Lesage was not, however, satisfied with a telegraph upon so small a scale as to be utilized only in one building, and on the 22nd of June 1782 he addressed a letter to M. Pierre Prévost, at Geneva, on the subject of “a ready and swift method of correspondence between two distant places by means of electricity.” This, he says, had occurred to him thirty or thirty-five years before, and had been “then reduced to a simple system, far more practicable than the form with which the new inventor has endowed it.” He employed a subterranean tube of glazed earthenware, divided at every fathom’s length by partitions with twenty-four separate openings intended to hold apart that number of wires, the extremities of the wires being “arranged horizontally, like the keys of a harpsichord, each wire having suspended above it a letter of the alphabet, while immediately underneath, upon a table, are pieces of gold leaf, or other bodies that can be as easily attracted, and are at the same time easily visible.” Upon touching the end of any wire with an excited glass tube, its other extremity would cause the little gold leaf to play under a certain letter, which would form part of the intended message.
Georges Louis Lesage (sen.) wrote a work on “Meteors,” etc., published at Geneva in 1730, and alluded to in Poggendorff, Vol. I. p. 1433.
References.—Abbé Moigno, “Traité,” etc., 2nd ed. Part II. chap. i. p. 59; Ed. Highton, “The Electric Telegraph,” 1852, p. 38; Journal des Sçavans, September 1782, p. 637; Pierre Prévost, “Notice,” etc., 1805, pp. 176–177.
A.D. 1774.—Wales (William), English mathematician and the astronomer of Captain Cook during the expeditions of 1772, 1773 and 1774, is the first to make scientific observations relative to the local attraction of a ship upon mariners’ compasses. While on his way from England to the Cape and during his passage through the English Channel he found differences of as much as 19 degrees to 25 degrees in the azimuth compass.
References.—Sturmy, at A.D. 1684; also Wales and Bayly’s “Observations on Cook’s Voyages,” p. 49.
A.D. 1775.—Gallitzin (Dmitri Alexewitsch Fürst, Prince de), an able Russian diplomat and scientist, carries on at the Hague, between the 4th of June, 1775, and the commencement of the year 1778, a series of experiments upon atmospherical electricity, the results of which he communicates to the St. Petersburg Academy of Sciences in a Memoir entitled “Observations sur l’Electricité naturelle par le moyen d’un cerf-volant.” Therein he states that the presence of electricity was always noticeable whenever he raised his kite, whether in the night or in the daytime, as well as during hot, dry, or damp weather, and he ascertained that electricity is generally positive during calm weather and more frequently negative when the weather is stormy.
He also observed during an extensive course of experiments upon animals that hens’ eggs hatch sooner when they are electrified, thus confirming the previous observations of Koeslin and Senebier, and he gives an account of the effects of battery shocks upon various species. He cites the case of a hen which had sustained the shock of sixty-four jars and appeared dead, but which revived and lived thirty-two days; and he gives the report of the dissection made by M. Munichs, as well as the very curious observations upon it noted at the time by M. Camper.
Reference.—Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 13–14, 66, and Vol. II. p. 48, etc.; “Anc. Mém. de l’acad. Belge,” Vol. III. p. 3, showing preference for the pointed form of electrical conductors; “Mercure de France,” 1774, p. 147; “Biog. Univ.,” Tome XV. p. 425; “Mém. de l’Acad. ... de Bruxelles,” Vol. III. p. 14; Journal de Physique, Vols. XXI and XXII for 1782 and 1783; “Opuscoli Scelti,” Vol. II. p. 305.
A.D. 1775.—Lorimer (Dr. John), “a gentleman of great knowledge on magnetics” (1732–1795), describes his combined dipping and variation needle for determining the dip at sea, which he calls universal magnetic needle or observation compass in a letter to Sir John Pringle, Bart., copied in Philosophical Transactions, Vol. LXV. p. 79. This apparatus is also to be found described in Lorimer’s “Essay on Magnetism,” etc., 1795, as well as at p. 168 of Cavallo’s “Treatise on Magnetism” published in 1787; and, at p. 333 of the latter work, the Doctor endeavours to explain the causes of the variation of the magnetic needle.
References.—For Lorimer, consult Hutton’s abridgments, Vol. XIII. p. 593, and, for dipping needles, refer to the same volume of Hutton, p. 613, wherein especial mention is made of those of Thomas Hutchins. The dipping needle of Robert Were Fox is described in the “Annals of Electricity,” as well as at p. 411, Vol. II. of “Abstract of Papers of Roy. Soc.,” and the two dipping needles of Edward Nairne are described in Phil. Trans. for 1772, p. 496. Capt. Henry Foster made a report on changes of magnetic intensity ... in dipping and horizontal needles, to be found in Phil. Trans. for 1828, p. 303 (“Abstracts Sc. Papers ... Roy. Soc.,” Vol. II. pp. 290–296, 344).