A.D. 1747.—Gralath (Daniel) publishes in the Dantzig Memoirs his “Geschichte der Electricität.”
He is the first to construct a Leyden phial with a long, narrow neck, through which is passed an iron wire bearing a tin knob in place of the iron nail theretofore used; and, with several of these phials joined together in the form of a battery, he had, during the previous year, transmitted a shock through a chain of twenty persons. His observations are recorded in the above-named Memoirs at pp. 175–304 and 506–534, Vol. I.; pp. 355–460, Vol. II.; pp. 492–556, Vol. III. Gralath’s “Electrische Bibliothek” is in Vols. II. and III.
A.D. 1747.—The Swedish mathematician and philosopher, Samuel Klingenstierna, and his pupil, M. Stroemer, were the first who properly electrified by the rubber, and their experiments were published in the Acts of the Royal Academy of Sciences at Stockholm for the year 1747 (see Priestley’s “History of Electricity,” Part I. period viii. s. 3, wherein he alludes to Wilcke’s “Herrn Franklin’s briefe,” etc., p. 112).
A.D. 1748.—Morin (Jean), French physicist, publishes at Chartres “Nouvelle dissertation sur l’électricité des corps,” etc., in which he details many of his experiments, and endeavours to give a correct explanation of all the extraordinary electrical phenomena hitherto observed. He is also the author of a “Reply to Mr. Nollet upon Electricity,” published in 1749 at Chartres and at Paris, as well as of a treatise upon Universal Mechanism, which latter, according to the Journal des Savants, contained more information upon Nature generally, and expressed in fewer words, than was embraced in any previous work.
References.—“Dict. Univ.,” Vol. XI. p. 568; “Biog. Générale,” Vol. XXXVI. p. 599.
A.D. 1749.—Stukeley (the Rev. William), M.D., is the first who advanced that earthquakes are probably caused by electricity. This he did in a paper read before the Royal Society, March 22, 1749, having reference to the subterranean disturbances noticed in London, February 8 and March 8 of the same year. In this communication, as well as in a subsequent one read to the same Society, December 6, 1750, bearing upon a similar disturbance observed throughout England during the previous month of September, he explains why earthquakes are not the result of subterraneous winds, fires, vapours, etc.
One of his strongest arguments is that no such vapours could instantaneously have destroyed thirteen great cities as did the earthquake which occurred in Asia Minor, A.D. 17, and which is reckoned to have shaken a cone of earth three hundred miles diameter in base and two hundred miles in the axis. This quantity of earth, he says, “all the gunpowder which has ever been made since the invention of it would not have been able to stir, much less any vapours, which could be supposed to be generated so far below the surface,” and, he adds, “if the concussion depended upon a subterraneous eruption the shock would precede the noise.”
He observes that the earth for months prior to the afore-named disturbances “must have been in a state of electricity ready for that particular vibration in which electrification exists”; that all the vegetation had been “uncommonly forward ... and electricity is well known to quicken vegetation”; that the aurora borealis had been very frequent about the same time and had been twice repeated just before the earthquake, “of such colours as had never been seen before,” there being, one evening, “a deep red aurora borealis covering the cope of heaven very terrible to behold”; that the whole year had been “remarkable for fire-balls, thunder, lightning and coruscations, almost throughout all England,” all which “are rightly judged to proceed from the electrical state of the atmosphere”; and, finally, that, a little before the earthquake, “a large and black cloud suddenly covered the atmosphere, which probably occasioned the shock by the discharge of a shower.” He adds that, according to Dr. Childrey, earthquakes are always preceded by rain and sudden tempests of rain in times of great drought.
Dr. Stephen Hales (1677–1761), who was Stukeley’s classmate at Bennet College, Cambridge, and later his chief assistant in the study of the natural sciences, and who afterward became celebrated for his physical investigations and discoveries, arrives at a like conclusion. He thinks that “the electric appearances were only occasioned by the great agitation which the electric fluid was put into by the shock of so great a mass of the earth.” The great noise which attended the disturbance of March 8, 1749, he conjectured was “owing to the rushing or sudden expansion of the electric fluid at the top of St. Martin’s spire, where all the electric effluvia, which ascended along the large body of the tower, being strongly condensed, and accelerated at the point of the weathercock, as they rushed off made so much the louder expansive explosion.” It may be added here that Dr. Hales is the one who, at a previous date, had communicated to the Royal Society his observation of the fact that the electric spark proceeding from warm iron is of a bright, light colour, while that from warm copper is green, and the colour from a warm egg of a light yellow. In his opinion, these experiments appeared to argue that some particles of those different bodies are carried off in the electric flashes wherein those different colours are exhibited.
For Stephen Hales, consult the Phil. Trans., Vol. XLV. p. 409, as well as the abridgments of Hutton, Vol. IX. p. 534, and for his portrait see “Essays in Historical Chemistry,” by T. E. Thorpe, London, 1894.