The theories advanced by Chladni were confirmed four years later by Brandes and Benzenberg at Göttingen, and, during the month of April 1809, he inserted a “Catalogue of Meteors” in the “Bulletin de la Société Philomathique,” which was followed by a paper on “Fiery Meteors” published at Vienna during 1819.
In his “Traité d’Acoustique,” Chladni treats of the line of experiments to which he was led, as well by the discovery of Lichtenberg’s electrical figures (see A.D. 1777, and Tyndall, “Sound,” Lecture IV), an account of which latter appeared in the “Mémoires de la Société Royale de Göttingen,” as through the suggestions made him by Lichtenberg himself during the year 1792 relative to the origin of meteors. The results of Chladni’s researches concerning the last named appeared in a Memoir published at Leipzig during 1794, translated by M. Eugène Coquebert Mombret for Vol. V of the Journal des Mines.
It may here be properly added that, in one of the editions of his “Lectures on Sound,” Prof. Tyndall gives a portrait of Chladni and quotes a letter received from Prof. Weber wherein he says: “I knew Chladni personally. From my youth up he was my leader and model as a man of science, and I cannot too thankfully acknowledge the influence which his stimulating encouragement during the last years of his life had upon my own scientific labours.”
References.—Quetelet (Lambert A. J.) in “Cat. Sc. Pap. Roy. Soc.,” Vols. V, VI, VIII; “Mém. de l’Acad. Roy. de Brux.,” 1830–1842; “Annali” of Ambroglio Fusinieri for 1854; “Phil. Mag.,” 1851; Secchi (Angelo) in “Cat. Sc. Pap. Roy. Soc.,” Vols. V, VIII; “Bull. Meteor. dell Osservat.,” 1862, 1866, 1867; Humboldt’s “Cosmos,” London, 1849, Vol. I. p. 104 (M. Schreiber), pp. 113, 114 (M. Capocci), also pp. 105, 108, 110, 121, and the entire “Review of Natural Phenomena,” with all the important references and notes thereunto attached. See likewise Peter Simon Pallas (Phil. Trans. for 1776 and “Act. Acad. Petrop.,” I for 1778); Chladni’s “Uber ... elektricität einer Katze,” Jena, 1797; J. Acton and Capel Lofft, in Phil. Mag., Vol. LI. pp. 109, 203; A Seguin, Phil. Mag., Vol. XLIV. p. 212; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 714, 762, for étoiles, filantes et météorites; F. B. Albinus, “Specimen,” etc., 1740; Voigt’s “Magaz.,” I, 1797; Schweigger’s Journal, XLIII, 1825; H. Atkinson, “On Hypotheses,” etc. (Phil. Mag., Vol. LIV. p. 336); Karstner, Archiven, Vol. IV; F. C. Von Petersdorff in “Great Divide”; Pierre Prevost and others in Poggendorff’s Annalen, Vols. II, VI and VII; Arago, “Annuaire pour 1826”; “The fall of Meteorites in Ancient and Modern Times” (“Sc. Progress,” Vol. II. N.S., pp. 349–370: numerous references given by Prof. H. A. Miers; “A Century of the Study of Meteorites,” by Dr. Oliver C. Farrington in “Pop. Sc. Monthly,” Feb. 1901, or the Report of Smiths. Instit. for 1901, pp. 193–197; Phil. Mag., Vol. IV. p. 332; “Cat. Sc. Papers ... Roy. Soc.,” Vol. I. pp. 916–918; D. Avelloni “Lettera,” etc., Venezia, 1760; Martin H. Klaproth’s different memoirs published at Berlin 1795–1809; Joseph Izarn, “Lithologie Atmosphérique”; J. Murray (Phil. Mag., Vol. LIV. p. 39); beside Chladni’s works in conjunction with Karl F. Anton von Schreibers, Wien, 1819 and 1820, and with Messrs. Steininger and Næggerath, London, 1827 (Schweigger’s Journal, N.R., XVI. 385, and Phil. Mag., Vol. II. p. 41, also Vol. IV. p. 332). For a very interesting account, see “A description of the great Meteor which was seen on the 6th of March 1715–1716, sent in a letter ... to R. Danuye ...” London, 1723 (Phil. Trans. for 1720–1721, Vol. XXXI), by Roger Cotes (1682–1716), of whom Sir Isaac Newton entertained so high an opinion as to frequently remark: “If Mr. Cotes had lived, we had known something” (“Biographia Philosophica,” pp. 512–516; English Encycl., “Biography,” Vol. II. p. 401). Other exceedingly interesting accounts of aerolites are to be found, more particularly in Frederic Petit’s works, published at Toulouse, in Bigot de Morogue’s “Catalogue,” London, 1814, and in the Phil. Mag., Vols., XVII, XX, XXVIII, XXXII, XXXVI, XLIII, XLVI, XLVIII, L, LIII, LIV, LVI-LIX, LXII. While treating of this subject, it may be well to add here that up to the year 1887 diamonds were not known to exist in meteorites. In a very remarkable paper by Prof. A. E. Foote, read before the Geological section of the Am. Asso. Adv. Sci., at its meeting in Washington, he described having, during the month of June 1891, explored Crater Mountain (Cañon Diablo), 185 miles north of Tucson, Ariz., where he found some extraordinary specimens. The extreme hardness of one of these attracted particular attention, and upon carefully examining it he discovered in some of the cavities many small black diamonds as well as a white diamond one-fiftieth of an inch in diameter. This is said to be the most extensive find of the kind yet made.
