Bibliographical history of electricity & magnetism, chronologically arranged

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Cassini Family

This celebrated family, to which allusion was made under A.D. 1700, deserves here additional notice.

Giovanni Domenico Cassini (1625–1712), the first and greatest of the name, succeeded Buonaventura Cavaliéri in the astronomical chair of the Bologna University in 1650, and remained there until given the directorship of the Paris Royal Observatory upon its completion in 1670. Partly with the assistance of his learned nephew, James Philip Maraldi, Cassini made many important discoveries, among which may be signalled the finding of the first, second, third and fifth satellites of Saturn, as well as the dual character of that planet’s ring, the determination of the rotation of Jupiter, Mars and Venus, and the laws of the moon’s axial rotation. (See Thomson, “Hist. of the Roy. Soc.,” p. 331; “Anc. Mém. de Paris,” I, VIII, X; Thos. Morrell, “Elem. of the Hist. of Phil. and Sc.,” London, 1827, pp. 377–379.)

Jacques (James) Cassini (1677–1756), the only son of the preceding, became director of the Paris Observatory upon the death of his father, made many very important astronomical observations, and wrote several treatises upon electricity, etc. In one of his works, “De la Grandeur et de la Figure de la Terre,” Paris, 1720, he gives an account of the continuation of the measurement of Picard’s arc of the meridian from Paris northward, begun by Domenico Cassini and La Hire in 1680, and recommenced by Domenico and Jacques Cassini in 1700. (See “Mém. de Paris,” Vol. VII. pp. 455, 456, 508, 572; and for years 1705, pp. 8, 80; 1708, pp. 173, 292; 1729, Hist. I., Mem. 321.)

Cesar François Cassini de Thury (1714–1784), son of Jacques, whom he in turn succeeded at the Observatory, was, as above stated, the father of Jean Dominique Cassini (1747–1845). He made numerous researches while in the Director’s Chair, his most remarkable work being the large triangulation of France published in 1744, under the title of “La Méridienne,” etc. (See “Hist. de l’Acad. des Sciences de Paris” pour 1752, p. 10.)

A.D. 1783.—Robespierre (François-Maximilien-Joseph-Isidore de), who afterward became leader of the famous French Jacobin Club, and was at the time practising law in his native town of Arras, distinguishes himself by successfully defending the cause of the Sieur de Vissery de Boisvalé, a landed proprietor of that place, who had erected a lightning conductor on his house, “much to the scandal of the discreet citizens” of the locality—“Deistical philosophy; away with it!” (Eighth “Britannica,” Vol. XIX. p. 233).

Mr. de Boisvalé’s case was an appeal from a judgment delivered by the sheriff of Saint-Omer, ordering the destruction of the lightning conductor, and its printed report bears the following epigraph:

“L’usage appuyé sur les temps

Et les préjugés indociles.

Ne se retire qu’à pas lents

Devant les vérités utiles.”

Jean Paul Marat, docteur en médecine et médecin des Gardes de corps de M. le Comte d’Artois, who, like Robespierre, was a member of the French National Convention as well as a declared enemy of the Girondins, and who was killed by Charlotte Corday, July 13, 1793, made many electrical experiments. These greatly interested Benjamin Franklin, who used to visit him (Ninth “Encycl. Brit.,” Vol. XV. p. 526). He was the author of many electrical works during the years 1779–1784, notably “Découvertes sur le feu, l’électricité et la lumière,” “Recherches Physiques,” and a memoir on medical electricity (“Œuvres de Marat,” Paris, 1788; A. Bougeart, “Marat, l’ami du peuple,” 1864; F. Chevremont, “Jean Paul Marat,” 1881).

References.—Ronalds’ “Catalogue,” p. 434; La Lumière Electrique for Sept. 5, 1891; the Electrician, London, Sept. 11, 1891.

A.D. 1783.—Wilkinson (C. H.), Scotch physician, publishes at Edinburgh his “Tentamen Philosophico-medicum de Electricitate,” which is followed, during 1798 and 1799, by other works upon electricity, wherein he cites a number of marvellous cures of intermittent fevers similar to those made by Cavallo, also of amaurosis (goutte sereine) and of quinsy (squinancie) like those performed by Lovet, Becket and Mauduyt.

During the year 1804 appeared the first edition, in two volumes, of his “Elements of Galvanism in Theory and Practice,” containing a very comprehensive review of the discovery from the time of Galvani’s early experiments. In this last-named work, however, he shows that incipient amaurosis and the completely formed gutta serena have not yielded to his own treatment by galvanic influence as had been the case with Dr. C. J. C. Grapengieser, who published many accounts of surprising cures (Grapengieser, “Versuche den Galvanismus ...” Berlin, 1801 and 1802, or Brewer and Delaroche, “Essai ...” Paris, 1802). The whole of Chap. XXXVI is devoted to the application of galvanism to medicine, whereto allusion had already been made in the first chapter of the same work.

Wilkinson refers also to the electricity of the torpedo, and to the observations made thereon by Hippocrates, Plato, Theophrastus, Pliny and Ælian, also by Belon, Rondelet, Salviana and Gesner, as well as by Musschenbroek, Redi, Réaumur, Walsh, Hunter, Spallanzani, ’Sgravesande, Steno, Borelli, Galvani and others. Much space is likewise given to the observations recorded on animal electricity, notably by Fontana, De La Méthérie, Berlinghieri, Vassali-Eandi, Humboldt, Pfaff, Lehot, Hallé, Aldini, and to the experiments of Valli as they were repeated before the French Academy of Sciences and before the Royal Society of Medicine of Paris, in presence of M. Mauduyt. When treating of the powers of galvanism as a chemical agent, reference is made to the decomposition of water, thus first effected in 1795 by Creve, the discoverer of metallic irritation, and to the operations of Nicholson and Carlisle, Dr. Henry, Cruikshanks, Haldane, Henry Moyes, Richter, Gibbes, etc.

References.—J. J. Hemmer, “Commentat Palatinæ,” VI, Phys., p. 47; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 314, 330, 483, and Vol. II. p. 299; “Bibl. Britan.,” 1808, Vol. XXXVIII. p. 270 (Phil. Mag., No. 105); Annales de Chimie, Vol. LXXVIII. p. 247; Phil. Mag., Vol. XXIX. p. 243, and Vol. XLIX. p. 299; F. Buzzi, “Osservazione ... amaurosi ... elettricita,” Milano, 1783 (“Opus. Scelti,” Vol. VI. p. 359); Nicholson’s Journal, Vol. VIII. pp. 1, 70, 206; also Vol. X. pp. 30–32, for letter relative to certain erroneous observations of Mr. Wilkinson respecting galvanism, by Mr. Ra. Thicknesse, who also wrote in Vol. IX. pp. 120–122, explaining the production of the electric fluid by the galvanic pile.

A.D. 1783.—Saussure (Horace-Benedict de), Professor of Physics at the University of Geneva and founder of the Society for the Advancement of the Arts in the same city, is the inventor of an electrometer designed to ascertain the electrical state of the atmosphere, which will be found described in Vol. VIII. p. 619 of the 1855 “Encycl. Britannica.”

He observed that electricity is strongest in the open-air, that it is weak in streets, under trees, etc., and that during the summer and winter, by night as well as by day, when the atmosphere is free from clouds, the electricity of the air is always positive. In contradistinction, Mr. T. Ronayne found in Ireland that the electricity of the atmosphere is positive in winter when the air is clear, but that it diminishes in frosty or foggy weather and that he could detect no electricity in the air during summer except on the approach of fogs, when the electricity proved to be positive. During the year 1785, M. de Saussure observed at Geneva that, during the winter, the intensity of atmospherical electricity attained its first maximum at 9 a.m., diminishing from that hour until it reached its minimum at 6 p.m., after which it began to increase until attaining its second maximum at 8 p.m., diminishing gradually thereafter till it recorded its second minimum at 6 a.m. During the summer he found the electricity increasing from sunrise till between 3 and 4 p.m., when it would reach its maximum; after that it appeared to diminish till the dew fell, when it again became stronger, but was scarcely sensible during the night.

Sir David Brewster informs us in his able article on “Electricity” in the “Britannica” that De Saussure made a number of elaborate experiments on the electricity of evaporation and combustion. He observed at first that the electricity was sometimes positive and sometimes negative when water was evaporated from a heated crucible, but in his subsequent trials he found it to be always positive in an iron and in a copper crucible. In a silver, also in a porcelain crucible, the electricity was negative and the evaporation of both alcohol and of ether in a silver crucible also gave negative electricity. M. de Saussure made many fruitless attempts to obtain electricity from combustion, and he likewise failed in his efforts to procure it from evaporation without ebullition.

To De Saussure is often erroneously attributed the authorship of Lullin’s “Dissertatio physica de electricitate,” alluded to at A.D. 1766.

References.—De Saussure’s “Dissertatio de Igne,” “Exposition abrégée,” etc. (translated by Giuseppe Toaldo, in both his “Della maniera,” etc., and “Dei conduttori,” etc., Venezia, 1772 and 1778), “Voyage dans les Alpes,” all published at Geneva, 1759, 1771, 1779, also the important 1786 Neuchatel edition of the last-named work, more particularly at pp. 194, 197, 203, 205, 206, 211, 212, 216, 218, 219, 228, 252, 254 of Vol. II, and at pp. 197, 257 of Vol. IV; likewise his Memoirs relative to the electricity of the atmosphere, of vegetables, of microscopic animals, etc., etc., alluded to in Journal de Physique for 1773, 1784, 1788; in Journal de Paris for 1784, 1785; in Vol. I of Lazaro Spallanzani’s “Opuscoli di fisica,” etc., for 1776; in Vol. III of the “Opuscoli Scelti di Milano,” and in the Philosophical Transactions. See also Jean Senebier, “Mémoire historique,” etc., Genève, 1801; Louis Cotte in his “Traité,” etc., “Mémoires,” etc., “Observation,” etc., Paris, 1762, 1769, 1772; in the “Mémoires de Paris,” Année 1769, “Hist.,” p. 19; Année 1772, “Hist.,” p. 16, and in the Journal de Physique for 1783, Vol. XXIII; the experiments of MM. Becquerel and Brachet in Becquerel’s “Traité d’El. et de Magn.,” Paris, 1836, Vol. IV. p. 110; Theodor Ægidius von Heller, “Beobach d. Atmosphär. Elektricität.” (F. A. C. Gren, “Neues Journal der Physik” for 1797, Vol. IV); Faujas de St. Fond, “Description,” etc., Vol. II. p. 271, as per George Adams’ “Essay on Electricity,” London, 1799, p. 419; Noad, “Manual,” etc., London, 1859, p. 16; Poggendorff, Vol. II. p. 755; Rozier, XXXI. pp. 317, 374; XXXIV. p. 161; articles “Meteorology and Electricity” in the “Encyclopædia Britannica”; Thomas Young, “Course of Lectures,” etc., London, 1807, Vol. II. pp. 447, 466–471.

A.D. 1784.—Swinden (Jan Hendrik Van) (1746–1823), who had been made Professor in the University of Franequer at the early age of twenty (1767), and was at this time occupying the Chair of Natural Philosophy and Mathematics at Amsterdam, publishes in three volumes, at La Haye, his “Recueil de Mémoires sur l’Analogie de l’Electricité et du Magnétisme,” etc. (“De Analogia ...” in Vol. II of the “Neue Abhandl. der Baierischen Akad. Phil.”). The latter contains all the essays sent to the Electoral Academy of Bavaria on the subject—“Is There a Real and Physical Analogy Between Electric and Magnetic Forces; and, if Such Analogy Exist, in What Manner Do These Forces Act Upon the Animal Body?”

Van Swinden’s essay, which gained him one of the prizes, shows that, in his opinion, the similarity between electricity and magnetism amounts merely to an apparent resemblance, and does not constitute a real physical analogy. He infers from this that these two powers are essentially different and distinct from one another, but the contrary opinion was maintained by Profs. Steiglehuer and Hubner, who contended that so close an analogy as that exhibited by these two classes of phenomena indicated the effects of a single agent, varied only in consequence of a diversity of circumstances.

The eminent professor, Gerard Moll, of Utrecht, has communicated to the Edinburgh Journal of Science (1826, Vol. I. part ii. pp. 197–208) a biographical notice of Van Swinden, wherein he gives a list of the latter’s principal works and there speaks of one of his best-known productions in following manner: “The Positiones Physicæ (Opusc. Scelti, X. 7), as far as they are published (Harderovici, 1786, Vol. I and Vol. II. part i.), are allowed to rank among the best elements of natural philosophy, and have been found by actual experience to belong to the best sources from which the young student could draw his information on those parts of natural philosophy, and its general principles, as are contained in the first volume and part of the second, which is all that was published. The work itself is on a most extensive plan; and the multifarious avocations which crowded on Van Swinden in Amsterdam delayed the publications, and made him afterward abandon all thoughts of completing a work which would have done the greatest honour to its author, and which even now, unfinished as it is, is celebrated as an excellent specimen of sound reasoning and profound learning.”

Van Swinden was the first President of the Royal Institute of the Netherlands. He entered with ardour into all the new discoveries of his day and kept up an extensive correspondence with many of the leading scientific characters of the time, notably with the Swiss philosopher, Charles Bonnet (whose “Contemplations de la Nature” he annotated extensively); with Dr. Matthew Maty (who became secretary of the Royal Society upon the resignation of Dr. Birch in 1765, and who was appointed, by the king, principal librarian of the British Museum upon the death of Dr. Gowin Knight, 1772); with the eminent French physician, Michel-Augustin Thouret, Dean of the Paris “Faculté de Médecine”; as well as with Delambre, Euler, De Saussure, and many others who have been named elsewhere in this “Bibliographical History.”

The following is further extracted from Prof. Moll’s interesting paper: “Mr. Biot, in his treatise on Natural Philosophy (Tome III. p. 143) asserts that we are indebted to Cassini IV. (see Jean Dominique, Comte de Cassini, at A.D. 1782–1791) for much of what we know even about the diurnal variation of the needle. This, I think, is not fair. We do not mean to undervalue Mr. Cassini’s observations, but it is unquestionable that long before the publication of that philosopher’s work, Mr. Van Swinden had observed and published (‘Recherches sur les aiguilles aimantées et leurs variations’—Mémoires présentés à l’Académie des Sciences de Paris, Tome VIII—prize essay 1777) that which Mr. Biot less accurately is pleased to ascribe to his countryman. In this respect, however, Mr. Van Swinden was treated with more justice by other eminent philosophers, such as Haüy, Halley and Burkhardt.” (Consult also the “Acta Acad. Petrop.” for 1780, Part I. Hist. p. 10.)

In the afore-named very meritorious work, “Recueil de Mémoires,” etc., crowned by the Bavarian Academy, Van Swinden has treated fully of the then current theories relative to electrical and magnetical phenomena, reviewing the entire field of their application. In so doing he has necessarily made numerous references to discoverers and experimenters of all countries, the names of many of which appear in the present compilation, and while it is, of course, useless here to quote these anew, it has been thought best, for a record, to specify such as are infrequently met with, and which appear in many of his most important articles, even at the risk of being accused of diffuseness or prolixity. They are as follows:

References.—John T. Needham (Vol. IV, Mem. Brussels Acad. for 1783); Phil. Trans., 1746, p. 247; J. G. Lehmann (“Abhandlung von Phosph.”; “Von Magnet Theilen im Sande,” “Novi Com. Acad. Petrop.,” Vol. XII. p. 368, etc.); M. De La Cépède, “Essai sur l’El. nat et artif.”; C. E. Gellert (“Com. Acad. Petrop.,” Vol. XIII. p. 382, Exp. 15, 16); J. F. Henckel, “Pyritologia,” etc.; J. E. Von Herbert, “Theor. Phæn. Elect.,” cap. 4, prop. 8; C. F. M. Déchales, “Mundus Mathematicus,” lib. 1, Quartus Exper. Ordo., exp. 16, Tome II. p. 488, ed. 2, etc.; M. Marcel’s Dissertation on powdered magnets, which appears in the Dutch “Uitgezogte Verhandelingen,” Vol. I. p. 261, etc.; Jean M. Cadet (“Nova Acta. Physico. Med. Acad. Natur. Curios.,” Tome III); Abbé Giraud-Soulavie (“Comment. ... Œuvres de Mr. Hamilton,” note 4, p. 303); J. B. Le Roy (“Mém. de l’Acad. de Paris,” for 1753, p. 447; for 1772, p. 499; Jour. de Phys., Vol. II); Rudolph Richard (“Magazin d. Hamb.,” IV. p. 681); Gilles A. Bazin, “Descrip. des Cour, Mag.,” Plates 14, 16–18; J. F. Gross, “Elektrische Pausen,” Leipzig, 1776; Jour. de Phys., Vol. X. p. 235; Niccolo Bammacaro, “Tentamen de vi Electrica,” etc., s. 6; Samuel Colepress (Phil. Trans., 1667, No. 27, Vol. I. p. 502); E. F. Du Tour, “Discours sur l’aimant,” s. 27; “Recueil des Prix de l’Acad. de Paris,” Tome V. mém. ii. p. 49; “Mém. Math, et Phys.”; Mr. Calendrin, at Van Swinden’s, Vol. I. pp. 233, etc.; M. Blondeau (“Mém. de l’Acad. de Marine,” Brest., Tome I. s. 46, pp. 401–431, 438); J. A. Braun, “Observations,” etc.; “Novi. Comment. Acad. Petrop.,” Vol. VII. pp. 388, 407; M. Antheaulme (“Mém. sur les aimants artif.” (prize essay), 1760; “Mém. de l’Acad. Roy.,” 1761, p. 211; Van Swinden, 1784, Vol. II. pp. 95, 170); J. N. Reichenberger, “Directorium magneticum magneticis,” etc., and “Hydrotica,” as at Van Swinden, 1784, Vol. II. pp. 272–273; Geo. C. Schmidt, “Beschr., einer Elektrisir Masch.,” etc., 1778; M. De la Folie (Jour, de Phys., 1774, Vol. III. p. 9); Cölestin Steiglehner, “Obs. phaenom. elect.,” “Ueber die Annal der Elek. und des Magn.”; Lorenz Hubner, “Abh. u. d. Annal. u. mag. Kraft”; Jos. Thad. Klinkosch, “Schreiben,” etc., “Beschreib. d. Volta ... Elektrophors.” Reference should also be made to Noad, “Manual,” etc., p. 641; Encycl. Brit., 1857, Vol. XIV. p. 6; “Messager des Sciences et des Arts,” Gand, 1823, pp. 185–201, detailing all of Van Swinden’s works; Antoine Thillaye’s treatise presented to the Ecole de Médecine le 15 Floréal, An. XI; Butet (“Bull, des Sc. de la Soc. Philom.,” No. 43, Vendémiaire, An. IX).

