A.D. 1779.—Lord Mahon, afterward third Earl of Stanhope, an Englishman of great ingenuity and fertility in invention and a pupil of Lesage of Geneva (at A.D. 1774), publishes his “Principles of Electricity,” in which he explains the effects of the return stroke or lateral shock of an electrical discharge which was first observed by Benjamin Wilson (at A.D. 1746).
He imagined that when a large cloud is charged with electricity it displaces much of that fluid from the neighbouring stratum of air, and that when the cloud is discharged the electric matter returns into that portion of the atmosphere whence it had previously been taken. According to Lord Cavendish, the theory developed in the above-named work is that “A positively electrified body surrounded by air will deposit upon all the particles of that air, which shall come successively into contact with it, a proportional part of its superabundant electricity. By which means, the air surrounding the body will also become positively electrified; that is to say, it will form round that positive body an electrical atmosphere, which will likewise be positive.... That the Density of all such atmospheres decreases when the distance from the charged body is increased.”
Tyndall says (Notes on Lecture VII) that Lord Mahon fused metals and produced strong physiological effects by the return stroke.
In 1781, the English scientist, John Turberville Needham (1713–1781), published at Brussels his French translation of Lord Mahon’s work under the title of “Principes de l’Electricité.” Needham was the first of the Catholic clergy elected to a fellowship of the English Royal Society, to whose Transactions he made several contributions. His numerous works include “A letter from Paris concerning some new electrical experiments made there,” London, 1746, also a volume of researches upon the investigations of Spallanzani. The list of his communications to the Phil. Trans. and to the “Mém. de l’Acad. de Bruxelles” will be found in Watt’s “Bibliotheca Britannica” and in Namur’s “Bibl. Acad. Belge” (“Dict. Nat. Biog.,” Vol. XL. p. 157; Phil. Trans., 1746, p. 247, and Hutton’s abridgments, Vol. IX. p. 263).
References.—“Electrical Researches” of Lord Cavendish, pp. xlvi-xlvii; Phil. Trans. for 1787, Vol. LXXVII. p. 130; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. I. p. 664; Dr. Thomas Thomson, “History of the Royal Society,” London, 1812, p. 449; Sturgeon, “Researches,” Bury, 1850, p. 398.
A.D. 1779.—Ingen-housz (Johan), distinguished English physician and natural philosopher, native of Breda, publishes, Phil. Trans., p. 661, an account of the electrical apparatus which is by many believed to have led to the invention of the plate electrical machine, although the same claim has been made in behalf of Jesse Ramsden (at A.D. 1768). Dr. Priestley states that Ingen-housz and Ramsden invented it independently of one another. He describes a circular plate of glass nine inches in diameter turning vertically and rubbing against four cushions, each an inch and a half long and placed at the opposite ends of the vertical diameter. The conductor is a brass tube bearing two horizontal branches extending to within about half an inch of the extremity of the glass, so that each branch takes off the electricity excited by two of the cushions (Dr. Thomas Young, “Course of Lectures,” Vol. II. p. 432).
The plate machine of Dr. Ingen-housz is illustrated at p. 16 of “Electricity” in the “Library of Useful Knowledge.” For other plate machines see, more particularly, Dr. Young’s “Course of Lectures,” Vol. II. p. 431; Phil. Trans. 1769, p. 659; Geo. K. Winter’s apparatus with ring conductor and peculiar-shaped rubbers, as well as the great machine at the Royal Polytechnic, and that of Mr. Snow Harris, illustrated and described in Vol. III. p. 787, “Eng. Ency.—Arts and Sciences,” and at pp. 223, 224 of J. H. Pepper’s “Cyclopædic Science,” London, 1869; “Allg. deutsche Biblioth.,” B. XXIV. Anh. 4, Abth., p. 549, 1760 (Poggendorff, Vol. II. p. 465), relative to the machines of Martin Planta, Ingen-housz and Ramsden; Reiser’s plate machine (Lichtenberg and Voigt’s “Magazin für das Neueste aus der Physik,” Vol. VII. St. 3, p. 73); Ferdinando Elice, “Saggio sull’Elettricita,” Genoa, 1824 (for two electricities); J. J. Metzger’s machine (Elice, “Saggio,” second edition, p. 55); Marchese C. Ridolfi, for a description of Novelluccis’ plate electrical machine (“Bibl. Italiana,” Vol. LXIII. p. 268; “Antologia di Firenze,” for August 1824, p. 159); Robert Hare, “Description of an Electrical Plate Machine,” London, 1823 (Phil. Mag., Vol. LXII. p. 8). See, besides, the machines of Bertholon (rubber in motion) in Lichtenberg and Voigt’s “Magazin,” Vol. I. p. 92 and Rozier XVI. p. 74; of Brilhac (Rozier, XV. p. 377); of Saint Julien (Rozier, XXXIII. p. 367); of Van Marum (Rozier, XXXVIII. p. 447).
Dr. Ingen-housz also constructed a small magnet, of several laminæ of magnetised steel firmly pressed together, capable of sustaining one hundred and fifty times its own weight, and he found that pastes into the composition of which the powder of the natural magnet entered were much superior to those made with the powder of iron; the natural magnet, he observed, having more coercitive force than iron.
