Part 1

[Illustration:

_Fig. 1._

_Fig. 2._

_Folwell. Sc._ ]

AN EPITOME OF ELECTRICITY & GALVANISM.

BY TWO GENTLEMEN OF PHILADELPHIA.

Causa latet; vis est notissima.——Ovid’s Met. B. IV. l. 287.

PHILADELPHIA:

PRINTED BY JANE AITKEN, No. 71,

NORTH THIRD STREET.

1809.

DISTRICT OF PENNSYLVANIA, TO WIT:

[Sidenote: SEAL.]

_BE IT REMEMBERED_, That on the fourteenth day of December, in the thirty-fourth year of the Independence of the United States of America, A. D. 1809. Jane Aitken, of the said District, hath deposited in this Office, the Title of a Book, the Right whereof she claims as Proprietor, in the words following, _to wit_:—

“An Epitome of Electricity and Galvanism. By two gentlemen of Philadelphia. Causa latet; vis est notissima.—Ovid’s Met. B. IV. l. 287.”

In conformity to the Act of the Congress of the United States, intituled, “An Act for the encouragement of Learning, by securing the Copies of Maps, Charts, and Books, to the Authors and Proprietors of such Copies, during the times therein mentioned.” And also to the Act, entitled “An Act, supplementary to an Act, entitled, “An Act for the encouragement of Learning, by securing the Copies of Maps, Charts, and Books, to the Authors and Proprietors of such Copies, during the times therein mentioned,” and extending the benefits thereof to the Arts of designing, engraving, and etching historical and other prints.”

D. CALDWELL, _Clerk of the District of Pennsylvania_.

RECOMMENDATIONS.

_Having perused this Epitome, it appears to me to comprise, in a concise and perspicuous manner, the principal discoveries that have been made in Electricity and Galvanism, illustrated with a variety of amusing experiments; and I have no doubt that it will prove useful and entertaining to those who wish for information on these subjects._

_JOHN M‘DOWELL_, Professor of Natural Philosophy, and Provost of the University of Pennsylvania.

Philad. Dec. 11, 1809.

* * * * *

_Having read, at the request of the authors, a work under the title of_ “An Epitome of Electricity and Galvanism,” _I am of opinion that it is well calculated for the instruction of youth; and also that it may prove a useful manual to gentlemen who wish to acquire, without extensive reading, a general knowledge of the subjects discussed_.

_JOHN MACLEAN_, Professor of Natural Philosophy and Chemistry in the College of New-Jersey.

Nassau Hall, Oct. 20, 1809.

_The Epitome of Electricity appears to me to contain a concise, but perspicuous and correct statement of the laws of that branch of Philosophy, and an interesting collection of facts and experiments, by which they are illustrated._

_JEREMIAH DAY_, Professor of Mathematics and Natural Philosophy.

Yale College, Nov. 25, 1809.

[As the authors could not transmit to Professor DAY a copy of the Epitome of Galvanism, without unduly delaying the publication, his testimonial, of course, refers only to the Epitome of Electricity.]

PREFACE.

Having denominated the following work an epitome of Electricity and Galvanism, it seems reasonable to request that the reader should keep the nature of our plan in view. If the book do not contain, on the subjects proposed to be treated, all that is most important, let it be condemned. But let not detail be expected where the design requires conciseness. There are some articles under which we were obliged, either to omit unimportant improvements, or to occupy several pages in describing them.

Where, however, omissions of any consequence have taken place, we have endeavoured carefully to refer to the books which will supply them; so that our work may not only teach the elements and substance of the science, but direct those who wish to pursue it most extensively—We particularly regretted that we could not describe a variety of electrometers.

Short as our work is, we found it, notwithstanding, scarcely practicable to avoid some repetition. In a few instances the historical and scientific parts may be observed, in a small degree, to interfere. Where history was useful to illustrate experiment, or experiment composed a part of history, we did not choose to separate what perspicuity required to be kept together. We hope, on the whole, that we do not need more indulgence in this respect, than we shall readily find, from those who are fond of the subjects which it was our business and our pleasure to investigate.