A.D. 1784.—Cotugno (Domenico), Professor of Anatomy at Naples, thus addresses Le Chevalier G. Vivenzio under date October 2, 1784: “The observation which I mentioned some days ago, when we were discoursing together of the electrical animals, upon which I said I believed the mouse to be one of that number, is the following: Toward the latter end of March, I was sitting with a table before me and observing something to move about my foot, which drew my attention. Looking toward the floor I saw a small domestic mouse, which, as its coat indicated, must have been very young. As the little animal could not move very quick, I easily laid hold of it by the skin of the back and turned it upside down; then with a small knife that laid by me, I intended to dissect it. When I first made the incision into the epigastric region, the mouse was situated between the thumb and finger of my left hand, and its tail was got between the last two fingers. I had hardly cut through part of the skin of that region, when the mouse vibrated its tail between the fingers, and was so violently agitated against the third finger that, to my great astonishment, I felt a shock through my left arm as far as the neck, attended with an internal tremor, a painful sensation in the muscles of the arm, and such giddiness of the head, that, being affrighted, I dropped the mouse. The stupor of the arm lasted upward of a quarter of an hour, nor could I afterwards think of the incident without emotion. I had no idea that such an animal was electrical; but in this I had the positive proof of experience.” (See G. Vivenzio, “Teoria e pratica della elettricità med.” ... Napoli, 1784.)

Cotugno’s observations attracted much attention throughout Italy and gave rise to many experiments, notably by Vassalli, who, however, merely concluded from them that the animal’s body could retain accumulated electricity in some unaccountable manner.

References.—Essai sur l’histoire, etc., J. B. Biot, p. 9; Journal de Physique, XLI. p. 57; Mémoires Récréatifs, etc., par Robertson, Paris, 1840, Vol. I. p. 233; Cavallo, Electricity, London, 1795, Vol. III. p. 6; Izarn, Manuel, Paris, 1804, p. 4; Journal Encyclopédique de Bologne, 1786, No. 8; Poggendorff, Vol. I. p. 417; Sue, aîné “Hist. du Galv.,” Vol. I. pp. 1–2.

A.D. 1785.—Coulomb (Charles Augustin de), the founder of electro-statics and of the school of experimental physics in France, invents the torsion balance, with which he discovers the true law of electric and magnetic attractions and repulsions. Some have asserted that Lord Stanhope had previously established the law with regard to electricity, but it has not been seriously questioned that its extension to magnetism belongs exclusively to Coulomb. Johann Lamont (“Handbuch ...” p. 427) gives the credit of the latter discovery to Giovannantonio Della Bella, of Padua, who is mentioned by Poggendorff (“Biog.-Liter. Handwörterbuch,” Vol. I. p. 139) as the author of several works on electricity and magnetism, but the claim does not appear to be established upon any satisfactory foundation.

With his torsion balance, or rather electrometer, Coulomb measured the force by the amount of twist it gave to a long silken thread carrying a horizontal needle, constructed, preferably, of a filament of gum-lac or of straw covered with sealing-wax. From his experiments he concluded: That the attractive force of two small globes, one electrified positively and the other negatively, is in the inverse ratio of the squares of the distances of their centres, and that the repulsive force of two small globes, charged either with positive or negative electricity, is inversely as the squares of the distances of the centres of the globes (“Mém. de l’Acad. Roy. des Sciences,” 1784, 1785).

In one of his three memoirs to the French Academy during 1785, he states that a balance used by him was so delicate that each degree of the circle of torsion expressed a force of only one hundred-thousandth of an English grain, that another, suspended by a single fibre of silk four inches long, made a complete revolution with a force of one seventy-thousandth of a grain, and turned to the extent of a right angle when a stick of sealing-wax, which had been rubbed, was presented to it at the distance of a yard. It is said that a similar electrometer has been constructed in which the movement of one degree recorded a force not exceeding twenty-one million six-hundred-thousandths of a grain.

The many valuable experiments made by Coulomb on the dissipation of electricity and upon the distribution of electricity upon the surfaces of bodies are fully recorded in the able article of Sir David Brewster in the “Encyclopædia Britannica” (F. C. Achard, “Mém. de Berlin,” 1780, p. 47); M. Vernier, “De la dist. ... conducteurs,” Paris, 1824; J. L. F. Bertrand, “Programme d’une thèse ...” Paris, 1839; D. Bourdonnay, “Sur la dist. ... conducteurs,” Paris, 1840; Ed. A. Roche in “Montp. Acad. Sect. Sciences,” Vol. II. p. 115).

He discovered that shellac is the most perfect of all insulators, also that a thread of gum-lac insulates ten times better than a dry silken thread of the same length and diameter: and he established the law that the densities of electricity insulated by different lengths of fine cylindrical fibres, such as those of gum-lac, hair, silk, etc., vary as the square root of the lengths of the fibre.

Besides the communications above alluded to, Coulomb sent to the French Academy, during the years 1786, 1787, 1788 and 1789, many papers upon Electricity and Magnetism, and, up to within two years of his death (1806), he made many notable experiments, especially in magnetism, of which full accounts are given in several of the Mémoires noted at foot. The theory of the two magnetic fluids appeared in his 1789 paper. It is also in this same paper that Coulomb describes his improved method of making artificial magnets by employing compound magnets as first made use of by Gowin Knight and as explained at A.D. 1746. Still further improvements in these were brought about more particularly by the young Flemish scientist, Etienne Jean Van Geuns (1767–1795), by Jean Baptiste Biot (see A.D. 1803), and by the Rev. Dr. Scoresby during the year 1836.

Coulomb found that a steel wire is, by twisting, rendered capable of being nine times more strongly magnetized; that the magnetic power dwells on the surface of iron bodies and is independent of their mass; that the directive force of a magnetized bar reached its maximum when tempered to a bright cherry-red heat at 900 degrees, and that every substance is susceptible of magnetism to a degree of actual measurement. This last important research was communicated by him to the French Institute during the year 1802. His experiments proved that a grain of iron could communicate sensible magnetism to twenty pounds’ weight of another substance, and that when even beeswax had incorporated with it a portion of iron filings equal only to the one hundred-and-thirty-thousandth part of its weight it was yet sensibly affected by the magnet.

According to Dr. Thomas Young, Coulomb’s improvements in the theory of electricity may be considered as having immediately prepared the way for the elegant inventions of Volta and for the still more marvellous discoveries of Davy. Dr. Young gives reports of some of Coulomb’s experiments at p. 439, Vol. II of his “Course of Lectures” London, 1807 (“Journal of the Royal Institution” Vol. I. p. 134; “Décade Philosophique,” No. 21).

References.—“Mém. de l’Acad. Royale des Sciences,” Paris, 1784, p. 266; 1785, pp. 560, 569, 578, 612; 1786, p. 67; 1787, p. 421; 1788, p. 617; 1789, p. 455; “Mém. de l’Institut,” Vol. III. p. 176; Vol. IV. p. 565, and Vol. VI. for 1806; “Mém. de Math. et de Phys.” Vols. VIII and IX; “Mémoires de Coulomb,” Vol. I of the “Collection de Mémoires relatifs à la Physique,” Paris, 1884; “Cat. of Sc. Papers Roy. Soc.,” Vol. III. p. 73; “Abstracts of Papers of Roy. Soc.,” Vol. II. p. 402; “Bull. de la Soc. Philom.,” Nos. 3, 31, 61, 63, and for 1795, 1802; Journal de Physique, Vols. XLV (II), pp. 235, 448; LIV. pp. 240, 267, 454; LV. p. 450 (for Carradori’s report); Ch. N. A. De Haldat du Lys (“Mém. de Nancy” for 1841); Phil. Magazine, Vols. XI. p. 183; XII. p. 278; XIII. p. 401; XV. p. 186; Rozier, XXVII. p. 116; XLIII. p. 247; Gilbert, XI. pp. 254, 367; XII. p. 194; Dr. Young, “Course of Lectures,” London, 1807, Vol. I. pp. 682, 685, 686; “Royal Society Cat. of Sc. Papers,” Vol. II. p. 73; Eighth “Britannica,” Vol. XIV. pp. 37–38; Humboldt, “Cosmos,” 1859, Vol. V. p. 61; Schaffner, “Manual,” 1859, p. 56; Biot’s article in the “Biographie Universelle” and Biot’s “Traité de Physique,” Paris, 1816, Vols. II, III; Dr. Thomas Thomson, “Outline of the Sciences,” etc., London, 1830, pp. 350, 351, 379–422; Harris, “Rudim. Magn.,” Parts I, II. p. 56. See also description of the electrometer of Colardeau and the electro-micrometer of Delaunay, in the latter’s “Manuel,” etc., Paris, 1809, pp. 66, 76–80, and Plate V. fig. 61, as well as Libes’ “Dict. de Phys.,” Vol. I. p. 406.

A.D. 1785.—The Canon Gottoin de Coma, friend of Alessandro Volta, observes that an iron wire about thirty feet in length will give a sound under certain conditions of the atmosphere when stretched in the open air. The circumstances that accompany, as well as those that favour the production of the phenomenon, says Prescott, demonstrate that it must be attributed to the transmission of atmospheric electricity. This transmission does not occur in a continuous manner, like that of a current, but is observable by a series of discharges.

References.—Knight’s Mechanical Dictionary, 1876, Vol. III. p. 2515; Prescott’s “The Speaking Telephone,” etc., 1879, p. 122; Encyl. Britannica, 1860, Vol. XXI. p. 631.

A.D. 1785.—Marum (Martin Van), a Dutch electrician who had in 1776 taken the degree of M.D. at the Academy of Gröningen, constructs for the Teylerian Society at Haarlem, with the assistance of John Cuthbertson, an electrical machine said to be the most powerful theretofore made. According to Cavallo (Nat. Phil., 1825, Vol. II. p. 194) it consisted of two circular plates of French glass, each sixty-five inches in diameter, parallel with each other on a common axis, and about seven and a half inches apart. Each plate was excited by four rubbers, the prime conductor being divided into two branches which entered between the plates and, by means of points, collected the electric fluid from their inner surfaces only.

In Van Marum’s machine, the positive and negative electricity could only be obtained in succession, but Dr. Hare, of the University of Pennsylvania, remedied this by causing the plates to revolve horizontally. It is said the machine was so powerful that bodies at a distance of forty feet were sensibly affected; a single spark from it melted a leaf of gold and fired various kinds of combustibles; a thread became attracted at the distance of thirty-eight feet, and a pointed wire was tipped with a star of light at a distance of twenty-eight feet from the conductor.

Descriptions of his machines are given by Dr. Van Marum in letters to the Chevalier Marsiglio Landriani and to Dr. Ingen-housz, both printed in Haarlem during 1789 and 1791. The first quarto volume of Nicholson’s Journal also contains a reference thereto and gives (p. 83) the extract from a letter read June 24, 1773 (Phil. Trans., Vol. LXIII. pp. 333–339), addressed to Dr. Franklin, F.R.S., by John Merwin Nooth, M.D., who describes improvements by which machines are rendered effective in all kinds of weather. Nooth was the inventor of the silk flap, of which mention was made in the description of Cavallo’s machine (under A.D. 1775).

Van Marum also constructed a powerful battery, the metallic coatings of which were equal to 225 square feet, enabling him to give polarity to steel bars nine inches long, nearly half an inch wide and one-twelfth of an inch thick, as well as to sever a piece of boxwood four inches diameter and four inches long, and to melt three hundred inches of iron wire one hundred-and-fiftieth of an inch in diameter, or ten inches of one-fortieth of an inch in diameter. It is said that, during these experiments, the report was so loud as to stun the ears, and the flash so bright as to dazzle the sight.

Dr. Van Marum likewise made experiments upon the electricity developed during the melting and cooling of resinous bodies, which are detailed in the article “Electricity” 8th Edit. “Encyclopædia Britannica,” Vol. VIII. p. 565, and also upon the effects of electricity on animals and vegetables, which are given at pp. 49–51 of the article “Electricity” in the “Library of Useful Knowledge,” as well as in the 1855 Edit. “Encyclopædia Britannica,” Vol. VIII. pp. 602, 603.

In 1785 again Van Marum discovered that electric sparks, on passing through oxygen gas, gave rise to a peculiar sulphurous or electrical odour, which Cavallo called “electrified air,” and the presence of which Dr. John Davy, brother of Sir Humphry Davy, found the means of detecting.

During the month of October 1801 Volta wrote a letter to Van Marum asking him to make, in concert with Prof. C. H. Pfaff, of Kiel, several experiments on the electricity of the pile with the very powerful apparatus of the Teylerian Society. The extended researches of these two scientists are embodied in the Phil. Mag., Vol. XII. p. 161, as well as in the “Lettre à Volta” etc., published at Haarlem during 1802, and are likewise treated of in a very complete manner throughout Chaps. XVI and XXXII of Wilkinson’s well-known work on galvanism. Their united observations confirm the doctrine of Volta as to the identity of the current of the fluid put in motion by the voltaic pile and that to which an impulsion is given by an electrical machine. Thus is answered the question asked during May 1801 by the Haarlem Society of Sciences, viz. “Can the voltaic pile be explained in a satisfactory manner by the known laws and properties of electricity; or is it necessary to conclude the existence of a particular fluid, distinct from the one which is denominated electrical?” They also demonstrated that the current put in motion by the voltaic pile has an enormous celerity “which surpasses all that the imagination can conceive.” With a pile of one hundred and ten pairs of very large copper and zinc plates, they made experiments on the fusion of iron wires and ascertained the causes of the more considerable effects of large piles in the fusion and oxidation of metals, proving, among other facts, as Biot and Cuvier had already done, that a part of the oxygen is absorbed whether the operation be carried on in the open air or in vacuo (Biot and Cuvier, Soc. Philomathique, An. IX. p. 40; Annales de Chimie, Vol. XXXIX. p. 247).

Another of Van Marum’s experiments is related in a letter to M. Berthollet, wherein he says: “... I have succeeded in the decomposition of water, by means of the current of the electrical machine, provided with a plate of thirty-one inches diameter, constructed by me on a new plan (see the Journal de Physique for June, 1795).... I took a thermometrical tube, of the kind employed in making the most sensitive thermometers of Crawford and Hunter, for which purpose I had procured several of these tubes some time before in London. Its diameter interiorly was not more than the one-hundredth part of an inch; and I introduced into it an iron wire of the diameter of about the three-hundredth part of an inch, to the depth of about twelve inches. I now closed the end of my thermometrical tube with sealing wax in such a way that the extremity of the iron wire should scarcely project, and I placed the tube itself, by means of a cork, within a larger tube containing water. The rest of the apparatus was arranged in the customary manner. By directing the powerful current of the above-mentioned machine to this apparatus, the copper ball belonging to which, placed on the thermometrical tube, was at the distance of about three or four lines from the conductor, I succeeded in decomposing the water with a promptitude nearly equal to that which results from a voltaic pile of a hundred pairs of metallic plates.” This method of decomposing water is a very tedious one, and is in fact the result of an interrupted explosion, while the process of Dr. Wollaston (alluded to at A.D. 1801) is tranquil and progressive.

References.—“Biogr. Univ.,” Vol. XLII. p. 600; J. G. Heinze, “Neue elekt. versuche ...” Oldenberg, 1777; Tries’ claim to Van Marum’s machine in Rozier, XL. p. 116; Prieur’s extract in Annales de Chimie, Vol. XXV. p. 312; “Verhand. Genootsch. Rott.,” VI for 1781 and VIII for 1787; Journal de Physique, XXXI, 1787; XXXIII, 1788 (Marum en Troostwyk); XXXIV, 1789; XXXVIII, 1791; XL, 1792; “Journal du Galvanisme,” XI, Cahier, p. 187; “Journal des Savants” for August 1905; “Revue Scientifique,” Paris, April 8, 1905, pp. 428–429; Nicholson’s Journal for March 1799, Vol. II. p. 527; Harris, “Electricity,” pp. 62, 90, 171; Cuthbertson, “Practical Electricity,” London, 1807, pp. 166, 172, 197, 225; Cavallo, “Electricity,” 4th ed., Vol. II. p. 273; “Lib. of Useful Knowledge,” “Electricity,” p. 45; Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 106–128, 384; “Teyler’s Tweede Genootschap”; Gilbert, Annalen, I. pp. 239, 256; X. p. 121; Rozier, XXVII. pp. 148–155; XXXI. p. 343; XXXIV. p. 274; XXXVIII. pp. 109, 447; XL. p. 270; “Opus. Scelti,” IX. p. 41; XIV. p. 210.

A.D. 1785.—Sigaud de la Fond, Professor at the Collège d’Harcourt in Paris, publishes in the latter city his “Précis historique et expérimental des phénomènes electriques,” wherein he states having, as far back as 1756, made use of a circular plate machine provided with cushions and similar in shape to that which many claim to have originated with Ingen-housz and with Ramsden. (See A.D. 1779 and A.D. 1768.)

Sigaud de la Fond is also the author of “Description d’un Cabinet de Physique” (1784), “Cours de Physique,” etc. (1786), “Examen.,” etc. (1803) and of several treatises on medical electricity.

