Bibliographical history of electricity & magnetism, chronologically arranged

by Unknown

“Of Electricity in General

“That the Electric Fire is a real Element,—That our Bodies at all Times contain enough of it to set an House on Fire,—That this Fire will live in Water,—A Representation of the seven Planets, shewing a probable Cause of their keeping their due Distances from each other, and the Sun in the Centre,—The Salute repulsed by the Ladies’ Fire, or Fire darting from a Lady’s Lips, so that she may defy any Person to salute her,—A Battery of Eleven Guns discharged by the Electric Spark, after it has passed through eight Feet of Water,—Several Experiments shewing that the Electric Fire and Lightning are the same, and that Points will draw off the Fire so as to prevent the Stroke,—With a number of other entertaining Experiments, too many to be inserted in an Advertisement.

“Tickets to be had either at his House above or at his Shop in Queen-Street.”

Another advertisement, which appeared in the Salem Gazette of Tuesday, January 1, 1771, is thus worded: “To-morrow evening (if the Air be dry) will be exhibited A Course of Experiments in that instructive and entertaining branch of Natural Philosophy called Electricity; to be accompanied with Methodical Lectures on the nature and properties of the wonderful element; by David Mason, at his dwelling-house near the North-Bridge. The course to consist of two lectures, at a pistareen each lecture.”

A.D. 1771.—Milly (Nicolas Christiern de Thy, Comte de) French chemist, constructs compass needles of an alloy of gold and ferruginous sand. These needles answered well their purpose, as did also the brass needle owned by Christian Huyghens (alluded to at A.D. 1706), a fact which received the confirmation of Messrs. Du Lacque, Le Chevalier d’Angos and M. Arderon, while the latter further ascertained that he could impart a feeble though distinct magnetic force to a brass bar either by striking it or by means of the “double touch.”

References.—The Comte de Milly’s “Mémoire sur la réduction des chaux métalliques par le feu electrique,” read before the Paris Academy May 20, 1774, brought about many controversial articles, notably from Sigaud de la Fond, Felice Fontana, Jean M. Cadet, Jean Darcet, G. F. Rouelle and Le Dru le Comus; “Biog. Univ.,” Vol. XXVIII. p. 312; Journal de Physique, Tome XIII. p. 393; Philosophical Transactions, Vol. L. p. 774; Duhamel, “Hist. Acad. Reg. Paris,” p. 184; Journal des Sçavans, Paris edition of December 1772, and Amsterdam edition of January 1773.

A.D. 1772.—Mesmer (Friedrich Anton), an Austrian physician, who, upon taking his diploma at Vienna in 1766, had published a thesis “On the Influence of the Planets upon the Human Body,” begins his investigations as to the power of the magnet with the steel plates of Father Hell. The results proved so favourable that Hell was induced to publish an account of them, but he incurred the displeasure of his friend by attributing the cures merely to the form of the plates.

Mesmer subsequently arrived at the conclusion that the magnet was incapable, by itself, of so acting upon the nerves as to produce the results obtained and that another principle was necessarily involved; he did not, however, give an explanation of it, and managed to keep his process a secret for quite a while. He had observed that nearly all substances can be magnetized by the touch, and in due time he announced his abandonment of the use of the magnet and of electricity in his production of what became known as mesmerism.

In 1779 he published his “Mémoire sur la découverte du magnétisme animal,” in which he says: “I had maintained that the heavenly spheres possessed a direct power on all of the constituent principles of animated bodies, particularly on the nervous system, by the agency of an all-penetrating fluid. I determined this action by the intension and the remission of the properties of matter and organized bodies, such as gravity, cohesion, elasticity, irritability and electricity. I supported this doctrine by various examples of periodical revolutions; and I named that property of the animal matter which renders it susceptible to the action of celestial and earthly bodies, animal magnetism. A further consideration of the subject led me to the conviction that there does exist in nature a universal principle, which, independently of ourselves, performs all that we vaguely attribute to nature or to art.”

The whole theory and practice of mesmerism was, however, openly rejected by one of Mesmer’s most capable pupils, Claude Louis Berthollet (A.D. 1803), a very distinguished French chemical philosopher, founder of the “Société Chimique d’Arcueil,” and who, in conjunction with Lavoisier (A.D. 1781), Guyton de Morveau (A.D. 1771), and Fourcroy (A.D. 1801), planned the new philosophical nomenclature which has since proved of such service to chemical science (“La Grande Encycl.,” Tome VI. p. 449; “Biog. Universelle,” Tome IV. pp. 141–149).

