1770, tried various methods and made numerous investigations from which he deduced that the force is inversely as the square of the distance. When he observed, however, some years afterward, that Æpinus had in 1777 conceived the force to vary inversely as the simple distance, he carefully again repeated the experiments and added others made with the same magnet and with the same needle placed at one side of the magnet instead of above it. By this simple arrangement the result was still more satisfactory, and the inverse law of the square of the distance was well established.

Throughout his numerous investigations, Prof. Robison found that when a good magnet was struck for three-quarters of an hour, and allowed in the meantime to ring, its efficacy was destroyed, although the same operation had little effect when the ringing was impeded; so that the continued exertion of the cohesive and repulsive powers appears to favour the transmission of the magnetic as well as of the electric fluid. The internal agitation, produced in bending a magnetic wire around a cylinder, also destroys its polarity, and, it is said, the operation on a file has the same effect. M. Cavallo found that brass becomes generally much more capable of being attracted when it has been hammered, even between two flints; and that this property is again diminished by fire: in this case, Dr. Thomas Young remarks, it may be conjectured that hammering increases the conducting power of the iron contained in the brass, and thus renders it more susceptible of magnetic action.

Of his other very important observations in the same line it would be difficult to select the most interesting, and it may suffice to call attention merely to such as are noted throughout Prof. Alfred M. Mayer’s valuable contributions on “The Magnet, Magnetism,” etc., in Johnson’s “New Universal Encyclopædia,” as well as in his “Practical Experiments in Magnetism,” etc., published through the columns of the _Scientific American Supplement_.

Prof. Robison’s electrical investigations are scarcely less interesting. In the theories advanced by Æpinus and Cavendish it was shown that the action of the electrical fluid diminished with the distance, while M. Coulomb proved, by a series of elaborate experiments, that it varied like gravity in the inverse ratio of the square of the distance. Robison had previously determined that in the mutual repulsion of two similarly electrified spheres the law was slightly in excess of the inverse duplicate ratio of the distance, while in the attraction of oppositely electrified spheres the deviation from that ratio was in defect; and he therefore arrived at the same conclusion formed by Lord Stanhope, that the law of electrical attraction is similar to that of gravity.

At the close of Richard Fowler’s “Experiments and Observations,” etc., Edinburgh, 1793, is a letter from Prof. Robison, wherein he gives the following results of many curious investigations, mostly made upon himself, to ascertain the effects of the galvanic influence. He found the latter influence well defined on applying one of two metallic substances to a wound which he had accidentally received; discovered by their tastes the solders in gold and silver trinkets; and showed that the galvanic sensation can be felt when the metallic substances are placed at a distance from each other. He proved the last-named fact by placing a piece of zinc between one of the cheeks and the gums, and a piece of silver on the opposite side within the other cheek. He next introduced a zinc rod between the piece of zinc and the cheek on the one side, and a silver rod between the silver and the cheek on the other, and when he afterward carefully brought into contact the extremities of the rods outside the mouth a flash appeared and a powerful sensation was noticeable in the gums. He experienced the same sensation when he again separated the rods and brought them to a short distance from each other, but he could perceive no galvanic effect when he placed the rods (or wires) in such manner that the silver rod should touch the zinc or the zinc rod touch the piece of silver. He also ascribed to galvanic effect the well-known fact that the drinking of porter out of a pewter pot produces a more brisk sensation than when it is taken out of a glass vessel. In this instance, he says there is a combination of one metal and of two dissimilar fluids. In the act of drinking, one side of the pewter pot is exposed to the saliva and the humidity of the mouth, while the other metallic side is in contact with the porter. In completing the circuit, in the act of drinking, a brisk and lively sensation arises, which imparts an agreeable relish to the liquid. He likewise observed that the conducting power of silk thread depends greatly on its colour, or rather on the nature of its dye. When of a brilliant white, or a black, its conducting power is the greatest; while either a high golden yellow or a nut-brown renders it the best insulator. Human hair, when completely freed from everything that water could wash out of it, and then dried by lime and coated with lac, was equal to silk.

Robison’s last publication was made in 1804, one year before his death, and constituted the first part of a series which was to appear under the head of “Elements of Mechanical Philosophy.” This portion, together with some MSS. intended for the second part, and his principal articles contributed to the “Encyclopædia Britannica,” were collected in 1822 by Sir David Brewster, and published with notes in 4 vols. under the title of “System of Mechanical Philosophy.”

REFERENCES.--Playfair in “Transactions of the Royal Society of Edinburgh,” Vol. VII. p. 495; Stark’s “Biographia Scotica”; _Philosophical Magazine_, Vol. XIII. pp. 386–394 (Biogr. Memoir); Aikin’s “General Biography,” London, 1813, Vol. VIII; Dr. Gleig in _Anti-Jacobin Magazine_ for 1802, Vol. XI; Chalmer’s “Biographical Dictionary,” London, 1816, Vol. XXV; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. II. pp. 438, 444.

=A.D. 1793.=--Prof. Georg. Fred. Hildebrandt of Erlangen (1764–1816), makes important observations relative to the influence of form and of substance upon the electric spark. He finds, among other results, that an obtuse cone with an angle of fifty-two degrees gives a much more luminous spark than one with an angle of only thirty-six degrees; that the greatest sparks are given by conical pieces of regulus of antimony and the least by tempered steel; also, that when the spark is _white_ by taking it with a metallic body, it will, under the same circumstances, be _violet_ if taken with the finger; that if the spark is taken with ice or water, or a green plant, its light will be red, and, if it is taken with an imperfect conductor, such as wood, the light will be emitted in faint red streams.

REFERENCES.--Biography in fifth ed. of “Lehrbuch der Physiologie des Mens. Koerpers,” Erlangen, 1817; “Encyl. Britannica,” Vol. VIII, 1855, pp. 544, 545; “Biog. Générale,” Vol. XXIV. pp. 671–672; Ersch und Gruber, “Allgem. Encyklopædie.”

=A.D. 1794.=--Read (John), mathematical instrument maker, at the Quadrant, in Kingsbridge, Hyde Park, gives, in his “Summary View of the Spontaneous Electricity of the Earth and Atmosphere,” the result of a very elaborate series of observations, which he continued almost hourly between the years 1791 and 1792. Of 987 trials, he found that 664 gave indications of positive electricity, and out of 404 trials made during twelve months, the air was positively electrical in 241, negatively in 156, and insensible in only seven observations. He also found the vapour near the ground, in the act of condensing into dew, always highly electric.

He made many observations upon the electricity of vegetable bodies, which were afterward developed by M. Pouillet, and it was also Mr. Read who introduced a new hand-exploring instrument as well as an improved fixed thunder rod for collecting atmospherical electricity. These are described at p. 608 of the eighth volume of the 1855 “Encyclopædia Britannica.”

According to Mr. Wilkinson (“Elements of Galvanism,” etc., London, 1804, Vol. II. p. 344), Mr. Read was the first to apply the apparatus called the condenser to the electroscope in order that it should evince small intensities of electricity. He says: “The very minute portion of the fluid given out by the single contact of two different metals, does not produce any disturbance of the gold leaves; but when several minute portions are accumulated, a separation of the leaves takes place. The electroscope, in its simple state, will be as much charged the first time as if the contact had been made a thousand times, and cannot therefore acquire a greater quantity of the fluid than suffices to place it _in equilibrio_ with the metallic plates. This portion being inadequate to the production of any divergency of the leaves, Mr. Read applied the principle of the electrical doubler to the above instrument, by which means he was enabled to charge an intervening plate of air. By thus accumulating every minute portion of the fluid imparted through the metallic plate, and by apparently condensing and increasing its intensity, he ultimately succeeded in producing marked signs of disturbance.”

REFERENCES.--_Philosophical Transactions_ for 1791, p. 185; for 1792, p. 225; for 1794, pp. 185, 266: also Hutton’s abridgments, Vol. XVII. pp. 52, 207, 423; “Bibl. Britan.,” Vol. II, 1796, p. 209; Vol. III, 1796, p. 272; Vol. X, an. vii. p. 283; Cavallo, “Nat. Phil.,” 1825, Vol. II. p. 226; Young’s “Course of Lectures,” Vol. I. p. 714; Ed. Peart, “On Electric Atmospheres ...” Gainsboro’, 1793; “Eng. Ency.,” “Arts and Sciences,” Vol. III. p. 805; Thomas Thomson, “Outline of the Sciences,” 1830, p. 446; _Journal de Physique_ for 1794, Vol. XLV. p. 468.

=A.D. 1794.=--Chladni (Ernst Florens Friedrich), founder of the theory of acoustics, publishes “The Iron Mass of Pallas,” etc. (“Ueber den Ursprung der von Pallas ...”), giving a list of recorded cases of the fall of meteorites or aerolites and all the important accounts of such that he was able to collect. As Prof. Alexander Herschel informs us, in his lecture, delivered (1867) before the British Association at Dundee, Chladni conceived that a class of cosmical bodies exists in all parts of the solar system, each forming by itself a peculiar concourse of atoms, and that the earth from time to time encounters them, moving with a velocity as great as its own, and doubtless in orbits of very various eccentricity around the sun. Prof. Muirhead says that through their exceeding great velocity, which is increased by the attraction of the earth and the violent friction of the atmosphere, a strong electricity and heat must necessarily be excited, by which means they are reduced to a flaming and melted condition, and great quantities of vapour and different kinds of gases are thus disengaged, which distend the liquid mass to a monstrous size, until, by still further expansion of these elastic fluids, they must at length explode (Chladni’s hypothesis in “Enc. Brit.,” article “Meteorolite”).

Humboldt gives (“Cosmos,” London, 1849, Vol. I. p. 104, note) the following upon the same subject, taken from Biot’s “Traité d’Astronomie Physique,” third edition, 1841, Vol. I. pp. 149, 177, 238, 312: “My lamented friend Poisson endeavoured in a singular manner to solve the difficulty attending an assumption of the spontaneous ignition of meteoric stones at an elevation where the density of the atmosphere is almost null. These are his words: ‘It is difficult to attribute, as is usually done, the incandescence of aerolites to friction against the molecules of the atmosphere, at an elevation above the earth where the density of the air is almost null. May we not suppose that the electric fluid, in a neutral condition, forms a kind of atmosphere, extending far beyond the mass of our own atmosphere, yet subject to terrestrial attraction, although physically imponderable, and consequently following our globe in its motion?’ According to his hypothesis, the bodies of which we have been speaking would, on entering this imponderable atmosphere, decompose the neutral fluid by their unequal action on the two electricities, and they would thus be heated, and in a state of incandescence, by becoming electrified” (Poisson, “Rech. sur la Probabilité des Jugements,” 1837, p. 6).

The theories advanced by Chladni were confirmed four years later by Brandes and Benzenberg at Göttingen, and, during the month of April 1809, he inserted a “Catalogue of Meteors” in the “Bulletin de la Société Philomathique,” which was followed by a paper on “Fiery Meteors” published at Vienna during 1819.

In his “Traité d’Acoustique,” Chladni treats of the line of experiments to which he was led, as well by the discovery of Lichtenberg’s electrical figures (see A.D. 1777, and Tyndall, “Sound,” Lecture IV), an account of which latter appeared in the “Mémoires de la Société Royale de Göttingen,” as through the suggestions made him by Lichtenberg himself during the year 1792 relative to the origin of meteors. The results of Chladni’s researches concerning the last named appeared in a Memoir published at Leipzig during 1794, translated by M. Eugène Coquebert Mombret for Vol. V of the _Journal des Mines_.

It may here be properly added that, in one of the editions of his “Lectures on Sound,” Prof. Tyndall gives a portrait of Chladni and quotes a letter received from Prof. Weber wherein he says: “I knew Chladni personally. From my youth up he was my leader and model as a man of science, and I cannot too thankfully acknowledge the influence which his stimulating encouragement during the last years of his life had upon my own scientific labours.”

REFERENCES.--Quetelet (Lambert A. J.) in “Cat. Sc. Pap. Roy. Soc.,” Vols. V, VI, VIII; “Mém. de l’Acad. Roy. de Brux.,” 1830–1842; “Annali” of Ambroglio Fusinieri for 1854; “Phil. Mag.,” 1851; Secchi (Angelo) in “Cat. Sc. Pap. Roy. Soc.,” Vols. V, VIII; “Bull. Meteor. dell Osservat.,” 1862, 1866, 1867; Humboldt’s “Cosmos,” London, 1849, Vol. I. p. 104 (M. Schreiber), pp. 113, 114 (M. Capocci), also pp. 105, 108, 110, 121, and the entire “Review of Natural Phenomena,” with all the important references and notes thereunto attached. See likewise Peter Simon Pallas (_Phil. Trans._ for 1776 and “Act. Acad. Petrop.,” I for 1778); Chladni’s “Uber ... elektricität einer Katze,” Jena, 1797; J. Acton and Capel Lofft, in _Phil. Mag._, Vol. LI. pp. 109, 203; A Seguin, _Phil. Mag._, Vol. XLIV. p. 212; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 714, 762, for étoiles, filantes et météorites; F. B. Albinus, “Specimen,” etc., 1740; Voigt’s “Magaz.,” I, 1797; Schweigger’s _Journal_, XLIII, 1825; H. Atkinson, “On Hypotheses,” etc. (_Phil. Mag._, Vol. LIV. p. 336); Karstner, _Archiven_, Vol. IV; F. C. Von Petersdorff in “Great Divide”; Pierre Prevost and others in Poggendorff’s _Annalen_, Vols. II, VI and VII; Arago, “Annuaire pour 1826”; “The fall of Meteorites in Ancient and Modern Times” (“Sc. Progress,” Vol. II. N.S., pp. 349–370: numerous references given by Prof. H. A. Miers; “A Century of the Study of Meteorites,” by Dr. Oliver C. Farrington in “Pop. Sc. Monthly,” Feb. 1901, or the Report of Smiths. Instit. for 1901, pp. 193–197; _Phil. Mag._, Vol. IV. p. 332; “Cat. Sc. Papers ... Roy. Soc.,” Vol. I. pp. 916–918; D. Avelloni “Lettera,” etc., Venezia, 1760; Martin H. Klaproth’s different memoirs published at Berlin 1795–1809; Joseph Izarn, “Lithologie Atmosphérique”; J. Murray (_Phil. Mag._, Vol. LIV. p. 39); beside Chladni’s works in conjunction with Karl F. Anton von Schreibers, Wien, 1819 and 1820, and with Messrs. Steininger and Næggerath, London, 1827 (Schweigger’s _Journal_, N.R., XVI. 385, and _Phil. Mag._, Vol. II. p. 41, also Vol. IV. p. 332). For a very interesting account, see “A description of the great Meteor which was seen on the 6th of March 1715–1716, sent in a letter ... to R. Danuye ...” London, 1723 (_Phil. Trans._ for 1720–1721, Vol. XXXI), by Roger Cotes (1682–1716), of whom Sir Isaac Newton entertained so high an opinion as to frequently remark: “_If Mr. Cotes had lived, we had known something_” (“Biographia Philosophica,” pp. 512–516; English Encycl., “Biography,” Vol. II. p. 401). Other exceedingly interesting accounts of aerolites are to be found, more particularly in Frederic Petit’s works, published at Toulouse, in Bigot de Morogue’s “Catalogue,” London, 1814, and in the _Phil. Mag._, Vols., XVII, XX, XXVIII, XXXII, XXXVI, XLIII, XLVI, XLVIII, L, LIII, LIV, LVI-LIX, LXII. While treating of this subject, it may be well to add here that up to the year 1887 diamonds were not known to exist in meteorites. In a very remarkable paper by Prof. A. E. Foote, read before the Geological section of the Am. Asso. Adv. Sci., at its meeting in Washington, he described having, during the month of June 1891, explored Crater Mountain (Cañon Diablo), 185 miles north of Tucson, Ariz., where he found some extraordinary specimens. The extreme hardness of one of these attracted particular attention, and upon carefully examining it he discovered in some of the cavities many small black diamonds as well as a white diamond one-fiftieth of an inch in diameter. This is said to be the most extensive find of the kind yet made.

=A.D. 1794.=--Mr. J. Churchman publishes his improved “Magnetic Atlas or Variation Charts of the whole terraqueous globe,” etc., which Sir John Leslie subsequently pronounced the most accurate and complete hitherto made. The charts preceding it worthy of note were those of Dr. Halley (see A.D. 1683), of Mountaine and Dodson, in 1744 and in 1756, of Wilcke, in 1772, and of Lambert, in 1779. In his charts, Churchman refers variation lines to two poles, one of which he places, for the year 1800, in lat. 58° N. and long. 134° W. of Greenwich, while the other pole is in lat. 58° S. and long. 165° E. of Greenwich. He supposes the northern pole to revolve in 1096 years and the southern one in 2289 years (“Ency. Brit.,” 1857, Vol. XIV. p. 49).

REFERENCES.--Churchman’s letters to Cassini, Phila., 1788, and his “Explanation of the Magn. Atlas ...” 1790; Harris, “Rudim. Mag.,” Part III. p. 101; “Bibl. Britan.,” Vol. II. 1796, p. 325 (atlas); Becquerel, “Traité d’Electr. et de Magn.,” Paris, 1856, III. p. 140.

=A.D. 1794.=--M. Reusser Reiser, of Geneva, addresses a letter to the “Magazin für das Neueste aus der Physik” of Johann Heinrich Voigt (Vol. IX. part i. p. 183), describing the construction of “a new species of electric letter post” (“Schreiben an den herausgeber”) in the following words: “... on an ordinary table is fixed, in an upright position, a square board, to which a glass plate is fastened. On this plate are glued little squares of tinfoil, cut after the fashion of luminous panes, and each standing for a letter of the alphabet. From one side of these little squares extend long wires, enclosed in glass tubes, which go underground to the place whither the despatch is to be transmitted. The distant ends are there connected to tinfoil strips, similar ... to the first, and, like them, each marked by a letter of the alphabet; the free ends of all the strips are connected to one return wire, which goes to the transmitting table. If, now, one touches the outer coating of a Leyden jar with the return wire, and connects the inner coating with the free end of that piece of tinfoil which corresponds to the letter required to be indicated, sparks will be produced, as well at the near as at the distant tinfoil, and the correspondent there watching will write down the letter....”

Reusser also suggested calling the attention of the correspondent by firing an electrical pistol through the spark; to him, therefore, belongs the credit of having first clearly indicated the use of a special call for the telegraph.

REFERENCES.--Vail’s “History,” p. 121; Voigt’s “Magazin ...” Vol. VII. part ii. p. 57; Shaffner, “Manual,” pp. 133, 134; Forster’s “Bauzeitung,” 1848, p. 238; Ed. Highton, p. 38; Sabine, p. 11; “Appleton’s Encycl.,” 1871, Vol. XV. p. 335; Reiser, “Der El. Würfel,” Gotha, 1791; _Comptes Rendus_, Tome VII for 1838, p. 80.

=A.D. 1794.=--Prof. Boeckmann improves upon Reusser’s idea, and does away with the thirty-six plates and the seventy-two wires which the latter is believed to have employed. As Dr. Schellen expresses it, he used “the sparks passing at the distant station, employing only two wires, through which first one and then, after certain intervals, more sparks are combinedly grouped” in a way to indicate particular letters. Like Reusser, he made use of the pistol as a call signal.

REFERENCES.--Zetzsche, “Geschichte der Elektrischen Telegraphie,” p. 32; Boeckmann, “Versuch über Telegraphie und Telegraphen,” Carlsruhe, 1794, p. 17; “El. Magn. Teleg.,” 1850, p. 46; Gren’s _Journal der Physik_, Vol. I for 1790; “Neue Abhandl. der Bairischen Akad. Philos.,” Vol. III.