A.D. 1794.—Mr. J. Churchman publishes his improved “Magnetic Atlas or Variation Charts of the whole terraqueous globe,” etc., which Sir John Leslie subsequently pronounced the most accurate and complete hitherto made. The charts preceding it worthy of note were those of Dr. Halley (see A.D. 1683), of Mountaine and Dodson, in 1744 and in 1756, of Wilcke, in 1772, and of Lambert, in 1779. In his charts, Churchman refers variation lines to two poles, one of which he places, for the year 1800, in lat. 58° N. and long. 134° W. of Greenwich, while the other pole is in lat. 58° S. and long. 165° E. of Greenwich. He supposes the northern pole to revolve in 1096 years and the southern one in 2289 years (“Ency. Brit.,” 1857, Vol. XIV. p. 49).
References.—Churchman’s letters to Cassini, Phila., 1788, and his “Explanation of the Magn. Atlas ...” 1790; Harris, “Rudim. Mag.,” Part III. p. 101; “Bibl. Britan.,” Vol. II. 1796, p. 325 (atlas); Becquerel, “Traité d’Electr. et de Magn.,” Paris, 1856, III. p. 140.
A.D. 1794.—M. Reusser Reiser, of Geneva, addresses a letter to the “Magazin für das Neueste aus der Physik” of Johann Heinrich Voigt (Vol. IX. part i. p. 183), describing the construction of “a new species of electric letter post” (“Schreiben an den herausgeber”) in the following words: “... on an ordinary table is fixed, in an upright position, a square board, to which a glass plate is fastened. On this plate are glued little squares of tinfoil, cut after the fashion of luminous panes, and each standing for a letter of the alphabet. From one side of these little squares extend long wires, enclosed in glass tubes, which go underground to the place whither the despatch is to be transmitted. The distant ends are there connected to tinfoil strips, similar ... to the first, and, like them, each marked by a letter of the alphabet; the free ends of all the strips are connected to one return wire, which goes to the transmitting table. If, now, one touches the outer coating of a Leyden jar with the return wire, and connects the inner coating with the free end of that piece of tinfoil which corresponds to the letter required to be indicated, sparks will be produced, as well at the near as at the distant tinfoil, and the correspondent there watching will write down the letter....”
Reusser also suggested calling the attention of the correspondent by firing an electrical pistol through the spark; to him, therefore, belongs the credit of having first clearly indicated the use of a special call for the telegraph.
References.—Vail’s “History,” p. 121; Voigt’s “Magazin ...” Vol. VII. part ii. p. 57; Shaffner, “Manual,” pp. 133, 134; Forster’s “Bauzeitung,” 1848, p. 238; Ed. Highton, p. 38; Sabine, p. 11; “Appleton’s Encycl.,” 1871, Vol. XV. p. 335; Reiser, “Der El. Würfel,” Gotha, 1791; Comptes Rendus, Tome VII for 1838, p. 80.
A.D. 1794.—Prof. Boeckmann improves upon Reusser’s idea, and does away with the thirty-six plates and the seventy-two wires which the latter is believed to have employed. As Dr. Schellen expresses it, he used “the sparks passing at the distant station, employing only two wires, through which first one and then, after certain intervals, more sparks are combinedly grouped” in a way to indicate particular letters. Like Reusser, he made use of the pistol as a call signal.