Mesmer gave all his manuscripts to Dr. Wolfart, of Berlin, who published in 1814, “Mesmerism ... as the general curative of mankind.” And it was one of Mesmer’s students, le Marquis de Puységur, who discovered magnetic somnambulism, an entirely new phenomenon in animal magnetism. (See the article “Somnambulism” in the “Encyl. Britannica,” as well as the numerous works therein quoted, relating to the above-named subjects, notably Mesmer’s own “Précis historique des faits relatifs au magnétisme animal, jusques en Avril 1781.”)

References.—“Bulletin de l’Acad. de Méd.,” Paris, 1837, Tome I. p. 343, etc., and Tome II. p. 370; Blavatsky, “Isis Unveiled,” Vol. I. p. 172, etc.; “L’Académie des Sciences,” par Ernest Maindron, Paris, 1888, pp. 57–63; Richard Harte, “Hypnotism and the Doctors,” Vols. I and II, New York, 1903 (from Mesmer to De Puységur, Dupotet, Deleuze, Charcot, etc.); Robert Blakey, “History of the Philosophy of Mind,” London, 1850, Vol. IV. pp. 570–582, 639–645; the report of Dr. Franklin and other Commissioners ... against mesmerism, translated by Dr. William Bache, London, 1785; J. C. Schäffer, “Abhandlung,” etc., and “Kräfte,” etc. (1776), “Fernere,” etc. (1777), also “Journal Encyclopédique” for March 1777; Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. pp. 373–446; C. H. Wilkinson, “Elements of Galvanism,” etc., Chapter XVIII; Champignon, “Etudes Physiques,” etc., Paris, 1843; “Archives du Magn. Animal,” published by M. Le Baron d’Hénin de Cuvillers, Paris, 1820–1823; “Report on Animal Magnetism” made by Charles Poyen Saint Sauveur, 1836; Dupotet’s “Manuel,” etc., Paris, 1868; Hale’s “Franklin in France,” 1888, Part II. chap. v. alluding to an interesting manuscript of T. Auguste Thouret now in the collection of the American Philosophical Society.

A.D. 1772.—Henley (William T.), F.R.S., invents the quadrant electrometer, an apparatus with which the quantity of electricity accumulated in a jar or battery can be measured through the amount of repulsion produced by the fluid upon a pith ball suspended from the centre of a graduated arc. It is generally attached to the prime conductor to measure the state of action of the electrical machine.

He is also the inventor of the universal discharger, for directing the charge of jars or batteries (Edw. Whitaker Gray—1748–1807—“Observations on manner glass is charged and discharged by the electric fluid” in Hutton’s abridgments, Vol. XVI. p. 407).

In the Philosophical Transactions for 1774, Henley and Nairne give an account of many curious experiments proving the superiority of points over balls as conductors. The same is shown by William Swift in the Phil. Trans., Vol. LXVIII. p. 155. (For Wm. Swift consult, besides, the Phil. Trans., Vol. LXIX. p. 454, and Hutton’s abridgments, Vol. XIV. pp. 314, 571.) Henley also states that the vapour of water is a conductor of electricity; that when the flame of a candle is introduced into the circuit and a Leyden jar is discharged through it, the flame always inclines toward the negative side; and he proves that electricity cannot effect a passage through glass (Phil. Trans., Vol. LXVIII. p. 1049). He likewise makes a number of experiments to determine the relative conducting power of the different metals according to the quantity of a wire, each of a given size, melted by equal electrical shocks passed through them, and finds the metals to hold the order following as conductors: gold, brass, copper silvered, silver, iron. It was also shown by Nairne that copper conducts better than iron, in the Phil. Trans. for 1780, Vol. LXX. p. 334.

