ELECTRICITY
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so agreeable relaxation to the serious and liberal mind, as philoso-phical experiments. The rational entertainment, and pleasing in-struction, conveyed by such inquiries, are constantly found to ex-tend the faculties of the soul with an exalted idea of the beautyand sublimity of nature, while the mind is almost irresistibly ledon to contemplate and adore its divine source. Few otljpr depart-ments of science yield phenomena so pleasing, so various, and, atthe same time, so astonishing, as that of electricity. The varietyof appearances produced by an electrical machine, in a copiouscurrent of the fluid, are, indeed, sometimes so strikingly curious,that the mind seems to be in a manner suspended between admi-ration of the effects, and inquiry into the cause. This affectionseems to be natural and rational. The human mind can neithercease to admire, nor remain satisfied with vague appearances.The superior objects of its desire are knowledge and certainty ; inthe pursuit of which its industry is cheerfully exerted and fre-quently rewarded with success.
Although the electric fluid, ever since the creation, has had thesame share in all the operations of nature, that it has at present,yet the discovery of its action, and even of its existence, is of avery late date. Thales the Milesian, who lived about B. C. 600,was the first who observed that amber, from which tire name elec-tricity is derived, would attract light bodies when it was rub-bed. 'I'he ancient naturalist, Theophrastus , who flourished 300Years later, tells us, that the hncurium (now called tourma-lin) has the property of attracting light bodies as well as amber.From this lime there is a chasm in the history of electricity for noless than 1900 years. Indeed, it is scarce to be supposed, thatduring this long interval any person applied himself to the investi-gation of the subject; as, for the greatest part of it, science ofevery kind was almost totally extinguished. The electrical pro-perties ofjet, however, and, according to Mr. Boze, of the agate,were some way or other discovered during this period. But itwas not till the beginning of the seventeenth century, that electri-city became properly a distinct science, and the foundation waslaid of those discoveries which have since taken place. Dr. WilliamGilbert, an English physician , who, in lGOO wrote a book deMagnete, containing various electrical experiments, was the first who properly merits the title of an electrician, lie, like his pre-decessors, however, considered only the attractive property ofelectric substances. Dr. Gilbert ’s merit consists in his havingbeen at great pains to find a number of such substances, and thusconsiderably enlarging the number of electrics; on which ac-count M. Cavallo says, “ he may be justly deemed the father ofthe present electricity.” Sir Francis Bacon also made some elec-trical experiments ; but no farther discoveries appear to have beenmade till 1670, except some trilling additions to the catalogue ofelectrics. About this time Mr. Boyle applied himself to the studyof electricity, lie enlarged the catalogue of electrics; and foundthat their electric properties wore increased by wiping and warm-ing them before they were rubbed. He observed also, that allkinds of bodies were attracted promiscuously ; anil imagined thatthey were attracted in vacuo as well as in air. This Iasi , position,however, is denied by Mr. Beccariu; and Mr. Boyle must havebeen mistaken. He also observed the electric light, though onlyin the instance of some diamonds. The science, however, wasmuch farther improved by Otto Guericke , who was cotemporary withMr. Boyle. He made use of a sulphur globe, w hirled on an axismuch in the same way with our present glass globes. Thus hecould excite a vastly greater power of electricity than any of idspredecessors, and try all their experiments to much more advan-tage. He discovered electric repulsion ; and not only saw theelectric light more clearly than Mr. Boyle, but heard the hissingsound with which it is emitted. He also made another remark-able discovery, hut which has since been very generally over-looked ; namely, that a feather, when repelled by an excited elec-tric, always keeps the same face towards the body which repelsit, as the moon does to the earth. The celebrated Sir Isaac New-ton made the next discovery of any moment; by observing, thatthe electric attraction and repulsion penetrated through glass; andit is much to be regretted that this accurate philosopher did notapply himself eo the study of electricity with greater assiduity. ATreatise on Electricity was published in 1709, by Mr. Ilawkes-bee ; who not only far excelled all his predecessors and contem-
