References.—See his “Examen des principaux systèmes ...” Paris, 1813; J. C. Poggendorff, Biogr. Liter. Hand. ... Vol. I. p. 1399; Larousse, Dict. Univ., Vol. X. p. 290; Journal de Médecine, Vol. XXVI. pp. 298–303; Catal. Sc. Pap. Roy. Soc., Vol. III. p. 910; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Vol. I. p. 461; V. Delaunay, “Manuel de l’Electricité,” Paris, 1809, pp. 151–153; Detienne, “De l’électricité de pression” (Journal de Physique, 1777, Vol. IX).
A.D. 1809.—Krafft (Wolfgang Ludwig), Professor of Experimental Philosophy in the Imperial Academy of Sciences of St. Petersburg is the author of “Uber ein hypothet ...” wherein is given the result of his investigations of the phenomena of terrestrial magnetism.
Comparing Biot’s examination of the dip observations previously made by Humboldt, Krafft simplified the former’s conclusions, showing that if we measure the latitude from the magnetic equator, the tangent of the dip is double the tangent of such latitude, or, as he expresses it: “If we suppose a circle circumscribed about the earth, having the two extremities of the magnetic axis for its poles, and if we consider this circle as a magnetic equator, the tangent of the dip of the needle, in any magnetic latitude, will be equal to double the tangent of this latitude.”
Krafft gave a complete theory of the electrophorus in the first part of the 1778 “Acta Acad. Petrop.,” which latter also contains his experiments with Canton’s phosphorus and his observations on the aurora of February 6–17 of the same year. The results of many of his other investigations are to be found in Part XI of the work mentioned as well as in Vols. XV, XVII and XIX of the “Novi Commentarii Academiæ Petropolitanæ.”
A.D. 1809.—Pinkerton (John), gives in his “Voyages and Travels,” published at London (Vol. IV. pp. 1–76) a reprint of the rare volume entitled “Account of Paris at the close of the Seventeenth Century,” by Martin Lister, M.D., wherein are detailed several surprisingly interesting experiments made by Mr. Butterfield with his wonderful collection of loadstones. It is therein stated that one of these loadstones, when unshod, weighed less than a dram and would suspend a dram and a half, but when shod would attract 144 drams of iron, whilst another of the loadstones, weighing 65 grains, attracted 14 ounces, or 140 times its own weight; another would work through a wall eighteen inches in thickness, etc. etc.
A.D. 1809.—Children (John George), an English scientist to whom reference has already been made, more particularly under Cruikshanks, A.D. 1800, communicates to the Philosophical Transactions, “An account of some experiments performed with a view to ascertain the most advantageous method of constructing a voltaic apparatus for the purposes of chemical research.” This paper appears also in Vol. XXXIV of the Philosophical Magazine.
Four years later (1813) he publishes a description of his magnificent galvanic battery, the largest ever constructed on the plan suggested by Dr. Wollaston. This consisted of twenty pairs of copper and zinc plates, each six feet long and two feet eight inches wide, the united capacities of the cells being 945 gallons. With this battery he confirmed Davy’s observation that “intensity increases with the number (of plates) and the quantity of the electricity with the extent of surface.” It is reported that, when in full action, the battery rendered a platinum wire five feet six inches long and ¹¹⁄₁₀₀ of an inch in diameter red-hot throughout so as to be visible in full daylight; that eight feet six inches of platinum wire ⁴⁴⁄₁₀₀ of an inch in diameter were easily heated red; that a bar of platinum one-sixth of an inch square and two and a quarter inches long was heated red-hot and fused at the end; and that a round bar of the same metal, 276/1000 of an inch in diameter and two and a half inches long, was heated bright red throughout.
The result of many other investigations which he also made in 1813 and during 1815 showed that metallic wires (eight inches long and ¹⁄₃₀ of an inch diameter) became red-hot in the following order: platinum, iron, copper, gold, zinc, silver; and he deduced that their conducting power was in the inverse order, silver conducting best and platinum least. Tin and lead fused immediately at the point of contact, and the oxides of tungsten, uranium, cerium, titanium, iridium and molybdenum were also fused. An opening made with a saw across an iron wire having been filled with diamond powder, the diamond was liquefied and the contiguous iron became steel. (See the Pepys entry at A.D. 1802.)
References.—For Children’s other experiments, consult “Phil. Mag.,” Vol. XLII. p. 144; Vol. XLVI. pp. 409–415; Phil. Trans. for 1815, pp. 368–370, also Dr. Wm. Henry’s “Elem. of Exper. Chem.,” London, 1823, Vol. I. pp. 168–174; Dr. Thomas Thomson, “Outline of the Sciences,” London, 1830, pp. 524–526; Louis Figuier, “Expos. et Hist. ...” Paris, 1857, Vol. IV. pp. 389–390; Becquerel, Vol. I. p. 52; “Encycl. Metrop.,” Vol. IV. pp. 179, 222; Gmelin’s “Chemistry,” Vol. I. p. 424; “Cat. Sc. Papers Roy. Soc.,” Vol. I. p. 317; Vol. II. p. 26; “Bibl. Britan.,” Vol. XLIII, 1810, p. 67 and Vol. I of the N.S. for 1816, p. 109.
A.D. 1809–1810.—Oken (Lorenz)—originally Lorenz Ockenfuss—celebrated German naturalist, while occupying the post of Extraordinary Professor of Medicine at the University of Jena, publishes the great work “Lehrbuch der Naturphilosophie,” which was translated into English by Dr. A. Tulk and published in London, during 1847, by the Royal Society, under the title of “Elements of Physico-Philosophy.”