References.—Harris, “Rud. Electricity,” 1853, p. 93, and his “Frictional Electricity,” 1867, p. 23; “The Electrical Researches of the Hon. Hy. Cavendish,” Cambridge, 1879, Nos. 559, 568, 569, 580; Thos. Young, “Nat. Phil.” passim; Phil. Trans., Vol. LXIV. pp. 133, 389; Vol. LXVI. p. 513; Vol. LXVII. pp. 1, 85; also Hutton’s abridgments, Vol. XIII. pp. 323 (new electrometer), 512, 551, 659; Vol. XIV. pp. 90, 97, 130, 473; Transactions of the Humane Society, Vol. I. p. 63; Ronayne and Henley, “Account of Some Observations ...” London, 1772 (Phil. Trans., p. 137).

A.D. 1772.—Cavendish (Henry), F.R.S., eldest son of Lord Charles Cavendish, and a prominent English scientist, sometime called “The Newton of Chemistry” (“the most severe and cautious of all philosophers”—Farrar, 284), commences investigating the phenomena of electricity, the results of which study were duly communicated to the Philosophical Transactions. His papers embrace twenty-seven mathematical propositions upon the action of the electric fluid, and contain the first distinct statement of the difference between common and animal electricity.

Cavendish made many very important experiments upon the relative conducting power of different substances. He found that a solution of one part of salt in one part of water conducts a hundred times better, and that a saturated solution of sea-salt conducts seven hundred and twenty times better than fresh water, also that electricity experiences as much resistance in passing through a column of water one inch long as it does in passing through an iron wire of the same diameter four hundred million inches long, whence he concludes that rain or distilled water conducts four hundred million times less than iron wire.

He decomposed atmospheric air by means of the electric spark, and he successfully demonstrated the formation of nitric acid by exploding a combination of seven measures of oxygen with three of nitrogen. The latter he did on the 6th of December, 1787, with the assistance of Mr. George Gilpin, in presence of the English Royal Society. (For George Gilpin, consult “Bibl. Britan.,” Vol. XXXVI, 1807, p. 3; Phil. Trans. for 1806.)

He improved upon Priestley’s experiments after studying thoroughly the power of electricity as a chemical agent. In one of his experiments he fired as many as five hundred thousand measures of hydrogen with about two and a half times that quantity of atmospheric air, and having by this means obtained 135 grains of pure water, he was led to the conclusion which Mr. Watt had previously maintained, that water is composed of two gases, viz. oxygen and hydrogen.

He explains why no spark is given by the electrical fishes: the latter may contain sufficient electricity to give a shock without being able to make it traverse the space of air necessary for the production of a spark, as the distance through which the spark flies is inversely (or rather in a greater proportion) as the square root of the number of jars in operation.

For an account of his experiments anticipating Faraday’s discovery of the specific inductive capacity of various substances, see Chap. XI. pp. 69–142 of Gordon’s “Physical Treatise,” etc., London, 1883. See, likewise, J. Clerk Maxwell’s “Electrical Researches,” etc., Cambridge, 1879, pp. liii-lvi, as well as references therein made, more particularly at articles Nos. 355–366, 376; also the notes 27, 29 as per Index at pp. 450 and 453; Phil. Trans., Vol. CLXVII (1877), p. 599; Sparks’ edition of Franklin’s “Works,” Vol. V. p. 201.

References.—Dr. G. Wilson’s “Life and Works of Hon. Henry Cavendish,” London, 1851; Sturgeon’s Annals, Vol. VI. pp. 137, 173, etc.; Noad, “Manual,” etc., pp. 14, 161; Harris, “Electricity,” pp. 136, 140; Harris, “Frictional Electricity,” pp. 23 and 45; Whewell, “Hist. of the Ind. Sciences,” 1859, Vol. II. pp. 203–206, 273–275, 278; C. R. Weld, “Hist. Roy. Soc.,” for Lord Charles Cavendish, Vol. II. pp. 171, 176–185, 221; T. E. Thorpe, “Essays in Historical Chemistry,” London, 1894, pp. 70, 110; Thomas Thomson, “Hist. Roy. Soc.,” London, 1812, pp. 456, 457, 471; Sir William Thomson’s “Works,” 1872, pp. 34, 235; Phil. Trans. for 1776, Vol. LXVI. p. 196; Thos. Young, “Lectures,” 1807, Vol. I. pp. 658, 664, 751, and Vol. II. p. 418.