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poraries, but also made some discoveries which w ell deserve theattention of the most expert electricians at this day. Besidesmany new experiments upon electric attraction and repulsion, aswell as the light emitted by electric bodies; he found a methodof rendering opaque bodies transparent by electricity. He linedmore than half the inside of a glass globe with sealing-wax; andhaving exhausted the globe, he put it in motion ; when applying hishand to excite it, lie saw the shape and figure of all the parts of hishand distinctly and perfectly on the concave superficies of the waxwithin, just as if only pure glass without any wax at all had beeninterposed between his eye and his hand. The lining of wax,where it was spread thinnest, would but just allow tbe light of acandle through it in the dark; but in some places tbe wax was atleast an eighth part of an inch thick. Yet even in these places thelight and figure of his hand were as distinguishable through it asany where else. The sealing-wax did not adhere to the glass inall places; but this made no difference with regard to-the trans-parency. Pitch answered the purpose equally well w ith sealing-wax.Mr. Hawkesbee also made a further improvement by using a glassglobe,which acts more powerfully thanasulphurone. After the deathof Mr. Hawkesbee, “ the science of electricity,” says M. Cavallo,“ however hitherto advanced, remained about twenty years in astate of quiescence, the attention of philosophers being at that timeengaged in other philosophical subjects, which on account of tbe.new discoveries of the incomparable Sir Isaac Newton were thengreatly in repute. Mr. Grey was the first after this period of ob-livion to bring tiie science again to light. He by his great disco-veries re-introduced it to the acquaintance of philosophers, andfrom him the true flourishing era of electricity may he said to takeits date.” Mr. Stephen Grey’s capital discovery was the distinc-tion between conductors anil non-conductors of electricity. InFeb. 1729, Mr. Grey, after some fruitless attempts to excite an elec-tric power in metals, recollected a suspicion he had for some timeentertained, that as a glass tube, when excited in the dark, com-municated its light lo various bodies, it might at the same timepossibly communicate lo them a power of attracting light bodies;which as yet was all that was understood by the word electricity.For this purpose he procured a glass tube, 3 feet 5 inches long,and near one inch and two lentils in diameter, To each end hefitted a cork, to keep out the dust when the tube was not used.Mr. Grev’s first experiments were made to determine whether thetube would attract equally well with the ends shut as with themopen. In this respect there was no difference ; but he found thatthe corks attracted and repelled light substances as well, and ra-ther better, than the tube itself. lie then fix- d an ivory ball upona stalk of fir about four inches long, and thrusting the end of thestalk into one of the corks, he found the hall endowed with astrong attractive and repulsive virtue. This experiment lie re-peated in many different ways; fixing the ball upon long sticks,and upon pieces of brass and iron wire, always with the same suc-cess; but lie constantly observed, that the ball at the end attractedmore vigorously than that part of the wire nearest the tube. Mr.Grev next tried whether the ball might be suspended by a pack-thread with a loop on the tube, and the event fully answered hisexpectation. Having thus suspended bodies of tiie greatest lengthhe conveniently could, he ascended a balcony 26 feet high, andfastening a string to Iiis tube, found that the ball would attractlight hmlies on the ground below. This experiment succeeding inthe greatest heights to which he could ascend, he next attemptedto carry the electricity horizontally ; hut in this lie failed, becausehe suspended his line, which was intended to carry the electricityhorizontally, by a pack-thread ; and thus the fluid got off from it.Whereupon he consulted Mr. Wheeler, and told him of the unsuc-cessful attempt ht*had made. Mr Wheeler proposed to suspendthe conducting line bv silk instead of pack-thread, as being smallerthan the other. With this they succeeded perfectly well, but byrepeated experiments they soon discovered that the silk refused toconduct the electric fluid, not on account of its smallness, as theyhad supposed, but on account of some difference in the matter.Tiie wires were smaller than the silk thread, yet the electricity waseffectually carried off by them. 'Ibis discovery of tbe con-con-ducting power of silk was made in the beginning of July, 1729,and was quickly followed by another, viz. that the same power ex-isted in many other substances: and thus, in fact, the foundationof almost all” the subsequent improvements in electricity was laid.Not long after Mr. Grey’s discovery of the difference between
conductors