=A.D. 1794.=--Edgeworth (Richard Lovell), an able English mechanical philosopher, better known as the father and literary associate of Maria Edgeworth, introduces his _tellograph_ (contraction of the word _telelograph_), “a machine describing words at a distance,” which originated in a wager relative to the prompt transmission of racing news from Newmarket to London. It consisted merely of four pointers, in the form of wedges or isosceles triangles, placed upon four portable vertical posts and the different positions of which were arranged to represent letters and numbers.

Edgeworth claimed to have made experiments, as early as 1767, with an ordinary windmill, the arms and sails of which were arranged in different positions to indicate the several letters of the alphabet.

REFERENCES.--Edgeworth’s Letter to Lord Charlemont on the Tellograph, also his “Essay on the Art of Conveying Secret and Swift Intelligence,” Dublin, 1797, republished in Vol. VI of the _Trans. of the Royal Irish Academy_; “Appleton’s Encycl.,” 1871, Vol. XV. p. 334.

A.D. 1795.--Lord George Murray, of England, submits to the Admiralty his six-shutter telegraph, an improvement upon Chappe’s original plan. Each of the six octagonal shutters was made to turn inside of two frames at different angles upon its own axis, thus affording sixty-three separate and distinct signals. By its means, information was transmitted from London to Dover in seven minutes, and it answered nearly all the requirements of the Admiralty up to the year 1816, when it was superseded by the semaphore of Rear Admiral Popham. Murray’s method was, however, useless during foggy weather, when relays of horses had to be employed for conveying the news.

REFERENCES.--English Encyclopædia, “Arts and Sciences,” Vol. VIII. p. 66; Tomlinson’s “Telegraph”; Turnbull, _El. Mag. Tel._, 1853, p. 18; “Penny Ency.,” Vol. XXIV. p. 147.

=A.D. 1795.=--Salvá (Don Francisco), a distinguished Spanish physician, reads a memoir, before the Academy of Sciences of Barcelona, from which the following is extracted: “... with twenty-two letters, and even with only eighteen, we can express with sufficient precision every word in the language, and, thus with forty-four wires from Mataro to Barcelona, twenty-two men there, each to take hold of a pair of wires, and twenty-two charged Leyden jars here, we could speak with Mataro, each man there representing a letter of the alphabet and giving notice when he felt the shock.... It is not necessary to keep twenty-two men at Mataro nor twenty-two Leyden jars at Barcelona, if we fix the ends of each pair of the wires in such a way that one or two men may be able to discriminate the signals. In this way six or eight jars at each end would suffice for intercommunication, for Mataro can as easily speak with Barcelona as Barcelona with Mataro ... or the wires can be rolled together in one strong cable ... laid in subterranean tubes, which, for greater insulation, should be covered with one or two coats of resin.”

He is said to have approved of the use of luminous panes as indicated by Reusser; to have also suggested, as early as December 16, 1795, the idea of a _submarine telegraphic cable_ carrying several conductors, and to have proposed, at the same period, the laying of a cable between Barcelona and Palma in the island of Majorca.

In 1798, Salvá constructed a single wire telegraphic line between Madrid and Aranjuez, a distance of twenty-six miles, through which the signals were transmitted in the shape of sparks from Leyden jars. This is the line which is credited to Augustin de Bétancourt, a French engineer, by Alexander Von Humboldt, in a note at p. 14 of Gauss and Weber’s _Resultate_, etc., for the year 1837.

On the 14th of May 1800, and on the 22nd of February 1804, Salvá communicated to the Academy of Sciences at Barcelona two papers on galvanism applied to electricity, wherein he shows that a cheaper motive power is produced by the electricity of a number of frogs, and proposes a telegraphic apparatus in conjunction with the voltaic column which is illustrated and described at pp. 224 and 225 of Fahie’s “History of Telegraphy.” From the latter the following is taken: “This illustrious Spanish physician (Salvá) was therefore the first person who attempted to apply electricity dynamically for the purpose of telegraphing. It is, says Saavedra, not without reason, I must confess, notwithstanding my cosmopolitan opinions on scientific questions, that _the Catalans hold Salvá to be the inventor of electric telegraphy_. With documents as authentic as those which I have seen with my own eyes in the very hand writing of this distinguished professor (which documents are at this present moment to be found in the library of the Academy of Sciences of Barcelona) it is impossible for any author to henceforth deny, even if others did precede Salvá in telegraphic experiments with static electricity, that no one preceded him in the application of the docile electro-dynamic fluid to distant communications.”

REFERENCES.--_Comptes Rendus_, séance, 1838; Memorial of Joseph Henry, 1880, p. 224; Ed. Highton, the _El. Tel._, 1852, pp. 38 and 43; “Appleton’s Encyclopædia,” 1871, Vol. XV. p. 335; _De Bow’s Review_, Vol. XXV. p. 551; Voigt’s _Magazin_, etc., Vol. XI. part iv. p. 61; _Sc. Am. Supp._, No. 547, p. 8735, and No. 384, p. 6127; Biography in Saavedra’s _Revista_, etc., for 1876; Noad’s _Manual_, pp. 747 and 748; Shaffner, _Manual_, p. 135; Turnbull, _El. Mag. Tel._, 1853, pp. 21, 22, 220; Du Moncel, _Exposé_, Vol. III; “Edinburgh Encyclopædia,” London, 1830, Vol. VIII. p. 535; “Gazette de Madrid” of November 25, 1796; “Mémoires de l’Institut,” Vol. III and “Bulletin de la Soc. Philom.,” An. VI for the new telegraph of MM. Bréguet and Bétancourt, and for the Report made thereon by MM. Lagrange, Laplace and others.

=A.D. 1795.=--Ewing (John), D.D., Provost of the University of Pennsylvania and one of the founders of the American Philosophical Society, makes a compilation of his course of lectures on natural experimental philosophy, which is subsequently revised for the press by Prof. Robert Patterson.

He devotes much attention to atmospheric electricity, detailing the Franklinian theory, and, besides reporting upon the hypotheses advanced by Henry Eales (at A.D. 1755), as well as treating of the attraction of magnetism, he gives a very interesting account of experiments with the _torpedo_ and the _gymnotus electricus_. He says that Mr. Walsh found the _torpedo_ “possessed of the power of shocking only in two parts of its body, directly opposite to each other and near to the head. A spot on the back and another on the belly opposite to the former being of a different colour led him to make the experiment, and he found that the electrical virtue was confined to these, and that any other part of the fish might be handled, without receiving a shock, while it was out of the water. Either of these places separately might be handled without the shock being received until a communication between them was formed. This makes it appear probable that the same may also be the case with the Guiana eel. One of these spots must therefore be always in the positive and the other in the negative state; or, rather, they are both generally in the natural state, until, by an effort of the fish’s will, they are suddenly put into different states, as we frequently found that the hand might be in the water, which formed the communication, without receiving any shock. This cannot be the case with the Leyden bottle when charged, which suddenly discharges itself upon forming the communication. Whether there be any electric atmosphere round these spots in the _torpedo_ we cannot tell, as we had no opportunity of examining this matter in the eel, nor have we heard whether Mr. Walsh made any experiments for ascertaining this.”

ELECTRICITY OF THE ATMOSPHERE

The investigations of John Ewing concerning atmospheric electricity were in reality quite extensive. He not only repeated the experiments of Franklin, but he examined thoroughly those of other scientists in the same channel, especially the investigations of Henry Eeles, which will be found detailed in the latter’s “Trinity College Lectures” as well as in his “Philosophical Essays,” London, 1771.

For a very interesting historical review of theories as to the origin of atmospherical electricity, it would be well to consult M. A. B. Chauveau’s article in “Ciel et Terre,” Bruxelles, March 1, 1903, and also Humboldt’s “Cosmos,” London, 1849, Vol. I. pp. 342–346. In the last-named work are cited: Arago, “Annuaire,” 1838, pp. 246, 249–266, 268–279, 388–391; Becquerel, “Traité de l’Electricité,” Vol. IV. p. 107; De la Rive, “Essai Historique,” p. 140; Duprez, “Sur l’électricité de l’air,” Bruxelles, 1844, pp. 56–61; Gay-Lussac, “Ann. de Ch. et de Phys.,” Vol. VIII. p. 167; Peltierin, “Ann. de Chimie,” Vol. LXV. p. 330, also in “Comptes Rendus,” Vol. XII. p. 307; Pouillet, “Ann. de Chimie,” Vol. XXXV. p. 405.

------+-----------------+-------------------------------+--------------------------- | | | Date | Name | Experiments | References | | | ------+-----------------+-------------------------------+--------------------------- 1751 |Franklin |Effects of lightning |Phil. Trans., xlvii. p. 289 ------+-----------------+-------------------------------+--------------------------- 1751 |Mazeas |Kite experiments independently |Phil. Trans., 1751–1753 | | of Franklin | ------+-----------------+-------------------------------+--------------------------- 1752 |Nollet |Theory of Electricity |Recher. sur les causes, | | | 1749–1754 | | |Lettres sur l’élect., 1753, | | | 1760, 1767, 1770 ------+-----------------+-------------------------------+--------------------------- 1752 |Watson |Electricity of clouds |Phil. Trans., 1751, 1752 ------+-----------------+-------------------------------+--------------------------- 1752 |De Lor and Buffon|Iron pole 99 ft. high, mounted |Letter of Abbé Mazeas, | | on a cake of resin 2 ft. sq.,| dated St. Germain, | | 3 in. high, Estrapade, May | May 20, 1742 | | 18, 1752 | ------+-----------------+-------------------------------+--------------------------- 1752 |D’Alibard |Sparks from thunder clouds, 40 |Mem. l’Acad., r. des | | ft. pole in garden at Marly, | Sci., May 13, 1762 | | also wooden pole 30 ft. high,| Hist. Abrégée, 1776 | | at Hôtel de Noailles | ------+-----------------+-------------------------------+--------------------------- 1752 |Le Monnier |Observations of air charge |Mém. de Paris, 1752, | | | pp. 8, 233 ------+-----------------+-------------------------------+--------------------------- 1752 |De Romas |Observations of air charge; |Mém. Sav. Etrangers, | | kite experiments | 1752, and Mém. de | | | Math., 1755, 1763 ------+-----------------+-------------------------------+--------------------------- 1752 |Mylius, Ch. |Observations of air charge |“Nachrichten,” Berlin, 1752 | | | ------+-----------------+-------------------------------+--------------------------- 1752 |Kinnersley |Observations of air charge |Franklin’s Letters, Phil. | | | Trans., 1763, 1773 ------+-----------------+-------------------------------+--------------------------- 1752 |Ludolf and Mylius|Observations of air charge |Letter to Watson ------+-----------------+-------------------------------+--------------------------- 1753 |Richman |Electrical gnomon |Phil. Trans., 1753 ------+-----------------+-------------------------------+--------------------------- 1753 |Canton |Electricity of clouds |Franklin’s letters and | | | Phil. Trans., 1753 ------+-----------------+-------------------------------+--------------------------- 1753 |Beccaria, C.B. |Systematic observations with |Lett. dell’ Elet. Bologna, | | an electroscope | 1758 ------+-----------------+-------------------------------+--------------------------- 1753 |Wilson |Experiments |Phil. Trans., 1753, p. 347 ------+-----------------+-------------------------------+--------------------------- 1754 |Lining |Kite experiments |Letter to Chas. Pinckney ------+-----------------+-------------------------------+--------------------------- 1755 |Le Roy |Experiments |Mém. de Paris, 1755 ------+-----------------+-------------------------------+--------------------------- 1756 |Van Musschenbroek|Kite experiments |Intro. ad Phil. Nat., 1762 ------+-----------------+-------------------------------+--------------------------- 1759 |Hartmann |Origin of electricity |Verbesseter ... Blitzes | | | (_Hamb. Mag._ vol. xxiv.) ------+-----------------+-------------------------------+--------------------------- 1769 |Cotte |Memoirs on meteorology |Journ. Phys., xxiii., 1783 | | | Mém. Paris, 1769–1772 ------+-----------------+-------------------------------+--------------------------- 1772 |Ronayne |Fog observations |Phil. Trans., 1772, p. 137 ------+-----------------+-------------------------------+--------------------------- 1772 |Henley |Quadrant electrometer |Phil. Trans., 1772–1774 ------+-----------------+-------------------------------+--------------------------- 1775 |Cavallo |Fogs, snow, clouds and rain; |Treatise on Elect., 1777 | | kite experiments | ------+-----------------+-------------------------------+--------------------------- 1784 |De Saussure |Observations |“Voyages dans les Alpes,” | | | Geneva, 1779–1796 ------+-----------------+-------------------------------+--------------------------- 1786–7|Mann |Daily observations with an |Ephémer. Météorol. of the | | electrical machine, timing | Mannheim Society, | | the revolutions to produce a | 1786–1792 | | given spark with a record of | | | the weather | ------+-----------------+-------------------------------+--------------------------- 1788 |Volta |New electroscope |Lettere Sulla Meteor, | | | 1788–1790 ------+-----------------+-------------------------------+--------------------------- 1788 |Crosse |Experiments with collectors |Gilb. Ann., Bd. 41, s. 60 ------+-----------------+-------------------------------+--------------------------- 1791 |Read |Insulation and conductors |Phil. Trans., 1791 and | | | Summary, 1793 ------+-----------------+-------------------------------+--------------------------- 1792 |Von Heller |Observations |Gren, “_Neues Journ. der | | | Phys._,” vol. ii. 1795 | | | and vol. iv. 1797 ------+-----------------+-------------------------------+--------------------------- 1792 |Schubler |Observations with weather rod |J. de Phys., lxxxiii. 184 ------+-----------------+-------------------------------+---------------------------

An attractive table, which we are permitted to rearrange and reproduce here, giving a _résumé_ of references to some of the most noted experiments of the chief investigators from the time of Franklin to the end of the eighteenth century, was made up by Mr. Alex. McAdie and first appeared in the “Amer. Meteor. Journal.” Mr. McAdie says that a detailed history of most of Franklin’s co-labourers will be found in the accounts given by Exner,[53] Hoppe,[54] Mendenhall,[55] Elster and Geitel[56] as well as by himself,[57] and that in making up this table he has passed over Peter Collinson, of London, who introduced to the notice of the Royal Society the experiments of Franklin, and the three less-known workers--J. H. Winkler, who wrote in 1746 on the electrical origin of the weather lights; Maffei, 1747; and Barberet, 1750.

=A.D. 1795.=--The telegraphs of the Rev. J. Gamble, Chaplain to the Duke of York, consisted either of five boards placed one above the other or of arms pivoted at the top of a post upon one axis and capable of producing as many signals as there are permutations in the number five, all of the combinations being possible at equal angles of forty-five degrees. His doubts as to the practicability of employing electricity “as the vehicle of information” are fully expressed at p. 73 of his “Essay on the Different Modes of Communicating by Signal,” etc., London, 1797.

REFERENCES.--J. Gamble, “Observations on Telegraphic Experiments,” etc.; Article “Telegraph” in Tomlinson’s “Encyl. of Useful Arts”; “Penny Ency.,” Vol. XXIV. pp. 147 and 148; “English Cyclopædia,” “Arts and Sciences,” Vol. VIII. p. 66.

=A.D. 1795.=--Garnet (John), proposes a telegraph consisting of only one bar moving about the centre of a circle, upon which latter the letters and figures are inscribed. On placing corresponding divisions, by means of wires, before the object glass of the telescope the coincidence of the two radii or of the arm would point out the letter intended to be repeated. As this plan proved impracticable for long distances, it did not come into general use (“Emporium of Arts and Sciences,” Phila., 1812, Vol. I. p. 293).

=A.D. 1795.=--Wells (Charles William), a physician, native of South Carolina but practising in England and a F.R.S., publishes in the _Phil. Trans._ a paper on the influence which incites the muscles of animals to contract in Galvani’s experiments. Therein he was the first to demonstrate that voltaic action is produced through charcoal combined with another substance of different conducting power, and this he did by causing noticeable convulsions in a frog through the combination of charcoal and zinc. (See “Ency. Met.,” Vol. IV. pp. 220, 221, for the experiments of both Dr. Wells and Dr. Fowler.) Fahie states that Davy subsequently constructed a pile which consisted of a series of eight glasses containing well-burned charcoal and zinc, using a red sulphate of iron solution as the liquid conductor. It is said this series gave sensible shocks and rapidly decomposed water and that, compared with an equal and similar series of silver and zinc, its effects were much stronger. (See Priestley’s discovery of the electrical conductibility of charcoal at A.D. 1767, and the description of Davy’s charcoal battery in “Jour. Roy. Inst.” and _Nicholson’s Journal_, N. S., Vol. I. p. 144.)

His biographer, in the “Eng. Cyclop.,” says (Vol. VI. pp. 631–632) that his last work and the one upon which his reputation as a philosopher must rest, is his “Essay upon Dew,” published in 1814 (“Journal des Savants” for Sept. 1817), whilst J. F. W. Herschel remarks at p. 122 of his “Prel. Disc ... Nat. Phil.,” 1855: “We have purposely selected this theory of dew, first developed by the late Dr. Wells, as one of the most beautiful specimens we can call to mind of inductive experimental inquiry lying within a moderate compass....”

REFERENCES.--Wells’ biography in the “English Cyclopædia,” Vol. VI. p. 631; _Phil. Trans._ for 1795, p. 246; Hutton’s abridgments of the _Phil. Trans._, Vol. XVII. p. 548; Fahie’s “History,” etc., pp. 201 and 202; “Aristotle on Dew” (Poggendorff, _Geschichte der Phys._, 1879, p. 42); Luke Howard, “On the Modification of Clouds ...” London, 1803; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. I. pp. 162–165 and Vol. II. p. 329.

=A.D. 1796.=--Gregory (George), D.D., F.R.S., Vicar of Westham, a miscellaneous writer of Scotch origin, for many years editor of the “New Annual Register,” is the author of “Economy of Nature,” etc., of which the second and third editions, considerably enlarged, appeared respectively in 1798 and 1804.

In the first volume of the last-named edition (Book I. chap. vi. pp. 35–54) he treats of natural and artificial magnets and of magnetic powers and theories of magnetism, while the whole of Book IV. (chaps. i.-viii. pp. 299–386) is devoted to the history of and discoveries relative to electricity, its principles and theories, as well as to electrical apparatus and electrical phenomena and to galvanism or animal electricity.

Gregory is also the author of “Popular Lectures on Experimental Philosophy, Astronomy and Chemistry; Intended Chiefly for the Use of Students and Young Persons,” 2 vols., 12 mo, published in London 1808–1809, one year after Gregory’s death.

It was the perusal of the latter work which led Joseph Henry to embrace a scientific career, just as the reading of “Mrs. Marcet’s Conversations on Chemistry” had induced Michael Faraday to enter the field in which he afterward became so highly distinguished. Prof. Asa Gray, in his Biographical Memoir of Henry, says that Gregory’s work alluded to is an unpretending volume but a sensible one, and that it begins by asking three or four questions, such as these: “You throw a stone, or shoot an arrow into the air; why does it not go forward in the line or direction that you give it? Why does it stop at a certain distance and then return to you?... On the contrary, why does flame or smoke always mount upward, though no force is used to send them in that direction? And why should not the flame of a candle drop toward the floor when you reverse it, or hold it downward, instead of turning up and ascending into the air?... Again, you look into a clear well of water and see your own face and figure as if painted there? Why is this? You are told that it is done by reflection of light. But what is reflection of light?” As Prof. Gray remarks, young Henry’s mind was aroused by these apt questions, and allured by the explanations. He now took in a sense of what knowledge was. The door to knowledge opened to him, that door which it thence became the passion of his life to open wider. The above-named volume is preserved in Prof. Henry’s library, and bears upon a fly-leaf the following entry:

“This book, although by no means a profound work, has, under Providence, exerted a remarkable influence upon my life. It accidentally fell into my hands when I was about sixteen years old, and was the first work I ever read with attention. It opened to me a new world of thought and enjoyment; invested things before almost unnoticed with the highest interest; fixed my mind on the study of nature, and caused me to resolve at the time of reading it, that I would immediately commence to devote my life to the acquisition of knowledge. J. H.” (See Prof. A. M. Mayer, “Eulogy of Joseph Henry,” Salem, 1880, pp. 29–30; “Smithsonian Report,” 1878, pp. 145, 146.)