A.D. 1773.—Walsh (John), F.R.S., demonstrates the correctness of Dr. Bancroft’s opinion that the shock of the torpedo is of an electrical nature, resembling the discharge from a Leyden jar. In the letter announcing the fact, which he addressed to Franklin, then in London, he says: “He, who predicted and showed that electricity wings the formidable bolt of the atmosphere, will hear with attention that in the deep it speeds a humbler bolt, silent and invisible; he, who analyzed the electric phial, will hear with pleasure that its laws prevail in animated phials; he, who by reason became an electrician, will hear with reverence of an instructive electrician gifted at its birth with a wonderful apparatus, and with skill to use it.”

Mr. Walsh’s experiments were made off Leghorn, in company with Dr. Drummond, as stated in Phil. Trans., 1775, p. 1, and were confirmed by Johan Ingen-housz as well as by the Italian naturalist, Lazaro Spallanzani (at A.D. 1780). The last named found the torpedo shocks strongest when it lay upon glass, and that when the animal was dying the shocks were not given at intervals, but resembled a continual battery of small shocks: three hundred and sixteen of them have been felt in seven minutes.

References.—Leithead, “Electricity,” p. 135; Gray, “Elements of Natural Philosophy,” 1850, p. 323; “Electrical Researches of Lord Cavendish,” 1879, pp. xxxv, xxxvi and 395–437; Fifth Dissertation of “Encycl. Britannica,” 8th ed. p. 738; Phil. Trans. for 1773, 1774, 1775 and 1776; also Hutton’s abridgments, Vol. XIII. p. 469; “Chambers’ Ency.,” 1868, Vol. III. p. 821; “People’s Cyclopædia,” 1883, Vol. I. p. 628; Kaempfer (A.D. 1702); Sc. American Supplement, No. 457, pp. 7300, 7301, “Lettera dell’ Abate Spallanzani al Signore Marchese Lucchesini,” Feb. 23, 1783, inserted in the Gothaische Gelehrte Zeitungen for 1783, p. 409. See also the experiments of Dr. Ingram, of Kaempfer and of Borelli, described in Van Swinden’s “Recueil,” etc., La Haye, 1784, Vol. II; Wilkinson’s “Galvanism,” 1804, Vol. I. pp. 318, 324; G. W. Schilling, “Diatribe de morbo,” etc., 1770, and Friedrich von Hahn in the preface to Schilling’s “De Lepra,” etc., 1778, as well as at pp. 436–442, Vol. I and at note, p. 160, Vol. II of Van Swinden’s “Recueil,” already noted; J. B. Leroy and M. Saignette “Sur. l’élect. de la Torpille,” etc. (Jour. de Phys., 1774, Vol. IV and for 1776, Vol. VIII); “Annales du Musée d’Hist. Nat.,” p. 392; R. A. F. De Réaumur, “Mém. de l’acad. des Sc. de Paris“ for 1714; C. Alibert, “Eloges,” etc., Paris, 1806.

A.D. 1773.—Odier (Louis), a well-known Swiss physician, thus addresses a lady upon the subject of an electric telegraph: “I shall amuse you, perhaps, in telling you that I have in my head certain experiments, by which to enter into conversation with the Emperor of Mogol or of China, the English, the French, or any other people of Europe, in a way that, without inconveniencing yourself, you may intercommunicate all that you wish, at a distance of four or five thousand leagues in less than half an hour! Will that suffice you for glory? There is nothing more real. Whatever be the course of those experiments, they must necessarily lead to some grand discovery; but I have not the courage to undertake them this winter. What gave me the idea was a word which I heard spoken casually the other day, at Sir John Pringle’s table, where I had the pleasure of dining with Franklin, Priestley and other great geniuses.”

References.—Necrology of Prof. Odier in “Bibl. Britan.,” Vol. IV. N. S., 1817, pp. 317–328; see also allusion to Odier at Schwenter (A.D. 1600), and in the report of Bristol meeting of the British Association, August 25, 1875; also Chambers’ “Papers for the People,” 1851, El. Com., p. 6; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. p. 357.

A.D. 1773.—Hunter (John), a native of Scotland, “by common consent of all his successors, the greatest man that ever practiced surgery,” gives at p. 481 of the Phil. Trans. for 1773 his observations on the anatomical structure of the raia torpedo.