In making our epitome, we have often written without a special reference to any book; sometimes we have abridged the writings of others; sometimes we have taken paragraphs with the alteration of a few words; and sometimes we have introduced full quotations. In the latter case, we have always wished to make a distinct reference to the author quoted; and in other cases, we have generally made our acknowledgments where we were particularly indebted. But as our work was begun without any determination to publish it, we have probably made some selections, of which we have ourselves forgotten the authors from whom they were taken. Of the fairness of a work of this nature, we suppose there can be no question. Johnson, when speaking of the system of logic published by Watts, has made our apology—“If he owes part of it to Le Clerk, it must be considered, that no man who undertakes merely to methodise or illustrate a system, pretends to be its author.”

As impositions are often attempted, by soliciting patronage for publications of little value, we felt the importance of obtaining, in behalf of our work, the approbation of competent judges—The public will admit that it has been obtained; and the professional gentlemen who have favoured us with it in the most obliging and disinterested manner, will excuse our offering them this public tender of our grateful acknowledgments.

With these remarks we commit our little work to the candour of the public, conscious of having assiduously laboured to furnish a book which, though it appeared to us to be much wanted, had not yet been written or compiled. Our views will be fully answered, if it shall be found well adapted to assist youth in their academical and philosophical studies, and at the same time, to afford amusement to men of learning, and some useful information to gentlemen of leisure.

INTRODUCTION.

SECTION I.

_Electricity as known among the Ancients._

In examining the progress of almost any branch of human knowledge, curiosity must meet with many repulses. By the time the attention of society is attracted to the accumulation of detached truths, which compose a science, it is often impossible to retrace its history. The real origin of most discoveries is obscured by antiquity, their authors have already sunk into oblivion, and important improvements are ascribed to different inventors.

Electricity is however oppressed by few of these difficulties. With the exception of some small discoveries mentioned by ancient authors, this science derives its origin and all its improvements from the two last centuries. Neither is the historian perplexed in giving every invention to its proper author. Those who cultivated this science were commonly men of talents and condition; they pursued it with ability and perseverance; and either themselves published the result of their observations, or deposited them in those literary institutions which they found established in their country. The historian of electricity, therefore, with no extraordinary exertion of industry or talent, may fully collect and accurately arrange the materials of his work.

On the subject of electricity nothing earlier is on record than the observation of Thales, that yellow amber, when rubbed, has the property of attracting light bodies.—So struck was he with this property of amber, that he imagined it was animated.

Thales, the contemporary of Pythagoras, was born at Miletus, a city of Ionia, about six hundred years before Christ. Like all the Grecian sages, he travelled into Egypt; lived in that country a number of years; contracted friendships with the priests, then the depositories of science; and became deeply skilled in all their mysteries and learning. Returning to his own country, stored with the knowledge of the East, he was ranked as the first of the seven wise men of Greece, and became the founder of the Ionic school, as Pythagoras did of the Italic.

It may deserve remark that the same philosopher who is recorded to have observed the first phenomenon in electricity, is also said to have discovered the cause of thunder and lightning. We shall give to the curious, the remarkable passage containing this account, as we find it in Apuleius, a learned and eloquent writer of the second century, while he is rapidly enumerating the discoveries of Thales.

_Thales Milesius ex septem illis sapientia memoratis viris facile præcipuus: fuit enim geometricæ penes Grajos primus repertor, et naturæ rerum certissimus explorator, et astrorum peritissimus contemplator, maximas res parvis lineis reperit, temporum ambitus, ventorum flatus, stellarum meatus_, tonitruum sonora miracula, _siderum obliqua curricula, Solis annula reverticula; idem Lunæ vel nascentis incrementa, vel senescentis dispendia, vel delinquentis obstacula_.