REFERENCES.--_Gentleman’s Magazine_, Vol. LXVII. p. 415; Beloe’s “Sexag.,” II. 128; “Living Authors” (1798), I. p. 225.

=A.D. 1797.=--Bressy (Joseph), French physician and able chemist, remarks, in his “Essai sur l’électricité de l’eau,” that the electric fluid is composed of three beams (_rayons_, i. e. rays, gleams, or sparks), vitreous, resinous and vital; that three principal agents exist in nature, viz. the air, isolating body; the water, conducting body, and movement, determining action; that vapours resolve themselves into clouds merely because friction enables the electric fluid to seize upon the aqueous molecules, and that, in water, the hydrogen is maintained in the form of gas by the electric fluid, while the oxygen becomes gaseous under influence of the caloric.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. II. p. 1236; Delaunay, “Manuel,” etc., 1809, pp. 15, 16.

=A.D. 1797.=--Treméry (Jean Louis), a French mining engineer, communicates his observations on elliptic magnets through Bulletin No. 6 of the “Société Philomathique” as well as through the sixth volume of the _Journal des Mines_.

His observations on conductors of electricity and on the emission of the electric fluid appear at p. 168 Vol. XLVIII of the _Jour. de Phys._, and in “Bull. de la Soc. Philom.,” No. 19, while his views in opposition to the two-fluid theory are to be found in Bulletin No. 63 of the last-named publication as well as in _Jour. de Phys._, Vol. LIV. p. 357.

REFERENCES.--Poggendorff, Vol. II. p. 1131; John Farrar, “Elem. of Elec.,” etc., p. 120.

=A.D. 1797.=--Pearson (George), English physician and chemist, communicates to the Royal Society a very interesting paper entitled, “Experiments and Observations made with the view of ascertaining the nature of the gas produced by passing electric discharges through water; with a description of the apparatus for these experiments.”

An abstract of the above appears in the _Phil. Trans._ for 1797, and a full transcript of it is to be found in _Nicholson’s Journal_, 4to, Vol. I. pp. 241–248, 299–305, and 349–355.

As Mr. Wilkinson has it, “Dr. Pearson supposes the decomposition of water by electricity to be effected by the interposition of the dense electric fire, between the constituent elements of the water, which he places beyond the sphere of attraction for each other, each ultimate

## particle of oxygen and hydrogen uniting with a determinate quantity

of the electric fire to bestow on them their gaseous form. Hence the doctor supposes that the electric fire, after effecting the disunion, assumes the state of caloric.

“On the reproduction of water by the passage of an electric spark through a proportionate quantity of oxygen and hydrogen gases, Dr. Pearson ingeniously conjectures that by the influence of the electric flame the ultimate particles of these gases, the nearest to the flame, are driven from it in all directions, so as to be brought within the sphere of each other’s attractions. In one of these cases Dr. Pearson supposes that the caloric destroys the attraction, which in the other instance it occasions.

“It is with diffidence that I take on me to controvert the opinions of this very respectable physician; but I presume that the whole of the phenomena of the synthesis and analysis of water are more readily to be explained on the principles I have laid down than by the adoption of the mysterious terms of attraction and repulsion. By the operation of galvanism, water is more rapidly decomposed than by common electricity. In this operation there is no evolution of dense electrical fire, but merely a current of a small intensity of electricity acting permanently and incessantly. To reproduce water, a flame must be generated sufficient to kindle the contiguous portion of the hydrogen gas, then the next portion, and so on, the combustion being preserved by the presence of the oxygen gas. As these processes proceed with immense rapidity as soon as the gases are intermixed, so as to appear like one sudden explosion, the caloric of each of them being thus disengaged, their bases unite and constitute water.”

Dr. Pearson also made many interesting experiments to ascertain the effect of the application of galvanic electricity for the treatment of diseases, and Noad, who describes one of his successful operations, also details (“Manual,” pp. 343–349) the observations of many others in the same line, notably those of Drs. Apjohn, Majendie, Grapengieser and of Wilson Philip, Petrequin, Pravaz, Prevost and Dumas (_Jour. de Physiol._, Tome III. p. 207), as well as of Sarlandière and Dr. Golding Bird, besides giving the very important conclusions arrived at by Stefano Marianini.

REFERENCES.--“Some Account of George Pearson,” M.D., F.R.S. (_Phil. Mag._, Vol. XV for 1803, p. 274); letter of Humboldt to M. Loder (“Bibl. Germ.,” Vol. IV, Messidor, An. VIII. p. 301); William Van Barneveld, “Med. Elektricität,” Leipzig, 1787; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, 2 vols. _passim_; Paragraph No. 328 of Faraday’s “Experimental Researches,” J. N. Hallé, “Journal de Médecine de Corvisart,” etc., Tome I, Nivose, An. IX. p. 351; “Annales de l’Electricité Médicale” _passim_; H. Baker (_Phil. Trans._, Vol. XLV. p. 270); “Jour. de la Soc. Philom.,” Messidor, An. IX; J. F. N. Jadelot, “Expériences,” etc., 1799; M. Butet (“Bull. des Sc. de la Soc. Philom.,” No. 43, Vendémiaire, An. IX); M. Oppermanno, “Diss. Phys. Med.” (see J. G. Krunitz “Verzeichnis,” etc.); Andrieux, “Mémoire ... maladies,” Paris, 1824; Lebouyer-Desmortiers (Sue, “Hist. du Galv.,” Vol. II. p. 420, and _Jour. de Phys._, Prairial, An. IX, 1801, p. 467); C. J. C. Grapengieser, “Versuche den Galvanismus,” etc., Berlin, 1801 and 1802; the works of J. Althaus, published in London and Berlin in 1859–1870; C. A. Struve’s works, published in Hanover and Breslau, 1797–1805; F. L. Augustin’s works, published in Berlin, 1801–1803; Karl Friedrich Kielmeyer (Kielmaier), works published at Tübingen (Poggendorff, Vol. I. p. 1253); Einhoff (Gilbert, XII. p. 230); Francesco Rossi’s treatises on the application of galvanism, published in 1809; Gilb. “Ann.,” Vol. XII. p. 450; _Jour. de Phys._, Vol. LII. pp. 391 and 467; Cuthbertson’s letter in _Phil. Mag._, Vol. XVIII. p. 358; J. G. Anglade, “Essai sur le Galvanisme,” etc. (Sue, “Hist. du Galv.,” Vol. III. p. 73); Jacques Nauche, in _Phil. Mag._, Vol. XV. p. 368, as well as in Poggendorff, Vol. II. p. 256, and throughout the “Journal du Galvanisme.”

=A.D. 1797.=--In No. CCXXII of the _Reichsanzeiger_, a German publication, it is said that a certain person having an artificial magnet suspended from the wall of his study with a piece of iron adhering to it, remarked, for several years, that the flies in the room, though they frequently placed themselves on other iron articles, never settled upon the artificial magnet.

REFERENCES.--Cavallo, “Experimental Philosophy,” 1803, Vol. III. p. 560, or the 1825 Philad. ed., Vol. II. p. 286.

=A.D. 1797–1798.=--Reinhold (Johann Christoph Leopold), while Bachelor of Medicine in Magdeburg, tendered for his theses, on the 16th of December 1797 and on the 11th of March 1798, two Latin dissertations on galvanism, one of which was offered concurrently with J. William Schlegel, then a medical student.

Numerous extracts from both the above very important papers, which treat extensively of galvanic experiments upon animals, vegetables, metals, etc., will be found at pp. 123–195, Vol. I of Sue’s “Histoire du Galvanisme,” Paris, 1802. Both dissertations review galvanism from its origin and make mention of many works which had not up to that time appeared in print.

In the first volume of his “Elements of Galvanism,” London, 1804, Mr. C. H. Wilkinson devotes the entire Chap. VIII (pp. 188–260) to Reinhold’s able review of galvanism, wherein are first cited Gardiner (author of “Observations on the Animal Economy”), Lughi, Klugel and Gardini as “anterior to the discovery of the doctrine of animal electricity.” Then follow accounts of their writings, as well as of those of Galvani and of Volta, “the Prince of Italian naturalists,” after which due mention is made, in their proper order, of the observations of Aldini, Valli, Fontana, Berlinghieri, Monro, Fowler, Corradori, Robison, Cavallo, Wells, Havgk, Colsmann, Creve, Hermestædt, Klein, Pfaff, Ackermann, Humboldt (letters to Blumenbach, Crell, Pictet and M. de Mons), Eschenmeyer, Achard, Grapengieser, Gren, Michaelis, Caldani, Schmuck, Mezzini, Behrends, Giulio, Ludwig, Webster, Vasco, Hebenstreit and others.

The subject of the eighth and last section of Reinhold’s Dissertations, as Wilkinson expresses it, consists of the exposition of the hypotheses of different authors on the galvanic fluid. These hypotheses he brings into two classes, as they relate to the seat which is assigned to the cause of the phenomena. The first of these classes belongs to the animal which is to be galvanized, and the second to the substance applied to its body, or to the arc. As the galvanic phenomena are ascribed by several physiologists to electricity, Reinhold makes a new division, relatively to the opinion of those who assert that the galvanic and electric fluids are the same, and of those who are persuaded that the former differs from the latter. Under the first head or division he ranges Galvani, Aldini, Valli, Carradori, Volta, in the early time of the discovery; then Schmuck, Voigt, and Hufeland; while under the second come Fowler and Humboldt. Of the latter division he makes subdivisions, in the first of which he comprehends Volta, Pfaff, Wells, Yelin and Monro, the second embracing Creve and Fabbroni. The other authors, not having openly avowed their opinion, he passes over in silence.

Reinhold is likewise the author of “Versuche um die eigentliche,” etc. (Gilb. “Annal.,” X, 1802, pp. 301–355), “Untersuchungen über die natur.,” etc. (Gilb. “Annal.,” X, 1802, pp. 450–481, and XII, 1803, pp. 34–48); “Galvanisch-elektrische Versuche,” etc. (Gilb. “Annal.,” XI, 1802, pp. 375–387); “Geschichte des Galvanismus,” Leipzig, 1803; “Versuch einer skizzirten,” etc. (Reil. “Archiv.,” VIII, 1807–1808, pp. 305–354); “Ueber Davy’s Versuche” (Gilb. “Annal.,” XXVIII, 1808, pp. 484–485).

REFERENCES.--Schlegel, “De Galvanismo”; Figuier, “Exp. et Hist. des Principales Découvertes,” Vol. IV. pp. 310, 433; J. W. Ritter, “Beweis ... in dem Thierreich ...” Weimar, 1796; G. R. Treviranus, “Einfluss ... thier, Reizbarkeit,” Leipzig, 1801, and Gilbert’s “Annalen,” Vol. VIII for the latter year.

=A.D. 1798.=--Perkins (Benjamin D.), is given an English patent for a process enabling him to cure aches, pains and diseases in the human body by drawing electrified metals over the parts affected. His metallic tractors, originally introduced from America and consisting of an alloy of different metals, awakened much curiosity both in England and on the Continent, and were successfully used by Dr. Haygarth and others, as related in the article “Somnambulism,” of the “Encyclopædia Britannica.”

In the Repert. II. ii. 179, it is said that one of the tractors was made of zinc, copper and gold, and the other of iron, platina and silver. M. V. Burq, in his “Métallo-thérapie,” makes a review of the successful cures of nervous complaints effected by metallic applications.

REFERENCES.--_Jour. de Phys._, Vol. XLIX. p. 232; Mr. Langworthy, “View of the Perkinian Electricity,” 1798; T. G. Fessenden, “Poetical petition against ... the Perkinistic Institution ...” London, 1803; B. D. Perkins, “The Influence of Metallic Tractors on the Human Body ...” London, 1798–1799; “Bibl. Britan.,” Vol. XXI, 1802, pp. 49–89; “Recherches sur le Perkinisme,” etc. (“Annales de la Soc. de Méd. de Montpellier,” Vol. XXIX. p. 274); “Sur les tracteurs de Perkins” (“Mém. des Soc. Savantes et Lit.,” Vol. II. p. 237); P. Sue, aîné, “Hist. du Galv.,” IV. p. 286 and “Hist du Perkinisme,” Paris, 1805; J. D. Reuss, “De re electrica,” Vol. XII. p. 20; J. Krziwaneck, “De electricitate ...” Prag., 1839.

=A.D. 1798.=--In a long letter written to Thomas Jefferson, President of the American Philosophical Society, and read before the latter body on the 4th of May 1798, the Rev. James Madison, then President of William and Mary College, details several experiments made by him to ascertain the effect of a magnet upon the Torricellian vacuum, and to explain the phenomena exhibited by magnets in proximity to iron filings.

He says: “Many ingenious men have supposed that the arrangement of the filings clearly indicated the passage of a magnetic fluid or effluvia in curved lines from one pole to another of a different denomination,” but that the experiments which he relates prove the attractive force of the magnets, at either pole, to be the real cause of the phenomena which the filings exhibit, and that the action of the magnet upon the filings, when they approach within a certain distance, renders them magnetic. In every magnet, says he, there is at least one line, called the equator, from which, in the direction of both poles, the attractive power increases so that the filings will “incline toward them, forming angles which appear to be such as the resolution of two forces, one lateral and the other polar, would necessarily produce.”

Thomas Jefferson, above named, succeeded Benjamin Franklin as United States Minister Plenipotentiary to Paris, 1784–1789, became Vice-President of the United States in 1796, and was sworn in as the successor of John Adams to the Presidency on the 4th of March 1801. The Rev. James Madison, D.D., second cousin of the fourth President of the United States bearing the same name, became President of William and Mary College in 1777, and was consecrated first Bishop of Virginia by the Archbishop of Canterbury in Lambeth Palace, Sept. 19, 1790.

REFERENCES.--“Transactions of the Am. Phil. Soc.,” Vol. IV for 1799, O.S. No. 39, pp. 323–328.

=A.D. 1798.=--Monge (Gaspar), Comte de Peluse, a very able French scientist, called “the inventor of descriptive geometry,” and from whom, it is said, that science received greater accessions than had before been given it since the days of Euclid and Archimedes, erects a telegraph upon the “Palais des Tuileries” in Paris. Of this, however, no reliable details are on record.

He also makes many experiments on the effects of optics and electricity, and, likewise, many useful observations on the production of water by inflammable air, independently of those carried on by Lord Cavendish.

REFERENCES.--Biography in Charles Dupin’s “Essai Historique,” etc., and in “English Cycl.,” Vol. IV. pp. 296, 297; Memoir at p. 175 of Vol. LV, _Phil. Mag._ for 1820; G. Monge, “Sur l’effet des étincelles ...” Paris, 1786, and “Précis des leçons,” Paris, 1805; _Sci. Am. Supp._, No. 621, p. 9916, and the note at foot of p. 701 of “Fifth Dissert.” eighth ed. of “Encyclopædia Britannica,” Vol. I; as well as “Mém. de l’Acad. des Sciences,” 1786.

=A.D. 1798.=--Berton (Henri Montan), a prominent French composer and Professor of Harmony at the Paris “Conservatoire de Musique,” also a member of the “Académie des Beaux-Arts,” devises a novel electric telegraph which is merely alluded to, under the heading of “Note historique sur le télégraphe électrique,” at p. 80 of the seventh volume of the _Comptes Rendus_ for July 1838, as well as in Julia Fontenelle’s “Manuel de l’électricité.”

=A.D. 1799.=--Fabbroni--Fabroni--(Giovanni Valentino M.), Professor of Chemistry at Florence, communicates to the _Journal de Physique_ (9th series, Tome VI, Cahier de Brumaire, An. VIII), an amplification of his able memoir, “Sur l’action chimique,” etc. (“Dell’azione chimica ...”), which was first presented by him during 1792 to the Florentine Academy and duly analyzed by Brugnatelli in his “Giornale physico-medico.” Therein is made the first known suggestion as to the chemical origin of voltaic electricity, inquiring whether the phenomenon of galvanism is not solely due to chemical affinities of which electricity may be one of the concomitant effects, and also ascribing the violent convulsions in a frog to a chemical change which is produced by the contact of one of the metals with some liquid matter on the animal’s body, the latter decomposing and allowing its oxygen to combine with the metal.

REFERENCES.--“Elogio ... A. Lombardi” (“Mem. Soc. Ital.,” Vol. XX); _Cornhill Magazine_, Vol. II for 1860, p. 68; “Biog. Univ.,” Vol. XIII. p. 311; “Encycl. Met.,” “Galvanism,” Vol. IV. p. 215; _Journal de Physique_, Vol. XLIX. p. 348; “Chambers’ Ency.,” 1868, Vol. IV. p. 593; “Mem. Soc. Ital.,” Vol. XX. pp. 1 and 26; P. Sue, aîné, “Histoire du Galvanisme,” Paris, An. X-1802, Vol. I. pp. 229–232; _Phil. Mag._, Vol. V. p. 270; _Nicholson’s Journal_, quarto, Vol. IV. p. 120; Sir Humphry Davy, “Bakerian Lectures,” London, 1840, p. 49; Young’s “Lectures,” Vol. I. p. 752; W. Sturgeon, “Scientific Researches,” Bury, 1850, p. 156; “Giornale di fisica” for 1810; “Giornale dell’ Ital. Lettera ...” IX. p. 97; “Atti della Reg. Soc. Economica di Firenze,” XX. p. 26; Brugnatelli, _Annali di chimica_, II. p. 316 and XXI. p. 277; C. Henri Boissier, “Mémoire sur la décomp. de l’eau, etc.,” Paris, 1801 (_Journal de Physique_, Prairial, An. IX).

=A.D. 1799.=--Jadelot (J. F. N.), French physician, translates Humboldt’s work on “Galvanism,” wherein he reviews the investigations of the great German scientist and treats of the application of the Galvanic fluid in medical practice. The observations of a friend of Humboldt, Dr. C. J. C. Grapengieser, are especially detailed and a complete account is given of all the noted physicians who have recorded experiments in the same line.

REFERENCES.--For the medical applications of Galvanism: _Journal de Physique_, Vol. LII. pp. 391, 467; Gilbert’s “Annalen,” XI. 354, 488 and XII. 230, 450; “An. of Sc. Disc.” for 1865, p. 123; Larrey, 1793, 1840; L. Desmortiers, 1801; Legrave, 1803; F. J. Double, 1803; J. Nauche, 1803; “Galv. Soc.” (_Phil. Mag._, Vol. XV. p. 281); Laverine, 1803; Mongiardini and Lando, 1803; F. Rossi, 1803–1827; J. Schaub, 1802–1805; B. Burkhardt, 1802; M. Butet, 1801; J. Le Roy d’Etiolle, “Sur l’emploi du Galv....”; P. L. Geiger, 1802–1803; J. D. Reuss in “De Re Electrica”; M. Buccio, 1812; La Beaume, 1820–1848; P. A. Castberg (Sue, “Hist. du Galv.,” IV. 264); Fabré-Palaprat and La Beaume, 1828; Rafn’s “Nyt. Bibl.,” IV; C. C. Person, 1830–1853; S. G. Marianini, 1841; C. Usiglio, 1844; F. Hollick, 1847; G. Stambio, 1847; Du Fresnel, 1847; H. de Lacy, 1849; M. Récamier, J. Massé, 1851; R. M. Lawrance, Robt. Barnes, and Crimotel de Tolloy, 1853; M. Middeldorpf, 1854; R. Remak, 1856, 1860, 1865; J. Seiler, 1860; V. Von Bruns, 1870.