References.—“Journal de Physique,” Vol. II. 1773; Figuier, “Exposition et Histoire,” Paris, 1857, pp. 50, 74–76, 178; Poggendorff, Vol. II. p. 927.

A.D. 1785.—In the “Nachricht von einer neuen Elektrisirmaschine des Herrn Walkiers von Saint Amand,” the last named gives a description of the electrical machine presented by him in 1784 to the Belgian Academy of Sciences.

It is also described and outlined in Delaunay’s “Manuel” named below, but, although very powerful in its effects, cannot be made readily available in consequence of its huge dimensions. M. Caullet de Veaumorel suggested the feasibility of changing the cylinders from a horizontal to a vertical position.

References.—“Lichtenberg’s Mag.,” Vol. III. 1 st. p. 118; Delaunay, “Manuel,” etc., 1809, pp. 14–16.

A.D. 1785.—Adams (George), mathematical instrument maker to his Majesty, writes an enlarged edition of his “Essay on Electricity,” etc., which first appeared the year previous and wherein, as its full title indicates, he endeavours to explain the theory and practice of that science and the mode of applying it to medical purposes. He illustrates many experiments and gives an Essay on Magnetism, in the treatment of which latter he acknowledges the valuable aid of Dr. J. Lorimer.

The fifth and last edition of the “Essay,” which was issued by William Jones in 1799, four years after Adams’ death, contains a communication on the subject of Medical Electricity by John Birch, the author of “Della Forza dell’ Elettricita,” etc., Napoli, 1778.

At p. 86 of the 1799 “Essay,” etc., Adams relates that, while M. Loammi Baldwin (“Memoirs of Amer. Acad.,” Vol. I. p. 257) held the cord of his kite during the approach of a thunderstorm, he “observed himself to be surrounded by a rare medium of fire, which, as the cloud rose nearer the zenith, and the kite rose higher, continued to extend itself with some gentle faint flashes.” At pp. 137, 186 and 222, he alludes to “A. Brook’s Miscellaneous Experiments and Remarks on Electricity,” etc., as well as to the Rev. John Lyon’s “Experiments and Observations of Electricity,” and refers to the “Journal of Natural Philosophy” (Vol. II. p. 438) for Nicholson’s experiments on the plus and minus of electricity.

A.D. 1785.—La Méthérie (Jean Claude de), French physicist naturalist, becomes sole editor of the “Journal de Physique, de chimie et d’histoire naturelle,” and publishes in Paris his “Essai Analytique,” etc., wherein amongst other observations he asserts that the electric spark results from the combination of oxygen with hydrogen.

He considers that all bodies exist in an electrical or magnetical condition, that we are only a temporary aggregation of molecules of matter governed in different ways by nature’s laws, and that excitability is produced by galvanic action resulting from the superposition of nervous and muscular fibres.

He is also the author of very interesting treatises on animal electricity communicated to the Journal de Physique (Vol. XLII. pp. 252, 255, 292), and of which an account is given in Sue’s “Histoire du Galvanisme,” Paris, 1802, Vol. I. pp. 64–68. The last-named work also gives, at p. 80, an account of the letter on “Galvanism” sent to M. De La Méthérie by M. Leopold Vacca-Berlinghieri (Journal de Physique, Vol. XLI. p. 314).

References.—“Biographie Générale,” Vol. XXIX. p. 209; Rozier, XLI. p. 437; Delaunay, “Manuel,” etc., 1809, p. 15, also Delaunay’s letter in Phil. Mag., Vol. XXVII. p. 260; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Vol. I. p. 62; Vol. II. p. 9; “Opus. Scelti,” XXI. p. 373; Journal de Physique et Chimie (of which La Méthérie remained editor up to the time of his death, during 1817), Vols. LIII, LIV, Pluviose, An. XI. p. 161; also p. 157 for letter sent him by Giuseppe Izarn; Ann. di Chim. di Brugnatelli, Vol. XIX. p. 156; Aubert, “Elektrometische Flasche,” Paris, 1789.

A.D. 1785.—According to Prof. Tyndall, George Cadogan Morgan sought to produce the electric spark in the interior of solid bodies. He inserted two wires into wood and caused the spark to pass between them; the wood was illuminated with blood-red light or with yellow light according as the depth at which the spark was produced proved greater or less. The spark shown within an ivory ball, an orange, an apple, or under the thumb, illuminates these bodies throughout. A lemon is especially suited to this experiment, flashing forth, at every spark, as a spheroid of very brilliant golden light, and a row of eggs is also brilliantly illuminated throughout, at the passage of every spark from a Leyden jar. Morgan likewise made several experiments to ascertain the influence of electricity on the animal functions. These are alluded to at p. 602, Vol. VIII of the 1855 “Britannica,” and at p. 49 of “Electricity” in the “Library of Useful Knowledge.”

This George Cadogan Morgan (1754–1798) was an English physician and also a Professor of Natural Philosophy at Hackney, in an establishment founded by his uncle, Dr. Price. His “Lectures on Electricity” appeared in Norwich during the year 1794. In the second volume he describes (pp. 225–236) “the form, noise, colours and devastation of the electric flash,” and treats (pp. 383–397) of the “relation of the electric fluid to vegetation,” alluding more particularly to the experiments of Maimbray, Nollet, Achard, Duvernier, Ingen-housz, Van Breda, Dr. Carmoy and the Abbé d’Ormoy. He likewise gives an account of the northern lights, as well as descriptions of Bennet’s movable doubler and electroscope, and of Lane’s electrometer.

References.—Morgan’s biography in Larousse, “Dict. Universel,” Tome XI. p. 562, and in “Biog. Générale,” Tome XXXVI. p. 570; “Bibl. Britan.” An. VII. vol. ii. pp. 129, 223, and Vol. XII. p. 3.

A.D. 1786.—Rittenhouse (David), an American physicist and astronomer who afterward became F.R.S. and succeeded Dr. Franklin as President of the Am. Philos. Soc., publishes his theory of magnetism in a letter to John Page at Williamsburg, which is reproduced at folio 178 of Vol. II, old series, of the Transactions of the above-named Society.

“Were we called upon,” says Renwick, “to assign him a rank among the philosophers whom America has produced, we should place him, in point of scientific merit, as second to Franklin alone.”

References.—“Trans. Am. Phil. Soc.,” Vol. II, O.S., pp. 173, 175, for Page and Rittenhouse, and Vol. III. for Rittenhouse and Jones, as well as Rittenhouse and Hopkinson, upon “Meteors and Lightning.”

A.D. 1786.—Galvani (Aloysio or Luigi), an Italian physician, who, at the age of twenty-five, was Professor of Anatomy at the University of Bologna, is led to the discovery of that important branch of electricity which bears his name. The manuscript giving the result of his experiments upon the Electricity of Metals is dated Sept. 20, 1786.

From papers in the “Bolognese Transactions” noted below, it would appear that he had, even before the year 1780, made many observations on the muscular contraction of frogs by electrical agency. Upon one occasion his wife happened to be holding a scalpel against the dissected legs and parts of the spine of a frog, which lay in close proximity to the conductor of an electrical machine recently charged by one of Galvani’s pupils. She noticed that whenever the dissecting knife touched the muscles they were violently convulsed, and, upon communicating the fact to her husband, he repeated and extended the experiment and found it necessary to pass the electric fluid through a metallic substance in order to develop the result originally observed. At first the frogs had been hung upon a copper hook fastened to an iron railing, but he afterward substituted an arc composed of both metals and with which he could readily produce the same results as were obtainable with an electrical machine.

Galvani also made experiments to ascertain the effect of atmospheric electricity upon the nerves of frogs. He connected the latter with rods leading to lightning conductors erected upon the roof of his house, attaching also ground wires to the legs of the animals, and found that the same convulsions appeared whenever lightning was seen and likewise when heavy storm clouds passed over the house.

The results of his many interesting observations were first made public in the celebrated work entitled “Aloysii Galvani de viribus electricitatis in motu musculari. Commentarius: cum Aldini dissertatione et notis,” which appeared during 1791–1792. Therein, he expresses the belief that the bodies of animals possess a peculiar kind of electricity by which motion is communicated through both nerve and muscle, positive electricity going to the nerve, while negative electricity goes to the muscle, and that the muscles represent the exterior and the nerves the interior of the Leyden jar, the discharge being similarly produced by the metal which communicates with both.

Galvani’s singular experiments naturally attracted everywhere the attention of philosophers, by whom they were repeated and varied, but by none were they more assiduously prosecuted than by Volta, who was then a Professor at the Pavia University, and who, as already indicated, was led by them to the discovery of the voltaic pile and of voltaic or galvanic electricity.

The announcement of Galvani’s observations was made in Germany, notably by J. F. Ackermann (“Medicinisch-chirurgische Zeitung”), by M. Er (“Physiologische Darstellung der Lebenskräfte”), by M. Smuck (“Beiträge zur weiteren Kenntniss,” etc.), and by F. A. C. Gren (“Journal der Physik,” Vols. VI, VII and VIII), while experiments were continued upon an extensive scale by the Italians F. Fontana, Carlo Francesco Bellingeri, M. Giulio and F. Rossi, as well as by Samuel T. Von Sömmering, by Wilhelm Behrends and by Karl Friedrich Kielmayer (Kielmaier), Professor of Medicine at the Tübingen University (Poggendorff, Vol. I. p. 1253). For the curious galvanic experiments of the celebrated French physician Larrey, and of Stark, Richerand, Dupuytren and Dumas, see “Bulletin des Sciences de la Société Philomathique,” 1793, Nos. 23, 24, and “Principes de Physiologie,” Vol. II. p. 312.

References.—C. Alibert, “Eloges Historiques de Galvani, Spallanzani, Roussel et Bichat ...” Paris and Bologna, 1802–1806 (“Mém. de la Soc. d’Emul. de Paris,” Vol. IV; S. Gherardi, “Rapporto sui Manoscrotti,” Bologna, 1840, p. 19); Poggendorff, Vol. I. p. 839; Thomas Thomson, “History of the Royal Society,” London, 1812, pp. 450, etc.; Thomas Young, “Course of Lectures,” London, 1807, Vol. II; “Bolognese Transactions” for papers dated April 9, 1772, April 22, 1773 and Jan. 20, 1774; Sabine, “El. Tel.,” 1872, pp. 16–18; Knight’s “Mech. Dict.,” Vol. II. pp. 936, 937, for extract from report of Nat. Inst. of France, July 4, 1798; “Johnson’s Encyclop.,” 1877, Vol. I. p. 1510; Bakewell’s “Electricity,” p. 26; “Encyclop. Britannica,” 1855, Vol. VIII. p. 530, and Vol. XXI. pp. 609, etc.; Fahie’s “History,” etc., 1884, pp. 180–185; Phil. Trans., 1793; Miller, “History Philos. Illustrated,” London, 1849, Vol. IV. p. 333; Thomson, “Hist. of Chemistry,” Vol. II. pp. 251, 252; Matteucci, “Traité des phénomènes,” etc., Part I. p. 7; the Address of M. Gavarret made in 1848 before the Paris Medical Faculty; J. C. I. A. Creve’s treatise on Galvanism (“Jour. de la Soc. de Méd.,” Vol. XVIII. p. 216); “Mém. de la Soc. Méd. d’Emul.,” Vol. I. p. 236); Biot et Cuvier (Ann. de Ch., Vol. XXXIX. p. 247); A. Richerand (“Mém. de la Soc. Méd. d’Em.” Vol. III. p. 311); “Opus. Scelt.,” Vol. XV. p. 113; “Giornale Fis. Med.,” Vol. II. pp. 115, 131 (letter of B. Carminati); Marsiglio Landriani, “Lettera,” etc., 1776; Lettre d’un ami au Comte Prosper Albo (“Bibl. de Turin,” 1792, Vol. I. p. 261; Jour. de Phys., Tome XLI. P. 57); “Comment Bonon. Scient.,” Vol. VII. p. 363; account of the experiments made by MM. Cortambert and Gaillard, reported in “Mém. de la Soc. Méd. d’Em.,” Vol. I. pp. 232, 235; G. Klein’s “Dissert. de Métal,” etc., Maintz, 1794; Ostwald’s Klassiker, No. 52, p. 4; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 Vols. passim; Wm. C. Wells, “Obs. on the Influence,” etc. (Phil. Trans., 1795, Pt. XI. p. 246); E. G. Robertson (An. de Ch., 1801, Vol. XXXVII. p. 132; Jour. de Paris, 10, 15 and 17 Fructidor de l’An. VIII); Paul Louis Simon, “Beschreibung neuengalvanisch,” etc., “Resultate,” etc., and “Versuche,” etc., all published in 1801 (L. W. Gilbert’s Annalen, 1801, Book V, An. de Chimie, No. 121, p. 106); L. W. Gilbert’s Book VI of the Annalen, containing the “Memoirs on Galvanism,” by J. L. Boeckmann, L. A. von Arnim, Paul Erman, M. Gruner and C. H. Pfaff; C. Dupuytren, “Faits Particuliers,” etc., 1801; J. B. Trommsdorff, “Expér. Galv.,” 1801; M. Rouppe’s letter of Aug. 28, 1801, in Van Mons’ Jour. de Ch., Vol. I. pp. 106, 108; M. Bichat (Sue, “Hist. du Galv.,” II. p. 216); A. M. Vassalli-Eandi (Jour. de Phys., Frimaire, An. X. p. 476); C. F. Hellwag and M. Jacobi fils, “Erfahrungen,” etc., 1802; M. le Comte de Pusckin’s experiments on Galvanism, made Sept. and Dec. 1801, with a colonne tournante (Sue, “Hist. du Galv.,” Vol. II. pp. 257, 258); Al. Volta, in Jour. de Leipzig, and in “Comment ... Med. gestis,” 1792; Johann Mayer, “Abh. ... Galvani, Valli, Carminati u. Volta ...” Prag, 1793); Junoblowiskiana Society (“Comment ... Med. gestis,” 1793); “Imperial Dictionary of Universal Biography,” Wm. McKenzie London, n. d., Vol. II. p. 546; M. Cortambert (“Mém ... Soc. ... d’Emul.,” I. p. 232); M. Payssé (“Jour. de la Soc. des Pharm.,” first year, p. 100); Geo. Couvier (Jour. de Physique, Vol. VII. p. 318; “Mém. des Soc. Sav. et Lit.,” Vol. I. p. 132), 1801; C. Mathieu (“Rec. de la Soc. d’Agr. ... d’Autun,” An. X. p. 21), 1802; Ponton d’Amécourt, “Exposé du Galvanisme,” Paris, 1803; Joseph Weber’s works, published in 1802–1803, 1815, 1816, and those of J. K. F. Hauff, Marburg and Leipzig, 1803, 1804; M. Curtet (Jour. de Van Mons., No. VI. p. 272; Jour. de Physique, An. XI. p. 54), 1803; William Meade (“On the origin and progress of Galvanism”), Dublin, 1805; J. C. Reil (Jour. de Van Mons., No. IV. p. 104; Sue, “Hist. du Galv.,” Vol. IV. p. 26); J. A. Heidmann (Phil. Mag., Vol. XXVIII. p. 97), 1807; Sir Richard Phillips, “Electricity and Galvanism explained ...” (Phil. Mag., Vol. LVI. p. 195), London, 1820; B. G. Sage, “Recherches ... Galvanisme”; Leopold Nobili, “Sur le courant....” Genève, 1827.

A.D. 1786.—Hemmer (J. J.), celebrated physician and secretary of the Meteor. Society of Mannheim, gives, in the “Transactions of the Electoral Society,” an account of what have been pronounced the most complete series of experiments ever made upon the electricity of the human body. They absolutely show that the human subject possesses no species of electrical organs which are under the regulation of the will. Of his many observations, the following are worth recording: He found that the electricity of the body is common to all ages and sexes; that its intensity and character often vary in the same body (in 2422 experiments, it was 1252 times positive, 771 times negative and 399 times imperceptible); that the electricity of the body is naturally positive, it being always so when subject to no violent exertion, and that when the body is subjected to sudden or violent motion the electricity becomes negative, the case also when the body experiences either cold or extreme lassitude.

References.—“Encycl. Brit.,” Vol. VIII, 1855, p. 571; “Rheinische Beiträgen zur Gelehrsamkeit” for 1781, Fifth Book, pp. 428–466; Van Swinden, “Recueil,” etc., La Haye, 1784, Vols. I and II passim; “Observ. sur la Phys.,” July, 1780; Phil. Mag., 1799, Vol. V. pp. 1, 140; “Comment. Acad. Theod.-Palat.,” Vols. IV, V and VI of Phys.; “Mém. de l’Acad. de Mannheim,” Vol. IV; “Pfalzbayr. Beiträge” for 1782.

A.D. 1787.—Lomond—Lomont—(Claude Jean-Baptiste), a very capable French machinist, and “one who has a genius for invention,” is the first to introduce a successful electric telegraph consisting of but one wire. Of this the following account appears under date Oct. 16, 1787, in Arthur Young’s “Voyage Agronomique en France” (“Travels”), fourth edition, Vol. I. p. 79: “You write two or three words on a paper; he takes it with him into an adjoining room and turns a machine in a cylinder case, on the top of which is an electrometer having a pretty little ball of pith of a quill suspended by a silk thread; a brass wire connects it to a similar cylinder and electrometer in a distant apartment, and his wife, on observing the movements of the corresponding ball, writes the words which it indicates. From this it appears that he (Lomond) has made an alphabet of motions. As the length of the brass wire makes no difference in the effect, you could correspond with it at a great distance, as, for example, with a besieged city or for objects of much more importance. Whatever be the use that shall be made of it, the discovery is an admirable one.”

References.—Ed. Highton, “Elec. Tel.,” 1852, p. 38; Sabine, “Elec. Tel.,” pp. 10–11; Shaffner, “Manual,” pp. 132, 133; Vail’s “History,” etc., p. 121; “Appleton’s Encycl.,” 1871, Vol. XV. p. 335.