The electricity of the animal, he found, is generated by organs on each side of the cranium and gills, somewhat resembling a galvanic pile, and consisting wholly of perpendicular columns reaching from the upper to the under surface of the body. Dr. Walsh gave him for examination a fish about eight inches long, two inches thick and twelve inches broad, and Hunter found in each electrical organ as many as 470 columns; but in a very large fish, four and a half feet long and weighing 73 pounds, he counted as many as 1182 in each organ.

He remarks that there is no part of any animal with which he is acquainted, however strong and constant its natural action, which has so great a proportion of nerves; and he concludes that, if it be probable these nerves are not necessary for the purposes of sensation or action, they are subservient to the formation, collection or management of the electric fluid.

References.—Phil. Trans. for 1773, p. 461; for 1775, p. 465 (gymnotus electricus); for 1776, p. 196; the Phil. Trans., Vol. LXIII. p. 481, (torpedo); Vol. LXV. p. 395 (gymnotus); and Hutton’s abridgments, Vol. XIII. pp. 478, 666; also John Davy’s account in Phil. Trans. for 1832, p. 259; “Am. Trans.,” Vol. II. p. 166; Nicholson’s Journal, Vol. I. p. 355; Journal de Physique, Vol. XLIX. p. 69; Becquerel et Brachet, Comptes Rendus, III. p. 135; Carlo Matteucci, “Recherches,” Genève, 1837; Delle Chiage, on the organs of the torpedo; Geo. Adams, “Essay on Electricity,” etc., 1785, p. 315; D. J. N. Lud. Roger, “Specimen Physiologicum,” etc., Göttingæ, 1760; Dr. Buniva’s experiments recorded in “Journal de Littér. Médicale,” Tome II. p. 112; Leithead, “Electricity,” Chap. XII; Scient. Am. Suppl., No. 457, pp. 7300–7302. See also the account of his having been the first to observe the galvanic sensation of light in the experiment on the eyes, published in “Opuscoli Scelti,” Vol. XXII. p. 364.

A.D. 1774.—At p. 16 of the third volume of Dr. Wm. Hooper’s “Rational Recreations,” etc., there is given a fine illustration of the electrical machine made by Dr. Priestley, and mention is made of the fact that, since the publication of the latter’s “History and Present State of Electricity,” he contrived, to be placed on the top of his house, a windmill by which the machine could be occasionally turned.

Much of the remainder of the volume is given to all kinds of experiments in the line of electricity and magnetism.

A.D. 1774.—Lesage (Georges Louis, Jr.), a Frenchman living at Geneva, Switzerland, makes in that city the first real attempt to avail of frictional electricity for the transmission of signals between two distant points (see C. M., or Charles Morrison, at A.D. 1753). His apparatus consists of twenty-four metallic wires insulated from each other and communicating with separate electrometers formed of small balls of elder held by threads and each marked with different letters of the alphabet. Whenever the electric current was transmitted, the balls indicated the desired letter.

Lesage was not, however, satisfied with a telegraph upon so small a scale as to be utilized only in one building, and on the 22nd of June 1782 he addressed a letter to M. Pierre Prévost, at Geneva, on the subject of “a ready and swift method of correspondence between two distant places by means of electricity.” This, he says, had occurred to him thirty or thirty-five years before, and had been “then reduced to a simple system, far more practicable than the form with which the new inventor has endowed it.” He employed a subterranean tube of glazed earthenware, divided at every fathom’s length by partitions with twenty-four separate openings intended to hold apart that number of wires, the extremities of the wires being “arranged horizontally, like the keys of a harpsichord, each wire having suspended above it a letter of the alphabet, while immediately underneath, upon a table, are pieces of gold leaf, or other bodies that can be as easily attracted, and are at the same time easily visible.” Upon touching the end of any wire with an excited glass tube, its other extremity would cause the little gold leaf to play under a certain letter, which would form part of the intended message.

Georges Louis Lesage (sen.) wrote a work on “Meteors,” etc., published at Geneva in 1730, and alluded to in Poggendorff, Vol. I. p. 1433.

References.—Abbé Moigno, “Traité,” etc., 2nd ed. Part II. chap. i. p. 59; Ed. Highton, “The Electric Telegraph,” 1852, p. 38; Journal des Sçavans, September 1782, p. 637; Pierre Prévost, “Notice,” etc., 1805, pp. 176–177.

