References.—Priestley’s “History of Electricity,” 1767, pp. 314–326. For Dessaignes’ other observations, see J. Farrar, “Elem. of Elec., Mag. and Electro-Mag.,” 1826, p. 125, and Phil. Mag., Vol. XLIV. p. 313. See also Phil. Mag., Vol. XXXVIII. p. 3; Journal des Mines, Vol. XXVII. p. 213; Poggendorff, Vol. I. p. 563; “Cat. Sci. Pap. Roy. Soc.,” Vol. II. pp. 272, 273; Chap. III. s. 3 of the “Electricity” article of the “Ency. Britannica.”
A.D. 1811.—The idea of placing a lightning conductor through the body of a ship is first suggested by Mr. Benjamin Cook, of Birmingham, and is carried out by Mr. William Snow Harris, of Plymouth. Mr. William Sturgeon, who mentions the fact (“Lectures of Electricity,” London, 1842, p. 208), adds that Mr. Harris “has formed the conductors into strips of copper, which are inserted in grooves in the after side of the masts from top to bottom and through the keelson to the sea. In one of the smaller men-of-war Mr. Harris carried his mizzen conductor through the powder magazine!!! The evils attending these conductors arise principally from lateral explosions and electro-magnetic influence.”
References.—For Wm. Sturgeon, consult Phil. Mag., Vol. XI, 1832, pp. 195, 270, 324; “Cat. Sc. Papers Roy. Soc.,” Vol. V. pp. 876–878, Vol. VI. p. 758 and Vol. VIII. p. 1042.
A.D. 1811–1812.—Schübler (Gustav), Professor, of Tübingen, is the first to present a connected series of observations upon the electricity of the air, which were made at Stuttgart, during all kinds of weather and at regular daily intervals, between May 1811 and June 1812. Other observations previously carried on by Schübler, during 1805 and subsequent years, at Ellvanguen and Stuttgart are detailed at pp. 579, 580, Vol. VIII—and are also alluded to in article “Meteorology”—of the eighth “Britannica.”
While De Lor was the first to observe, in 1752, the existence of electricity in the atmosphere, even when no lightning is visible, Schübler made the earliest known report upon the daily periodicity of the intensity of the electricity. The annual periodicity had been previously demonstrated by G. B. Beccaria, who published at Turin two able treatises on the subject during 1769 and 1775.
The origin of atmospheric electricity was, by Lavoisier, Laplace and Sir H. Davy, attributed in great part to the constant combustion taking place upon the earth’s surface. Volta and Saussure believed it to arise from the process of evaporation, while Pouillet pointed out the influence of the processes of vegetation; Reich, however, showed that as neither developed electricity they could not produce it in the atmosphere. Peltier advanced the theory that mere evaporation without chemical action is not enough, and the experiments of Faraday and Armstrong showed that evaporation without friction is likewise insufficient. These theories are treated of in “Gaea-Natur und Leben,” Köln and Leipzig, 1873, p. 322, and in Lardner’s “Popular Lectures,” 1859, Vol. II. pp. 149–160. The last named gives tables of many observations, and reports, among other matters, that the series of observations on the diurnal changes of atmospheric electricity which Schübler made, in 1811–1812, were repeated and confirmed at Paris in 1830 by M. Arago. During the month of March 1811 Schübler found that the mean time of the morning maximum was eight hours thirty minutes, and M. Arago ascertained the mean time for the same month to be eight hours forty-eight minutes.
References.—Edin. Jour. of Sci., new series, Vol. III; Biblio. Univers., Vol. XLII; Annales de Ch. et de Ph. for 1816, Vol. II. p. 85; “Jahrbuch der Ch. und Ph.,” 1829; Gilbert’s Annalen, Vols. XXXIX, XLIX, LI; Schweigger’s Journal, Vols. II. p. 377; III. p. 133; VIII. pp. 21, 22, 25, 26, 28, 29; IX. pp. 348, 350, 351; XV. p. 130; XIX. pp. 1 and 11; XXV. p. 249; XXXI. p. 39; Jour. de Phys., Vol. LXXV. p. 177; Vol. LXXXIII. p. 184; “Lehrbuch der Meteor,” L. F. Kaemtz, Halle, 1832, Vol. I. p. 337; Vol. II. pp. 411, 414; “Annual of Sc. Disc.” for 1862, pp. 99–103; L. Palmieri in Lum. Elec., Paris, Oct. 31, 1891, pp. 209–212; “Sci. Pap. Roy. Soc.,” Vol. V. pp. 559–562; Vol. VI. p. 755; “Bibl. Britan.,” Vol. II, N.S. for 1816 pp. 93–113 (atmosph. electricity); Poggendorff, Vol. II. p. 853; Report on Atmospheric Electricity by F. J. F. Duprez, 1858, Part III. chap. ii. pp. 363–368; Foggo, p. 124, Vol. IV of Edin. Jour. Sci.; J. J. Hemmer’s observations at Mannheim from 1783 to 1787, Lehrbuch, etc., Vol. II. p. 418, and the recorded investigations of De Luc, Girtannier, Mayer, Monge, Pouillet, Becquerel, De Tressan, Arago, De Saussure, Delezenne, Helwig and Kaemtz.
A.D. 1811.—In the first volume of his “Cosmos” (London, 1849, Vol. I. pp. 240–241) Humboldt speaks of islands of eruption, or marine volcanoes, which can properly be classed among electrical phenomena, and alludes to the one observed on the 13th of June 1811 by Captain Tillard (Tilland), and to which he gave the name “Sabrina.”
This volcano, which had previously appeared June 11, 1638 and December 31, 1719, off the island of St. Michael, in the Azores, is thus described in the Philosophical Transactions:
“Imagine,” says Captain Tillard, “an immense body of smoke rising from the sea, the surface of which was marked by the silver rippling of the waves occasioned by the slight and steady breezes incidental to those climates in summer. In a quiescent state, it had the appearance of a circular cloud, revolving on the water like a horizontal wheel, in various and irregular involutions, expanding itself gradually on the lee side, when suddenly a column of the blackest cinders, ashes, and stones, would shoot up in the form of a spire, rapidly succeeded by others, each acquiring greater velocity and breaking into various branches resembling a group of pines; these again forming themselves into festoons of white feathery smoke. During these bursts, the most vivid flashes of lightning continually issued from the densest portion of the volcano, and the columns rolled off in large masses of fleecy clouds, gradually expanding themselves before the wind, in a direction nearly horizontal, and drawing up a quantity of water spouts, which formed a striking addition to the scene. In less than an hour, a peak was visible, and, in three hours from the time of our arrival, the volcano then being four hours old, a crater was formed twenty feet high, and from four to five hundred feet in diameter. The eruptions were attended by a noise like the firing of cannon and musketry mixed; as also with shocks of earthquakes sufficient to throw down a large part of the cliff on which we stood.” (See description of the sudden appearance of the Island of St. Michael, etc., in Lectures by Dr. Webster, Professor of Chemistry and Mineralogy at Harvard College, Boston, 1822.)