=A.D. 1799.=--Humboldt (Friedrich Heinrich Alexander, Baron Von) (1769–1859), native of Berlin, is the author of “Cosmos” so frequently alluded to in these pages, and, in the words of one of his biographers, “will be remembered in future times as perhaps, all in all, the greatest descriptive naturalist of his age, the man whose observations have been most numerous and of the widest range, and the creator of several new branches of natural sciences.”

The French translation of his work on “Galvanism” (“Expériences sur le Galvanisme ... traduit de l’allemand par J. F. N. Jadelot”) appeared in Paris during the year 1799, before which date, Noad remarks, no one had applied the galvanic arc, as he did, to so many animals in various parts of their bodies. Among other results, he discovered the action of the electric current upon the pulsation of the heart, the secretions from wounds, etc., and he proved upon himself that its action was not limited to the sole instants of the commencement and end of its passage.

In the first volume of his very interesting work on “Galvanism” (pp. 166–174, 261–310, 407–434) Wilkinson reviews the above-named publication which M. Vassalli-Eandi, in 1799, pronounced “the most complete that has hitherto appeared.” The following sectional extracts are mainly taken from Mr. Wilkinson’s book, Chap. IX. part ii. Humboldt’s first experiments were made with the aid of M. Venturi, Professor of Natural Philosophy at Modena, and they were followed quite assiduously for a while, but it was not until he learned of the important observations made by Fowler, Hunter and Pfaff on animal electricity and irritability, that he was spurred on to still further extended investigations, which were carried on more particularly in presence of Jurine, Pictet, Scarpa, Tralles and Volta. Humboldt’s work is divided into ten sections, as follows:

Sect. I treats of the relation between galvanic irritation and incitability.

Sect. II deals with the galvanic irritation produced without a coating, or metallic or charcoal substances (repeating the investigations of M. Cotugno, which led to the experiments of Vassalli during 1789).

Sect. III treats of the excitement produced by a simple metallic substance, or by homogeneous metallic parts (detailing the experiments of Aldini, Galvani, Berlinghieri, Lind, Pfaff and Volta).

Sect. IV discourses on heterogeneous metals. During his experiments in this line, which were aided by his elder brother, chance led him to a very interesting discovery. He found that the coatings of the nerve and muscle being homogeneous, the contractions may be produced when the degree of excitability is extremely feeble, provided the coatings of this nature are united by exciting substances, among which there is a heterogeneous one, having one of its surfaces covered by a fluid in a state of vapour. This observation, which was originally made at the commencement of 1796, surprised Humboldt so much that he instantly communicated it to Sömmering, Blumenbach, Hertz and Goethe. He had not as yet found recorded in the published works on galvanism any experiment the result of which had the smallest analogy with his discovery; and it was not until after the publication of the works of Pfaff on animal electricity that he became acquainted with any one similar to his own. There were, however, some differences, as he proves by several passages cited from the above author.

Sect. V relates to the classification of active substances into _exciters_ and _conductors_ of the galvanic fluid.

Sect. VI treats of experiments on the comparative effects of animal and vegetable substances employed in the galvanic chain.

Sect. VII describes, in a tabular form, the conducting substances, and those by which the galvanic fluid is insulated. In the employment of very long conductors, it was not possible for Humboldt to remark any interval between the instant when the muscle contracts and the moment the contact of the conductor takes place, the muscle and nerve being from two hundred to three hundred feet distant from each other. This announces a celerity of twelve hundred feet per second. The effect would be the same, should the conductors even be from ten thousand to twenty thousand feet in length. Thus Haller, in his physiology, ascribes to the nervous fluid a swiftness sufficient to enable it to run over a space of nine thousand feet a second. The calculation of Sauvages is carried to thirty-two thousand four hundred feet in the same space of time; and what is still infinitely more surprising, its celerity is estimated by the author of the essays on the mechanism of the muscles at five hundred and seventy-six millions of feet (upward of one hundred thousand miles) in the above space of a second of time. It ought here to be noticed that the great differences in these calculations arise from the different kinds of experiments on which they are founded.

Sect. VIII proves that the nerve which is intended to excite contractions in a muscle should be organically united with it, and it deals with the effects of galvanism upon vegetables, aquatic worms, insects and fishes.

Sect. IX describes the effects of galvanism upon amphibious animals, referring to the observations of Nollet, Rosel, Haller, Spallanzani, P. Michaelis and Herembstads.

Sect. X treats of the all-important effects of galvanism upon man, and makes allusion to the experiments of Hunter, Pfaff, Fowler, Munro, Robison, Hecker, Carradori, Achard, Grapengieser, Schmuck, Ludwig, Creve, Webster and Volta. In speaking of the observations made by the last named upon the tongue, he observes that some idea of them had been given thirty years before, in Sulzer’s work entitled “The New Theory of Pleasures,” published in 1767; and that if, at the above period, the consideration of the superficial situation of the nerves of the tongue had led to the artificial discovery of a nerve, the important discovery of metallic irritation would have been made in the time of Haller, Franklin, Trembley, Camper, and Buffon. How great a progress would not this revelation have made if the above philosophers had transmitted to us, thirty years ago, the theory and experiments which we leave to our successors?

Volta having singled out the differences, in point of savour, which result from galvanic experiments on the tongue according to the nature and disposition of the coatings, Humboldt repeated these experiments and added to them several of his own, with a nearly similar result. His different trials, however, having failed to produce any contraction of the tongue, appear to have established the truth of the ancient assertion of Galen, confirmed by Scarpa, namely, that the nerve with which the tongue is supplied by the third branch of the fifth pair is exclusively devoted to the sense of tasting, and that the ninth pair are exclusively destined for the motion of the tongue. This has been evidently proved by the galvanic experiments on the nerve in question.

The termination, in the pituitous membrane, of the nerves belonging to the organ of smelling, which originate in the first pair and in the first two branches of the fifth, together with the observation of the innumerable phenomena of sympathy between the organs of sight and those of smell and taste, had led to a presumption that, by galvanizing the nostrils, the smell would be affected. This supposition has not, however, been confirmed by any experiment.

The eleventh chapter of Wilkinson’s work contains the analysis of the report drawn up by Mr. J. N. Hallé in behalf of the commission appointed by the French National Institute. This commission, which was organized to look into (_examiner et vérifier_) the different galvanic experiments which had been made and to ascertain their effects and results, was composed of such distinguished French physiologists as Coulomb, Fourcroy, Vauquelin, Charles, Sabathier, Hallé, Pelletan and Guyton de Morveau, who were afterward joined by both Humboldt and the celebrated Prof. Venturi, of Modena.

Humboldt’s observations respecting the application of galvanism to medicine are embodied in his well-known letter to M. Loder, inserted in “La Bibliothèque Germanique,” Vol. IV, Messidor, An. VIII. p. 301, and are likewise detailed by Wilkinson (Chap. XIII) where references are made, more particularly, to the experiments of Hufeland, Behrends, Creve, Hymly, Pfaff and Anschell.

Between the years 1799 and 1804 Von Humboldt made observations upon the magnetic intensity of the earth, of which an account will be found in Vol. XV of the _Annalen der Physik_. These were made upon the American Continent during the course of his well-known journey, the equal of which latter, says Petersen, has not been seen since the days when Alexander the Great fitted out an extensive scientific expedition for Aristotle.

Humboldt’s observations in the same line were continued for many years, notably between 1805 and 1806, in company with Gay-Lussac during a tour which they made together through France, Switzerland, Italy and Germany, as related in the first volume of the _Mémoires de la Société d’Arcueil_.

Some idea can be formed of the extent of Humboldt’s share in the magnetical labours of the first half of the century by perusing the last chapters of his “Cosmos” and the third volume of his “Relation Historique.” At p. 615 of the last-named work, he himself says: “The observations on the variation of terrestrial magnetism, to which I have devoted myself for thirty-two years, by means of instruments which admit of comparison with one another, in America, Europe and Asia, embrace an area extending over 188 degrees of longitude from the frontier of Chinese Dzoungarie to the West of the South Sea, bathing the coasts of Mexico and Peru, and reaching from 60 degrees North latitude to 12 degrees South latitude. I regard the discovery of the law of the decrement of magnetic force from the pole to the equator as the most important result of my American voyage.”

Humboldt was the first who made especial observations of those irregular perturbations to which he applied the name of “magnetic-storms,” and the effects of which he originally observed at Berlin in 1806. These are treated of in his “Cosmos,” London, 1858, Vol. V. pp. 135, etc., wherein he states that, when the ordinary horary movement of the needle is interrupted by a magnetic-storm, the perturbation manifests itself often simultaneously, in the strictest sense of the word, over land and sea, covering hundreds and thousands of miles, or propagates itself gradually, in short intervals of time, in every direction over the earth’s surface. In this same work (“Cosmos,” Sabine’s translation, Vol. I. p. 180), he contributes a graphic description of the concurrent and successive phases of a complete aurora borealis, reference to which is made by Noad (“Manual,” etc., pp. 228, 229, 235), who, likewise, gives (pp. 612–615) an account of the establishment of magnetic stations at different points, for simultaneous observations, upon a plan originally laid out by Humboldt.

As early as 1806, this great naturalist had published at Erfurt his “Inquiry Concerning Electrical Fishes.” While at Naples with Gay-Lussac, during the previous year, they had examined the properties of the _torpedo_, and had observed more particularly that the animal must be irritated previous to the shock, preceding which latter a convulsive movement of the pectoral fins is noticeable, and that electrical action is prevented by the least injury done to the brain of the fish; also, that a person accustomed to electrical discharges could with difficulty support the shock of a vigorous torpedo only fourteen inches long; that the discharge can be felt with a single finger placed upon the electrical organs, and that an insulated person will not receive the shock if the fish is touched with a key or other conducting body (_Phil. Mag._, Vol. XXII. p. 356; _Annales de Chimie_, No. 166; “Encycl. Brit.,” 1855, Vol. VIII. p. 573). Humboldt’s account of the mode of capturing gymnoti is detailed at pp. 575, 576 of the last-named work, as well as at pp. 472–474 of Noad’s “Manual of Electricity,” London, 1859.

At request of the King of Prussia, Humboldt returned from Paris to his native city in 1827, and it was during the winter of 1827–1828 that he began in Berlin his lectures on “Cosmos, or Physical Universe.” This is the title of his chief work, which has universally been recognized one of the greatest productions ever published, and one which Ritter pronounced as being the culminating point both in the history of science and in the annals of civilization.

REFERENCES.--Klenke, “Alex. Von Humboldt, ein biographisches Denkmal,” 1851: “Alex. Von Humboldt ... von Wittwer,” Leipzig, 1861; “Life of Alex. Von Humboldt,” translated by J. and C. Lassell, 2 Vols., London, 1873; “Meyer’s Konversations-Lexikon,” Leipzig und Wien, 1895, Vol. IX. pp. 44–47; Delambre’s eulogium on Humboldt will be found at p. 15, Vol. XV of “Edinburgh Review”; Gren’s “Neues Journal der Physik,” Vol. IV; _Annales de Chimie_, Vol. XXII; _An. Chim. et Physique_, Vol. XI; Poggendorff’s “Annalen,” Vols. XV, XXXVII; “Société Philomathique,” Tome I. p. 92; “Opus. Scelti,” XXI. p. 126; Knight’s “Mech. Dict.,” Vol. II. p. 1874; _Phil. Mag._, Vol. VI (1800), pp. 246, 250; “Cat. of Sc. Papers of Roy. Soc.,” Vol. III. pp. 462–467; Vol. VI. p. 692; Vol. VII. pp. 1035–1036; _Sc. Am. Supp._, No. 457, pp. 7301, 7302; Noad, “Manual,” pp. 425, 528, 529, 612; Harris, “Rudim. Magn.,” Part III. p. 103; Walker, “Ter. and Cos. Magn.,” 1866, p. 81; Humboldt, “Aphorismi ex doctrina ...” 1793; “Voyage, etc., dans les années, 1799–1804”; “Report of Seventh Meeting of British Association,” Vol. VI, London, 1838, pp. 1, 5 and 7, and the remainder of Major Sabine’s able article upon “Magnetic Intensity,” in the same volume; “Report of the Meeting of the French Academy of Sciences” of May 21, 1849, for extract of a letter from Emile H. Du Bois-Reymond, sent by Humboldt, and treating of the Electricity of the Human Frame (“L’Institut,” Mai 23, 1849); S. H. Christie and Sir G. B. Airy, “Report upon a Letter ...” London, 1836; C. H. Pfaff, “Mém. sur les expér. de Humboldt ...” 1799; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 168, 1580–1581.

=A.D. 1800.=--William Nicholson, editor of the journal bearing his name, as well as an able chemist, and Sir Anthony (then Mr.) Carlisle, an English surgeon, while carrying on a series of chemical experiments, discover that, by means of the voltaic pile, water is decomposed into its constituents of oxygen and hydrogen. Their pile consisted of seventeen silver half-crown pieces alternated with equal discs of copper and cloth soaked in a weak solution of ordinary salt, and, having used a little water to make good the contact of the conducting wire with a plate to which the electricity was to be transmitted, Carlisle observed that gas was being set free in the water, while Nicholson recognized the odour of hydrogen proceeding from it. The better to observe this result they afterward (May 2, 1800) employed a small glass tube, which, after being filled with water, was stopped at both ends with corks through which passed two brass wires extending a little distance into the water. When platinum wires were used, gas bubbles appeared from both wires, and the two gases, hydrogen from the negative and oxygen from the positive end, were found to be nearly in the proportion to constitute water. (See account of above in Pepper’s “Electricity,” p. 312, as well as at pp. 193 and 194 of Fahie’s “History of Telegraphy to 1837,” and at pp. 339 and 340 of Vol. I of Lardner’s “Lectures.”)

During the year 1781 William Nicholson had published the first edition of “An Introduction to Natural Philosophy.” In the second section of the third book of the latter work he treats of magnetism, the methods of communicating it, and the variation of the compass. The loadstone, he says, “is a ponderous ore of iron, usually of a dirty black colour and hard enough to emit sparks with steel. It is found in most parts of the world, and possesses a natural magnetism acquired most probably from its situation or position with respect to the earth.” In the third section of the same third book he discourses upon electrical matter, electrical jars, electrical instruments, and devotes much space to the explanation of experiments and facts touching natural and atmospheric electricity, balls of fire, of the _ignis fatuus_, or _will-with-the-wisp_, of waterspouts, earthquakes, etc., alluding to most of the then well-known observations thereon recorded by different scientists.

To Nicholson is due the invention of a revolving doubler, an improvement upon that of Abraham Bennet, which is described and illustrated in the “Encyclopædia Britannica,” as well as in No. 647, p. 10327, of the _Sci. Am. Supplement_ (Read at A.D. 1794, also _Phil. Trans._, Vol. LXXVIII. p. 1, for M. Cavallo’s remarks upon the defects in Bennet’s doubler).

The above-named discovery of Nicholson and Carlisle, which, Mr. Davy says (_Phil. Trans._ for 1826, p. 386) was the true origin of all that had been previously done in electro-chemical science, together with Hisinger and Berzelius’ decomposition of salts, and the successful decomposition of ammonia, nitric acid, etc., made by the distinguished English chemical philosopher, Dr. William Henry (_Nicholson’s Journal_, Vol. IV. pp. 30, 209, 223 and 245; “Encyclopædia Metropolitana,” Vol. IV. pp. 221 and 611; Hutton’s abridgment of _Phil. Trans._, Vol. X. pp. 505, 599), as well as Davy’s decomposition of the earths and alkalies, creates at the commencement of another century, as we have already observed, an entirely new epoch in the history of chemistry.

REFERENCES.--Nicholson’s letter to the Royal Society, read June 5, 1788, entitled “A description of an instrument which, by the turning of a winch, produces the two states of electricity without friction or communication with the earth” (influence or induction machine!); _Nicholson’s Journal_, 1800, Vol. IV. p. 179; Despretz, “Physique,” 1827, p. 432; _Mechanics’ Magazine_, Nov. 9, 1839; biography in “English Cyclopedia,” Vol. II. p. 82; Tomlinson, “Cyclopedia of Arts,” etc., 1862, Vol. I. p. 566; “Memoir of Joseph Henry,” 1880, p. 78; Highton, “The Electric Telegraph,” p. 28; Noad, “Manual,” p. 353; “Encycl. Brit.,” 1855, Vol. XXI. p. 628; _Phil. Trans._, Vol. LXXIX. p. 265; _Philosophical Magazine_, Vol. VII. p. 337, and XLV. p. 396; C. H. Wilkinson, “Elements of Galvanism,” 1804, Vol. II. pp. 21, 22, 46, 68, 375, etc.; “Bibl. Brit.,” Vol. XIX. p. 274; “Sciences et Arts,” Part I. p. 274, and Part II. p. 339, for Volta’s answer to Nicholson. For various treatises on, and methods of, effecting the decomposition of water, consult Adam W. Von Hauch (_Mons’ Jour. de Chimie_, Vol. I. p. 109); G. Carradori (_Journal de Physique_, An. XII. p. 20, “Nuova Scel. d’Op.,” quarto, Vol. I. p. 29, Paris and Milan, 1804); W. Wilson (_Phil. Mag._, Vol. XXII. p. 260); Cioni e Petrini (Brugnatelli’s _An. di Chim._, Vol. II. p. 322, 1805); M. Van Marum’s letter to Nauche (_Jour. du Galvan._, Eleventh Book, p. 187; _Gilb. Ann._, XI. p. 220); J. C. I. A. Creve, as at Ronalds’ “Catalogue,” p. 119; “Bibl. Britan.,” An. VIII. vol. xv. p. 23 and An. IX. vol. xvi. p. 23; J. C. Cuthbertson (_Phil. Mag._, Vol. XXIV. p. 170, 1806); Jos. Mollet’s Memoirs published at Aix and Lyons, 1821, 1823, as well as in the Reports of the Lyons Academy, 1823, 1825, and in the _Comptes Rendus_ for 1823; Mr. Leeson (_Sturgeon’s Annals_, Vol. IV. p. 238, 1839; Robert Hare, _Trans. Am. Phil. Soc._, N.S., Vol. VI. p. 339; L. Palmieri and P. Linari-Santi, “Telluro-Elettricismo,” 1844; M. Merget’s theses, read before the Paris Academy, Aug. 30, 1849; A. Connel, _Phil. Mag._, 4th Ser., for June 1854, p. 426); Dr. Edward Ash, “On the action of Metals ... upon water,” in letter to Humboldt, April 10, 1796.

=A.D. 1800.=--Grout (Jonathan, Jr.), of Belchertown, Mass., takes out, October 24, the first telegraph patent in the United States. It was for a contrivance which he operated between Martha’s Vineyard and Boston, about ninety miles’ distance, from hilltop to hilltop, and which was sighted by telescopes (“Telegraph in America,” J. D. Reid, 1887, p. 5; also “Growth of Industrial Art,” Washington, 1888, p. 55).

=A.D. 1800.=--Cruikshanks (William), of Woolwich, England, confirms Nicholson and Carlisle’s experiments, and, in his further prosecution of them, employs a pile consisting of from forty to a hundred pairs of zinc and silver plates, as well as a tube holding silver terminals or electrodes, in place of the platinum electrodes, which they were first to make use of.