“Thales the Milesian was decisively the most eminent of the seven famous sages; for he was the first inventor of geometry among the Greeks, the most judicious inquirer into nature, and the most skilful observer of the stars; he made great discoveries by small geometrical lines, the regulation of times and seasons, the theory of the winds, the course of the stars, _the wonderful causes of thunder_, the oblique motions of the planets, the annual revolution of the sun, the reason of the increase, decrease, and eclipse of the moon.”[1]

Though it is no where expressly affirmed that electricity was discovered by Thales to be the cause of thunder, yet when the two facts are placed together, they will furnish an additional argument to those writers who contend that the ancients knew much more than we are willing to allow them of those shining truths, which are the peculiar boast of modern ages. Nor should this early discovery, if we could admit it to be real, excite our surprise. Whatever hindrances might impede the progress of the ancients in other branches of knowledge, from the abstruse nature of the subject, or the want of necessary helps, it may rather excite our wonder, that the effects of electricity should remain so long unobserved. The electric fluid is no local or occasional agent; it is coeval with the world; its presence pervades every substance; it is the principal cause of the grandest scenes in nature, and its operations can hardly fail to show themselves wherever bodies are concerned.

From the time of Thales, there is a chasm in the history of electricity for three hundred years. Indeed, natural science of all kind appears to have languished, during this period. Theophrastus, who flourished 371 years before Christ, the disciple and successor of Aristotle, and he to whom the learned are indebted for the preservation of his master’s works, then adds one more fact to the history of electricity.

In his treatise on stones, after speaking of the attractive power of amber, found on the coast of Liguria, he goes on to ascribe the same properties to the lapis lyncurius, the same substance now called tourmaline. “It possesses (says he) an attractive power like amber: and as they say attracts not only straws and leaves, but copper also, and iron, if in small particles.[2]”

These two discoveries of Thales and Theophrastus are all, on the subject of electricity, that industry has been able clearly to collect from the barren records of antiquity. Pliny indeed has observed that “amber being rubbed with the fingers, and having thereby become warmed, attracts to itself straws and dried leaves, in the same manner as the magnet does iron.” He also attributes to the Lyncurium the same properties.—Solinus and Priscian, also, make similar statements. But as these are no more than what Thales and Theophrastus had remarked before, they are to be considered only as a repetition of what the preceding writers had made known, not as any addition to the information possessed on this subject. In like manner it might be mentioned that Aristotle, Pliny, Oppian and Claudius, were fully acquainted with the benumbing effects produced by the touch of the Torpedo; but as they do not appear to have suspected that these effects were produced by electricity, they cannot be considered as communicating or possessing any additional knowledge in regard to this powerful agent.[3]

On subjects which regard taste, or which address themselves to the imagination, on poetry, eloquence and the fine arts, it is to the ancients we are to look for information and the models of perfection. But on the various branches of knowledge which depend on observation, on experiment, on investigation, which comprehend all the parts of mechanical philosophy, the philosophers of antiquity afford little that is either new or just. Hurried away by the vivacity of their genius, which their peculiar complexion invited them to cultivate, and the particular circumstances of the age were calculated to inflame, they investigated facts, not that by accumulated discoveries they might lay the foundation of solid science, but so far only as they served to support or illustrate some favourite hypothesis.

Aristotle, to whose profound and elevated genius we are accustomed to turn for satisfactory information on so many other subjects, affords no remarks on electricity, and little worthy of observation on most of the branches of natural science. One, who on this point has a right to speak, observes.—“That though there are several very sublime questions in his physics, which he clears up in a very masterly way, yet the main, the gross of the work is good for nothing, infelix operis summa.[4]”

From the time of Theophrastus till the beginning of the 17th century of the christian æra, there is no unequivocal evidence that in the science of electricity any discovery or improvement was made, except the solitary and unimportant fact that jet, and perhaps agate, is endued with the same power as amber, of attracting and repelling light bodies.—Nor is it ascertained by whom, or at what particular period, this fact was added to the slender stock of electrical knowledge which was then possessed. And thus it appears that for the space of about 1900 years, the part of philosophy, of which we trace the history, was nearly stationary.

SECTION II.

