THE LEYDEN JAR. 515 charge? So they put alcohol and a wire in a bottle and electrified it, and put it down and contemplated it, and saw nothing, and wrote to Von Kleist that his apparatus, whatever it was, must be of peculiar strength, as theirs would not work. And Von Kleist answers naively that he has never seen any apparatus but his own, and hence cannot draw comparisons, but that he has not found the least difficulty in his performances, and in fact has made an excellent little contrivance out of a thermometer tube four inches long, containing water and a wire tipped with a lead ball, which lights spirits satisfactorily and sometimes gives two discharges. Hitherto he has spoken of his device only generally as a machine; now he names it the "Electrical Thermometer," a designation which it has never borne.1 The title which it has received, and how it came so to be known, is now to be told. Meanwhile the Dantzic philosophers, with such new light as Von Kleist afforded, returned to the charge, and at their task for the present I leave them. The two most eminent physicists of Holland, during the 1 The weight of evidence from all sources examined is in favor of the foregoing account of the discovery of the Leyden jar; but a passage in one of Winkler's treatises (Die Eigenschaften der Electrischen Materie und des Electrischen Feuers, etc., Leipsic, 1745), which bears date the 20th of August, 1745, and hence some months prior to Von Kleist's formal communication of his experiment to Lieberkuhn and others, indicates that Von Kleist not only made the experiment considerably before this time, but essayed to describe it to Winkler. Winkler's understanding of it was evidently not clear, for in discussing the strengthening of electric sparks, he says that he placed iron and brass tubes of different lengths one upon another, and hung a large hollow copper ball from them, electrifying all together, and getting stronger sparks than when a single tube four ells long was employed. He then notes that Von Kleist has bound together two iron rods and got similar results, and adds: "The electrical sparks from metal were especially strengthened if the metal object were placed on silk cords in such a way that either the object itself or an iron rod hanging therefrom reached the surface of water, which in a thin glass vessel was electrified while resting upon a silk net." period under review, were Wilhelm Jacob s'Gravesande and Peter Van Musschenbroeck. To them is due the introduction of experimental philosophy and the Newtonian doctrines into the country, and the establishment of systematic study of these subjects in the University of Leyden. s'Gravesande was rather a mathematician than a physicist, and Van Musschenbroeck,' who was originally his pupil and protegé, became, under his guidance, a remarkably able teacher and experimentalist rather than an investigator. As an instructor, it may be said without exaggeration, that kings vied with one another for the possession of him. He held the chair of philosophy in the University of Duisberg; then in that of Utrecht. From the latter Denmark sought to entice him to Copenhagen, the English king to Göttingen, and the king of Spain vainly offered the tempting salary of 20,000 florins per year. The simple request of his native town proved more potent than all these allurements, and he left Utrecht to succeed Wittich as professor of philosophy in the Leyden University, where he remained for the rest of his life, adding to the number of his multifarious physical treatises, and attracting crowds of students from all over Europe, despite the dazzling inducements to abandon his chosen field held out by the king of Prussia and the empress of Russia. One recognizes something characteristically Dutch in the solidity of attainments and persistent fixity of purpose which Van Musschenbroeck above all else possessed, just as something typically French is apparent in the dazzling abilities and captivating style of the Abbé Nollet, whose celebrity at that time, in France at least, even exceeded that of the Leyden professor. Jean Antoine Nollet was an abbé of the ancien régime, not even ordained a priest, but assuming a minor order, and with it the ecclesiastical garb and name of abbé, as many another brilliant man had done, not for the sake of the vocation, but for social distinction and security of posi 1 1 Nouv. Biographie Generale, 37. tion about the court, which otherwise might prove unattainable to the simple student of science, letters or art. Dufay had been his preceptor, guide and friend, and left him stamped with his own charming qualities, to which Nollet added an individual genius for simplifying and expounding physical science, which made his lecture-rooms at Versailles the resort of the gay French court; and this, not because he had become tutor to Monsieur the Dauphin, nor even because his experiments were astonishing, but because his talk was delightful and witty. There is many an old print representing the Abbé in his curled wig and skull cap, with his black gown barely concealing the richlylaced coat and rapier beneath, daintily conducting Madame la Marquise to the electrical machine, where, to the edification of the other assembled grandes dames, she will receive, with a little grimace, a little shock which will not disarrange a patch on her face, nor disturb a fold of her furbelows; or, perhaps, inviting Monsieur le Comte to witness the spirits burst into flame beneath his sword point, or to laugh at the overthrow, by the fierce discharge, of some stolid serf wearing the king's uniform. Indeed there was no startling experiment of Hauksbee, Gray, Dufay or Bose which Nollet did not repeat, and in many instances on a scale greater than the originator had ever attempted. There was a great contrast between this French philosopher of the salon and the Dutch philosopher pedagogue: as different from one another as both were from that German "wizard" Bose; and yet alike in each being a philosopher, which Von Kleist, whose discovery has contributed so inuch to the immortality of the memories of both of them, certainly was not. But, at the time when Van Musschenbroeck wrote his famous letter to Réaumur, which Nollet made public in France, neither writer nor promulgator had ever heard of the Pomeranian Dean and his medicine vial. The British Magazine, the Universal Magazine, the London Maga 1 Reproduced in fac simile from the frontispiece of Nollet's Essai sur l'électricité des corps. Paris, 1746. The boy is suspended on silk lines and electrified by the excited glass tube held by the lecturer, so that his hand attracts bits of loose foil on the table below. THE LEYDEN JAR. 519 zine, the Gentleman's Magazine, even the Newcastle Journal and the Caledonian Mercury, and perhaps dozens of other public prints in England, were giving the new electrical discoveries as part of the regular news of the day, as fast as they were told by those who made them; but journalistic enterprise of that sort had not yet reached the Continent, and for quick intelligence the private letter was still the best and safest medium. In January, 1746 (the Dantzic philosophers still puzzling over Von Kleist's instructions), Musschenbroeck wrote to Réaumur as follows:1 "I wish to inform you of a new, but terrible experiment, which I advise you on no account personally to attempt. I am engaged in a research to determine the strength of electricity. With this object I had suspended by two blue silk threads,' a gun barrel, which received electricity by communication from a glass globe which was turned rapidly on its axis by one operator, while another pressed his hands against it. From the opposite end of the gun barrel hung a brass wire, the end of which entered a glass jar, which was partly full of water. This jar I held in my right hand, while with my left I attempted to draw sparks from the gun barrel. Suddenly I received in my right hand a shock of such violence that my whole body was shaken as by a lightning stroke. The vessel, although of glass, was not broken, nor was the hand displaced by the commotion: but the arm and body were affected in a manner more terrible than I can express. In a word, I believed that I was done for." He then proceeds to say that the shape of the vessel is unimportant, but that he believes that a thin white glass five inches in diameter would possibly give a shock strong enough to kill. The person receiving the discharge may 1 Mémoire de l'Acad. Roy. des Sciences, 1746, Paris. 'Gordon imagined that he discovered that blue silk threads insulated better than any others, and for this reason every one about this time was using them. |