He discovers that hydrogen is always evolved from the silver or copper end of the voltaic pile and oxygen from the other; that, under like circumstances, metals can be “completely revived” from their solutions; that pure oxygen is freed when a wire of non-oxidable metal, like gold, is connected with the zinc plate, and that fluids that contain no oxygen cannot transmit the voltaic current. These results were verified by Lieut. Col. Henry Haldane, whose many observations upon the series of metals best suited to the production of voltaic electricity and their respective powers in connection therewith are related at pp. 242 and 313, Vol. IV of _Nicholson’s Journal_ for Sept. and Oct. 1800.

Cruikshanks was also the first to discover, in 1800, that when passing the electric current through water tinged with lithmus, the wire connected with the zinc end of the pile imparted a red tinge to the fluid contiguous to it, and that by using water coloured with Brazil wood, the wire connected with the silver end of the pile produced a deeper shade of colour in the surrounding fluid, whence it appeared that an acid was formed in the former case, and an alkali in the latter. Fahie, who thus mentions the fact, justly remarks that upon this discovery are dependent the electro-chemical telegraphs proposed by Bakewell, Caselli, Bonelli, D’Arlincourt, Sawyer and others.

Cruikshanks is the inventor of the galvanic trough, an improvement upon the voltaic pile, made by soldering together rectangular plates of zinc and copper, and so arranging them horizontally, in a box of baked wood coated with an insulating substance, as to allow of open spaces which can be filled with a solution of salt and water or with diluted acid, to take the place of the wet plates of cloth, paper or pasteboard. Cruikshanks’ plan was adopted in the construction of the powerful battery of 600 pairs, which Napoleon Bonaparte presented to the Ecole Polytechnique and upon which Gay-Lussac and Thénard made their important experiments during the year 1808. As Noad remarks, it is a very convenient form when sulphate of copper is used, for Dr. Fyfe has shown (_Phil. Mag._, Vol. XI. p. 145) that this exciting agent increases the electro-chemical intensity of the electric current as compared with that evolved by dilute sulphuric acid in the proportion of 72 to 16.

Both the above and Volta’s form of battery were much improved upon by Dr. William Babington (1756–1833), who united the pairs of zinc and copper plates by soldering them at one point, and by attaching them to a strip of wood in such a manner as to allow of the entire line being immersed at will into an earthenware or wooden trough having a corresponding number of cells or partitions. The extraordinarily strong voltaic battery, constructed in 1808 for the Royal Institution of London, by Mr. Eastwick under the direction of Sir Humphry Davy and of John George Children, was built upon this plan. It consisted of 200 separate parts, each part being composed of ten double plates, in all 2000 double plates of zinc and copper with a total surface of 128,000 square inches, and the charge which William H. Pepys was accustomed to give it consisted of a mixture of 1168 parts of water, 108 parts nitrous acid, and 25 parts sulphuric acid.

REFERENCES.--Wilkinson, “Elements of Galvanism,” 1804, Vol. II. pp. 52–63, 96–99; Pepper, “Electricity,” 1809, pp. 313–315; Noad, “Manual,” pp. 263, 264; Tomlinson, “Cyclopædia of Arts,” Vol. I. p. 566; Napier, “Electro-Metallurgy,” 1853, pp. 27, 28; _Nicholson’s Journal_, Vol. IV. pp. 187, 254, 261 and 511; _Sturgeon’s Annals_, Vol. IX. p. 309; Cruikshanks, “Some Experiments and Observations on Galvanic Electricity,” July 1800; also “Additional Remarks on Galvanic Electricity,” September 1800.

=A.D. 1801.=--Davy (Humphry), a very eminent English chemical philosopher, whose early studies had been greatly influenced both by Dr. John Tonkin, of Penzance, and by Gregory Watt, son of the celebrated inventor, James Watt, as well as by Mr. Davies Giddy Gilbert, who brought him to the notice of the English Royal Institution, delivers before the latter body, on the 25th of April 1801, his first lecture, wherein he traces the history of galvanism, and describes the different methods of “accumulating” it.

His first communication to the Royal Society was made in June of the same year, and is entitled, “An Account of Some Galvanic Combinations Formed by the Arrangement of Single Metallic Plates and Fluids, Analogous to the New Galvanic Apparatus of Volta.” As his able biographer, Prof. T. James Stewart Traill, M.D., of Edinburgh, remarks, this paper is the first of that series of electro-chemical investigations which have immortalized his name. In all hitherto constructed piles, the series had consisted of not less than two metals, or of one plate of metal, another of charcoal, and some interposed fluid. He showed in this paper that the usual galvanic phenomena might be energetically exhibited by a single metallic plate and two strata of different fluids, or that a battery might be constructed of one metal and two fluids, provided one of the fluids was capable of causing oxidation on one of the surfaces of the metal (“Bakerian Lectures,” London, 1840, pp. 32, etc., and _Phil. Trans._, Vol. XCI. p. 297).

On the 20th of November 1806 was read before the Royal Society Davy’s first Bakerian lecture, “On Some Chemical Agencies of Electricity.” This essay was universally regarded as one of the most valuable contributions thus far made to chemistry, and obtained for Davy the prize founded by Napoleon when First Consul, to be awarded by the French Institute, “à celui, qui par ses expériences et ses découvertes, fera faire a l’électricité et au galvanisme un pas comparable à celui qu’ont fait faire à ces sciences Franklin et Volta” (“Bakerian Lectures,” 1840, p. 56, and notes at p. 349, Vol. I of Dr. Lardner’s “Lectures,” etc., 1859).

Of the French Institute Davy became a member in 1817. Regarding the above-named important paper, given in full at pp. 1–56, of the volume of “Bakerian Lectures,” already referred to, Davy says (_Phil. Trans._ for 1826, p. 389): “Referring to my experiments of 1800, 1801 and 1802, and to a number of new facts, which showed that inflammable substances and oxygen, alkalies and acids, and oxidable and noble metals, were in electrical relations of positive and negative, I drew the conclusion _that the combinations and decompositions by electricity were referable to the law of electrical attractions and repulsions_,” and advanced the hypothesis “_that chemical and electrical attractions were produced by the same cause, acting in the one case on particles; in the other on masses; ... and that the same property, under different modifications, was the cause of all the phenomena exhibited by different voltaic combinations_” (Vol. I. pp. 678–684 of Dr. Thomas Young’s “Course of Lectures,” London, 1807, on “Electricity in Motion,” also Dr. Henry M. Noad’s “Manual,” London, 1859, pp. 362–365).

The second Bakerian lecture, “On some new phenomena of chemical changes produced by electricity, particularly the decomposition of the fixed alkalies, and the exhibition of the new substances which constitute their bases; and on the general nature of alkaline bodies,” was read Nov. 19, 1807. In this he gives an account of the most brilliant of all his discoveries (made during the previous month), proving that the so-called fixed alkalies are merely combinations of oxygen with metals. It has been stated by Dr. John Ayrton Paris that since the days of Newton no such happy and successful instance of philosophical induction has ever been afforded as that by which Davy reached the above-named results (_Phil. Trans._ for 1808, Vol. XCVIII. pp. 1–44). Davy’s observations were fully confirmed by Gay-Lussac, Thénard, Berzelius and Pontin (_Annales de Chimie_, Vol. LXXII. p. 193; Vol. LXXV. pp. 256–291; _Bibl. Brit._ for June 1809, p. 122). Although Davy was less successful in his attempt to decompose the proper earths, he proved that they consist of bases united to oxygen. It was reserved for Friedrich Wöhler, Berzelius and Bussy to exhibit the bases by themselves, and to show that all, excepting silica, are metallic, and capable of uniting with iron.

It is said that the original 500-plate batteries of the Royal Institution were so worn in the course of Davy’s experiments as to be almost unserviceable, and that he suggested to the managers the propriety of starting a subscription for the purchase of a large galvanic battery. This being acted upon during the month of July 1808, he was placed in possession of the battery already alluded to in the Cruikshanks article (A.D. 1800), and which was the most powerful constructed up to that time. “With this battery Davy did not reach any new results of importance; but he was enabled to demonstrate the galvanic phenomena upon a more brilliant scale. Nor was the increased power necessary to carry on successfully the experiments on the decomposition of the alkalies and the earths as was apparently believed by many of those historians of science ... who attributed the author’s brilliant success in electro-chemical research to his supposed extraordinary means, the enormous voltaic batteries of the Royal Institution.” In this connection, the terse notes appearing at foot of pp. 62, 63, 106, 107 of the 1840 edition of the “Bakerian Lectures” will prove interesting reading.

It was with the afore-named galvanic combination that Davy openly made--in 1809–1810, and not in 1813, as has been frequently stated--the first display of the continuous electric arc (John Davy, “Memoirs of the Life of Sir Humphry Davy,” p. 446).

“When the cells of this battery were filled with sixty parts of water mixed with one part of nitric acid and one part of sulphuric acid,” he says, “they afforded a series of brilliant and impressive effects. When pieces of charcoal about an inch long and one-sixth of an inch in diameter were brought near each other (within the thirtieth or fortieth part of an inch), a bright spark was produced, and more than half the volume of the charcoal became ignited to whiteness, and by withdrawing the points from each other a constant discharge took place through the heated air, in a space equal at least to four inches, producing a most brilliant ascending arch of light, broad and conical in form in the middle. When any substance was introduced into this arch, it instantly became ignited; platina melted as readily in it as wax in the flame of a common candle; quartz, the sapphire, magnesia, lime, all entered into fusion; fragments of diamond, and points of charcoal and plumbago, rapidly disappeared, and seemed to evaporate in it, even when the connection was made in a receiver exhausted by the air pump; but there was no evidence of their having previously undergone fusion” (“Elements of Chemical Philosophy,” 1812, p. 154).

Dr. Paris says that Davy had already produced the spark upon a small scale as far back as 1800 (_Nicholson’s Journal_, Vol. III, quarto, p. 150), and we learn, through an article published upon the early experiments with the electric light, the names of others who had likewise noticed the arc at about the same period, while Quetelet informs us that M. Curtet is reported to have observed the light between carbon points during the year 1802 (Curtet’s letter to J. B. Van Mons in the latter’s _Journal de Chimie_, No. VI. p. 272, and in _Journal de Physique_, An. XI. p. 54). The article referred to is as follows:

“Dr. S. P. Thompson has given the following interesting details in regard to this subject: In looking over an old volume of the _Journal de Paris_, I found, under date of the Twenty-second Ventose, An. X (March 12, 1802), this passage, which evidently refers to an exhibition of the electric arc: ‘Citizen (E. G.) Robertson, the inventor of the phantasmagoria (magic lantern), is at present performing some interesting experiments that must doubtless advance our knowledge concerning galvanism. He has just mounted metallic piles to the number of 2500 zinc plates and as many of rosette copper. We shall forthwith speak of his results, as well as of a new experiment that he performed yesterday with two glowing carbons. The first having been placed at the base of a column of 120 zinc and silver elements, and the second communicating with the apex of the pile, they gave at the moment they were united a brilliant spark of an extreme whiteness that was seen by the entire society. Citizen Robertson will repeat the experiment on the 25th.’”

The date generally given for this discovery by Humphry Davy is 1809, but earlier accounts of his experiments are found in Cuthbertson’s “Electricity” (1807), and in several other works.

In the _Phil. Mag._, Vol. IX. p. 219, under date of Feb. 1, 1801, in a memoir by Dr. H. Moyes, of Edinburgh, relative to experiments made with the pile, we find the following passage: “When the column in question had reached the height of its power, its sparks were seen by daylight, even when they were made to jump with a piece of carbon held in the hand.” In the same volume of the _Phil. Mag._, and immediately following Dr. Moyes’ letter to Dr. Garthshore, on experiments with the voltaic pile, will be found an account of similar investigations made in Germany, and communicated by Dr. Frulander, of Berlin.

In the “Journal of the Royal Institution” (1802), Vol. I. p. 106, Davy describes a few experiments made with the pile, and says: “When instead of metals, pieces of well-calcined carbon were employed, the spark was still larger and of a clear white.” On p. 214 he describes and figures an apparatus for taking the galvano-electric spark into fluid and aeriform substances. This apparatus consisted of a glass tube open at the top, and having at the side another tube through which passed a wire that terminated in a carbon. Another wire, likewise terminating in carbon, traversed the bottom, and was cemented in a vertical position.

But all these observations are subsequent to a letter printed in “Nicholson’s Journal” for October 1800, p. 150, entitled “Additional experiments on Galvanic Electricity in a letter to Mr. Nicholson.” The letter is dated Dowry Square, Hotwells, Sept. 22, 1800, and is signed by Humphry Davy, who at this epoch was assistant to Dr. Beddoes at the Philosophical (Pneumatic) Institution of Bristol. It begins thus:

“Sir: The first experimenters in animal electricity remarked the property that well calcined carbon has of conducting ordinary galvanic

## action. I have found that this substance possesses the same properties

as metallic bodies for the production of the spark when it is used for establishing a communication between the extremities of Signor Volta’s pile.”

Among the papers read by Davy before the Royal Society between June 30, 1808, and Feb. 13, 1814, are the following: “Electro-chemical researches on the decomposition of the earths, with observations on the metals obtained from the alkaline earths, and on the amalgam procured from ammonia”; “An account of some new analytical researches on the nature of certain bodies,” etc., and the Bakerian lecture “On some new electro-chemical researches, on various objects, particularly the metallic bodies from the alkalies and earths, and on some combinations of hydrogen”; “Elements of chemical philosophy, detailing experiments on electricity in vegetation.”

In alluding to the important subjects covered by him during the above-named period, his brother and biographer, John Davy, M.D., F.R.S., says: “I shall not attempt an analysis of these papers; I shall give merely a sketch of the most important facts and discoveries which they contain, referring the chemical reader to the original for full satisfaction. After the extraction of metallic bases from the fixed alkalies, analogies of the strongest kind indicated that the alkaline earths are similarly constituted; and he succeeded in proving this in a satisfactory manner. But, owing to various circumstances of peculiar properties, he was not able on his first attempts to obtain the metals of those earths in a tolerably pure and insulated state for the purpose of examination. On his return to the laboratory after his illness, this was one of the first undertakings. He accomplished it to a certain extent by uniting a process of Messrs. Berzelius and Pontin, who were then engaged in the same enquiry, with one of his own. By negatively electrifying the earths, slightly moistened, and mixed with red oxide of mercury, in contact with a globule of mercury, he obtained amalgams of their metallic bases; and, by distillation, with peculiar precautions, he expelled the greater part of the mercury. Even now, in consequence of the very minute quantities of the bases which he procured, and their very powerful attraction for oxygen, he was only able to ascertain a few of their properties in a hasty manner. They were of silvery lustre, solid at ordinary temperatures, fixed at a red heat, and heavier than water. At a high temperature they abstracted oxygen from the glass, and, at ordinary temperatures, from the atmosphere and water, the latter of which in consequence they decomposed. The names he proposed for them, and by which they have since been called, were barium, strontium, calcium and magnium, which latter he afterwards altered to magnesium....”

The reviewer of Davy, in the columns of the “Chemical News,” writing in 1879, states that his papers on numerous subjects flowed into the Royal Society’s archives in an uninterrupted stream, and it may be said, without exaggeration, that his work, especially during the six years from 1806 to 1812, did more for chemistry than the 60 which followed them.

Between the last-named dates, Davy was asked by the Dublin Society to give a course of lectures on electro-chemical science, which he delivered Nov. 8–29, 1810. Trinity College afterward conferred on him the degree of LL.D., and he was knighted by the Prince Regent one day before resigning from the Royal Institution, wherein he gave his farewell address on April 9, 1812.

In 1813, accompanied by his bride and Mr. Faraday (his “assistant in experiments and in writing”), Davy made his first trip to the Continent, where he met Ampère, Humboldt, Gay-Lussac, Vauquelin, Cuvier, Laplace and other distinguished scientists, and where he carried on many experiments, of which the results were duly communicated to the Royal Society, as were also the observations made by him up to the time of the completion of his second trip in 1820.

Besides the Rumford medal conferred on him in 1816, he received a baronetcy two years later, and was given, in 1827, the medal of the Royal Society, the presidential chair of which he occupied for seven consecutive years.

One of the four memoirs produced by Davy in 1818–1829 treats of electro-magnetism. In 1820, Davy, Arago and Seebeck independently discovered the magnetizing power of the electric current on steel and iron needles or filings. In Davy’s experiments, it is said, the filings adhered to the wire connecting the poles of a voltaic apparatus, consisting of a hundred pairs of plates of four inches, in such considerable quantities as to form a mass around it ten or twelve times the thickness of the wire (_Phil. Trans._ for 1821, p. 9; _Annales de Chimie et de Physique_, Vol. XV. p. 93).

Davy was actively engaged during 1821–1822 in experiments on electro-magnetism and on electricity in vacuo, reaching the conclusion, in the last-named channel, that electric light as well as electrical attractions and repulsions are observable in the most perfect vacuum obtainable. This is readily demonstrated with either the apparatus employed by Tyndall in his Lecture VIII, “On the analogies of light, heat and sound,” or with the apparatus used by Davy and illustrated at Plate CCXXIII of the “Encyclopædia Britannica,” eighth edition. From the numerous experiments and observations recorded in the last-named work the following are extracted:

“A spark capable of passing through only half an inch in common air will pass through six inches of the Torricellian vacuum.... When the minutest quantity of rare air was introduced into the mercurial vacuum, the colour of the electric light changed from bright _green_ to _sea green_, and by increasing the quantity, to _blue_ and _purple_. At a low temperature the vacuum became a much better conductor. A vacuum above fused tin exhibited nearly the same phenomena. At temperatures below zero the light was yellow and of the palest phosphorescent kind, just visible in great darkness, and not increased by heat. When the vacuum was formed by pure olive oil and by chloride of antimony, the electric light through the vapour of the chloride was more brilliant than that through the vapour of the oil; and in the last it was more brilliant than in the vapour of mercury at common temperatures. The light was of a _pure white_ with the chloride, and of a _red_ inclining to _purple_ in the oil.... In carbonic acid gas the light of the spark is white and brilliant, and in hydrogen gas it is red and faint. When the sparks are made to pass through balls of wood or ivory they are of a _crimson_ colour. They are _yellow_ when taken over powdered charcoal, _green_ over the surface of silvered leather, and _purple_ from imperfect conductors.”

Davy’s Bakerian lecture for 1826 was entitled “On the relation of electrical and chemical changes.” Two years previous to its reading he had communicated to the English Government his discovery of what he erroneously considered a remedy against the rapid deterioration of copper sheathing for ships. His plan consisted in altering the electrical condition of the copper by adding plates of zinc or iron (called “protectors”), but the bottoms of the vessels became so foul through the deposition of calcareous matter and the adhesion of large balani and lepades, etc., to the copper, that the attempt had to be abandoned (A. Bobierre, “Thèse ... pour doubler les navires,” Nantes, 1858). It was in the same year (1824) that Davy made an important journey through Sweden, Norway, Denmark, Holstein, and Hanover, during which he met Oersted, Berzelius, Gauss, Olbers, Schumacher and other savants.