_Electricity as known to the Moderns._

Having seen, in the preceding section, the very limited knowledge of electricity possessed by the ancients, we now come to give an account of what may properly be called its real origin, and to trace its progress to the present day. In doing this, we shall be careful to note all the original authors who have touched upon this subject; and to exhibit most of their discoveries.

We believe it to be generally the case, that, in the earlier periods of a science, the mind is curious to observe the gradual developement of principles, and the gradual increase of facts, however unimportant these facts may afterwards appear. But as the science progresses, as the ground widens and observations multiply, this curiosity proportionably abates, and we require of the historian selection rather than detail.

However minute, therefore, the history of the first stages of this branch of philosophy must be, the after periods will exact only a careful selection of those more prominent discoveries, which show the advances of the science and mark its gradations.

During the sixteenth century, the phenomena of magnetism having engaged the study of philosophers, they were naturally led to bestow some attention on substances which appeared to possess similar properties with the load-stone. Indeed, it was not till after 1729 that the idea was entertained, that electricity was a distinct fluid, or any thing else than a certain property of bodies, resembling magnetism; nor was any other meaning affixed to the word, than a power of attracting and repelling.

Fifteen centuries having elapsed from the time of Theophrastus, William Gilbert, physician to king James I, in 1600 published a latin work, entitled, _De Magnete, magnetesque corporibus_, in which, having discussed the phenomena of magnetism, he, towards the close, relates a great variety of electrical experiments.

The principal merit of this philosopher is, that he greatly augmented the list of electrical substances, noted the bodies on which electrics can act, and remarked several circumstances relating to the manner of their action.

He enumerates, as having the power of attracting light bodies, Diamonds, Saphirs, Carbuncles, Iris, Opals, Amethysts, Beryl, Crystal, Bristol-stones, Sulphur, Mastick, Hard Wax, Hard Rosin, Arsenic, Sal-gemm, Rock-Alum, common-glass, Stibium, or glass of Antimony. He also observed that the influence of these substances extended, not only to leaves and straws, but to all matter which was not extremely rare. Friction, he says, is, in general, necessary to excite the virtue of these substances; and the most effectual friction, he affirms, is that which is light and quick. Electrical appearances, he asserts, were strongest when the air was dry, and the wind north or east, at which time electrics would act ten minutes after excitation.

The simple experiments of this philosopher were mostly made with long thin pieces of metal, and other substances freely suspended on their centers, to the extremities of which he presented the electrics he had excited.

The phenomena of magnetism were accounted for, in the time of Gilbert, by means of emanating effluvia, and he applies the same theory to the explanation of electrical attraction, imagining it to be performed in the same manner as the attraction of cohesion. Two drops of water, rush together when they are brought into contact, and electrics, he says, are virtually brought into contact by means of their effluvia. _Effluvia illa tenuiora concipiunt et amplectuntur corpora, quibus uniuntur, et electris tanquam extensis brachiis, et ad fontem propinquitate, invalescentibus effluviis, deducuntur._ “Those subtle effluvia continually embrace certain bodies, to which they are united, as it were by their extended electric arms; and the effluvia prevailing, the bodies are drawn to the contiguous source of the effluvia.”

Gilbert has been stiled the father of modern electricity; and when we consider how little was known of the subject prior to his time, and the merit that belongs to himself, not only from his own experiments, but also from turning the attention of philosophers to a new branch of natural science, we cannot but allow that he eminently deserves the title.

Cabeus followed Gilbert, but did little else than add to the list of electrics, wax, gum elemi, Gum guaiaci, Pix Hispanica and Gypsum.

Thirty years after the publication of Gilbert’s work, the celebrated Sir Kenelm Digby, in his “Treatise of the nature of Bodies,” touches upon electricity: but as the age in which he lived was still busying itself with the hypothetical philosophy of Aristotle, so this philosopher in what he says of electricity, appears to be rather amusing himself in inventing theories, to explain the manner in which electric attraction is performed, than in advancing the science by new facts and experiments. His theory of electric attraction is, however, of some celebrity: it was allowed by his contemporary Des Cartes, in his principles of philosophy, and was embraced by the chief writers of his age; though it does not differ essentially from that of Gilbert.