A.D. 1787.—Brard (Cyprien Prosper), French mineralogist, first observes that some crystals of axinite (consisting mainly of silica, alumina, lime and peroxide of iron) become electric by heat.

References.—Gmelin, article “Electricity,” etc., Vol. I. p. 319; Larousse, “Dict. Univ.,” Vol. II. p. 1205; Thomas, “Dict. of Biog.,” Vol. I. p. 429; “Enc. Brit.,” 8th ed., Vol. VIII. p. 530; Brard, “Manuel du Minéralogiste,” etc., Bordeaux Academy of Sciences Report for 1829, p. 39, and for 1838, p. 84—the latter containing M. Hatchett’s observations on one of M. Brard’s meteorolites.

A.D. 1787.—Haüy (Le Père René Just), native of Picardie and member of the Académie Royale des Sciences, publishes an abridgment of the doctrines of Æpinus (at A.D. 1759) under the title of “Exposition raisonnée de la Théorie de l’Électricité et du Magnétisme.” He was doubtless the first to observe that in all minerals the pyro-electric state has an important connection with the want of symmetry of the crystals, and no proof of the extent to which he directed his investigations in that line can more readily be had than by consulting general “Encyclopædia” articles relative to the pyro-electricity of boracite (borate of magnesia), of prehnite (silica, alumina and lime), of mesotype (hydrated silicate of alumina and of lime or of soda), of sphene (silica, titanic acid and lime), calamine (silicate of zinc) and of Siberian topaz.

At pp. 480, 481 of his “Outline of the Sciences,” etc., London, 1830, Dr. Thomas Thomson states:

“There is a hill of sulphate of lime, called Kalkberg, situated near Lunebourg, in the duchy of Brunswick, in which small cubic crystals are found. These cubes are white, have a specific gravity of 2·566, and are composed of two atoms of boracic acid combined with one atom of magnesia. They are distinguished among mineralogists by the name of boracite. If we examine the cubic crystals of boracite, we shall find that only four of the solid angles are complete, constituting alternate angles placed at the extremity of two opposite diagonals at the upper and lower surface of the cube. The other four solid angles are replaced by small equilateral triangles. When the boracite is heated all the perfect solid angles become charged with negative electricity, while all the angles replaced by equilateral triangles become charged with positive electricity. So that the boracite has eight poles: four positive and four negative. Those are obviously the extremities of four diagonals connecting the solid angles with each other. One extremity of each of these diagonals is charged with positive and the other extremity with negative electricity. In general, the electricity of boracite is not so strong as that of the tourmaline.” This curious law of the excitability of the boracite and of its eight poles was discovered by Haüy in 1791 (Haüy’s “Minéralogie,” 260, second edition).

Axinite, mesotype, and the silicate of zinc are also minerals which become electric when heated, and which, like the tourmaline, exhibit two opposite poles, the one positive, the other negative. It is not every crystal of axinite and mesotype which possesses this property, but such only as are unsymmetrical, that is to say, such as have extremities of different shapes. No doubt this remark applies also to the silicate of zinc; though as the crystals of that mineral are usually acicular it is not so easy to determine by observation the degree of symmetry which they may possess.

The topaz, prehnite, and the titaniferous mineral called sphene are also capable of being excited by heat, and have two opposite poles like those already mentioned.

Haüy also made the most extensive and accurate observations known upon the development of electricity in minerals by friction. Detailed lists of the different classes of minerals, as well as the conclusions arrived at through various experiments, are given in the “Encyclopedia Britannica,” Vol. VIII, 1855, pp. 538, 539, while at pp. 529 and 558 of the same work are to be found accounts of his observations on the electricity of the tourmaline, as well as a description of the different electroscopes employed in his many experiments.

References.—Priestley, “History of Electricity,” 1767, pp. 314–326; Gmelin’s “Chemistry,” Vol. I. p. 319; Noad, “Manual,” pp. 27–31; also article “Electricity” in “Library Useful Knowledge,” pp. 3, 54, 56; M. Lister, “Collection Académique,” Tome VI; “Société Philomathique,” An. V. p. 34; An. XII. p. 191; “Mém. du Museum d’Hist. Nat.,” Vol. III; “Mém. de l’lnstitut,” An. IV. tome i., “Sciences Math. et Phys.” p. 49; “Mém. de l’Académie,” 1785, Mem. p. 206; Philosophical Magazine, Vols. XX. p. 120; XXXVIII. p. 81; Thomas Thomson, “Hist. of the Roy. Soc.,” London, 1812, pp. 180, etc.; Young’s “Lectures,” London, 1807, Vol. II; Haüy, “Traité Élémentaire de Physique,” Chap VII, “Magnetism”; Experiments of J. L. Treméry (author of “Observations sur les Aimants Elliptiques,” recorded in Journal des Mines, Vol. VI for 1797, also in Jour. de Phys., Vols. XLVIII and LIV) and of M. De Nelis, some of whose observations are given in the Phil. Mag., Vol. XLVIII. p. 127, and in the Jour. de Phys., Vols. LXI. p. 45; LXII. p. 150; LXIII. p. 147; LXIV. p. 130; LXVI. pp. 336, 456, as shown and illustrated at pp. 153–162 of Delaunay’s “Manuel,” etc., of 1809; “Séances de l’Acad. de Bordeaux” for 1835, giving M. Vallot’s report on the difference existing between the chalcedony and the tourmaline. Regarding the latter, consult S. Rinmann (“K. Schwed. Akad. Abh.,” XXVIII. pp. 46, 114); C. Rammelsberg, “Die Zuzam ... und Feldspaths”; Mr. Magellan’s edition of Cronstedt’s Mineralogy for Steigliz’s tourmaline; Cesare G. Pozzi, on the tourmaline; H. Von Meyer (“Archiv. ... Ges. Natural,” XIV. 3, p. 342); M. Lechman (Berlin Academy Reports); Carl Von Linné (Linnæus), “Flora Zeylanica,” Stockholm, 1747; M. Leymerie (Toulouse Acad. Reports); Brewster, “Journal” I. p. 208; J. K. Wilcke (“Vetensk. Akad. Handl.,” 1766 and 1768); Jos. Muller, “Schreiben ... Tourmaline,” Wien, 1773; F. J. Muller von Reichenstein, “Nachr. ... an Born,” Wien, 1778; H. B. de Saussure (“Jour. de Paris”), 1784; Louis Delaunay’s letter on the tourmaline, 1782; D. G. Fischer’s works, published at Mosk, 1813, 1818; J. D. Forbes (“Edin. Trans.,” Vol. XIII), 1834.

A.D. 1787.—Charles (Jacques Alexandre César), a singularly able French physicist and experimentalist, who became the Secretary of the Académie des Sciences, relates many of his electrical experiments in the thirtieth volume of the Journal de Physique.

He was one of the first to study and develop the theories of Franklin, who, in company with Volta, frequently attended the brilliant lectures which Charles was enabled to give in what was then considered the most complete philosophical laboratory of Europe. In many of his experiments on atmospherical electricity, Charles has been known to produce thousands of sparks, beams or flashes, which exceeded 12 feet in length and which made reports similar to those of fire-arms. The French Academy endorsed the opinion given the Minister of War by Charles to the effect that “a conductor will effectually protect a circular space whose radius is twice the length of the rod.”

Charles invented the megascope and was the first to make an ascension in a hydrogen balloon, which he did in company with M. Robert on the 1st of December (not on the 2nd of August) 1783, ten days after the first trip made by Pilatre de Rozier and Comte d’Arlandes in a Montgolfière from the Paris Bois de Boulogne.

References.—“Biographie Générale,” Vol. IX. pp. 929–933; Larousse, “Dict. Univ.,” Vol. III. p. 1020; Journal de Physique for 1791, p. 63; “Mémoires de l’Acad. des Sciences” for 1828; George Adams, “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. III. pp. 462–464; Edin. Encycl., 1813, article “Aeronautics,” Vol. I. p. 160, “Franklin in France,” 1888, Part II. pp. 256, 270, 276–280; M. Veau Delaunay, Introduction to his “Manuel,” etc., Paris, 1809, pp. 19, 25 and 61–63; also pp. 23, 68, 92, 96, 122, 176 and 214.

A.D. 1787.—Mann (Théodore Augustin), Abbé, Flemish writer and antiquary, becomes perpetual secretary of the Brussels Academy of Sciences ten years after leaving the Nieuport Monastery (1777), and is charged with the duty of making meteorological observations, which are regularly transmitted to the Mannheim Academy officials, who receive similar reports regularly from different parts of Europe and publish them under the title of “Ephémérides Météorologiques.”

His many investigations made with electrical machines are embraced in the last-named publication and are also alluded to in his “Marées Aériennes,” etc., which appeared in Brussels during the year 1792.

References.—“Biog. Générale,” Tome XXXIII. p. 231; Larousse, “Dict. Universel,” Tome X. p. 1085; Phil. Mag., Vol. IV. p. 337; “Comm. Ac. Theod. Pal.,” 1790, Vol. VI. p. 82.

A.D. 1787.—Bennet (Rev. Abraham), F.R.S., first describes in the Philosophical Transactions for this year, pp. 26–32, the gold-leaf electroscope which bears his name and which is considered the most sensitive and the most important of all known instruments for detecting the presence of electricity. It consists of a glass cylinder which is covered with a projecting brass cap, made flat in order to receive upon it whatever article or substance is to be electrified, and having an opening for the insertion of wires and of a metallic point to collect the electricity of the atmosphere. The interior of the cap holds a tube which carries two strips of gold leaf in lieu of the customary wires or threads, and upon two opposite sides of the interior of the cylinder are pasted two pieces of tinfoil directly facing the gold-leaf strips. The cap is turned around until the strips hang parallel to the pieces of tinfoil, so that any electricity present will cause the strips to diverge and make them strike the tinfoil, which will carry the electricity through the support of the cylinder to the ground.

This electroscope, says Wilkinson, possesses great sensibility, and through the movable coatings introduced by Mr. Pepys, very small portions of electricity are discernible. Another very excellent electroscope is formed with either extremely fine silver thread, prepared after the manner of Mr. Read, or with the minutest thread found in a bundle of very fine flax, having a little isinglass glue applied gently over it with the finger and thumb.

Of the numerous observations made by Bennet, the following interesting extract relative to the phenomenon of evaporation is taken from the Philosophical Transactions for the year 1787. “If a metal cup with a red hot coal in it be placed upon the cap of a gold leaf electroscope, a spoonful of water thrown in electrifies the cup resinously; and if a bent wire be placed in the cup with a piece of paper fastened to it to increase its surface, the vitreous electricity of the ascending column of vapour may be seen by introducing the paper into it. The experiments on the evaporation of water may be tried with more ease and certainty of success by heating the small end of a tobacco pipe and pouring water into the head, which, running down to the heated part, is suddenly expanded, and will show its electricity when projected upon the cap of the electrometer more sensibly than any other way that I have tried. If the pipe be fixed in a cloven stick and placed in the cup of one electrometer while the steam is projected upon another, it produces both electricities at once.”

Some of Mr. Bennet’s experiments with the electroscope on the electricity of sifted powders, upon the electricity of the atmosphere, etc., are recorded at pp. 564 and 566 of the “Britannica,” Vol. VIII, and at p. 56 of “Library of Useful Knowledge.”

Mr. Bennet also invented the electrical doubler, designed to increase small quantities of electricity by continually doubling them until visible in sparks or until the common electrometer indicates their presence and quality (Phil. Trans. for 1787, p. 288). It consists of three plates of brass, illustrated and explained at Fig. 9, p. 20, Vol. I of Prescott’s “Electricity and the Electric Telegraph,” 1885 edition, wherein it is stated that in forty seconds the electricity can thus, by continual duplication, be augmented five hundred thousand times. (See, for doublers, C. B. Désormes and J. N. P. Hachette, in Annales de Chimie, Vol. XLIX for 1804; J. Read (Phil. Trans. for 1794, p. 266); Sir Francis Ronalds (Edin. “Phil. Journal,” Vol. IX. pp. 323–325).)

At p. 105 of his “Rudim. Magnetism,” Snow Harris mentions the fact that, in some of his experiments, Mr. Bennet employed a magnetic needle suspended by filaments of a spider’s web as a magnetometer. In this connection, it may be said that, in the Philosophical Transactions for 1792, the assertion is made that a fine, and weakly magnetic steel wire suspended from a spider’s thread of three inches in length will admit of being twisted around eighteen thousand times and yet continue to point accurately in the meridian, so little is the thread sensible of torsion (Young’s “Course of Lectures,” 1807, Vol. II. p. 445). The use of the spider’s line had, during the year 1775, been recommended as a substitute for wires by Gregorio Fontana, who, it is said, obtained threads as fine as the eight-thousandth part of a line. In a lecture delivered at Boston, Mass., during the year 1884, Prof. Wood alluded to spiders’ threads estimated to be one two-millionths of a hair in thickness.

References.—Bennet, “New Experiments on Electricity,” etc., Derby, 1789, and “A New Suspension of the Magnetic Needle,” etc., London, 1792; Introduction to “Electrical Researches,” by Lord Henry Cavendish; Sc. Am. Supplement, No. 647, pp. 10, 327; Noad, “Manual,” p. 27; Cavallo, “Nat. Phil.,” 1825, Vol. II. pp. 199, 216; Phil. Trans., Vol. LXXVII. pp. 26–31, 32–34, 288–296; also the abridgments by Hutton, Vol. XVI. pp. 173, 176, 282 and Vol. XVII. p. 142; Sc. American, Vol. LI. p. 19; Annales de Chimie, Vol. XLIX. p. 45; Ezekiel Walker, Phil. Mag. for 1813, Vol. XLI. p. 415 and Vol. XLII. pp. 161, 215, 217, 371, 476, 485; also Vol. XLIII. p. 364.

A.D. 1788.—Barthélémy (Jean Jacques), who, after completing his studies in a French seminary of Jesuits, succeeded Gros de Boze as keeper of the king’s cabinet of medals, publishes in four volumes, at Paris, the first edition of his “Voyage du Jeune Anacharsis.” In this well-known work, begun by him in 1757, and translated into English under the title “Travels of Anacharsis the Younger in Greece,” Barthélémy alludes to the possibility of telegraphing by means of clocks (pendules, not horloges), having hands similarly magnetized in conjunction with artificial magnets. These were “presumed to be so far improved that they could convey their directive power to a distance, thus, by the sympathetic movements of the hands or needles in connection with a dial alphabet, communications between distant friends could be carried on.”

Writing to Mme. du Deffand in 1772, he observes:

“It is said that with two timepieces the hands of which are magnetic, it is enough to move one of these hands to make the other take the same direction, so that by causing one to strike twelve the other will strike the same hour. Let us suppose that artificial magnets were improved to the point that their virtue could communicate itself from here to Paris; you have one of these timepieces, we another of them; instead of hours we find the letters of the alphabet on the dial. Every day at a certain hour we turn the hand, and M. Wiard [Mme. du Deffand’s secretary] puts together the letters and reads.... This idea pleases me immensely. It would soon be corrupted by applying it to spying in armies and in politics, but it would be very agreeable in commerce and in friendship.”

References.—“Correspondance inédite de Mad. Du Deffand,” Vol. II. p. 99; letter of J. MacGregor in Journal Society of Arts, May 20, 1859, pp. 472, 473.

A.D. 1789.—Adriaan Paets Van Troostwÿk and Jean Rodolphe Deimann, Dutch chemists, associated for the purpose of scientific research, complete the experiments of Lord Cavendish and announce, in the Journal de Physique, their discovery of the decomposition of water through the electric spark, which latter is conveyed by means of very fine gold wires. As is now well known, water is by this means resolved into its two elements of oxygen and hydrogen, both of which assume their gaseous form.

The electric machine they employed was a very powerful double-plate one, of the Teylerian mode of construction, causing the Leyden jar to discharge itself twenty-five times in fifteen revolutions.

References.—“Mém. de la Soc. de Phys. Exp. Rotterdam,” Tome VIII; Journal de Physique, Vol. XXXIII; Noad, “Manual,” p. 161; “Encyl. Brit.,” Vol. VIII, 1855, pp. 530, 565; “Biog. Universelle,” Vol. X. p. 282; De La Rive, “Electricity,” Vol. II. p. 443; Wm. Henry, “Elements of Experimental Chemistry,” London, 1823, Vol. I. pp. 251, 252; Delaunay’s “Manuel,” etc., 1809, pp. 180–183; “Verhandl. van het Genootsch te Rotterdam” (“Mém. de la Soc. de Phys. Exp. de Rotterdam”) Vol. VIII; Poggendorff, Vol. I. p. 1555; Dove, p. 243; G. Carradori (Brugnatelli’s Annali di chimica, Vol. I. p. 1); John Cuthbertson, “Beschreibung einer Elekt. ...” Leipzig, 1790.

A.D. 1790.—Reveroni—Saint-Cyr (Jacques Antoine, Baron de), French Colonel and author, best known by his very interesting work, “Mécanismes de la Guerre,” proposes an electric telegraph for the purpose of announcing the drawings of lottery numbers; no satisfactory information as to its construction, however, appears obtainable.

References.—Fahie, “History,” etc., London, 1884, p. 96; Etenaud, “La Télégraphie Electrique,” 1872, Vol. I. p. 27; Sc. Am. Supp., No. 384, pp. 6, 126.

A.D. 1790.—Mr. Downie, master of his Majesty’s ship “Glory,” makes a report on local attraction wherein he observes “that in all latitudes, at any distance from the magnetic equator, the upper ends of iron bolts acquire an opposite polarity to that of the latitude,” an observation, Harris remarks, which accords with Marcel’s experiment (at A.D. 1702).