His last communication to the Royal Society, “Remarks on the Electricity of the _Torpedo_,” was sent from Rome in 1828, one year before his death, and embodies the result of many observations made while on the Continent, more especially during the years 1814–1815. The investigations in this line which, owing to continued ill health, he was unable to carry on, were completed by his brother, Dr. John Davy, who established the following points of difference between the phenomena of the _torpedo_ and those of other kinds of electricity:

“Compared with voltaic electricity, its effect on the multiplier is feeble: its power of decomposing water and metallic solutions is inconsiderable; but its power of giving a shock is great, and so also is its power of magnetizing iron. Compared with common electricity, it has a power of affecting the multiplier, which, under ordinary circumstances, common electricity does not exhibit; its chemical effects are more distinct; its power of magnetizing iron and giving a shock appears very similar; its power of passing through air is infinitely less as is also (if it possess it at all) the power of producing heat and light.”

Davy likewise made noteworthy observations concerning the pyro-electricity of the tourmaline, confirming previous investigations in the same line, and asserting that “when the stone is of considerable size, flashes of light may be seen along its surface” (“Elements of Chemical Philosophy,” Vol. I. p. 130), a curious fact which Sir David Brewster says he does not believe has ever been verified by any subsequent observer.

It is not within the scope of this “Bibliographical History” to describe Davy’s other notable papers relative to the miner’s safety lamp, etc., but reference should be made here to his first scientific memoir, “On heat, light and the combination of light” (Sir H. Davy’s works, Vol. II) of which copious extracts are given by Prof. John Tyndall in the appendix to his third lecture on “Heat considered as a mode of motion.”

As regards the caloric theory, which had deservedly been engaging the attention of so many scientists, it is, however, thought best to quote here from Deschanel’s article on thermo-dynamics: “Strange to say, this theory survived the many exposures of its weakness and the, if possible, still more conclusive experiment of Sir Humphry Davy, who showed that two pieces of ice, when rubbed together, were converted into water, a change which involves not the evolution but the absorption of latent heat, and which cannot be explained by diminution of thermal capacity, since the specific heat of water is much greater than that of ice. Davy, like Rumford, maintained that heat consisted in motion, and the same view was maintained by Dr. Thomas Young; but the doctrine of caloric nevertheless continued to be generally adopted until about the year 1840, since which time the experiments of Joule, the eloquent advocacy of Meyer, and the mathematical deductions of Thomson, Rankine and Clausius, have completely established the mechanical theory of heat, and built up an accurate science of thermo-dynamics.”

REFERENCES.--“The Life of Sir H. Davy,” by John Ayrton Paris, M.D., 1831, and by T. E. Thorpe, New York, 1896, also his life by Dr. John Davy, F.R.S., 1836; and his biography and articles “Chemistry” and “Voltaic Electricity” in the “Encyclopædia Britannica”; “Works of Sir Humphry Davy,” edited by John Davy, 1839–1840; “The Fragmentary Remains ... of Sir H. Davy,” 1858; “Dic. Tech. et Prat. d’Electricité” de Mr. Geo. Durant, Paris, 1887–1889; W. T. Brande, “Manual of Chemistry,” London, 1848, Vol. I. pp. xciii-cv, 213–224; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Vol. II. pp. 80–86, and Chap. XXVII; Thomas Thomson, “History of the Royal Society,” London, 1812, pp. 454–455; “Galvanism,” in Dr. Lardner’s Lectures; Noad’s “Lectures on Chemistry,” pp. 32–33; Bakewell’s “Elec. Sc.,” pp. 33–35; Daniel Davis, “Manual of Magnetism,” 1846–1852; Thomson, “History of Chemistry,” Vol. II. pp. 260–261; “Elem. of Exp. Chem.,” Wm. Henry, London, 1823, Vol. I. p. 192; “Elements of Chemical Philosophy,” p. 155; Thomas Thomson, M.D., London, 1830; “Outline of the Sciences of Heat and Electricity,” pp. 467, et. seq., 491–495, 533; De la Rive’s “Treatise on Electricity ...” Vol. II. pp. 282–283; “Encyclopedia Metropolitana,” Vol. IV (Galv.), pp. 176, 178, 222, and (Elec. Mag.) pp. 9 and 10; Gay-Lussac and Thénard, _Phil. Mag._, Vol. XXXII. p. 88, 1809; Jacquin, _Phil. Mag._, Vol. XXXVI. p. 73, 1810; M. Donovan, _Phil. Mag._, Vol. XXII. pp. 227, 245, 1811; M. Yatman, “A Letter ...” and Davy’s “Enquiries ...” London, 1811, 1814; W. Henry, “On Sir H. Davy and Dr. Wollaston,” London, 1830; Contessi G. Lelandri, “Ann. Reg. Lomb., Veneto,” 11, 78, 1832, and F. I. Roux, “Conservation des plaques ...” Paris, 1866; _Nicholson’s Journal_, 4to, Vol. IV. pp. 275, 337 and 394; and 8vo., Vol. I. p. 144, Vol. III. p. 135; Dredge, “Electric Illumination,” Vol. I. pp. 24, 25, 30; _Phil. Mag._, Vol. VII. p. 347, for experiments of Dr. Henry Moyes, also Vol. XI. pp. 302, 326; XXVIII. pp. 3, 104, 220; XXIX. p. 372; XXXI. p. 3; XXXII. pp. 1, 18–22, 101, 146, 193; XXXIII. p. 479; XXXV. p. 401; XXXVI. pp. 17, 85, 352, 404; XL. p. 145; LVIII. pp. 43, 406; LIX. p. 468; LX. p. 179; _Phil. Mag. or Annals_, Vols. I. pp. 31, 94, 190; VI. p. 81; X. pp. 214, 379, 426; _Phil. Trans._ for 1801, 1809, 1810, 1822; Sturgeon’s “Scientific Researches,” Bury, 1850, pp. 14–16, 23; _Annales de Chimie_, Vol. XV. p. 113; “Société Philomathique,” An. X. p. 111; Becquerel, Paris, 1850, Vol. I. pp. xi and 33 note; “Nuova Scelta d’Opusc.” Vol. II. pp. 190, 282; “Beiträge zur Erweiterung,” etc., Berlin, 1820; “Elemente d. Chemischen,” etc., Berlin, 1814; “Royal Society Catalogue of Scientific Papers,” London, 1868, Vol. II. pp. 171–175; “Biographie Générale,” Vol. XIII. p. 264; “Engineering,” London, Vol. LII. p. 759; “Abstracts of Papers ... Roy. Soc.,” London, 1832–1833, Vol. I. pp. 59, 247, 278, 313, 350; Vol. II. pp. 154, 159, 189, 213, 242, 281, 354; “Royal Society Catalogue of Scientific Papers,” Vol. II. pp. 175–180, and Vol. VI. p. 633 (likewise Vol. VII. pp. 494–495--for John Davy); “Bibliothèque Britannique,” Vol. XVII for 1801, pp. 237, 246; Vol. XXV, N.S. for 1824, p. 98; Vol. XXXIV, O.S. for 1807, p. 397 (the same as “Nicholson’s Journal,” for January 1807); Vol. XXXV. pp. 16, 141; “Edin. Phil. Journ.,” Vol. X. p. 185.

Of the afore-named references in the _Phil. Magazine_, Vol. XXXI, that at p. 3 relates to Davy’s new Eudiometer acting by the electric spark exactly in the same manner as that of Il Marchese de Brezé, described in the “Opuscoli.”

=A.D. 1801.=--Flinders (Matthew), a very able navigator and captain in the English merchant service, sails in the bark “Investigator” for the purpose of circumnavigating and exploring New Holland. During this memorable voyage he carefully observed the cause of errors in the variation of the magnetic needle as depending on the direction in azimuth of the ship’s head, having often noticed, as a writer in the English _Quarterly Review_ expresses it (Vol. CXVIII. p. 343), that the direction of the compass needle frequently wandered from that which the known variation due to the geographical position of the ship assigned to it. To correct those disturbances he suggested placing aft of the compass a vertical bar of soft iron, whose upper end, having like magnetism as the imaginary mass in the ship’s head, would, in acting on the opposite pole of the compass needle, rectify its disturbances.

Flinders had, during the year 1795, made observations in the same line as those recorded by the astronomer Bayly, who had sailed with Captain Cook during his last two voyages, but it was not until his return from the unfortunate first voyage above alluded to that he properly recorded his investigations for the benefit of navigators.

REFERENCES.--“Encyclopædia Britannica,” 1856, Vol. X. p. 295, and article “Australia,” Vol. IV. pp. 253, 254; “English Cyclopædia” (Biography), Vol. II. pp. 933–935; _Sci. Am. Supp._, No. 534, p. 8526; William Walker, “The Magnetism of Ships,” London, 1833, pp. 21–23; “Abstracts of Papers of the _Phil. Trans._, 1800–1830,” p. 187; _Phil. Trans._ for 1805; John Farrar, “Elem. of Elect.,” 1826, p. 381; “Cat. Sc. Papers Royal Soc.,” Vol. I. p. 187.

=A.D. 1801.=--Gautherot (Nicholas), able French chemist (1753–1803), discovers that when a current has passed through two plates or wires of the same metal in dilute sulphuric acid, a secondary, reverse or polarization current is obtainable after disconnecting the battery. This was the first step in the storage of electricity and an account is given of it in the _Philosophical Magazine_, Vol. XXIV. pp. 185–186, which contains a report of the proceedings before the Galvani Society of Paris. Gautherot says that the results he obtained should become the source or basis of several other experiments, and concur more than any other to the discovery of the theory of this new branch of physics.

In this same year Gautherot observed the power of adhesion of the two wires in contact with the upper and lower ends of the pile, a report upon which appears at p. 209, Vol. XXXIX of the _Annales de Chimie_, while a full account of his observations on the subject forms the substance of a separate work printed in London during the year 1828.

The French physicist, C. J. Lehot, makes allusion to the last-named discovery in the following words, at p. 4 of his pamphlet entitled “Observations sur le Galvanisme et le Magnétisme”:

“It has long been known that the two wires which terminate a pile attract one another, and, after contact, adhere like two magnets. This attraction between the two wires, one of which receives, and the other loses, the galvanic fluid, differs essentially from electrical attraction, as Ritter observed, since it is not followed by a repulsion after contact, but continues as long as the chain is closed.”

J. J. Fahie, who also quotes this passage, says:

“The discovery in question seems to have been made independently, and at about the same time by Gautherot (_Philosophical Magazine_ or _Annals_ for 1828, Vol. IV. p. 458), by P. S. Laplace, and by J. B. Biot (_Journal de Physique et de Chimie_, for 1801, Vol. LIII. p. 266). The latter made the further very acute observation that, if the wires are attached to plates of metal, and these plates approached by their edges, they will attract one another; while if approached by their faces no action whatever takes place. For other interesting experiments of this kind see ‘Nicholson’s Journal’ for 1804, Vol. VII. p. 304.”

Previous to the aforesaid discoveries, on the 12th Brumaire, An. IX (Nov. 1800), Gautherot had published his refutation of Volta’s contact theory, through the Paris “Société Philotechnique,” and it is to be found recorded at p. 471, Vol. I of the “Mémoires des Sociétés Savantes et Littéraires de la République Française.”

Later on he devoted so much attention to galvanic researches that Messrs. A. F. de Fourcroy and L. N. Vauquelin made a special report upon the five important memoirs containing the results of his many observations to the French Institute on the 21st Fructidor.

The first memoir gives the whole theory and practice of the various kinds of conductors, and describes an apparatus devised by Gautherot to ascertain the conducting powers of different natural, solid, liquid and even gaseous bodies (Izarn, “Manuel du Galvanisme” 1804, pp. 56–60). He enters into full details as to the effects of the voltaic pile in many experiments made upon himself, and draws consequences which apparently disprove the identity of the electric and the galvanic fluids.

The second memoir treats of the galvanic properties of charcoal, and shows that it is a less perfect conductor than are metallic substances.

In the third memoir he makes known his discovery that charcoal and zinc form a galvanic apparatus which will produce shocks, the decomposition of water, etc. He observes “that in the decomposition of water, charcoal decomposes that fluid in the same way with non-oxydable metals; or, in other words, that when two pieces of charcoal are employed for this purpose, one of them disengages the hydrogen gas, and the other the oxygen ... when the portions of charcoal touch each other in the water, its decomposition is not stopped on that account, as happens when metallic substances are brought in contact under the same circumstances. Indeed, if to bring more immediately together, one of the pieces of charcoal be cut in a furcated shape, this does not become an obstacle to the decomposition of the water.”

The fourth memoir treats further of different kinds of conductors, and of various methods of constructing galvanic columns.

In the fifth and last memoir, Gautherot relates his important discovery that an effective galvanic apparatus can be made without metals. He constructed one of forty layers of charcoal and plumbago, which communicated a strong and pungent taste, accompanied by the galvanic flash of light, and which finally produced the decomposition of water, the charcoal side disengaging the hydrogen gas (Izarn, “Manuel du Galvanisme,” 1804, p. 177).

During the month of March 1803, he read before the “Institut National” a memoir entitled “Recherches,” etc. (researches upon the causes which develop electricity in the galvanic apparatus). This appeared in the _Journal de Physique_, Vol. LVI. p. 429.

REFERENCES.--“Biographie Générale,” Vol. XIX. p. 694; Larousse, “Dict. Univ.,” Vol. VIII. p. 1089; Izarn, Giuseppe (Joseph) “Manuel du Galvanisme,” Paris, An. XII. 1804, s. 6, pp. 95, 250–254: _Mém. des Soc. Savantes_, etc., Vol. I. pp. 164, 168; P. Sue, aîné, “Hist. du Galvanisme,” Paris, An. X, 1802, Vol. II. pp. 191, 196–203, 213, 214, 316; Alglave et Boulard, _Lumière Electrique_, Paris, 1882, p. 219; _Poggendorff_, Vol. I. p. 857; “Extrait d’une lettre de Brugnatelli,” etc., Bruxelles, 1802 (Van Mons, _Journal de Chimie_, Vol. II. p. 216).

=A.D. 1801.=--Robertson (Etienne Gaspard), a very capable French experimentalist and one of the founders of the Paris Galvani Society, who has already been alluded to in the article relating to Sir Humphry Davy, writes a memoir, “Expériences nouvelles sur le fluide galvanique,” which was read before the Institute on the 11th Fructidor, An. VIII, and which appeared in the _Annales de Chimie_ (Vol. XXXVII. p. 132), as well as in the “Mémoires Récréatifs, Scientifiques,” etc., published in Paris during 1840, three years after Robertson’s death.

Robertson states that as he was delivering a lecture on the 9th Vendémaire, An. IX, during which he alluded to differences which he found to exist between the galvanic and electric fluids, he was interrupted by Prof. Brugnatelli, who stated that Volta, who was then present, desired an opportunity to correct the wrong impressions the lecturer laboured under. Volta called upon him early the day following and brought a live frog as well as apparatus, with which they experimented quite extensively, and the results of which brought Robertson completely over to the views of the Italian scientist. Volta frequently repeated his visits, which led to the development of a lasting friendship between the two. They visited together all the prominent scientific bodies, such as l’Ecole de Médecine, l’Ecole Polytechnique, etc., but found to their great astonishment that Robertson was the only one in Paris who had as yet given the new discovery any serious attention. At pp. 250–253, Vol. I of his “Mémoires,” etc., will be found a full account of the above as well as of the very indifferent reception first given them by the celebrated Prof. Charles.

Robertson adds (p. 256 of last-named work) that he was asked by Volta to witness the latter’s notable experiments made before the members of the National Institute of France, Nov. 16, 18, 20, 1800, and already alluded to herein at A.D. 1775. The sessions of that body were being held at the time in the Palais du Louvre, and the excitement caused by the meetings was so great that all the approaches were guarded by soldiery. After Prof. Volta had explained his theory and alluded to the identity of electricity and galvanism, he announced that Robertson had first illustrated the fact, and he asked him to repeat his original experiment, which the latter did after the necessary hydrogen gas had been procured from the neighbouring cabinet of Prof. Charles.

Robertson is also the author of several other interesting memoirs on the electrophorus, the improved “couronne de tasses” and “acide galvanique” which can be found in Vol. XXXVII of the _Journal de Physique_ and in the _Journal de Paris_ for the year 1800 (“Recueil des Actes de la Soc. de Lyon,” Tome II. p. 370).

=A.D. 1801.=--Gerboin (A. C.), Professor at the Medical School of Strasbourg, is the first to report upon the peculiar agitation of mercury when the voltaic current passes through it.

He states, in his “Recherches expérimentales sur un nouveau mode de l’action électrique” (Strasbourg, 1808), that his many researches were instigated by the observation he had made during the winter of 1798, while in company with some friends watching a child play with a hollow wooden ball. The Italian physicist, Abbate Fortis (1740–1803), who wrote several works on natural philosophy, but who is best known by his “Viaggio di Dalmazia,” had already announced that a pyritical cube suspended by a thread held between the thumb and index would immediately, without any movement of the fingers, assume a circular motion upon being approached by another body. The “Morgenblatt” of Tübingen and the French “Archives Littéraires” render in 1807 a very complete account of Ritter’s researches upon the Fortis pendulum, and N. Meissas states, at pp. 181–187 of his “Nouveaux Eléments de Physique,” Paris, 1838, that he repeated the experiment of Ritter and of his friend Gerboin and observed many very curious results. These he embodied in a communication during the month of April 1829 to Ampère, who looked into Meissas’ work in company with M. Becquerel, also a member of the French Institute.

In his experiments, Gerboin employed a tube bent in U[ symbol] form, filled half full of mercury, which later was covered with a stratum of water, and he placed therein the wires connecting with a pile. The surface of the mercury beneath the negative pole was slightly oxidized, but the surface under the positive point moved so violently as to cause small bodies placed within to be thrown outward upon the surface of the tube. These bodies moved in a contrary direction, v from the circumference toward the interior, if the positive pole was made to touch the liquid metal.

REFERENCES.--Observations of M. Erman, of the Berlin Academy of Sciences, upon M. Gerboin’s experiments related in the _Annales de Chimie_, Tome LXXVII. p. 32. Also, _Annales de Chimie_, Tome XLI. pp. 196, 197, _Mém. des Soc. Sav. et Lit._, Vol. II. p. 199; Dr. Gore, “El. Metal,” 1877, p. 3; De la Rive, “Treatise on Electricity,” 1856, Vol. II. p. 433; Gmelin’s “Chemistry,” Vol. I. p. 487.

=A.D. 1801.=--Trommsdorff (Johann Bartholomäus), German chemist and pharmacist, who became Professor of Physics and Chemistry in the University of Erfurt, discovers that by employing large plates in galvanic batteries he can produce the combustion of fine wires and of thin leaves of metal.

After having obtained very strong shocks and large sparks, and effected the decomposition of water, etc., with his first pile consisting of 180 discs of copper, zinc and wet cardboard, he experimented with very thin leaves of the following metals, and found them to burn as follows: Gold, with a bright white light; silver, with a blue light; yellow copper, with a reddish blue light; red copper, with an emerald blue flame; zinc, with a bluish white flame; tin, with a reddish white light, etc. When oxidizing the noble or perfect metals, gold, silver, platinum, in hollow glass spheres, he found them to melt so thoroughly as to completely line the sides of the latter.

Trommsdorff afterward constructed a much larger pile of nearly 600 discs, not doubting that with a larger apparatus he could consume very thick plates. It was while carrying on subsequent experiments that MM. Fourcroy, Vauquelin and Thénard ascertained the fact that metals were more effectively deflagrated by piles with large plates than by piles having a great many plates of smaller surfaces.

In a letter dated Erfurt, March 16, 1801, Trommsdorff alludes to the galvanic decomposition of water spoken of at p. 98 of the “Archives du Nord pour la Physique et la Médecine,” published at Copenhagen, and expresses doubts as to the correctness of the conclusions therein pointed out by Pfaff and Ritter.