A.D. 1774.—Wales (William), English mathematician and the astronomer of Captain Cook during the expeditions of 1772, 1773 and 1774, is the first to make scientific observations relative to the local attraction of a ship upon mariners’ compasses. While on his way from England to the Cape and during his passage through the English Channel he found differences of as much as 19 degrees to 25 degrees in the azimuth compass.

References.—Sturmy, at A.D. 1684; also Wales and Bayly’s “Observations on Cook’s Voyages,” p. 49.

A.D. 1775.—Gallitzin (Dmitri Alexewitsch Fürst, Prince de), an able Russian diplomat and scientist, carries on at the Hague, between the 4th of June, 1775, and the commencement of the year 1778, a series of experiments upon atmospherical electricity, the results of which he communicates to the St. Petersburg Academy of Sciences in a Memoir entitled “Observations sur l’Electricité naturelle par le moyen d’un cerf-volant.” Therein he states that the presence of electricity was always noticeable whenever he raised his kite, whether in the night or in the daytime, as well as during hot, dry, or damp weather, and he ascertained that electricity is generally positive during calm weather and more frequently negative when the weather is stormy.

He also observed during an extensive course of experiments upon animals that hens’ eggs hatch sooner when they are electrified, thus confirming the previous observations of Koeslin and Senebier, and he gives an account of the effects of battery shocks upon various species. He cites the case of a hen which had sustained the shock of sixty-four jars and appeared dead, but which revived and lived thirty-two days; and he gives the report of the dissection made by M. Munichs, as well as the very curious observations upon it noted at the time by M. Camper.

Reference.—Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 13–14, 66, and Vol. II. p. 48, etc.; “Anc. Mém. de l’acad. Belge,” Vol. III. p. 3, showing preference for the pointed form of electrical conductors; “Mercure de France,” 1774, p. 147; “Biog. Univ.,” Tome XV. p. 425; “Mém. de l’Acad. ... de Bruxelles,” Vol. III. p. 14; Journal de Physique, Vols. XXI and XXII for 1782 and 1783; “Opuscoli Scelti,” Vol. II. p. 305.

A.D. 1775.—Lorimer (Dr. John), “a gentleman of great knowledge on magnetics” (1732–1795), describes his combined dipping and variation needle for determining the dip at sea, which he calls universal magnetic needle or observation compass in a letter to Sir John Pringle, Bart., copied in Philosophical Transactions, Vol. LXV. p. 79. This apparatus is also to be found described in Lorimer’s “Essay on Magnetism,” etc., 1795, as well as at p. 168 of Cavallo’s “Treatise on Magnetism” published in 1787; and, at p. 333 of the latter work, the Doctor endeavours to explain the causes of the variation of the magnetic needle.

References.—For Lorimer, consult Hutton’s abridgments, Vol. XIII. p. 593, and, for dipping needles, refer to the same volume of Hutton, p. 613, wherein especial mention is made of those of Thomas Hutchins. The dipping needle of Robert Were Fox is described in the “Annals of Electricity,” as well as at p. 411, Vol. II. of “Abstract of Papers of Roy. Soc.,” and the two dipping needles of Edward Nairne are described in Phil. Trans. for 1772, p. 496. Capt. Henry Foster made a report on changes of magnetic intensity ... in dipping and horizontal needles, to be found in Phil. Trans. for 1828, p. 303 (“Abstracts Sc. Papers ... Roy. Soc.,” Vol. II. pp. 290–296, 344).

A.D. 1775.—Cavallo (Tiberius), a distinguished Italian natural philosopher, publishes in London “Extraordinary Electricity of the Atmosphere at Islington,” which volume was reprinted by Sturgeon, and contains his many experiments and important observations upon the line indicated by Franklin. This work was followed in 1777, 1782, 1787, 1795, 1802 by his “Complete Treatise on Electricity,” etc.; by his “Essay on the Theory and Practice of Medical Electricity” (London, 1780, 1781; Leipzig, 1782, 1785; Naples, 1784); and during 1787 was also published in London the first edition of his “Treatise on Magnetism,” a supplement to which appeared eight years later.

He had made many very remarkable observations during the year 1787 on the phenomena of electricity in glass tubes containing mercury, and he had particularly experimented with various substances floating upon mercury in order to test their magnetism.