“I am convinced,” says Mr. Downie, “that the quantity and vicinity of iron, in most ships, has an effect in attracting the needle; for it is found by experience that the needle will not always point in the same direction when placed in different parts of a ship; also, it is very easily found that two ships, steering the same course by their respective compasses, will not go exactly parallel to each other; yet when their compasses are on board the same ship they will agree exactly.”

References.—William Walker, “The Magnetism of Ships,” London, 1853, p. 20; J. Farrar, “Elements,” p. 376; Harris, “Rudim. Magn.,” 1852, Part III. p. 161.

A.D. 1790.—Tralles (Johann Georg), a German scientist, is the first to make known the negative electricity of cascades. This he communicates through his “Uber d. Elektricität d. Staubbachs,” published at Leipzig.

In the Report on Atmospheric Electricity of Francis J. F. Duprez, translated from the Memoirs of the Royal Academy of Brussels by Dr. L. D. Gale, we read that one day while in the Alps, opposite the cascade of Staubbach, near Lauterbrunnen, Tralles “presented his atmospheric electrometer, not armed with the metallic wire, to the fine spray which resulted from the dispersion of the water. He immediately obtained very distinct signs of negative electricity. The same effect was exhibited at the cascade of Reichenbach. Volta, a short time after, verified the correctness of this observation, not only above the great cascades, but also wherever a fall of water existed, however small, provided the intervention of the wind caused the dispersion of the drops. The electricity always appeared to him, as it did to Tralles, negative. Schübler repeated the same experiments in his journey to the Alps in 1813. He observed farther, that this negative electricity was very strong, since it became perceptible at a distance of 300 feet from the cascade of Reichenbach; and at a distance of 100 feet his electrometer indicated 400 and even 500 degrees.... Tralles attributed it at first to the friction of the minute drops of water against the air; but soon after he thought, with Volta, that the cause was to be found in the evaporation which the same minute drops experience in falling....”

The Italian physicist, Giuseppe Belli, who published at Milan, during 1836, “Sulla Elettricità negativa delle cascate,” entertains an opinion contrary to that advanced by M. Becquerel, and believes “that the electrical phenomenon of the water of cascades is owing to the development of electricity by the induction which the positive electricity of the atmosphere exercises on the water. The water, he says, is by induction in the negative state, when the atmosphere is, as it is ordinarily, charged with positive electricity. At the moment when this water divides into thousands of minute drops, it cannot fail to carry the electricity with which the electrical induction of the atmosphere has impregnated it to all bodies which it meets.”

References.—“Œuvres de Volta,” Vol. II. p. 239; Franz Samuel Wilde, “Expériences sur l’électricité des cascades” (“Mémoires de Lausanne,” Vol. III, “Histoire,” p. 13, 1790); “Bibliographie Universelle,” N. S., 1836, Vol. VI. p. 148; Houzeau et Lancaster, “Bibl. Générale,” Vol. II. p. 265; “Biblio. Ital.,” LXXXIII. p. 32; Schweigger, Journal f. Chemie u. Physik, Vol. IX. p. 358; Tralles, “Beyträge zur Lehre von der Electricität”; L. W. Gilbert’s Annalen der Physik und Chemie, Vol. XXVIII for 1808; F. A. C. Gren’s Journal der Physik, Vol. I. for 1790; Humboldt, “Cosmos,” London, 1849, Vol. I. p. 344, and the reference to Gay-Lussac in Ann. de chimie et de physique, Vol. VIII. p. 167.

A.D. 1790.—Eandi (Giuseppe Antonio Francesco Geronimo), an able physicist, native of Saluces (1735–1799), reads, May 10, before the Academy of Sciences of Turin, a Memoir upon Electricity in vacuo which is printed in the Collections of that Institution. He studied for the priesthood and entered the Normal College of Turin, where he followed protracted courses of literature under Bartoli and of natural philosophy under Beccaria, becoming the assistant of the latter, whom he finally replaced from 1776 to 1781. He afterward became Professor of Natural Philosophy at the College of Fine Arts, where he gave particular attention to electrical studies, and published several papers on that science, as well as upon natural philosophy generally.

He bequeathed all his possessions to his nephew Vassalli, upon condition of the latter’s taking the name of Eandi.

Besides the above, he wrote: “Memorie istorische,” etc., or “Historical Memoir upon the Studies of Father Beccaria,” Turin, 1783, which is dedicated to Count Balbi and gives the new theories of electricity, also an “Essay upon the Errors of Several Physicists in Regard to Electricity,” Turin, 1788.

References.—“Notice sur la vie ... d’ Eandi par Vassalli-Eandi,” Turin, 1804; “Biographie Générale,” Vol. XV. p. 589; Larousse, “Dict. Universel,” Vol. VII. p. 5; the Turin Academy Memoirs for the years 1802–1804; Eandi e Vassalli-Eandi, “Physicæ Experimentalis,” etc., Turin, 1793–1794.

A.D. 1790.—Vassalli-Eandi (Antonio Maria), Italian savant (1761–1825), nephew of G. A. F. G. Eandi, who was, like his uncle, a pupil of Beccaria, publishes his views concerning the electricity of bodies and regarding other investigations, as well as a report upon experiments relative to the electricity of water and of ice, which appear respectively in L. V. Brugnatelli’s Annali di Chimica, Vol. I. p. 53, in the “Bibl. Fis. d’Europa,” Vol. XVII. p. 144, and in the third volume of “Mem. della Soc. Italiana.”

He was one of the most prolific of Italian writers, his more important essays, which number 160, being written in Italian, Latin and French, and covering almost every leading branch of physical science. One of his biographers tells us, Il a embrassé, pour ainsi dire, l’ensemble des connaissances humaines, and that he is one of whom his country may justly be proud.

In his investigations concerning aerolites, which appeared in 1786 (“Memoria ... sopra ... bolidi in generale”), he explains the movements of those bodies much more satisfactorily than had previously been done by any scientist. Essays published by him during the same year, as well as in 1789 and 1791, treat of the effect of electricity upon vegetables; then follow his papers relative to Bertholon’s “Electricité des Météores,” to Haüy’s theories and to the meteorological observations of Senebier, De Saussure, Toaldo and Monge, up to 1792, when Vassalli was made Professor of Natural Philosophy at the Turin University. He had also in the meantime carefully looked into the scientific knowledge possessed by the ancients, and was led to believe, as shown in his “Conghietture sopra l’arte,” etc., that they had the means of attracting and directing thunder and lightning. The latter fact has been alluded to in this “Bibliographical History,” under the B.C. 600 entry. (See J. Bouillet, “De l’état des connaissances,” etc., Saint Etienne, 1862.)

He was after this made perpetual secretary of the Royal Academy of Sciences of Turin, then became Director of the Museum of Natural History, as well as of the Observatory situated in the last-named city, which position he held at the time of his death.

His other essays treat more particularly of animal electricity, the electricity of fishes, the effects of electricity upon recently decapitated bodies, the application of electricity and of galvanism to medicine, and cover very extended observations on meteorology. He was the editor of both the “Memoirs of the Academy of Sciences of Turin, from 1792 to 1809,” and of the “Annals of the Turin Observatory, from 1809 to 1818” (Larousse, “Dictionnaire Universel,” Vol. XV. p. 801); was likewise editor of the “Bibliothèque Italienne,” in conjunction with Giulio Gioberti and Francesco Rossi, and is said to have devised an electrometer superior to that of Volta.

References.—Vassalli-Eandi, Giulio (or Julio) e Rossi, “Rapport présenté,” etc., Turin, 1802, or “Transunto del Rapporto,” etc., Milano, 1803 (“Opusc. Scelti,” Vol. XXII. p. 51), translated into English, London, 1803 (Phil. Mag., Vol. XV. p. 38); also Vassalli-Eandi, F. Rossi et V. Michelotti, “Précis de nouvelles expériences galvaniques,” Turin, 1809 (“Mém. de Turin,” Années, 1805–1808, p. 160). See likewise, S. Berrutti, “Elogio,” etc., 1839; “Saggio sulla vita ... Vassalli-Eandi,” Torino, 1825; “Notizie biografiche ... Vassalli Eandi” (“Mem. di Torino,” Vol. XXX. p. 19); “Elogio, scritto dal Berrutti” (“Mem. of the Ital. Soc.,” Vol. XXII. p. liv); Phil. Mag., Vol. XV. p. 319; Journal de Physique, An. VII. p. 336 and Vols. XLIX, L; “Ital. Soc. Mem.,” Vols. VIII. p. 516; X. p. 802; XIII. p. 85; XVII. p. 230; XIX. p. 347; “Mémoires de Turin,” Vols. X-XIII; “Mem. dell’ Acad. di Torino,” Vols. VI, X, XXII, XXIV, XXVI, XXVII, XXIX; “Mem. della Soc. Agrar. di Torino,” Vol. I; “Opuscoli Scelti,” Vols. XIX. pp. 215, etc.; XXII. p. 76; “Nuova Scelta d’Opuscoli,” Vol. I. p. 167; “Opuscoli Scelti di Milano,” quarto, Vol. XIV; “Mem. Soc. Ital.,” Vols. IV. p. 263; X. p. 733; “Biblioteca Oltramontana”; Brugnatelli’s Annali di Chimica; “Giornale Scientifico ... di Torino,” Vols. I, III; “Giornale Fis. Med.,” Vol. II. p. 110; “Biblioteca Italiana”—“Bibliothèque Italienne,” Vols. I. p. 128; II. p. 25; “Recueil périodique ... de Sédillot,” Vol. II. p. 266.

A.D. 1790–1800.—Morozzo—Morotius—(Carlo Luigi, Comte de), Italian savant, who studied mathematics under Lagrange, and was President of the Turin Academy of Sciences, publishes numerous scientific memoirs in French through the reports of the last-named institution, in one of which he is said to have described an experiment suggesting the electro-magnet.

References.—Biography in Larousse, “Dictionnaire Universel,” Tome XI. p. 577, and in the “Biographie Générale,” Tome XXXVI. p. 643.

A.D. 1791.—Leslie (Sir John), an able English scientist (April 1766–Nov. 1832), who, upon the death of Prof. John Playfair, was called to the Chair of Natural Philosophy in the University of Edinburgh, writes a very interesting paper entitled “Observations on Electric Theories,” which is read the following year at the meeting of the Royal Society of Edinburgh, and is published at the latter place during 1824.

According to Carnevale Antonio Arella, “Storia dell’ Elettricità,” Alessandria, 1839, Vol. I. p. 130, Sir John Leslie is the author of quite an interesting treatise on the inefficacy of lightning conductors, and the “English Cyclopædia” (Biography), Vol. III. p. 866, gives a list of many of the numerous contributions he made to the leading publications of his day, more particularly in the “Edinburgh Philos. Transactions,” the “Encyclopædia Britannica,” the “Edinburgh Review,” and “Nicholson’s Philos. Journal.” The reviewer adds, what will surprise many readers, that, although some papers by Sir John Leslie treating of physical subjects were also read before the Royal Society of London, none were ever printed in their “Philos. Transactions.”

Professor John Playfair above alluded to (1748–1819), became, during 1785, Joint Professor of Mathematics with Dr. Adam Ferguson in the University of Edinburgh and, in 1805, exchanged this for the Professorship of Natural Philosophy in the same university.

References.—Macvey Napier, “Memoir of Sir John Leslie,” 1838, which appeared in seventh edition of “Encycl. Britan.,” Vol. XIII; “Engl. Cycl.” (Biography); Rose, “New Gen. Biogr.”; Hœfer, “Nouv. Biogr. Gen.,” Paris, 1862, Vol. XXX. pp. 949–952 (giving full account of his works); “Encycl. Britan.,” ninth edition, Edinburgh, 1882, Vol. XIV. pp. 476–477; Sidney Lee, “Dict. Nat. Biogr.,” Vol. XXXIII. pp. 105–107 and Vol. XLVIII. pp. 413–414; Pierre Larousse, “Grand Dict. Univ.,” Vol. X. pp. 406–407; “Caledonian Mercury,” article of Prof. Napier summarized in the “Gentleman’s Magazine” for 1833, Vol. I. pp. 85–86. Consult also A.D. 1751 at Adanson; “Dove,” p. 256; Philosophical Magazine, Vols. XL and XLII.

A.D. 1791.—At p. 353, Chap. III of the first volume of Gmelin’s “Handbook of Chemistry,” it is stated that during 1791 James Keir (Kier) first showed, by immersing iron in a solution of nitrate of silver or fuming nitric acid, that many metals can be made to pass from their ordinary active state into a passive or electro-negative state and lose either wholly or in part their tendency to decompose acids and metallic oxides.

At pp. 167–170, Sixth Memoir, of Wm. Sturgeon’s “Scientific Researches” (Bury, 1850), treating of the application of electro-chemistry to the dissolution of simple metals in fluids, reference is made to the long line of investigations carried on by both Bergman and Keir, the last named having demonstrated that iron “acquires that altered state by the action of nitric acid which Sir John Herschel met with in his experiments, and has called prepared state, and that Schönbein and others call the peculiar or the inactive state” (Noad’s “Manual of Electricity,” London, 1859, p. 534). The iron which is active in nitric acid was called by Keir “fresh iron,” while that which became inactive he designated as “altered iron” (Sturgeon’s “Annals of Electricity,” Vol. V. p. 439).

Some remarkable phenomena in the display of which but one individual piece of metal is used, as first shown by Keir, remain, Sturgeon says, “without even an attempt at explanation by any of the philosophers under whose notice they have appeared.” Sir John Herschel pronounces them as of an “extraordinary character”; Prof. Andrews, after giving some very satisfactory explanations of several phenomena, acknowledges that he “can offer no explanation of most of the particular facts which have been described,” and Professor Schönbein “has not made public any conclusive explanation of them whatever” (Phil. Mag. for October 1837, p. 333, and for April 1838, p. 311).

This same James Keir, called by Watt “a mighty chemist” (1735–1820), has strangely by some been confounded with Robert Kerr, also a Scotchman, who was an able scientific writer and lived at about the same period (1755–1813). Kerr made valuable translations from Lavoisier and Linnæus which, during 1805, won for him a fellowship in the Edinburgh Royal Society. (Consult Sidney Lee, “Dict. of Nat. Biogr.,” London, 1892, Vol. XXI. p. 64, also the references therein given; and the article “Faraday” in the “Encycl. Britan.,” ninth edition, Edinburgh, 1879, Vol. IX. p. 30.)

References.—Mrs. Amelia Moillet, “Sketch of the Life of James Keir,” 1859; Sidney Lee, “Dict. of Nat. Biog.,” London, 1892, Vol. XXX. pp. 313–314; Annales de Chimie for October 1837; Phil. Trans. for 1790, p. 353, as well as Hutton’s abridgment of the same, Vol. XVI. p. 694; Sturgeon’s “Annals of Electricity,” Vol. V. p. 427; Gmelin’s Chemistry, pp. 367, 370.

A.D. 1791.—Shaw (George), English naturalist, who became a Fellow of the Royal Society during the year 1789, communicates to the latter body a paper on the Scolopendra electrica and Scolopendra subterranea (“Linn. Soc. Trans.” I. pp. 103–111). This was afterward translated into Italian and appeared in Vol. IX. p. 26, of Brugnatelli’s Annali di Chimica. Mr. James Wilson, F.R.S.E., in his “Encycl. Brit.” article on Myriapoda, alludes to the Scolopendra electrica as figured by Frisch and described by Geoffroy in his “Histoire des Insectes,” Vol. II. p. 676, n. 5. Shaw also treats of the Trichiurus Indicus, which Sir David Brewster believes to be the same as the trichiurus electricus, known to inhabit the Indian Seas and to have the power of giving electric shocks.

Five years before the above date (1786), the Phil. Trans. contained (p. 382) the description of the tetraodon electricus, which Lieutenant William Paterson discovered in the cavities of the coral rocks of one of the Canary Islands and which he found to possess the properties of other electrical fishes. (See Hutton’s abridgments, Vol. XVI. p. 134.)

References.—“Biographie Générale,” Vol. XLIII. p. 922; “Gentleman’s Magazine,” Vol. LXXXIII; Poggendorff, Vol. II. p. 918; “Cat. Royal Society Sc. Papers,” Vol. V. p. 674; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. II. p. 436, for the Trichiurus Indicus....

Having thus far called attention to the most important varieties of the electrical fishes, notably at the articles Adanson (A.D. 1751), Bancroft (A.D. 1769), Walsh, also Hunter (A.D. 1773), the following original list of additional references will prove interesting:

Raia Torpedo.—Stephani Lorenzini, “Osservazioni ...” Firenze, 1678; R. A. F. de Réaumur, “Des Effets ...” Paris, 1714; Templeman, in “Nouvelliste,” 1759; Ingen-housz (Phil. Trans., 1775); Cavendish (Phil. Trans., 1776, Vol. LXI. p. 584, Vol. LXVI. p. 196, also Hutton’s abridgments, Vol. II. p. 485; Vol. XIII. p. 223; Vol. XIV. p. 23); F. Soave (“Scelta di Opuscoli,” Vol. XV), Milano, 1776; J. A. Garn, “De Torpedine ...” Witteb., 1778; R. M. de Termeyer (Raccolta Ferr. di Op. Sc. ... Vol. VIII), Venice, 1781; L. Spallanzani (“Goth. Mag.,” V. i. 41; “Opusc. Scelti,” VI. 73), Milano, 1783; Girardi and Walter (“Mem. Soc. Ital.,” III. 553), Verona, 1786; W. Bryant (“Tr. Amer. Phil. Soc.,” II. 166, O. S.), Philad., 1786; J. W. Linck, “De Raja Torpedine,” Lips., 1788; Vassalli-Eandi (Journal de Physique, Vol. XLIX. p. 69); Geoffroy Saint-Hilaire (“Annal. du Mus.,” An. XI. Vol. I., No. 5, and Phil. Mag., Vol. XV. p. 126), 1803; J. F. M. Olfers, “Die Gattung Torpedo ...” Berlin, 1831; Linari-Santi in “Bibl. Univ.,” Ser. II., Geneva, 1837–1838, and in “Bibl. Ital.,” Vol. XCII. p. 258, Milan, 1839; C. Matteucci, “Recherches ...” Genève, 1837 (“Royal Soc. Catalogue of Sc. Papers,” Vol. IV. pp. 285–293); also Delle Chiaje, “On the Organs ...” and P. Savi, “Etudes ...” Paris, 1844; G. Pianciani (“Mem. Soc. Ital.,” XXII. 7); F. Zantedeschi (“Bull. Acad. Brux.,” VIII. 1841); A. Fusinieri (“Ann. del Reg. Lomb.-Veneto,” VIII. 239), Padova, 1838; A. F. J. C. Mayer, “Spicilegium ...” Bonnæ, 1843; L. Calamai, “Osservazioni ...” 1845; C. Robin, “Recherches ...” Paris, 1847; Krünitz, “Abhandl.,” XVII; Nicholson’s Journal, Vol. I. p. 355; Rozier, IV. p. 205; “Acad. Brux.,” 111; “Phil. Hist. and Mem. of the Roy. Acad. of Sc. Paris,” 1742, Vol. V. pp. 58–73; John Ewing, at A.D. 1795; Dr. Godef. Will. Schilling (in original Latin, also the French translation), “Biblioth. Britannique,” Vol. XL. pp. 263–272; Dr. Jan Ingen-housz in Phil. Tr. Vol. LXV. p. 1; Vol. LXVIII. pp. 1022, 1027; Vol. LXIX. pp. 537, 661; also Hutton’s abridgments, Vol. XIII. p. 575; Vol. XIV. pp. 462, 463, 589, 598; “Journal des Sçavans,” Vol. LXXVIII. for January-April, 1726, p. 58; “The System of Natural History, written by M. De Buffon,” Edinburgh, 1800, Vol. II. pp. 24–25.