REFERENCES.--“Encycl. Metrop.” (Galvanism), Vol. IV. p. 221; “Roy. Soc. Sci. Papers,” Vol. VI. pp. 45–52; _Poggendorff_, Vol. II. pp. 1136, 1137; C. H. Wilkinson, “Elem. of Galv.,” London, 1804, Vol. II. pp. 134–136; J. S. Ersch, “Handbuch,” etc., p. 119; L. F. F. Crell, “Chemische Annalen” for 1801; 4^e Cah., p. 337; J. B. Van Mons, _Journal de Chimie_, Vol. I. p. 41; Larousse, “Dict. Univ.,” Vol. XV. p. 535. His pile is described at pp. 253–254, Vol. II of “Hist. du Galvanisme,” P. Sue, aîné, Paris, An. X, 1802, with references to Von Crell’s “Chemische Annalen,” 1801, 4th Book, p. 237, and Van Mons’ “Journal de Chimie,” Vol. I. p. 41.

=A.D. 1801.=--Libes (Antoine), Professor of Natural Philosophy at the Collège de Beziers and at the Paris Ecole Normale and Lycée Charlemagne, publishes in three volumes, at Paris, his “Traité élémentaire de Physique,” which had been preceded by his “Théorie de l’électricité,” etc., and was followed by a valuable “Dictionnaire de Physique” in 1806 (C. F. V. Delaunay, “Manuel,” etc., Paris, 1809).

In his “Traité,” Prof. Libes dispels the previous generally accepted belief as to the production of electricity by pressure. Experiments made by Æpinus and by Haüy had shown that such minerals as developed positive electricity by friction likewise exhibited the same electricity by pressure, and that those furnishing resinous or negative electricity by pressure developed the same electricity by friction.

It is known that varnished silk (_taffetas gommé_) acquires resinous electricity by ordinary friction, but Libes found the means of causing it to develop vitreous or positive electricity. This is shown when a metallic disc insulated by a glass handle is _pressed_ upon the silk; the latter will acquire positive electricity while the disc will develop resinous or negative electricity. If, on the contrary, the disc is _rubbed_ or _rolled_ upon the silk so as to produce friction, the silk acquires resinous electricity and the disc vitreous or positive electricity. If a glass plate is substituted for the disc, the silk again acquires vitreous electricity and the glass resinous electricity, that is to say, they both develop contrary electricities to that furnished through ordinary rubbing.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. X. p. 475; _Poggendorff_, Vol. I. pp. 1449, 1450; Volpicelli, “Sul cognito fenomeno ...” Roma, 1859; Haüy, “Traité Elémentaire de Physique,” Paris, 1806, Vol. I. pp. 371, 372; A. C. Becquerel, “Expériences ... par la pression,” Paris, 1823; “Catal. of Sci. Papers of Roy. Soc.,” Vol. IV. p. 5; Thos. Thomson, “An Outline of the Sciences of Heat and Electricity,” London and Edinburgh, 1830, p. 482; Dove, p. 229; “Encycl. Brit.,” Vol. VIII, 1855, p. 563; _Annales de Chimie et de Physique_, Vol. XXII. p. 5; _Phil. Mag._, Vol. LXII. pp. 204, 263.

=A.D. 1801.=--Fourcroy (Antoine François de), an eminent French chemist, physician and author, who succeeded Macquer in the professorship at the Jardin du Roi, for which Lavoisier was likewise a candidate, publishes (Vol. XXXIX. p. 103, of the _Annales de Chimie_) the result of galvanic experiments which he made in conjunction with Louis Nicholas Vauquelin (1763–1829), and also with Baron Louis Jacques Thénard (1777–1857), who, in turn, became the successor of Fourcroy as Professor of Chemistry at the Ecole Polytechnique. They thought that by using many discs they could increase the force of the current and also decompose water more rapidly, but found this was not the case, and that with an enlarged pile the combustion of metallic wires was more rapid and brilliant, thus proving that the degree of combustion is relative to the surface of the plates (“Encyclopædia Britannica,” 1855, Vol. XXI. p. 626).

The grand experiment made conjointly by Fourcroy, Vauquelin and Seguin on the composition of water from its constituent gases was commenced May 13, 1790, and continued by them without intermission until its completion, nine days later. “The gases were fixed in a close vessel by means of electricity, and produced a nearly equal weight of water” (_Trans. Amer. Phil. Soc._, N. S., Vol. VI. p. 339, giving description of apparatus for the decomposition and recomposition of water).

Fourcroy was also one of the savants appointed in 1798 by the Academy of Sciences of Paris to examine and report upon the experiments of Galvani. The committee was composed of Guyton de Morveau, Coulomb, Vauquelin, Sabathier, Pelletan, Charles, Fourcroy and Hallé, the last named being charged with the verification of all the then recent discoveries, which were repeated with the assistance of Humboldt, who went to Paris especially for the purpose. The official report fully endorsed the praiseworthy line of researches prosecuted by both Galvani and Humboldt, and the entire series of experiments was at once repeated by many leading physicists throughout Germany.

On June 19, 1803, one of Antoine Fourcroy’s most interesting memoirs, treating of meteoric stones, was read by C. Fourcroy before the French Institute.

REFERENCES.--_Phil. Mag._, Vol. XVI. p. 299; Noad’s “Lectures,” pp. 183, 184; Ure, “Dict. of Chem.”; also the interesting biography embracing a list of his very numerous works and treatises, at pp. 846–849, Vol. IX of 1855 “Encyclopædia Britannica.” See likewise, “Royal Society Catalogue of Scientific Papers,” Vol. II. pp. 677–682; Thomas Thomson, “History of Royal Society,” p. 454; Wilkinson’s “Elements of Galvanism ...” 1804, Vol. II. pp. 113, 145, 151, 152, 208, 359; Fahie’s “History of Electric Telegraphy,” p. 194; Izarn, “Manuel du Galv.,” 1804, s. 4, p. 167; “Journal des Savants” for Jan. 1860; P. Sue, aîné, “Hist. du Galvanisme,” Paris, 1802, Vol. II. pp. 159–160, 241, 264. For Louis N. Vauquelin, consult “Cat. Sc. Papers of Roy. Soc.,” Vol. VI. pp. 114–128, 761; also “Mém. des Soc. Savantes et Litt.,” Vol. I. p. 204.

=A.D. 1801.=--Lehot (C. J.), French physicist, sends a curious and lengthy memoir, regarding the circulation of a very subtile fluid in the galvanic chain, to the Institut National, before which body it is read on the 26 Frimaire, An. IX.

To the analyzation of the above-named memoir, Wilkinson devotes more than half the tenth chapter of his “Elements of Galvanism,” calling attention to a very singular result from numerous experiments which is worthy of special mention. It is the possibility of actually distinguishing one metal from another without seeing or feeling either of them, and he says that by his arrangement of the chain, M. Lehot was able to recognize a portion of zinc from a piece of silver, at the extremity of metallic threads several yards in length.

Lehot’s contributions to the science of animal electricity are too numerous to be given here. Noad summarizes them in the translation from pp. 17, 18 of C. Matteucci’s “Traité des phénomènes ...” Paris, 1844.

He ascertained that in a recently killed animal contractions are excited by the electric current in whatever direction it may be applied, but, when the vitality of the animal has become diminished, if the current is sent in the direction of the ramifications of the nerves, contractions are produced only at the _commencement_ of the current; the reverse takes place when the current is directed contrary to the ramifications of the nerves; _i. e._ in this case the contractions only take place when the current ceases. After studying the sensation excited by the current on the organs of taste, Lehot concluded that the current which traverses a nerve in the direction of its ramifications excites a sensation when it ceases to pass, though this influence is only exerted at the _commencement_ of its passage when the nerve is traversed in a direction contrary to its ramifications. The later experiments of Carlo Francesco Bellingeri and Stefano Giovanni Marianini entirely confirm those of Lehot.

REFERENCES.--_Annales de Chimie_, Vol. XXXVIII. p. 42; _Journal de Physique_, An. IX, Pluviose, LII. 135; Gilbert, _Annalen_, IX. 188; P. Sue, aîné, “Hist. du Galvanisme,” Vol. II. pp. 123, 124, 129, 132, 141,142; “Encyclopedia Metropolitana,” Vol. IV (“Electro-Magnetism,” p. 8).

=A.D. 1801.=--Wollaston (William Hyde), celebrated English chemist and natural philosopher, an associate of Sir Humphry Davy, who had taken the degree of M.D., and joined the Royal Society in 1793, but soon abandoned the practice of medicine to devote himself exclusively to scientific researches, is the first to demonstrate the identity of galvanism and frictional electricity, through a paper read before the above-named society in June 1801.

The latter communication shows that he succeeded in decomposing water as rapidly by means of mere sparks from frictional electricity as through the agency of the voltaic pile, and in a more tranquil and progressive manner than can be assured through shocks from large and powerful apparatus. He concluded that the decomposition must depend upon duly proportioning the strength of the charge to the quantity of water, and that the quantity exposed to its action at the surface of communication depends on the extent of that surface. He observes:

“Having procured a small wire of fine gold, and given to it as fine a point as I could, I inserted it into a capillary glass tube, and after having heated the tube so as to make it adhere to the point and cover it at every part, I gradually ground it down till, with a pocket lens, I could discern that the point of gold was disclosed. I coated several wires in this manner, and found that when sparks from a conductor were made to pass through water by means of a point so guarded, a spark passing to the distance of ⅛ of an inch would decompose water, when the point did not exceed ¹⁄₇₀₀ of an inch in diameter. With another point, which I estimated at ¹⁄₁₅₀₀, a succession of sparks ¹⁄₂₀ of an inch in length afforded a current of small bubbles of air. With a still finer filament of gold, the mere current of electricity, without any perceptible sparks, evolved gas from water.”

In his Bakerian lecture of Nov. 20, 1806, Sir Humphry Davy relates experiments made after the manner contrived by Wollaston, showing that the principle of action is the same in common as in voltaic electricity. Dr. Robert Hare, in a paper read before the Academy of Natural Sciences, “On the Objections to the Theories Severally of Franklin, Dufay and Ampère,” etc., says that, instead of proving the identity of galvanism with frictional electricity, the above-named experiments show that in one characteristic at least there is a discordancy, but that at the same time they possibly “indicate that ethereal may give rise to ethereo-ponderable undulations.” Noad remarks that in these ingenious experiments true electro-chemical decomposition was not effected; that is, “the law which regulates the transference and the final place of the evolved bodies had no influence.” The water was decomposed at both poles independently of each other, and the oxygen and hydrogen gases evolved at the wires are the elements of the water before existing in those places. Faraday observes:

“That the poles, or rather points, have no mutual decomposing dependence, may be shown by substituting a wire or the finger for one of them, a change which does not at all interfere with the other, though it stops all action at the charged pole. This fact may be observed by turning the machine for some time; for though bubbles will rise from the point left unaltered in quantity sufficient to cover entirely the wire used for the other communication, if they could be applied to it, yet not a single bubble will appear on that wire.”

Wollaston communicated a paper to the Royal Society (_Phil. Trans._, Vol. XCI. p. 427) showing that the oxidation of the metal is the primary cause of the electrical phenomena obtained in the voltaic pile. The oxidating power is finely shown by his eighth experiment, which he thus describes:

“Having coloured a card with a strong infusion of litmus, I passed a current of electric sparks along it, by means of two fine gold points, touching it at the distance of an inch from each other. The effect, as in other cases, depending on the smallness of the quantity of water, was most discernible when the card was nearly dry. In this state a very few turns of the machine were sufficient to occasion a redness at the positive wire, very manifest to the naked eye. The negative wire, being afterward placed on the same spot, soon restored it to its original blue colour.”

He verified in 1802 the laws of double refraction in Iceland spar announced by Huyghens, and wrote a treatise thereon which was read before the Royal Society on the 24th of June, and which contains additional evidence deduced from Dr. Wollaston’s superior mode of investigation.

He is said to have been the first to propose forming the spectrum by using a very narrow pencil of daylight instead of sunlight, and to have first made an accurate examination of the electric light. In his communication to the Philosophical Transactions for 1802 he says:

“When the object viewed is a _blue_ line of electric light, I have found the spectrum to be separated into several images; but the phenomena are somewhat different from the preceding (viz. the spectrum of the blue portion of the flame of a candle). It is, however, needless to describe minutely appearances which vary according to the brilliancy of the light, and which I cannot undertake to explain.”

During the year 1815, Wollaston made a great improvement in the construction of voltaic batteries. Having observed that the power of a battery is much increased with a corresponding economy in zinc plates, when both zinc surfaces are opposed to a surface of copper, he devised what he called an _elementary galvanic battery_. Each couple of the latter is made up only of a plate of copper doubled up around a zinc plate from which it is kept apart by strips of cork or wood, and the connecting strips of metal are attached to a wooden rod which is lowered or elevated when the battery is in or out of action. He found that a properly mounted plate of zinc, one inch square, was more than sufficient to ignite a wire of platina ¹⁄₃₀₀₀ of an inch in diameter, even when the acid is very diluted (fifty parts of water to one of sulphuric acid).

He was a very careful workman, and in order to adapt his apparatus to the popular uses, he generally endeavoured to construct them upon the most reduced scale (_dans des proportions très exigues_). He produced platinum wire so extremely fine as to be almost imperceptible to the naked eye. It was estimated that 30,000 pieces of this wire, placed side by side in contact, would not cover more than an inch; that it would take 150 pieces of this wire bound together to form a thread as thick as a filament of raw silk, and that a mile of this wire would not weigh more than a grain. It may be well to add here that the wire made with John Wennstrom’s sapphire plates, for delicate electrical apparatus, is so fine that thirty-six miles of it, properly insulated for Government use in torpedo experiments, measures only about five inches in length by three in diameter when wound upon a spool. The fibre used as carbon filaments in the incandescent lamps is scraped to an even thinness by being drawn through sapphire plates from ³⁰⁄₁₀₀₀ to ⁴⁄₁₀₀₀ of an inch in diameter.

The smallest battery that Wollaston formed of the above-described construction consisted of a thimble without its top, flattened until its opposite sides were about two-tenths of an inch asunder. The bottom part was then nearly one inch wide and the top about three-tenths, and as its length did not exceed nine-tenths of an inch, the plate of zinc to be inserted was less than three-fourths of an inch square (_Annals of Philosophy_, Vol. VI. p. 210).

We are also indebted to Dr. Wollaston for the first idea of the possibility of producing electro-magnetic rotations. Prof. Schweigger opposed the action of revolving magnetism upon the ground that if it were true, a magnet might be made to revolve around the uniting wire, but Faraday found experimentally not only that a magnet could be made to revolve round the uniting wire, but that a movable uniting wire might be made to revolve around a magnet. (See Faraday’s “Experimental Researches,” Vol, II. pp. 159–162 for “Historical Statement Respecting Electro-magnetic Rotation.”)

Wollaston was made secretary of the Royal Society in 1806, became its president in 1820 after the death of Sir Joseph Banks, and contributed in all thirty-eight memoirs to the _Philosophical Transactions_ of that Institution.

His death occurred Dec. 22, 1828, and during the following February Dr. Fitton, President of the Geological Society, concluded his annual address with the following encomium:

“It would be difficult to name a man who so well combined the qualities of an English gentleman and a philosopher, or whose life better deserves the eulogium given by the first of our orators to one of our most distinguished public characters; for it was marked by a constant wish and endeavour to be useful to mankind.”

REFERENCES.--_Phil. Mag. or Annals_, Vol. V. p. 444. See also “The Roll Call of the Royal College of Physicians of London,” by William Munk, M.D., Vol. II; _Edin. Phil. Jour._, Vol. X. p. 183; Gmelin’s “Chemistry,” Vol. I. p. 424; De la Rive, “Treatise on Electricity,” pp. 444, 445; _Phil. Mag._, Vol. XXXIII. p. 488; LXIII. p. 15; James Napier, “Manual of Electro-Metallurgy,” 4th Am. ed., pp. 492, 518; Desbordeaux, in _Comptes Rendus_, Vol. XIX. p. 273; _Le Moniteur_, No. 40 for 1806; Sue, aîné, “Galvanisme,” Vol. II. pp. 193–195, 199, 202; Joseph Izarn, “Manuel du Galvanisme,” p. 137; _Poggendorff_, Vol. II. p. 1362; “Encycl. Metrop.,” Vol. IV (Galvanism), pp. 180, 181, 216, 222; _Nicholson’s Journal_, Vol. V. p. 333; Thos. Young, “Lectures,” London, 1807, Vol. II. p. 679; W. Sturgeon, “Scientific Researches,” Bury, 1850, p. 29; _Quarterly Journal of Science_ for January 1821; _British Quarterly Review_ for August 1846; “Biog. Générale,” Tome XLVI. p. 822; Highton’s “Electric Telegraph,” p. 14; Larousse, “Dict. Universel,” Tome XV. p. 1370; “Cat. Sc. Papers ... Roy. Soc.,” Vol. I. p. 61; Vol. II. pp. 136, 199; “Bibl. Britan.,” 1801, Vol. XVIII. p. 274; 1810, Vol. XLIII. p. 347 (_Phil. Mag._, June 1809); Vol. I., N.S., 1816, p. 119.

=A.D. 1802.=--Walker (Adam), English writer and inventor of several very ingenious mathematical instruments, publishes in London his enlarged edition of “A System of Familiar Philosophy,” two volumes, 8vo, in which he devotes ss. 5–9 of Lecture II. vol. i. to magnetism, and all of Lectures VII and VIII of the second volume to electricity.

We are informed, through his preface, that “the identity of fire, light, heat, caloric, phlogiston and electricity, or rather their being but modifications of one and the same principle, as well as their being the grand agents in the order of nature ... are the leading problems of the work.” In another part he tells us:

“If electricity, light and fire be but modifications of one and the same principle ... and they have their origin or foundation in the sun, it is natural to suppose, in issuing from that luminary, they proceed from him first in their purest state, or in the character of electricity; that joining the particles of our atmosphere, electricity becomes _light_, and uniting with the grosser earth, _fire_ ... that this _fire_ shall be culinary when called forth from the earth by ordinary _combustion_, and electric when called forth by _friction_. Thus have I exhibited this wonderful agent in most of the lights in which it has yet been seen; and flatter myself the reader’s deductions from these appearances will be similar to my own, viz. that electricity emanates in a perfect state from the sun and fixed stars; that its particles repel each other and fill all space; that they have an affinity to the earth and planets, but an affinity that cannot easily be gratified, because the surrounding atmospheres are in part non-conductors, being already saturated, and, of course, repellent of the electric fluid” (Lecture VIII. p. 72).

In the section devoted to “Miscellaneous Observations,” he remarks that the magnetic power may almost be said to be created by friction, rather than communicated by it; for a magnet acquires strength by giving magnetism to iron; so that, if all the magnets in the world were lost, magnetism might be revived by rubbing the end of one steel bar against the side of another.

Section V, treating of “Magnetic Attraction,” concludes as follows: “How far these observations and experiments go to establish the doctrine of a magnetic effluvium flowing through the earth, or from one end of a magnet to the other, must be left to the reader’s judgment and opinion. We are apt to laugh at the _subtil matter_ of Descartes and the _aether_ of Euler, as occult qualities, which modern philosophy will not admit into its creed, but this effluvium is a _subtil_ matter, an _aether_, equally as inexplicable and as equally out of the reach of our five senses to scrutinize; however, if we may venture to guess at causes by effects, and to compare analogies with what we can see, feel, etc., I think we have infinite data in favour of an electro-magnetic fluid, superior to any proof that can be brought of æther being the cause of gravity, light, vision, etc.”

John Read’s letter to the author concerning the _electrophorus_ appears at pp. 47–49 of the second volume (Poggendorff, Vol. II. pp. 1248–1249).

