He is the inventor of the balance electrometer, employed for regulating the amount of a charge to be sent through any substance, as well as of an electrical condenser and of an apparatus for oxidating metals, all of which are respectively described at pp. 593, 614 and 620, Vol. VIII. of the 1855 “Encycl. Brit.”
At the end of Part VI of his “Practical Electricity and Galvanism,” Cuthbertson gives the conclusions he reached from his numerous experiments with wire. These, as well as Mr. George Adams’ own observations (“Essay,” etc., 1799, p. 285), proved that the quantity of electricity necessary to disperse a given portion of wire will be the same, even though the charged surface be greatly varied; and that equal quantities of electricity in the form of a charge will cause equal lengths of the same steel wire to explode, whether the jar made use of be of greater or less capacity (Nicholson’s Journal, Vol. II. p. 217).
During his many experiments Cuthbertson made the very extraordinary discovery that a battery of fifteen jars and containing 17 square feet of coated glass, which, on a very dry day in March 1796 could only be made to ignite from 18 to 20 inches of iron wire of ¹⁄₁₅₀ part of an inch in diameter, took a charge which ignited 60 inches when he breathed into each jar through a glass tube (Noad, “Manual,” p. 122; also Cuthbertson, “Prac. Elec. and Magnetism,” 1807, pp. 187, 188).
References.—Cuthbertson’s communication to the “Emporium of Arts,” Vol. II. p. 193, regarding his experiments on John Wingfield’s “New Method of Increasing the Charging Capacity of Coated Electric Jars”; Cuthbertson’s “Electricity,” Parts VIII, IX and XI; Cuthbertson’s letter addressed to Nicholson’s Journal, Vol. II. p. 526, also Phil. Mag., Vol. II. p. 251. for electrometers; “Bibl. Britan.,” Vol. XXXIX. 1808, p. 97; Vol. XLVII. 1811, p. 233; Cuthbertson’s several works published at Amsterdam and Leipzig, 1769–1797, and alluded to in Phil. Mag., more particularly at Vols. XVIII. p. 358; XIX. p. 83; XXIV. p. 170; XXXVI. p. 259, as well as at p. 313, Vol. XII. of J. B. Van Mons’ Journal de Chimie; Nicholson’s Journal, Vols. II. p. 525; VIII. pp. 97, 205, and the New Series, Vol. II. p. 281; Gilbert’s Annalen, Vol. III. p. 1; “Bibl. Brit. Sc. et Arts,” Genève, 1808, Vol. XXXIX. p. 118; Noad’s “Manual,” p. 118; Van Marum (A.D. 1785); Harris, “Electricity,” p. 103, and his “Frictional Electricity,” p. 76; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 242, 266–268; Phil. Trans., 1782, for A. Brook’s electrometer, which apparatus is described in the latter’s work published, under the head of “Miscellaneous Experiments,” at Norwich, 1789, as well as in the “Electricity” article of the “Encycl. Britannica.”
A.D. 1769.—St. Paul’s Cathedral, London, is first provided with lightning conductors. Dr. Tyndall, who mentions this fact (Notes of Lecture VI, March 11, 1875) likewise states that Wilson, who entertained a preference for blunt conductors as against the views of Franklin, Cavendish and Watson, so influenced King George III that the pointed conductors on Buckingham House were, during the year 1777, changed for others ending in round balls.
In 1772, St. Paul’s Cathedral was struck by lightning, which “heated to redness a portion of one of its conductors consisting of a bar of iron nearly four inches broad and about half an inch thick.” In 1764, the lightning had struck St. Bride’s Church, London, and “bent and broke asunder an iron bar two and a half inches broad and half an inch thick” (Sturgeon, “Sc. Researches,” Bury, 1850, p. 360; Phil. Trans. for 1764 and 1762).
The Rev. James Pilkington, Bishop of Durham, published in London a detailed account of the partial destruction of St. Paul’s Church by lightning, June 4, 1561, which is also to be found at pp. 53–55 of Strype’s “Life of Grindall,” published in London, 1710, and of which an abstract appears under the A.D. 1754 date.
References.—Sturgeon’s Annals, Vol. X. pp. 127–131; also, Biography of John Canton in “Encycl. Britannica”; Sir John Pringle, at A.D. 1777; Hutton’s abridgments of the Phil. Trans., Vol. XII. pp. 620–624.
A.D. 1769.—Mallet (Frederick) member of the Royal Society of Upsal and of the Stockholm Academy of Sciences, acting upon the observations of Anders Celsius (at A.D. 1740), is the first to make an attempt to determine the intensity of magnetism simultaneously at distant points. He ascertains that the number of oscillations in equal times at Ponoi, China (latitude, 67 degrees 4 minutes north; longitude, 41 degrees east) are the same as at St. Petersburg, Russia (59 degrees 56 minutes north latitude; 30 degrees 19 minutes east longitude).
References.—Walker, “Magnetism,” Chap. VI; “Novi Commen. Acad. Sc. Petropol.,” Vol. XIV for 1769, part ii. p. 33; Le Monnier, “Lois du Magnétisme,” etc., 1776, p. 50; “Biog. Univ.,” Vol. XXVI. p. 258.