M. R. A. F. De Réaumur, mentioned above, has communicated the results of his investigations relative to the torpedo in “Mém. de Paris” for 1714, following it up more particularly with another article in the issue for year 1723 on magnetization, which is also alluded to in “Journal des Sçavans,” Vol. LXXXII. for 1727, p. 4.

Silurus Electricus.—Ranzi, on the discovery of the discharge of this animal; P. Forskal “Beobachtungen ...” 1775; F. Pacini, “Sopra l’ Organo ...” Bologna, 1846; Abd-Allatif, Relation de l’Egypte, p. 167, quoted at p. 250; Note XI. vol. i. of Libri’s “Hist. des Mathém.”; C. Maspero, “The Dawn of Civilization,” New York, 1894, p. 36, wherein it is said that the silurus was the nârû of the ancient Egyptians, as described by Isidore Geoffroy de St. Hilaire in his “Histoire Naturelle des Poissons du Nil.”

Gymnotus Electricus.—T. Richer, “Observations ...” Paris, 1679 (“Hist. et Mém. de l’Acad. Roy. des Sciences,” Vols. I. p. 116; VII. i. pt. 2, p. 92); “Edinburgh Review,” Vol. XVI. pp. 249–250; John Ewing at A.D. 1795; P. Sue, aîné “Histoire du Galvanisme,” Paris, An. X, 1802, Vol. II. pp. 94–97; A. Van Berkel, “Reise nach Rio ...” Memming, 1789, for the observations made in 1680–1689; J. B. Duhamel (“Hist. Acad. Sc.,” 168); J. N. Allamand, “On the Surinam Eel ... by S’Gravesande,” Haarlem, 1757; Gronov-Gronovius (“Acta Helvetica ...” IV. 26, Basle, 1760; Phil. Trans., Vol. LXV. part i. p. 94, 102, and part ii. p. 395); P. V. Musschenbroek (“Hist. et Méms. de l’Acad. des Sc.,” 1760); G. W. Schilling, “Diatribe de Morbo ...” 1770, treating of the torpedo as well as of the magnetism of the Gymnotus (which latter was observed by him in 1764, and is alluded to besides by Jan Ingen-housz in his “Nouv. Exper.,” Paris, 1785); “Mem. of Berlin Acad. of Sc.,” Bonnefoy, “De l’app. de l’élect ...” 1782–1783, p. 48; Ferdinando Elice, “Saggio sull’ Elettricità,” p. 26; H. Williamson, Alexander Garden and John Hunter in the Phil. Trans. for 1775, p. 94, 102, 105, 395, and in Hutton’s abridgments, Vol. XIII. pp. 597–600; R. M. de Termeyer (“Opus. Scelti,” IV. 324, for 1781); H. C. Flagg (“Trans. Amer. Phil. Soc.,” O. S., Vol. II. p. 170); Samuel Fahlberg, “Beskrifning ofver elektriska alen Gymnotus electricus,” Stockholm, 1801; (See Fahlberg at A.D. 1769, and in “Vet Acad. Nyr. Handl.”; Gilbert, Annalen, XIV. p. 416); Humboldt, “Observations ... anguille elect ...” Paris, 1806; “Versuche ... elec. fische,” Jena, 1806; also in the Annales de Chimie et de Physique, Vol. XI for 1819, and at p. 256 of the “Harmonies of Nature,” by Dr. G. Hartwig, London, 1866, will be found a picture showing mode of capture of the Electric Eel; F. S. Guisan, “De Gymnoto ...” Tübingen, 1819, Carl Palmstedt (“Skand. Naturf. motets Forhand,” 1842); H. Letheby (“Proceedings London El. Soc.,” Aug. 16, 1842, and June 17, 1843); M. Vanderlot’s work, alluded to by Humboldt at p. 88 of his “Voyage ...”; F. Steindachner, “Die Gymnotidie ...” Wien, 1868.

Consult likewise, for reputed magnetic powers of the echeneis, or sucking-fish, Gaudentius Merula, “Memorabilium,” 1556, p. 209; Fracastorio, “De Sympathia,” lib. 1, cap. 8; W. Charleton, “Physiologia,” 1654, p. 375; Cornelius Gemma, “De Naturæ Divinis,” 1575, lib. 1, cap. 7, p. 123; and, for electrical fishes generally, Rozier, Intr., II. p. 432; Bloch, “Naturgeschichte ...” Berlin, 1786; A. De la Rive, “Traité de l’électricité,” Paris, 1858, Vol. III. pp. 61–82; Rozier, Vol. XXVII. pp. 139–143; “Works of Michael de Montaigne,” by W. Hazlitt, New York, 1872, Vol. II. pp. 158–159; R. J. Haüy, “Traité de Physique,” p. 41; Geoffroy Saint-Hilare (Journal de Physique, LVI. 242; Phil. Mag. XV. 126–136, 261; “B. Soc. Phil.” N. 70; Gilbert, Annalen, XIV. 397; “Ann. du Mus.” for 1803); M. Schultze, “Zur Kentniss ... elect ... fische,” Halle, 1858 and 1859; Jobert (de Lamballe) “Des Appareils ...” Paris, 1858; W. Keferstein and D. Kupffer (Henle u. Pfeuffer’s “Zeitschr. f. rat. Med. Newe Folgc,” III. 1858) and Keferstein’s “Beitrag ... elekt. fische,” Göttingen, 1859; “Annual of Sc. Discovery” for 1863, giving, at pp. 115–116, the views of Sir John Herschel, of Charles Robin and of M. Moreau on the electrical organs of fishes.

A.D. 1792.—Berlinghieri (Francesco Vacca, and not Vacca Leopold nor Andrea Vacca), Italian surgeon and anatomical writer, communicates to M. De La Méthérie the result of the extensive experiments made by him in concert with M. Pignotti and his brother. After describing his investigations with frogs, he remarks that the same movements and contractions can be produced on animals with hot blood, but that the latter require a peculiar process. He says that after having dissected the crural or any other considerable nerve, and cut it at a certain height to separate it from its superior part, it should have a piece of tinfoil wrapped around its summit, and the communication should be made in the usual way by touching the coating with one of the extremities of the exciting arc and the muscles in which the nerve is distributed with the other extremity.

Many other investigations of Berlinghieri were, later on, communicated to the Société Philomathique, by whom they were successfully renewed, and, during the year 1810, a translation of his paper on the method of imparting magnetism to a bar of iron without a magnet appeared at p. 157, Vol. XXXV. of the Philosophical Magazine.

References.—Rozier, XL. p. 133, and XLI. p. 314; “Giorn. di Med. Prac. di Brera,” IX. pp. 171–298; L. B. Phillips, “Dict. of Biog. Ref.,” 1871, p. 137; Tipaldo, “Biografia ...” 1834.

A.D. 1792.—Lalande (Joseph Jérome le Français de), a distinguished scientist, and, doubtless, the best known of all French astronomers, who had previously communicated (1761) observations on the loadstone to the “Mémoires de Paris,” and had likewise written upon meteoric displays (1771), addresses to the Journal des Sçavans of Nov. 1792 a treatise entitled “Une Notice sur la découverte du Galvanisme,” justifying his claim to being the first introducer of galvanism into France, which he had before made through the columns of the Journal de Paris of the 17 Pluviôse, An. VII.

References.—Lalande, “Abrégé de l’Astronomie,” pp. 101, etc.; “Biog. Générale,” Vol. XXVIII. p. 948; “Biog. Universelle,” Vol. XXII. pp. 603–613; Ninth “Enc. Britannica,” Vol. XIV. p. 225; P. Sue, aîné, “Hist. du Galv.,” Paris, An. X (1802), Vol. I. p. 1.

A.D. 1792.—Chappe (Claude), a French mechanician (1763–1805), introduces the sémaphore, which he at first called a tachygraphe, from two Greek words meaning to write fast, but to which M. Miot, chief of one of the divisions of the War Department, gave the name of telegraph during the year 1793. Chappe had not long before devised a contrivance somewhat like that alluded to by Barthélémy (A.D. 1788), but it was not apparently brought into use.

His sémaphore consisted of a vertical wooden pillar 15 feet or 16 feet high, bearing a transverse beam 11 feet or 12 feet long, which turned upon its centre and held at each extremity pivoted arms so worked by cords or levers as to admit of 256 distinct signals. The semaphores were placed upon high towers, about four miles apart, on level ground, and even as much as ten miles apart upon intervening elevations. This system of signals was presented by Chappe to the Assemblée Législative, and was originally erected during the month of August 1794 upon stations between Paris and Lille (Lisle), a distance of about 148 miles. One of the first sentences conveyed between the two places by the Committee of Public Safety consumed 13 minutes and 40 seconds, but it was not long before dispatches could be conveyed in two minutes’ time, and it was through Chappe’s apparatus that the news of the recapture of the city of Condé was conveyed to the Assembly shortly after the entry of the troops of the Republic.

It is not now believed that Claude Chappe was acquainted with the devices of either Robert Hooke (at A.D. 1684) or of Guillaume Amontons (at A.D. 1704), as was at the time claimed by many of his jealous contemporaries. No doubt exists that he is justly entitled to the credit of having, with the assistance of other members of his family, developed an entirely new system of signals as well as the mechanism by which they were operated. The histories of telegraphy written by I. U. J. Chappe (Paris, 1824; Le Mans, 1840) review Claude Chappe’s investigations and the difficulties he encountered, besides making reference to the false magnetic telegraphs of A. T. Paracelsus (A.D. 1490–1541), William Maxwell (A.D. 1679), and F. Santanelli (“Philosophiæ reconditæ ...” Coloniæ, 1723) alluded to in the “Dictionnaire des Sciences Médicales.”

Claude Chappe’s uncle, L’Abbé Jean Chappe d’Auteroche (1722–1769), French astronomer, who succeeded N. L. de la Caille at the Paris Observatory as assistant to Cassini de Thury and edited a translation of the works of Dr. Halley, is the author of several memoirs upon the declination and inclination and upon lightning, meteors, etc., alluded to in J. B. J. Delambre’s “Hist. de l’Astron. au 18^e siècle,” in J. C. Poggendorff’s “Biog.-Liter. Hand.,” Vol. I. p. 420, and in the “Mém. de Paris,” 1767, Mém. p. 344.

References.—English Encycl., “Arts and Sciences,” Vol. VIII. p. 65; “Johnson’s Encycl.,” Vol. IV. p. 757; “Penny Ency.,” Vol. XXIV. p. 146; Shaffner, “Manual,” pp. 27, 45 and 48; “Le Cosmos,” Paris, Feb. 4, 1905, p. 128; Nicholson’s “Journ. of Nat. Phil.,” Vol. VIII. p. 164, note; Sc. American Supplement, No. 475, p. 7579; “Emporium of Arts and Sciences,” Vol. I. p. 292; Rozier, XXXIV. p. 370, and XL. p. 329; “Bull. des Sc. de la Société Philomathique,” March 1793, No. 21, for an account of the experiments of Galvani and of Valli repeated for the Society by C. Chappe, M. Robillard and A. F. de Silvestre.

A.D. 1792.—Valli (Eusebius), Italian physician of Pisa, corresponding member of the Royal Academy of Sciences at Turin, publishes his “Experiments on Animal Electricity” the results of which were communicated to the French Academy of Sciences and found to be of such great importance that a committee composed of Messrs. Le Roy, Vicq d’Azyr, Coulomb and Fourcroy, was directed to repeat them. The most important were repeated in Fourcroy’s laboratory on the 12th of July 1792.

Valli was the first to demonstrate that when an arc of two metals, plumber’s lead and silver, is employed upon an animal, the most violent contractions are produced while the lead is applied to the nerves and the silver to the muscles. He also showed that of all metals, zinc, when applied to the nerves, has the most remarkable power of exciting contractions; and he found that when a frog had lost its sensibility to the passage of a current, it regained it by repose.

These experiments were also repeated before the French Royal Society of Medicine. M. Mauduyt, who was present, deduced from the results obtained by Valli that the metals were charged with a different quantity of the electric fluid, in so much that when they were brought in contact with each other a discharge ensued. And, secondly, that the animal body, by which the electric fluid is rendered perceptible, is a more delicate electrometer than any one heretofore discovered.

Many new and very interesting investigations were afterward made by Valli upon different animals, the results of which were given to the public through the columns of the Journal de Physique as shown below. These embrace thirteen experiments upon animals rendered insensible by means of opium and powdered tobacco, showing electricity to be independent of their vitality, as well as others to show that the electric fluid is necessary to man and animals. He fully established the identity of the nervous and the electric fluids, and proved that the convulsions took place by merely bringing the muscles themselves into contact with the nerves, without the intervention of any metal whatever. In answer to the inquiry of M. Vicq d’Azyr, member of the late French Academy of Sciences, he supported by nineteen experiments the assertion that however the blood vessels may be, as they assuredly are, conductors of electricity, the nerves alone prove capable of exciting muscular movements in consequence of the mode in which they are disposed.

References.—Brugnatelli, Annali di Chimica, Vol. VII. pp. 40, 213, 228 (and pp. 138, 159, 186, 208 for Caldani); also the “Giornale Fis. Med. di Brugnatelli,” Vol. I. p. 264; Sue, “Histoire du Galvanisme,” Paris, An. X-1802, Vol. I. p. 45; “Société Philomathique,” Vol. I. pp. 27, 31, 43; Journal de Physique, Vol. XLI. pp. 66, 72, 185, 189, 193, 197, 200, 435; Vol. XLII. pp. 74, 238, the last named containing the “Lettre sur l’Electricité Animale” (“De animalis electricæ theoriæ ...” Mutinæ, 1792) sent by Valli to MM. De La Méthérie and Desgenettes; Report of MM. Chappe, Robillard and Silvestre on Valli’s and Galvani’s experiments (“Soc. Phil.” for March 1793, No. 21); Report of Messrs. Le Roy, Vicq d’Azyr and Coulomb in “Médecine éclairée par les Sciences Physiques,” Tome IV. p. 66; “Epitome of Electricity and Magnetism,” Philad., 1809, p. 133; “Versuche ... animal, electricität” of Karl Friedrich Kielmayer (Kielmaier) of the Tübingen University (Poggendorff, Vol. I. p. 1253; F. A. C. Gren, Journal der Physik, Vol. VIII for 1794); Floriano Caldani’s works, 1792–1795, and those of Leopoldo Marc-Antonio Caldani, 1757–1823; Junoblowiskiana Society, 1793–1795.

A.D. 1793.—Fontana (Felice), distinguished Italian experimental philosopher and physiologist, gives in his “Lettere sopra l’ Elettricità Animale,” the result of further extensive investigations carried on by him to ascertain more especially all the features of galvanic irritability and the peculiar actions of the several organs in cases of death by electricity. Some of his previous observations in the same line had already been made known through his “Di Moti dell’ Iride,” 1765, and “Richerche filosofiche,” 1775, all which led to an active correspondence in after years with the Italian Giochino Carradori, as will be seen by consulting the volumes of Luigi Valentino Brugnatelli’s well-known “Giomale Fisico-Medico” (Cuvier, in “Biog. Univ.,” Vol. XV. p. 8, par. 1816; “Giornale Fisico-Medico,” Vol. IV. p. 116).

Fontana (Gregorio), younger brother of Felice Fontana, likewise an able natural philosopher, succeeded the celebrated Ruggiero Giuseppe Boscovich in the Chair of Higher Mathematics at the University of Padua, and is the author of “Disquisitiones physico-mathematicæ,” Papiæ, 1780, as well as of many papers in the “Mem. della Soc. It. delle Scienze,” wherein he gives detailed accounts of many very interesting electrical observations. Mention of Gregorio Fontana’s name has already been made under Bennet, A.D. 1787.

References.—Houzeau et Lancaster, “Bibl. Gén.,” Vol. I. part i. p. 334, and, for R. G. Boscovich, “The Edinburgh Encyclopædia,” 1830, Vol. III. pp. 744–749.