“Attraction (says he) is made by a tenuious emanation, or continued effluvium, which after some distance retracteth into itself, as is observable in drops of syrups, oil and seminal viscosities, which spun at length, retire to their dimensions. Now these effluviums advancing from the body of an electric, in their return do carry back the bodies whereon they have laid hold, within the sphere or circle of their continuities; and these they do not only attract, but with their viscous arms, hold fast a good while after. And if any shall wonder why these effluvium issuing forth, impel and protrude not the straw before they can bring it back; it is because the effluvium passing out in a smaller thread, and more enlengthened filament, stirreth not the bodies interposed; but returning into its original, falls into a closer substance and carrieth them back into itself.”

Sir Thomas Brown succeeded to Sir Kenelm Digby. In his “Inquiry into Vulgar Errors,” this inquisitive philosopher has a chapter on electricity, in which he corrects some mistakes into which his predecessor had fallen, adds some new experiments of his own, and gives us a summary view of the state of electrical knowledge at the time he wrote.

“By electrical bodies, (says he) I understand not such as are metallical, mentioned by _Pliny_, and the ancients; for their _electrum_ was a mixture made of gold, with the addition of a fifth part of silver; a substance now as unknown as true _Aurichalcum_, or _Corinthian_ brass, and set down among things lost by _Pancirollus_. Nor by electric bodies do I conceive such only as take up shavings, straws, and light bodies, in which number the ancients only placed _Jet_ and _Amber_; but such as conveniently placed unto their objects attract all bodies palpable whatsoever. I say conveniently placed, that is, in regard of the object, that it be not too ponderous, or any way affixed; in regard of the agent, that it be not foul or sullied, but wiped, rubbed, and excitated; in regard of both, that they be conveniently distant, and no impediment interposed. I say, all bodies palpable, thereby excluding fire, which indeed it will not attract, nor yet draw through it; for fire consumes its effluxions by which it should attract.”

Brown augmented the list of electrics, and found attraction not only in simple bodies, but in such also as were compounded. He observed, that the attractions of bodies were different. Resinous bodies, he says, attract most vigorously, and “good hard wax so powerfully, that it will convert the needle almost as actively as the load-stone. Gums easily dissolved in water, draw not at all; no metal attracts, nor wood, though never so hard and polished. “Glass, (he says,) attracts but weakly, though clear: and some slick stones, and thick glasses but indifferently.”

These experiments on the electricities of bodies, he performed by means of a needle, “settled freely upon a well pointed pin, so that the electrics might be applied to it without disadvantage;” he tried them also in straws and paleous bodies, powders of wood and iron, in gold and silver foliated.

How the attraction of electrics is performed, he acknowledges is not easily determined; though, he says, “that it is performed by effluviums is plain, and granted by most; for electrics will not commonly attract, except they grow hot and perspirable. For if they be foul and obnubilated, it hinders their effluxion; nor if they be covered, though but with linen or sarsenet, or if a body be interposed, for that intercepts the _effluvium_. If also a powerful and broad electric of wax or _anime_ be held over fine powder, the atoms or small particles will ascend most numerously unto it; and if the electric be held unto the light, it may be observed that many thereof will fly, and be as it were discharged from the electric to the distance sometime of two or three inches. Which motion is performed by the breath of the _effluvium_ issuing with agility; for as the electric cooleth, the projection of the atoms ceaseth.”

Sir Francis Bacon in his “Physiological Remains,” has inserted a catalogue of bodies attractive and not attractive; but he differs in nothing worth mentioning from his predecessors.

Mr. Boyle, who so eminently distinguished himself in the latter part of the seventeenth century, was led by the study of chemistry, to give some attention to electricity. He enlarged the catalogue of electrics; and noticed some circumstances relating to electrical attraction, which had escaped former philosophers. The electrical properties of bodies he found were increased by wiping and warming them, before they were rubbed. Bodies of all kinds, he observed, were indiscriminately attracted; and this attraction he supposed took place in vacuo as well as in the open air.