=A.D. 1802.=--Alexandre (Jean), who is said to have been the natural son of Jean Jacques Rousseau, and to have studied for the medical profession, operates his secret telegraph (_télégraphe intime_) at Poitiers, and afterwards addresses M. Chaptal, Ministre de l’Intérieur, asking for financial aid in order that he may be enabled to go to Paris and submit his invention to the French Government. This request being refused on account of Alexandre’s unwillingness to divulge his secret, he next obtained an audience of M. Cochon, Prefect of Vienne, before whom he demonstrated his invention so successfully that the latter was induced to make a report of it to M. Chaptal, advising him to invite Alexandre to Paris at the expense of the State. A second refusal, however, followed, and Alexandre went to Tours, where he there also failed to obtain the desired assistance, after giving successful exhibitions of his telegraph before the Prefect of Indre-et-Loire, General Rommereul, as well as before the Mayor and the city officials.

The substance of Prefect Cochon’s communication is to be found translated at pp. 111–113 of Fahie’s “History of Electric Telegraphy,” which latter also contains a full translation of the report addressed, 10 Fructidor, An. X by the celebrated French astronomer, J. B. J. Delambre, to the First Consul, suggesting for the inventor’s representative, M. Beauvais, an interview which Bonaparte, however, refused to grant.

Alexandre died, 1832–1833, without having revealed his secret to any one but M. Beauvais. It is stated by Fahie that in the English _Chronicle_ of June 19–22, 1802, appears a brief account of the above-named exhibition given at Tours, concluding as follows: “The art or mechanism by which this is effected is unknown, but the inventor says that he can extend it to the distance of four or five leagues, even though a river should be interposed.” A copy of the above-named newspaper, doubtless unique, was in Latimer Clark’s library.

REFERENCES.--“Annales Télégraphiques,” March-April, 1859, pp. 188–199, for M. Edouard Gerspach’s Memoir; “Sci. Am. Suppl.,” No. 384, for a translation of M. Auguste Guéroult’s article in “La Lumière Electrique”; M. Cézanne, “Le Cable Transatlantique,” Paris, 1867, p. 32; M. Bério, “Ephemerides of the Lecture Society,” Genoa, 1872, p. 645.

=A.D. 1802.=--Sue (Pierre, aîné), a very able French physician, publishes, at Paris, “Histoire du Galvanisme et analyse des différents ouvrages publiés sur cette découverte ...” which is considered by scientists one of the most important works on the subject.

REFERENCES.--“Biographie Générale,” Vol. XLIV. pp. 618–619; Larousse, “Dictionnaire Universel,” Vol. XIV. p. 1200; Wilkinson, “Elem. of Galv.,” 1804, Vol. I. p. 182.

=A.D. 1802.=--Brugnatelli (Luigi Valentino), who, after being a pupil, became the close friend and subsequently the colleague of Volta at the Pavia University, is the first to obtain, by means of the voltaic pile, a decidedly practical result in electro-plating. He gilded two large silver medals on bringing them in communication, by means of the steel wire, with the negative pole of a voltaic pile, and by keeping them one after the other immersed in ammoniurets of gold newly prepared and well saturated (_Phil. Mag._ for 1805).

He also electro-deposited bright metallic silver upon platinum, and observed that when the current entered the liquid by means of a pole of copper or zinc, those metals were dissolved and then deposited upon the negative pole. Spon tells us (“Dictionary of Engineering,” London, 1874, Vol. II. p. 1378) that the solutions employed by Brugnatelli were alkaline; they consisted of ammoniurets of gold, silver or platina, that is, the product obtained by treating the chlorides of gold and platina or the azotate of silver, by ammonia. There is much obscurity in the descriptions of Brugnatelli, but according to the _Journal de Physique et Chimie_ of Van Mons, the most expeditious method of reducing, by means of the battery, dissolved metallic oxides, is to make use of their ammoniurets by placing the ends of two conducting wires of platina into ammoniuret of mercury. The wire of the negative pole speedily becomes covered with small particles of this metal. MM. Barral, Chevalier and Henri tried to reproduce Brugnatelli’s operation by following his descriptions, but with very imperfect results, the nature of the dissolvent employed by the learned Italian not being known.

At p. 136, Vol. XVIII of his _Annali di Chimica_, etc., Brugnatelli publishes a memoir entitled “Chemical Observations on the Electric Acid.” He says:

“Naturalists have hitherto merely abandoned one erroneous hypothesis for another, in considering the nature of the electric fluid. Some have regarded it as identical with heat; while others have been led to consider it as a modified caloric. The disciples of Stahl ascribed it to the nature of their _phlogistic_ or, at least, supposed it to be a fluid abundantly provided with that principle. Henley conjectured it to be phlogistic, when in a state of repose, and fire, when in a state of activity. Among the moderns, several have been found who have declared it to be an acid; but their opinion has been combated by Gardini, who, by means of several ingenious observations, has endeavoured to demonstrate that it is composed of caloric and hydrogen.”

In the earlier experiments on the decomposition of even chemically pure water by the voltaic column, the presence of an acid was always apparent at the pole evolving oxygen, while alkaline matter appeared at the other (_Nicholson’s Journal_, quarto, Vol. IV. p. 183).

Mr. William Cruikshanks supposed the former to be the nitrous acid resulting from a combination of the oxygen at the positive pole with the azote of the air held in solution by the water, while the alkali, he said, proceeded from the combination of the same principle with the hydrogen evolved at the negative pole (_Nicholson’s Journal_, quarto, Vol. IV. p. 261). Mr. C. B. Desormes afterward endeavoured to show that the products were ammonia and muriatic acids (_Annales de Chimie_, Vol. XXXVII. p. 233). Brugnatelli’s experiments with the _couronne de tasses_, however, led him to consider it to be an acid _sui generis_ produced by the combination of one of the constituents of water with positive electricity. He classed it as _oxi-electric_, and of all the metals, gold and platina alone appeared to him not to be sensibly affected by this electric acid.

REFERENCES.--For Brugnatelli’s record of other experiments and observations and for his Memoirs upon different piles, upon animal electricity, upon the identity of the electric and galvanic fluids, etc. etc., see his “Principes,” etc., 1803, and “Grundsätze des Elektricität,” etc., 1812, his _Annali di Chimica_, Vols. VII. p. 239; XIX. pp. 77, 153, 274, 277, 280–281; XXI. pp. 3, 143, etc., 239; XXII. pp. 1, etc., 77–92, 257, 301; the _Giornale di Chimica, Fis. e Storia Nat._ of L. and G. Brugnatelli, G. Brunacci and P. Configliachi, Vol. I. pp. 147–163, 337–353; IX. p. 145; XI. p. 130, and the “Commentarii Medici,” edited by L. Brugnatelli and L. V. Brera; also Brugnatelli’s _Giornale Fisico-Medico_, etc., and its continuation, _Avanzamenti della Medicina e Fisica_, the first named containing (Vol. I. p. 280), a repetition of Galvani’s experiments, made by Volta, Rezia and Brugnatelli; G. Bianconi, “Intorno ...” and “Cenni intorno ... Galvanoplastica” (_Nuovi Annali della Scienze Naturali_); the “Biblioteca Italiana,” of which his son Gaspare Brugnatelli was an editor, in conjunction with Breislak, Configliachi, Carlini, Cotena, Acerbi, Brunacci, Fantonelli, Fumagelli, Ferrario, Giordiani, Gironi and Monti; G. A. Giobert, “Gior. Fis. Med.,” 1188; Du Pré, “Ann. di Chimica,” IX. 156; P. Mascagni, “Lettera ...” for Brugnatelli’s notes; A. Cossa, “Notizie ... elettro-chimica,” 1858; J. Napier, “Man. of El. Met.,” 4th ed., pp. 491, 492; J. B. Van Mons’ _Journal de Chimie_, Vols. I. pp. 1, 24, 101, 216, 325; II. pp. 106, 216; IV. p. 143; X. p. 114; XVI. p. 132; also Vol. LXXVI; _Giornale di Fis. Chim._, Vol. I. pp. 4–32, 28, 139–147, 164–166, 338; “Effemeridi Chim. Mediche di Milano,” 1807, Sem. I. p. 57; A. F. Gehlen’s _Journal für die Chemie_, Vol. I. pp. 54–88; VI. pp. 116–124; VIII. pp. 319–359; L. W. Gilbert, _Annalen der Physik_, Vols. VIII. pp. 284–299; XVI. pp. 89–94; XXIII. pp. 177–219; _Philosophical Magazine_, Vols. XXI. p. 187; XXV. pp. 57–66, 130–142; LIII. p. 321; Dr. Thos. Thomson’s _Annals of Philosophy_, Vol. XII. p. 228; Alfred Smee’s “Elements of Electro-Metallurgy,” _History_, pp. xxv-xxvi; _Journal de Pharmacie_, Vol. III. pp. 425, 426; J. Nauche, _Journal du Galvanisme_, etc., Vol. II. pp. 55–60; P. Sue, aîné, “Histoire du Galvanisme,” An. X, 1802, Vol. I. p. 305; II. pp. 263, 316, 320, 328; _Annales de Chimie_, Feb. 1818; for Brugnatelli, “Biblioth. Britan.,” Vol. XXXI., 1806, pp. 43, 122, 223 (pile végétale).

=A.D. 1802.=--Jäger (Karl Christoph Friedrich van), a well-known physicist of Wurtemberg and professor at Stuttgart, confirms by mathematical analysis the theory of electrical distribution and equilibrium, as will be seen by his papers in Gilbert’s _Annalen der Physik_, Vols. XII. pp. 123, 127; XIII. pp. 399–433; XXIII. pp. 59–84, and LII. pp. 81–108.

The views of Jäger were fully endorsed by Berzelius, who, like Scholz and Reinhold, endeavoured to extend them, and who says that we are indebted to the German physicist for actually the most complete elucidation of the theory of the voltaic pile.

In Vol. XLIX of Gilbert’s _Annalen_ for 1815, pp. 47–66, will be found Jäger’s observations and experiments on Zamboni’s column as well as the papers of Zamboni and Deluc on dry piles. Dr. Thomson says that since Dr. Jäger found that, when the temperature was raised to 104 degrees, or as high as 140 degrees, the pile begins again to act as well as ever, we must conclude from this that dry paper, while cold, is a nonconductor of electricity, but that it becomes again a conductor when heated up to 104 degrees or 140 degrees.

REFERENCES.--Poggendorff, Vol. I. pp. 1186, 1187; “Catalogue of Scientific Papers of the Royal Society,” Vol. III. p. 525; Jäger on the tourmaline in Gilbert’s _Annalen_ for 1817, Vol. LV. pp. 369, 416, and Jäger, Bohnenberger and Zamboni in the _Annalen_ for 1819, Vol. LXII. pp. 227–246; Figuier, “Expos. et Histoire,” 1857, Vol. IV. p. 433; Davy, “Bakerian Lectures,” 1840, pp. 44–56, on the “Agencies of Electricity.”

=A.D. 1802.=--Gale (T.), an American physician, publishes at Troy “Electricity or Ethereal Fire ... considered naturally, astronomically and medically, and comprehending both the theory and practice of medical electricity,” etc. Among other things, he describes at pp. 27, 28, various experiments made with his galvanometer; explains at pp. 46–64 how the Newtonian principles are erroneous; and shows at p. 264 how to extract lightning from the clouds; while at pp. 272, etc., are given directions for using electricity both as a sure preventive and cure of diseases.

=A.D. 1802.=--Gibbes (George Smith), M.D., of Bath, reads before the Royal Society a paper on the Phenomena of Galvanism thus noticed by Dr. Young at pp. 672, 673, Vol. II. of his “Course of Lectures,” London, 1707:

“Dr. Gibbes begins with reciting some experiments on the oxidation produced during the union of tinfoil with mercury, first in the air and then under water. He assumes a different opinion from that of Dr. Wollaston, respecting the origination of electricity in chemical changes, and maintains on the contrary that the electrical changes are to be considered as preceding and favouring the chemical. He imagines that the simple contact of various substances produces changes of electrical equilibrium, and that the action of acids is effectual in promoting these changes, by bringing their surfaces into contact. Dr. Gibbes observes upon Dr. Wollaston’s experiment of immersing zinc and silver in an acid solution, that if they are placed in two separate portions of the fluid, and the parts not immersed are brought into contact there is no emission of gas from the silver; but that it is copiously produced when the contact takes place in the same fluid. He proceeds to relate some experiments which seem to show a difference between galvanism and electricity, particularly that galvanism does not appear to be attracted by metallic points. He also states an experiment in which a piece of paper is placed on tinfoil, and rubbed with elastic gum, and although the tinfoil is not insulated, sparks are produced on raising the paper. Dr. Gibbes concludes with some arguments against the doctrine of the decomposition of water; and advances as a probable opinion, that oxygen and hydrogen gas are composed of water as a basis, united with two other elements, which, combined, form heat.”

As remarked by Wilkinson (“Elements of Galvanism,” London, 1804, Vol. II. pp. 385, 386), Dr. Gibbes’ hypothesis as to the composition of water having been deduced from Richter’s experiments, and these latter proving erroneous, the ingenious superstructure which the doctor has erected must necessarily fall to the ground.

=A.D. 1802.=--Romagnosi (Gian Domenico Gregorio Giuseppe), Italian jurist of Salsomaggiore, near Piacenza, who had devoted much time to scientific investigation, and was about taking the law professorship at the Parma University, communicates, Aug. 3, 1802, to the _Gazetta di Trento_, his important paper entitled “Articulo sul Galvanismo.” Of the latter, a translation, made from the reprint at p. 8 of Gilb. Govi’s “Romagnosi e l’Elettro-magnetismo,” appears at pp. 259, 260 of Fahie’s “History of Electric Telegraphy.”

To Romagnosi has by many been given the credit of having discovered the directive influence of the galvanic current upon a magnetic needle. This claim has of late years been again made for him, notably by Dr. Donato Tommasi, of Paris (_Cosmos, les Mondes_ of June 30, 1883), while Dr. J. Hamel endeavoured to prove (pp. 37–39 of “Historical Account ... Galv. and Mag. Elec. ...” reprinted by W. F. Cooke for the Society of Arts, London, 1859) that Oersted was aware of Romagnosi’s experiments at the time he published the discovery of electro-magnetism. This is what Dr. Hamel says:

“I cannot forego stating my belief that Oersted knew of Romagnosi’s discovery announced in 1802, which was eighteen years before the publication of his own observations. It was mentioned in the book of Giovanni Aldini (the nephew of Galvani) ... Oersted was in Paris 1802 and 1803, and it appears from the book of Aldini, that at the time he finished it Oersted was still in communication with him; for he says at the end (p. 376) he had not been able to add the information received from Oersted, Doctor of the University at Copenhagen, about the galvanic labours of scientific men in that country.... It deserves to be remembered, that from Aldini’s book (“Essai théorique et expérimental sur le galvanisme,” etc., Paris, 1804, qto. p. 191, or Vol. I. of the 8vo ed., pp. 339–340) it was known that the chemist, Giuseppe Mojon (Joseph Mojon, in the French), at Genoa, had before 1804 observed in unmagnetized needles exposed to the galvanic current ‘a sort of polarity.’ Joseph Izarn repeats this also in his ‘Manuel du Galvanisme’ (Paris, An. xii., 1804, sec. iii. p. 120, or 1805, sec. ix.), which book was one of those that by order were to be placed in the library of every lycée of France.”

Robert Sabine remarks (“The Electric Telegraph,” 8vo., 1867, p. 22; “History of the Electric Telegraph,” in Weale’s Rudimentary Treatises, 1869, pp. 23, 24; “History and Progress of the Electric Telegraph,” 3rd ed., 1872, p. 23):

“The discovery of the power of a galvanic current to deflect a magnetic needle, as well as to polarize an unmagnetized one, were known to, and described as early as 1804, by Prof. Izarn.... The paragraph which especially refers to this subject is headed ‘Appareil pour reconnaitre l’action du galvanisme, sur la polarité d’une aiguille aimantée.’ After explaining the way to prepare the apparatus, which consists simply in putting a freely suspended magnetic needle parallel and close to a straight metallic conductor through which a galvanic current is circulating, he described the effects in the following words: ‘According to the observations of Romagnosi, a physicist of Trent, a magnetized needle which is submitted to a galvanic current undergoes (_éprouve_) a declination; and according to those of J. Mojon, a learned chemist of Genoa, unmagnetized needles acquire by this means a sort of magnetic polarity.’ To Romagnosi, physicist of Trent, therefore, and not, as is generally believed, to Oersted, physicist at Copenhagen (who observed, in 1820, the phenomenon of the deflection of a magnet needle by a voltaic current), is due the credit of having made this important discovery.”

On the other hand, Gilb. Govi, who gives in his afore-named work a good illustration of Romagnosi’s experiment, explains that it resembles in no way the experiment of Oersted, there being no magnetic action of the column on the magnetic needle, which latter is in fact repelled by the mere electricity of the pile. Ronalds states that Romagnosi’s experiment, much like that made by Schweigger (A. F. Gehlen’s _Journal für die Chimie und Physik_, 1808, pp. 206–208), was a modification if not a repetition of the one which Thomas Milner performed with static electricity (T. Milner’s “Experiments and Observations in Electricity,” London, 1783, p. 35), wherein a magnetic needle forms the electrometer since improved upon by J. C. A. Peltier.

To the ordinary mind, a conclusive proof that Romagnosi had no part in the discovery of electro-magnetism would seem to be, as Fahie rightly observes, the fact that he himself never claimed any, although he lived until 1835, fifteen years after the announcement made by the Danish philosopher. Fahie calls attention, for some experiments in the same line, to J. B. Van Mons’ _Journal de Chimie_, Bruxelles, January 1803, p. 52, and to Nicholson’s _Journal of Nat. Phil._, Vol. VII. p. 304, as well as to the 1746 and 1763 _Phil. Trans._ for investigations made by B. Robins and Ebenezer Kinnersley, and he likewise alludes to others recorded in the _Amer. Polytechnic Review_ for 1831, and in the _Quarterly Journal of Science and the Arts_ for 1826, to all of which, he says, as little real attention should be given as can properly be attached to the observations of Aldini and of Izarn previously referred to.

REFERENCES.--“Notizia di G. D. Romagnosi, stesa da Cesare Cantù,” Milan, 1835; “Nuova Scelta d’ Opuscoli,” Vol. I. p. 201; _Gazetta di Roveredo_ for 1802, No. 65; “Atti della Reale Accad. delle Scienze di Torino,” Vol. IV, April 7, 1869; J. C. Poggendorff, Vol. II. pp. 681, 682; S. I. Prime’s “Life of Morse,” 1875, p. 264; _Phil. Mag._, Vol. LVIII. p. 43; _Journal Soc. of Arts_, April 23, 1858, p. 356, and July 29, 1859, pp. 605, 606; _Bibl. Ital._, Vol. XCVIII. p. 60; Gilbert, _Annalen_, 1821, Vol. LXVIII. p. 208; Larousse, “Dict. Univ.,” Vol. XIII. p. 1318; “Biographie Générale,” Vol. XLII. pp. 574, 575, the last named remarking that the discovery alluded to in the works of Aldini and Izarn passed unnoticed till Oersted caused its value to be fully appreciated.

=A.D. 1802.=--Parrot (George Friedrich), Russian physician and professor at Dorpat, is, of all the European savants, the one who developed most extensively the chemical theory of the voltaic pile. The superior manner in which all his observations were carried on have led many to consider him justly entitled to the credit of being the founder of the theory (Figuier, “Exposition et Histoire,” etc., Paris, 1857, Vol. IV.