A.D. 1793.—Aldini (Giovanni), nephew of Luigi Galvani and one of the most active members of the National Institute of Italy, who succeeded his former instructor, M. Canterzani, in the Chair of Physics at the Bologna University, established in the last-named Institution a scientific society whose open object was to combat all of Volta’s works and which became very hostile to the organization already formed in the University of Pavia by Felice Fontana, Bassiano Carminati and Gioachino Carradori against the followers of Galvani. Similar societies espousing the cause of Volta were subsequently organized in England, at the suggestion of Cavallo and others, and during five years, the scientists of Europe were divided between the two discoverers, without, however, any material benefit accruing therefrom to either faction.

Aldini proved to be an indefatigable investigator, as shown by the numerous Memoirs sent by him to the publications named below, up to the month of October 1802, when he experimented before the Galvani Society of Paris. An account of these experiments is given in his “Essai théorique,” etc., where, among other results, attention is called to the curious fact that contractions can be excited in a prepared frog by holding it in the hand and plunging its nerves into the interior of a wound made in the muscle of a living animal (Figuier, “Exposition,” etc., Vol. IV. p. 308). His interesting investigations of the artificial piles of muscle and brain, first made by M. La Grave and shown to the French Galvani Society, are alluded to in Nicholson’s Journal, Vol. X. p. 30, in the Journal de Physique, An. XI. pp. 140, 159, 233, 472, and in Sturgeon’s “Scientific Researches,” Bury, 1850, p. 195.

Nearly all of Aldini’s experiments were successfully repeated in London at Mr. Wilson’s Anatomical Theatre, where Mr. Cuthbertson assisted Prof. Aldini in arranging the apparatus, and where a student, by the name of Hutchins, furnished the anatomical preparations, but the demonstration, of all others, which attracted most attention was doubtless the one made in London on the 17th of January 1803. The murderer Forster had just been executed and, after his body lay for one hour exposed in the cold at Newgate, it was handed over to Mr. Koate, President of the London College of Surgeons, who, with Aldini, made upon it numerous important observations to ascertain the precise effects of galvanism with a voltaic column of one hundred and twenty copper and zinc couples. The extraordinary results obtained, which cannot properly be enumerated here, are to be found in the “Essai Théorique,” etc., already alluded to. They led Aldini to believe he could, by the galvanic agency, bring back those in whom life was not totally extinct, such as in cases of the recently drowned or asphyxiated. (Consult M. Bonnejoy’s method of proving death by ... Faradization, Paris, 1866, and Georgio Anselmo, “Effets du Galvanisme ...” Turin, 1803; S. T. Sömmering, “On the application of Galvanism to ascertain the reality of death,” Ludwig scripter nevrolog., III. 23; Ure, “Exper. on the body of a criminal ...” “Journal of Sc. and Arts,” No. XII; Phil. Mag., Vol. LIII. p. 56; Jean Janin de Combe Blanche, “Sur les causes,” etc., Paris, 1773 (hanging); C. W. Hufeland, 1783, for the app. of Elec. in cases of asphyxia; T. Kerner, for the app. of Galv. and Magn. as restoratives, Cannstadt, 1858; Wm. Henley, for electricity as a stimulant ... drowned or ... suffocated, “Trans. of the Humane Society,” Vol. I. p. 63.)

Another of Aldini’s curious experiments was the production of very powerful muscular contractions upon the heads of oxen and other animals recently decapitated, by introducing into one of the ears a wire connecting with one of the battery poles and into the nostrils or tongue a wire communicating with the other pole. Thus were the eyes made repeatedly to open and roll in their orbits while the ears would shake, the tongue move and the nostrils dilate very perceptibly (De la Rive, “A Treatise on Electricity,” 1856, Vol. II. p. 489, and 1858, Vol. III. p. 588; Pepper, “Voltaic Electricity,” 1869, pp. 287, 288). In the experiments which Aldini made during 1804 upon corpses, the body became violently agitated and even raised itself as if about to walk, the arms alternately rose and fell and the forearm was made to hold a weight of several pounds, while the fists clenched and beat violently the table upon which the body lay. Natural respiration was also artificially re-established and, through pressure exerted against the ribs, a lighted candle placed before the mouth was several times extinguished.

For the experiments of the eminent French physiologist and anatomist Marie François Xavier Bichat, of Vassalli-Eandi, Giulio, Rossi, Nysten, Hallé, Mezzini, Klein, Bonnet, Pajot-Laforest, Dudoyon, Berlinghieri, Fontana, Petit-Radel, Alizeau, Lamartillière, Guillotin, Nauche and others upon animals and men recently decapitated, see Bichat’s “Recherches Physiologiques sur la vie et la mort,” Paris, 1805; Francesco Rossi’s “Rapport des expériences,” etc., Turin, 1803; P. H. Nysten’s “Nouvelles Expériences Galvaniques,” etc., Paris, 1811, and also the latter’s “Expériences faites ... le 14 Brumaire, An. XI.” (Consult likewise, J. R. P. Bardenot, “Les Recherches ... refutées,” Paris, 1824, and, for an account of Bichat consult F. R. Buisson, “Précis historique ...” Paris, 1802; Larousse, Vol. II. pp. 703, 704; “Biog. Univ.,” Vol. XI. pp. 2–19.)

In Aldini’s “Account of Galvanism,” printed for Cuthell and Martin, London, 1803, it is said (p. 218) that, on the 27th of February 1803, he transmitted current through a battery of eighty silver and zinc plates from the West Mole of Calais harbour to Fort Rouge, by means of a wire supported on the masts of boats, and made it return through two hundred feet of intervening water.

References.—J. B. Van Mons’ treatise on animal electricity in Tome III of the sixth year of the “Magasin Encyclopédique”; Fowler, in “Bibl. Britannica,” May 1796; Giulio e Rossi (“Gior. Fis. Med. di Brugnatelli,” 1793, Vol. I. p. 82); P. Sue, ainé, “Hist. du Galvanisme,” Paris, An. X, 1802, Vol. I. pp. 31, 67, 73; Vol. II. p. 268; Brugnatelli, Annali di Chimica, Vols. XIII. p. 135; XIV. p. 174; XIX. pp. 29, 158; “Opuscoli Scelti,” Vols. XVII. p. 231; XIX. p. 217; XX. p. 73; XXI. p. 412; “Mem. Soc. Ital.,” Vol. XIV. p. 239; Poggendorff, Vol. I. p. 27; “Bibl. Britan.,” Vol. XXII. 1803, pp. 249–266; “Galvanische und elektrische ... Körpern,” 4to, Frankfort, 1804; “Bull. des Sc. de la Soc. Philom.,” No. 68; J. C. Carpue, “Bibl. Britannica,” Nos. 207, 208, p. 373; Phil. Mag., Vols. XIV. pp. 88, 191, 288, 364; XV. pp. 40, 93; Cassius Larcher, M. Daubancourt et M. Zanetti, ainé (Ann. de Chimie, Vol. XLV. p. 195); also Larcher, Daubancourt et M. de Saintiot (Précis succinct, etc., Paris, 1803); W. Sturgeon, “Scientific Researches,” Bury, 1850, p. 194; M. Kilian, “Versuche über restitution ...” Giessen, 1857; Gilbert, IV. 246; J. Tourdes (“Décade Philos.” No. 3, An. X. p. 118); Francesco Rossi (“Bibl. Ital.,” Vol. I. p. 106; Phil. Mag., Vol. XVIII. p. 131; and in the “Mémoires de Turin”); J. J. Sue, “Recherches Physiol.,” etc., 1803, p. 77; Vassalli-Eandi (“Expériences sur les décapités ...” Turin, 1802 and “Recueil ... de Sédillot,” Vol. II. p. 266); C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 Vols. passim; Report of MM. Chappe, Robillard and Silvestre (“Bull. des Sciences de la Soc. Philom.,” No. 21 for March 1793; also Jour. de Phys., Vol. XLII. p. 289); M. Payssé (“Jour. de la Soc. de Pharm.,” first year, p. 100); Dr. Crichton (“Rec. Périod. de Litt. Méd. Etrangère,” Tome II. p. 342); J. Louis Gauthier, “Dissertatio,” etc., Hales, 1793 (“Com. de Leipzig,” Tome XXXVI. p. 473); Gardiner’s “Observ. on the animal œconomy”; Humboldt (“Soc. Philom.,” Vol. I. p. 92); Alex. Monro’s “Experiments,” etc., Edin., 1793, 1794 (“Trans. Edin. Roy. Soc.,” Vol. III); Felice Fontana, “Lettere ...” 1793; Joseph Izarn, “Manuel du Galvanisme,” Paris, An. XII, 1804, pp. 97, 138, 141, 160, 163, 285; Louis Figuier, “Exposition et Histoire,” Vol. IV. pp. 307–308, 358, 360–363, 365, 366, 370, 371.

A.D. 1793.—Fowler (Richard), a very ingenious physician, of Salisbury, makes known in Edinburgh his “Experiments and Observations relative to the influence lately discovered by Galvani and commonly called Animal Electricity,” of which a very complete review is made by Dr. G. Gregory at pp. 374–381, Vol. I of his “Economy of Nature,” etc., third edition, published in London during the year 1804.

Dr. Fowler observed that the contractions in a frog are excited by making the metals touch under water even at the distance of an inch from the divided spine of the animal. He succeeded in causing the heart to contract, but could not produce the same effect upon the stomach and intestines. He also found, as did Prof. John Robison, of Edinburgh, at the same period, that the senses of touch and smell are unaffected by the metals, but that when these are applied to the eye, or, what is better, when they are thrust up between the teeth and the lips, and then made to touch, a flash of light is rendered visible. This is the case also when the metals are placed between the gums and the upper and lower lips, as proven by the experiments of Dr. Rutherford and of Mr. George Hunter, of York. Fowler likewise observed that all pure metals prove excellent conductors of the galvanic influence and that living vegetables afford it a ready passage, but that stones and oils seem to be possessed of no conducting power whatsoever.

In conjunction with Mr. Alexander Munro, Fowler published a work on animal electricity (translated into German under the title of “Abhandlung ueber thierische elekt.” etc.), while, in the “Bibliotheca Britannica” for May 1796, mention will be found of the observations of Dr. Fowler respecting the muscular irritability excited by electricity, as well as on the reproduction of the nervous substance, on the action of poisons, on the phenomena of muscular contraction, etc. etc.

References.—“Essays and Observations,” etc., Edinburgh, 1793, in Library of the Royal Institution; Gilbert Blane’s paper read to the English Royal Society, of which an extract can be found in Bacher’s “Medical Journal,” Vol. XC. p. 127; Figuier, “Exp. et Hist. des Princip. Déc.,” Vol. IV. p. 309; C. H. Wilkinson, “Elements of Galvanism,” London, 1804, Chap. VI. et passim; eighth “Encyc. Brit.,” Vol. XXI. p. 634.

A.D. 1793.—Dalton (John), LL.D., F.R.S. (1766–1844), a very able English natural philosopher and the illustrious author of the “Atomic Theory of Chemistry and of the Constitution of Mixed Gases,” gives in his earliest separate publication, “Meteorological Observations and Essays,” the result of many experiments upon the electricity of the atmosphere, made by him at Kendal and at Keswick during the seven years ending May 1793.

He proved, as Sir David Brewster expresses it, that the aurora exercises an irregular action on the magnetic needle, that the luminous beams of the aurora borealis are parallel to the dipping needle; that the rainbow-like arches cross the magnetic meridian at right angles; that the broad arch of the horizontal light is bisected by the magnetic meridian; and that the boundary of a limited aurora is half the circumference of a great circle crossing the magnetic meridian at right angles, the beams perpendicular to the horizon being only those on the magnetic meridian.

In the eighth “Encyclopædia Britannica” (Vol. IV. p. 246), treating of the height of polar lights, reference is made to the extraordinary aurora borealis observed by Dalton on the 29th of March 1826, and of which a description is given in a paper read before the Royal Society, April 17, 1828 (Phil. Mag. or Annals, Vol. IV. p. 418; Philosophical Transactions for 1828, Part II; James Hoy in Phil. Mag., Vol. LI. p. 422; J. Farquharson in Phil. Trans. for 1839, p. 267). This aurora was seen in places one hundred and seventy miles apart and covered an area of 7000 to 8000 square miles. In Vol. XIV of the same Encyclopædia will be found (p. 15), an account of another aurora observed at Kendal, February 12, 1793, while at p. 12 are given Dalton’s views as to the connection between the heat and magnetism of the earth, and, at p. 66, his conclusions as to the cause of the aurora and its magnetic influence.

References.—“Memoirs of Dalton’s Life,” by Dr. W. C. Henry, London, 1854; “Life and Discoveries of Dalton,” in British Quarterly Review, No. 1; Pharmaceutical Journal, London, October 1841; Thomson’s “History of Chemistry,” Vol. II; Young’s “Course of Lectures,” London, 1807, Vol. I. pp. 706–709, 753, and Vol. II. pp. 466–470; Noad, “Manual,” etc., London, 1859, pp. 226, 269, 534; article, “Aurora Borealis,” immediately following A.D. 1683; Sir H. Davy, “Bakerian Lectures,” London, 1840, pp. 322, 323, 328–330; “Dict. of Nat. Biog.,” Vol. XIII. pp. 428–434, as well as the numerous references therein cited. Consult also, for theories, investigations, observations, records, etc., of the Aurora Borealis: Georg. Kruger, 1700; J. J. Scheuchzer, 1710–1712, 1728–1730; L. Feuillée, 1719; J. L. Rost, 1721; J. C. Spidberg, 1724; W. Derham, 1728, 1729–1730; F. C. Mayer—Meyer, 1726; J. F. Weidler, 1729, 1730, 1735; J. Lulolfs, 1731; M. Kelsch, 1734; F. M. Zanotti, 1737, 1738; also Zanotti and P. Matteucci, 1739; B. Zendrini, J. Poleni, F. M. Serra, E. Sguario and D. Revillas in 1738; G. Bianchi, 1738 and 1740; J. M. Serantoni, 1740; G. C. Cilano de Maternus, 1743; S. von Trienwald, 1744; G. Guadagni, 1744; J. F. Ramus, 1745; C. Nocetus, 1747; P. Matteucci, 1747; Jno. Huxham, 1749–1750; G. W. Krafft, 1750; P. Kahm—Kalm, 1752; G. Reyger, 1756; A. Hellant, 1756, 1777; Jos. Stepling, 1761; H. Hamilton, 1767, 1777; M. A. Pictet, 1769; J. E. Silberschlag, 1770; C. E. Mirus, 1770; J. E. B. Wiedeburg, 1771; Max. Hell, 1776; Mr. Hall, J. H. Helmuth, 1777; E. H. de Ratte, W. L. Krafft, 1778; J. E. Helfenzrieder, 1778; G. S. Poli, 1778–1779; Marcorelle and Darguier, 1782; L. Cotte, 1783; J. A. Cramer, 1785; D. Galizi, in A. Calogera’s “Nuova Raccolta ...” Vol. XXXIX. p. 64; J. L. Boeckmann, in “Mem. de Berlin” for the year 1780; H. Ussher, 1788; G. Savioli, 1789, 1790; J. J. Hemmer, 1790; P. A. Bondoli, 1790, 1792, 1802; A. Prieto, 1794; J. D. Reuss’s works published in Göttingen; Jacopo Penada, 1807–1808; M. Le Prince, “Nouvelle Théorie ...”; W. Dobbie, 1820, 1823; Col. Gustavson, in Phil. Mag. for 1821, p. 312; M. Dutertre, 1822; J. L. Späth, 1822; Chr. Hansteen, 1827, 1855; L. F. Kaemtz, 1828, 1831; G. W. Muncke, 1828; J. Farquharson, 1829; D. Angelstrom, Rob. Hare, 1836; Ant. Colla, 1836, 1837; L. Pacinotti, 1837; G. F. Parrot, 1838; J. H. Lefroy, 1850, 1852; Don M. Rico-y-Sinobas, 1853; A. A. de La Rive, 1854; A. Boué (Katalog), 1856, 1857; C. J. H. E. Braun, 1858; E. Matzenauer, 1861; F. Dobelli, 1867; F. Denza, 1869.

A.D. 1793–1797.—Robison (John), a very distinguished English natural philosopher, completes what are without question the most important of all his scientific publications. These are to be found throughout the eighteen volumes and two supplements to the third “Encyclopædia Britannica,” where they cover such subjects as Physics, Electricity, Magnetism, Thunder, Variation, etc. etc. Taken together, “they exhibited,” according to Dr. Thomas Young, “a more complete view of the modern improvements of physical science than had previously been in the possession of the British public.”

It was after his retirement from the navy that Robison devoted himself to scientific studies, becoming the successor of Dr. Black in the lectureship of chemistry at the University of Glasgow during 1766, and accepting, seven years later (1773), the Professorship of Natural Philosophy at Edinburgh, where he taught all branches of physics and of the higher mathematics. In 1783 he was made Secretary of the Philosophical Society of Edinburgh, received the degree of Doctor of Laws, 1798–1799, and was elected foreign member of the Saint Petersburg Academy of Sciences in 1800. Of him, Mr. James Watt wrote, Feb. 7, 1805: “He was a man of the clearest head and the most science of anybody I have known” (Arago’s “Eloge of Jas. Watt,” London, 1839, p. 81).

It was while acting as midshipman under Admiral Saunders that Robison himself observed the effect of the aurora borealis on the compass, which had been remarked by Hiörter, Wargentin, and Mairan several years before, but which was not then generally known. The aurora borealis, he afterwards wrote, “is observed in Europe to disturb the needle exceedingly, sometimes drawing it several degrees from its position. It is always observed to increase its rate of deviation from the meridian; that is an aurora borealis makes the needle point more westerly. This disturbance sometimes amounts to six or seven degrees, and is generally observed to be greatest when the aurora borealis is most remarkable.... Van Swinden says he seldom or never failed to observe aurora borealis immediately after any anomalous motion of the needle, and concluded that there had been one at the time, though he could not see it.... This should farther incite us to observe the circumstance formerly mentioned, viz., that the South end of the dipping needle points to that part of the heavens where the rays of the aurora borealis appear to converge....”

