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.