References.—Journal de Physique for February 1786, and for May 1788, containing the letters of Dr. Ingen-housz, which show that the vegetation of plants is in no sensible degree either promoted or retarded by common electricity. An account is also given of his experiments in “Versuche mit Plantzen,” Vienna, 1778, in the “Catalogue of the Royal Society,” p. 313, in “Goth. Mag.,” Vol. V. iii. 13; Rozier, XXXII. p. 321; XXXIV. p. 436; XXXV. p. 81; Journal de Physique, Vol. XXXV for 1789. See also, Journal de Physique, XLV (II), 458; Rozier, XXVIII. p. 81; M. Nuneberg, “Osservazioni ...” Milano, 1776 (“Scelta d’Opuscoli,” XVII. p. 113); Pietro Moscati, “Lettera ...” Milano, 1781 (“Opus Scelti,” IV. p. 410); H. B. de Saussure (Journal de Physique, Vol. XXV for 1784); G. da San Martino, “Memoria ...” Vicenza, 1785; M. Schwenkenhardt, “Von dem Einfluss ...” (Rozier, XXVII. p. 462; Journal de Physique for 1786, Vol. I); A. M. Vassalli-Eandi in the “Mem. della Soc. Agr. di Torino,” Vol. I for 1786, particularly regarding the experiments of Ingen-housz and Schwenkenhardt; also in the “Giornale Sc. d’una Soc. Fil. di Torino,” Vol. III; N. Rouland, “Elec. appliquée aux vegétaux” (Journal de Physique, 1789–1790); Ingen-housz, Rouland, Dormoy, Bertholon and Derozières (Rozier, XXXV. pp. 3, 161, 401; XXXVIII. pp. 351, 427, and in Journal de Physique, Vols. XXXII, XXXV, XXXVIII); M. Carmoy, on the effects of electricity upon vegetation, in Rozier, XXXIII. p. 339; Jour. de Physique 1788, Vol. XXXIII; M. Féburier, “Mémoire sur quelques propriétés ...”; G. R. Treviranus, “Einfluss ...” Kiel, 1800 (Gilbert’s Annalen, Vol. VII for 1801 and “Nordisches Arch. f. Nat. u. Arzneiw.,” 1st Band, 2tes Stück); C. G. Rafn (“Mag. Encyclopédique,” No. 19, Ventose An. X. p. 370), Paris, 1802; J. P. Gasc, “Mémoire sur l’influence ...” Paris, 1823; E. Solly, “On the influence ...” London, 1845 (“Journ. of the Hortic. Society,” Vol. I. part ii.); E. Romershausen, “Galv. El. ... Vegetation,” Marburg, 1851; M. Menon, “Influence de l’électricité sur la végétation,” and his letters to R. A. F. de Réaumur. Consult likewise J. Browning’s letter to H. Baker, Dec. 11, 1746 (Phil. Trans. for 1747, Vol. XLIV. p. 373); G. Wallerius, “Versuch ...” Hamb. and Leipzig, 1754; (“K. Schwed. Akad. Abh.,” XVI. p. 257; also “Vetensk Acad. Handl.,” 1754;) L. F. Kamtz (Kaemtz), “Über d. Elek ...” Nürnberg, 1829; (Schweigger’s Journal f. Chemie u. Physik, Vol. LVI;) Bartolomeo Zanon, “Intorno un punto ...” Belluno, 1840; Francesco Zantedeschi “Dell influsso ...” Venezia, 1843; (“Mem. dell Instit. Veneto,” I. p. 269;) E. F. Wartmann, “Note sur les courants ...” Genève, 1850; (“Bibl. Univ. de Genève,” for Dec. 1850;) T. Pine, “Connection between Electricity and Vegetation,” London, 1840; (“Annals of Electricity,” Vol. IV. p. 421.) For the effects of galvanism on plants, see Giulio in “Bibl. Ital.,” Vol. I. p. 28; also E. J. Schmuck “On the Action of Galvanic Electricity on the Mimosa Pudica,” and M. Rinklake, as well as Johann W. Ritter, “Elektrische versuche an der Mimosa Pudica.” For an account of M. P. Poggioli’s observations on the influence of the magnetic rays on vegetation, and the reply of F. Orioli thereto, see Vol. I of the “Nuova collezione d’opuscoli scientifici ...” Bologna, 1817. Dr. Thomas Young’s “Course of Lectures,” Vol. II. pp. 432–433; N. K. Molitor’s “John Ingen-housz. Anfangsgrunde ...” 1781; Geo. Adams, “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. I. pp. 512–515; John Senebier, “Expériences,” etc., 1st and 2nd Memoirs, Genève and Paris, 1788; Becquerel in the Comptes Rendus for November 1850, also Tome XXXI. p. 633; M. Buff (Phil. Mag. N. S. Vol. VII. p. 122); Priestley’s “History ...” 1775, p. 487; Walsh at A.D. 1773; Cavallo’s “Exper. Philosophy,” 1803, Vol. III. p. 357; Pouillet (Poggendorff’s Annalen, Vol. XI. p. 430); Reiss, in Poggendorff’s Annalen, Vol. LXXIX. p. 288; G. F. Gardini, “De inflvxu ...” s. 7, p. 10; Philosophical Transactions for 1775, 1778, p. 1022; 1779, p. 537; Journal de Physique, Vol. XVI for 1780; “Erxleben’s phys. bibliothek,” s. 530; papers relative to the effects of electricity upon vegetation alluded to in “Le Moniteur Scientifique,” more particularly at pp. 904, 907, 1026, Vol. XX for 1878, and at p. 23, Vol. XXI for 1879.
A.D. 1780.—Spallanzani (Lazaro), celebrated Italian naturalist, to whom the French Republic vainly offered the Professorship of Natural History at the Paris Jardin des Plantes, and who has been already particularly alluded to in connection with John Walsh, at A.D. 1773, writes a second treatise upon the operations of Charles Bonnet, of Geneva, as regards the effects of electricity upon nerves and muscles. He is also the author of works upon electrical fishes as well as upon meteors, etc., which will be found detailed in Vol. VII of the “Biographie Médicale,” as well as at Vol. XLIII. p. 246, of the “Biographie Universelle.”