The experiments of J. H. Lambert (at A.D. 1766–1776) upon the laws of magnetic action were carefully repeated by Robison, who, in 1769 or 1770, tried various methods and made numerous investigations from which he deduced that the force is inversely as the square of the distance. When he observed, however, some years afterward, that Æpinus had in 1777 conceived the force to vary inversely as the simple distance, he carefully again repeated the experiments and added others made with the same magnet and with the same needle placed at one side of the magnet instead of above it. By this simple arrangement the result was still more satisfactory, and the inverse law of the square of the distance was well established.

Throughout his numerous investigations, Prof. Robison found that when a good magnet was struck for three-quarters of an hour, and allowed in the meantime to ring, its efficacy was destroyed, although the same operation had little effect when the ringing was impeded; so that the continued exertion of the cohesive and repulsive powers appears to favour the transmission of the magnetic as well as of the electric fluid. The internal agitation, produced in bending a magnetic wire around a cylinder, also destroys its polarity, and, it is said, the operation on a file has the same effect. M. Cavallo found that brass becomes generally much more capable of being attracted when it has been hammered, even between two flints; and that this property is again diminished by fire: in this case, Dr. Thomas Young remarks, it may be conjectured that hammering increases the conducting power of the iron contained in the brass, and thus renders it more susceptible of magnetic action.

Of his other very important observations in the same line it would be difficult to select the most interesting, and it may suffice to call attention merely to such as are noted throughout Prof. Alfred M. Mayer’s valuable contributions on “The Magnet, Magnetism,” etc., in Johnson’s “New Universal Encyclopædia,” as well as in his “Practical Experiments in Magnetism,” etc., published through the columns of the Scientific American Supplement.

Prof. Robison’s electrical investigations are scarcely less interesting. In the theories advanced by Æpinus and Cavendish it was shown that the action of the electrical fluid diminished with the distance, while M. Coulomb proved, by a series of elaborate experiments, that it varied like gravity in the inverse ratio of the square of the distance. Robison had previously determined that in the mutual repulsion of two similarly electrified spheres the law was slightly in excess of the inverse duplicate ratio of the distance, while in the attraction of oppositely electrified spheres the deviation from that ratio was in defect; and he therefore arrived at the same conclusion formed by Lord Stanhope, that the law of electrical attraction is similar to that of gravity.

At the close of Richard Fowler’s “Experiments and Observations,” etc., Edinburgh, 1793, is a letter from Prof. Robison, wherein he gives the following results of many curious investigations, mostly made upon himself, to ascertain the effects of the galvanic influence. He found the latter influence well defined on applying one of two metallic substances to a wound which he had accidentally received; discovered by their tastes the solders in gold and silver trinkets; and showed that the galvanic sensation can be felt when the metallic substances are placed at a distance from each other. He proved the last-named fact by placing a piece of zinc between one of the cheeks and the gums, and a piece of silver on the opposite side within the other cheek. He next introduced a zinc rod between the piece of zinc and the cheek on the one side, and a silver rod between the silver and the cheek on the other, and when he afterward carefully brought into contact the extremities of the rods outside the mouth a flash appeared and a powerful sensation was noticeable in the gums. He experienced the same sensation when he again separated the rods and brought them to a short distance from each other, but he could perceive no galvanic effect when he placed the rods (or wires) in such manner that the silver rod should touch the zinc or the zinc rod touch the piece of silver. He also ascribed to galvanic effect the well-known fact that the drinking of porter out of a pewter pot produces a more brisk sensation than when it is taken out of a glass vessel. In this instance, he says there is a combination of one metal and of two dissimilar fluids. In the act of drinking, one side of the pewter pot is exposed to the saliva and the humidity of the mouth, while the other metallic side is in contact with the porter. In completing the circuit, in the act of drinking, a brisk and lively sensation arises, which imparts an agreeable relish to the liquid. He likewise observed that the conducting power of silk thread depends greatly on its colour, or rather on the nature of its dye. When of a brilliant white, or a black, its conducting power is the greatest; while either a high golden yellow or a nut-brown renders it the best insulator. Human hair, when completely freed from everything that water could wash out of it, and then dried by lime and coated with lac, was equal to silk.

Robison’s last publication was made in 1804, one year before his death, and constituted the first part of a series which was to appear under the head of “Elements of Mechanical Philosophy.” This portion, together with some MSS. intended for the second part, and his principal articles contributed to the “Encyclopædia Britannica,” were collected in 1822 by Sir David Brewster, and published with notes in 4 vols. under the title of “System of Mechanical Philosophy.”

References.—Playfair in “Transactions of the Royal Society of Edinburgh,” Vol. VII. p. 495; Stark’s “Biographia Scotica”; Philosophical Magazine, Vol. XIII. pp. 386–394 (Biogr. Memoir); Aikin’s “General Biography,” London, 1813, Vol. VIII; Dr. Gleig in Anti-Jacobin Magazine for 1802, Vol. XI; Chalmer’s “Biographical Dictionary,” London, 1816, Vol. XXV; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. II. pp. 438, 444.

A.D. 1793.—Prof. Georg. Fred. Hildebrandt of Erlangen (1764–1816), makes important observations relative to the influence of form and of substance upon the electric spark. He finds, among other results, that an obtuse cone with an angle of fifty-two degrees gives a much more luminous spark than one with an angle of only thirty-six degrees; that the greatest sparks are given by conical pieces of regulus of antimony and the least by tempered steel; also, that when the spark is white by taking it with a metallic body, it will, under the same circumstances, be violet if taken with the finger; that if the spark is taken with ice or water, or a green plant, its light will be red, and, if it is taken with an imperfect conductor, such as wood, the light will be emitted in faint red streams.

References.—Biography in fifth ed. of “Lehrbuch der Physiologie des Mens. Koerpers,” Erlangen, 1817; “Encyl. Britannica,” Vol. VIII, 1855, pp. 544, 545; “Biog. Générale,” Vol. XXIV. pp. 671–672; Ersch und Gruber, “Allgem. Encyklopædie.”

A.D. 1794.—Read (John), mathematical instrument maker, at the Quadrant, in Kingsbridge, Hyde Park, gives, in his “Summary View of the Spontaneous Electricity of the Earth and Atmosphere,” the result of a very elaborate series of observations, which he continued almost hourly between the years 1791 and 1792. Of 987 trials, he found that 664 gave indications of positive electricity, and out of 404 trials made during twelve months, the air was positively electrical in 241, negatively in 156, and insensible in only seven observations. He also found the vapour near the ground, in the act of condensing into dew, always highly electric.

He made many observations upon the electricity of vegetable bodies, which were afterward developed by M. Pouillet, and it was also Mr. Read who introduced a new hand-exploring instrument as well as an improved fixed thunder rod for collecting atmospherical electricity. These are described at p. 608 of the eighth volume of the 1855 “Encyclopædia Britannica.”

According to Mr. Wilkinson (“Elements of Galvanism,” etc., London, 1804, Vol. II. p. 344), Mr. Read was the first to apply the apparatus called the condenser to the electroscope in order that it should evince small intensities of electricity. He says: “The very minute portion of the fluid given out by the single contact of two different metals, does not produce any disturbance of the gold leaves; but when several minute portions are accumulated, a separation of the leaves takes place. The electroscope, in its simple state, will be as much charged the first time as if the contact had been made a thousand times, and cannot therefore acquire a greater quantity of the fluid than suffices to place it in equilibrio with the metallic plates. This portion being inadequate to the production of any divergency of the leaves, Mr. Read applied the principle of the electrical doubler to the above instrument, by which means he was enabled to charge an intervening plate of air. By thus accumulating every minute portion of the fluid imparted through the metallic plate, and by apparently condensing and increasing its intensity, he ultimately succeeded in producing marked signs of disturbance.”

References.—Philosophical Transactions for 1791, p. 185; for 1792, p. 225; for 1794, pp. 185, 266: also Hutton’s abridgments, Vol. XVII. pp. 52, 207, 423; “Bibl. Britan.,” Vol. II, 1796, p. 209; Vol. III, 1796, p. 272; Vol. X, an. vii. p. 283; Cavallo, “Nat. Phil.,” 1825, Vol. II. p. 226; Young’s “Course of Lectures,” Vol. I. p. 714; Ed. Peart, “On Electric Atmospheres ...” Gainsboro’, 1793; “Eng. Ency.,” “Arts and Sciences,” Vol. III. p. 805; Thomas Thomson, “Outline of the Sciences,” 1830, p. 446; Journal de Physique for 1794, Vol. XLV. p. 468.

A.D. 1794.—Chladni (Ernst Florens Friedrich), founder of the theory of acoustics, publishes “The Iron Mass of Pallas,” etc. (“Ueber den Ursprung der von Pallas ...”), giving a list of recorded cases of the fall of meteorites or aerolites and all the important accounts of such that he was able to collect. As Prof. Alexander Herschel informs us, in his lecture, delivered (1867) before the British Association at Dundee, Chladni conceived that a class of cosmical bodies exists in all parts of the solar system, each forming by itself a peculiar concourse of atoms, and that the earth from time to time encounters them, moving with a velocity as great as its own, and doubtless in orbits of very various eccentricity around the sun. Prof. Muirhead says that through their exceeding great velocity, which is increased by the attraction of the earth and the violent friction of the atmosphere, a strong electricity and heat must necessarily be excited, by which means they are reduced to a flaming and melted condition, and great quantities of vapour and different kinds of gases are thus disengaged, which distend the liquid mass to a monstrous size, until, by still further expansion of these elastic fluids, they must at length explode (Chladni’s hypothesis in “Enc. Brit.,” article “Meteorolite”).

Humboldt gives (“Cosmos,” London, 1849, Vol. I. p. 104, note) the following upon the same subject, taken from Biot’s “Traité d’Astronomie Physique,” third edition, 1841, Vol. I. pp. 149, 177, 238, 312: “My lamented friend Poisson endeavoured in a singular manner to solve the difficulty attending an assumption of the spontaneous ignition of meteoric stones at an elevation where the density of the atmosphere is almost null. These are his words: ‘It is difficult to attribute, as is usually done, the incandescence of aerolites to friction against the molecules of the atmosphere, at an elevation above the earth where the density of the air is almost null. May we not suppose that the electric fluid, in a neutral condition, forms a kind of atmosphere, extending far beyond the mass of our own atmosphere, yet subject to terrestrial attraction, although physically imponderable, and consequently following our globe in its motion?’ According to his hypothesis, the bodies of which we have been speaking would, on entering this imponderable atmosphere, decompose the neutral fluid by their unequal action on the two electricities, and they would thus be heated, and in a state of incandescence, by becoming electrified” (Poisson, “Rech. sur la Probabilité des Jugements,” 1837, p. 6).

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.

References.—Zetzsche, “Geschichte der Elektrischen Telegraphie,” p. 32; Boeckmann, “Versuch über Telegraphie und Telegraphen,” Carlsruhe, 1794, p. 17; “El. Magn. Teleg.,” 1850, p. 46; Gren’s Journal der Physik, Vol. I for 1790; “Neue Abhandl. der Bairischen Akad. Philos.,” Vol. III.

A.D. 1794.—Edgeworth (Richard Lovell), an able English mechanical philosopher, better known as the father and literary associate of Maria Edgeworth, introduces his tellograph (contraction of the word telelograph), “a machine describing words at a distance,” which originated in a wager relative to the prompt transmission of racing news from Newmarket to London. It consisted merely of four pointers, in the form of wedges or isosceles triangles, placed upon four portable vertical posts and the different positions of which were arranged to represent letters and numbers.

Edgeworth claimed to have made experiments, as early as 1767, with an ordinary windmill, the arms and sails of which were arranged in different positions to indicate the several letters of the alphabet.

References.—Edgeworth’s Letter to Lord Charlemont on the Tellograph, also his “Essay on the Art of Conveying Secret and Swift Intelligence,” Dublin, 1797, republished in Vol. VI of the Trans. of the Royal Irish Academy; “Appleton’s Encycl.,” 1871, Vol. XV. p. 334.

A.D. 1795.—Lord George Murray, of England, submits to the Admiralty his six-shutter telegraph, an improvement upon Chappe’s original plan. Each of the six octagonal shutters was made to turn inside of two frames at different angles upon its own axis, thus affording sixty-three separate and distinct signals. By its means, information was transmitted from London to Dover in seven minutes, and it answered nearly all the requirements of the Admiralty up to the year 1816, when it was superseded by the semaphore of Rear Admiral Popham. Murray’s method was, however, useless during foggy weather, when relays of horses had to be employed for conveying the news.

References.—English Encyclopædia, “Arts and Sciences,” Vol. VIII. p. 66; Tomlinson’s “Telegraph”; Turnbull, El. Mag. Tel., 1853, p. 18; “Penny Ency.,” Vol. XXIV. p. 147.

A.D. 1795.—Salvá (Don Francisco), a distinguished Spanish physician, reads a memoir, before the Academy of Sciences of Barcelona, from which the following is extracted: “... with twenty-two letters, and even with only eighteen, we can express with sufficient precision every word in the language, and, thus with forty-four wires from Mataro to Barcelona, twenty-two men there, each to take hold of a pair of wires, and twenty-two charged Leyden jars here, we could speak with Mataro, each man there representing a letter of the alphabet and giving notice when he felt the shock.... It is not necessary to keep twenty-two men at Mataro nor twenty-two Leyden jars at Barcelona, if we fix the ends of each pair of the wires in such a way that one or two men may be able to discriminate the signals. In this way six or eight jars at each end would suffice for intercommunication, for Mataro can as easily speak with Barcelona as Barcelona with Mataro ... or the wires can be rolled together in one strong cable ... laid in subterranean tubes, which, for greater insulation, should be covered with one or two coats of resin.”

He is said to have approved of the use of luminous panes as indicated by Reusser; to have also suggested, as early as December 16, 1795, the idea of a submarine telegraphic cable carrying several conductors, and to have proposed, at the same period, the laying of a cable between Barcelona and Palma in the island of Majorca.

In 1798, Salvá constructed a single wire telegraphic line between Madrid and Aranjuez, a distance of twenty-six miles, through which the signals were transmitted in the shape of sparks from Leyden jars. This is the line which is credited to Augustin de Bétancourt, a French engineer, by Alexander Von Humboldt, in a note at p. 14 of Gauss and Weber’s Resultate, etc., for the year 1837.

On the 14th of May 1800, and on the 22nd of February 1804, Salvá communicated to the Academy of Sciences at Barcelona two papers on galvanism applied to electricity, wherein he shows that a cheaper motive power is produced by the electricity of a number of frogs, and proposes a telegraphic apparatus in conjunction with the voltaic column which is illustrated and described at pp. 224 and 225 of Fahie’s “History of Telegraphy.” From the latter the following is taken: “This illustrious Spanish physician (Salvá) was therefore the first person who attempted to apply electricity dynamically for the purpose of telegraphing. It is, says Saavedra, not without reason, I must confess, notwithstanding my cosmopolitan opinions on scientific questions, that the Catalans hold Salvá to be the inventor of electric telegraphy. With documents as authentic as those which I have seen with my own eyes in the very hand writing of this distinguished professor (which documents are at this present moment to be found in the library of the Academy of Sciences of Barcelona) it is impossible for any author to henceforth deny, even if others did precede Salvá in telegraphic experiments with static electricity, that no one preceded him in the application of the docile electro-dynamic fluid to distant communications.”

References.—Comptes Rendus, séance, 1838; Memorial of Joseph Henry, 1880, p. 224; Ed. Highton, the El. Tel., 1852, pp. 38 and 43; “Appleton’s Encyclopædia,” 1871, Vol. XV. p. 335; De Bow’s Review, Vol. XXV. p. 551; Voigt’s Magazin, etc., Vol. XI. part iv. p. 61; Sc. Am. Supp., No. 547, p. 8735, and No. 384, p. 6127; Biography in Saavedra’s Revista, etc., for 1876; Noad’s Manual, pp. 747 and 748; Shaffner, Manual, p. 135; Turnbull, El. Mag. Tel., 1853, pp. 21, 22, 220; Du Moncel, Exposé, Vol. III; “Edinburgh Encyclopædia,” London, 1830, Vol. VIII. p. 535; “Gazette de Madrid” of November 25, 1796; “Mémoires de l’Institut,” Vol. III and “Bulletin de la Soc. Philom.,” An. VI for the new telegraph of MM. Bréguet and Bétancourt, and for the Report made thereon by MM. Lagrange, Laplace and others.

A.D. 1795.—Ewing (John), D.D., Provost of the University of Pennsylvania and one of the founders of the American Philosophical Society, makes a compilation of his course of lectures on natural experimental philosophy, which is subsequently revised for the press by Prof. Robert Patterson.

He devotes much attention to atmospheric electricity, detailing the Franklinian theory, and, besides reporting upon the hypotheses advanced by Henry Eales (at A.D. 1755), as well as treating of the attraction of magnetism, he gives a very interesting account of experiments with the torpedo and the gymnotus electricus. He says that Mr. Walsh found the torpedo “possessed of the power of shocking only in two parts of its body, directly opposite to each other and near to the head. A spot on the back and another on the belly opposite to the former being of a different colour led him to make the experiment, and he found that the electrical virtue was confined to these, and that any other part of the fish might be handled, without receiving a shock, while it was out of the water. Either of these places separately might be handled without the shock being received until a communication between them was formed. This makes it appear probable that the same may also be the case with the Guiana eel. One of these spots must therefore be always in the positive and the other in the negative state; or, rather, they are both generally in the natural state, until, by an effort of the fish’s will, they are suddenly put into different states, as we frequently found that the hand might be in the water, which formed the communication, without receiving any shock. This cannot be the case with the Leyden bottle when charged, which suddenly discharges itself upon forming the communication. Whether there be any electric atmosphere round these spots in the torpedo we cannot tell, as we had no opportunity of examining this matter in the eel, nor have we heard whether Mr. Walsh made any experiments for ascertaining this.”