Before the year 1795 he contrived what he called a multiplier of electricity, a good illustration of which is to be found, more particularly, opposite p. 270, Vol. II. of his “Elements,” etc., published at Philadelphia in 1825. It consisted of two brass plates insulated upon glass pillars, and of a third plate which could be insulated or uninsulated at will, and which, turning on a pivot, or rather a movable arm, could be made to successively convey electricity from one plate to the other until the desired quantity was accumulated. (For the multiplier, see Jean Damel Colladon in “Bibl. Britan.,” Vol. XXIX, N.S. for 1825, p. 316.)

Cavallo also invented a small electroscope and a condenser of electricity. The latter consisted of an insulated tin plate between the sides of a wooden frame lined with gilt paper, one edge of the plate being connected with the body containing the electricity, and the condensation making itself observable at the opposite edge by the electroscope.

In the fourth edition of his “Treatise on Electricity” (1795), which, like the previous editions, was freely translated into other languages, will be found at pp. 285–296 of the third volume mention of the possibility of transmitting intelligence by combinations of sparks and pauses. For his experiments he made use of brass wires 250 English feet in length, and his electric alarm was based upon either the explosion of a mixture of hydrogen and of oxygen, or of gunpowder, phosphorus, phosphuretted hydrogen, etc., fired by the Leyden phial (vide Bozolus at A.D. 1767). It is in Vol. I. p. 358 of the afore-named fourth edition that Cavallo explains the mode of action of the charged Leyden jar. His concluding words deserve reproduction: “Which shows that one side of a charged electric may contain a greater quantity of electricity than that which is sufficient to balance the contrary electricity of the opposite side. This redundant electricity should be carefully considered in performing experiments of a delicate nature.” The same is expressed in other words in the 1825 American edition of his “Natural Philosophy,” Chap. IV. Therein he asserts that glass is impervious to the electric fluid, saying: “If the additional electric fluid penetrates a certain way into the substance of the glass, it follows that a plate may be given so thin as to be permeable to the electric fluid, and, of course, incapable of a charge; yet glass balls blown exceedingly thin, viz. about the six-hundredth part of an inch thick, when coated, etc., were found capable of holding a charge.” (Consult Cavendish’s experiments which produced this remarkable discovery, in Phil. Trans., Vols. LXXV and LXXVIII.)

An electrical machine used by Cavallo in 1777 had a glass cylinder rotated by means of a cord passing around the neck and the wheel, also a cushion (amalgamated with two parts of mercury, one of tinfoil, some powdered chalk and grease) holding a silk flap and freely moving along a groove, and provided with a prime conductor resting on glass legs and with collecting points.

References.—Sturgeon, “Lectures,” London, 1842, p. 12; Young’s “Lectures,” London, 1807, Vol. I. pp. 682, 686, 694, 714; Nicholson’s Journal, 1797, Vol. I. p. 394; Du Moncel, “Exposé,” Vol. III; Aikin’s “General Biography,” Vol. X; Phil. Transactions, 1776, Vol. LXVI. p. 407; 1777, Vol. LXVII. pp. 48, 388; 1780, Vol. LXX. p. 15; 1786, p. 62; 1787, p. 6; 1788, pp. 1 and 255, and 1793, p. 10 (Volta’s letters); likewise Hutton’s abridgments, Vol. XVI. pp. 57, 170, 354, 449; Vol. XIV. pp. 60, 129, 180, 608; see also “Encycl. Britannica,” art. “Magnetism,” Chap. III. s. 1. for Cavallo’s “Observations on the Magnetism of Metals,” etc.

A.D. 1775.—Bolten (Joach. Fred.), a German physician, is the author of “Nachricht von einem mit dem Künstlichen magneten gemachten Versuchein einer Nerven-Krankheit” (Hamburg, 1775), the title of which is here given in full, as the work is not usually found recorded in publications and is considered to be of excessive rarity.

Contrary to the accepted belief of many at the time, Bolten asserts that the application of magnetic plates for the cure of nervous and other affections is not only useless, but has, in many instances, been shown to greatly increase pain. This is proven by M. Fonseca in his Journal, which forms part of the above-named work; by Andry and Thouret (“Obs. et Rech sur ... l’Aimant ...” 8, pp. 599, 661), and by J. David Reuss (“Repertorium,” Vol. XII. p. 18), as well as by observations recorded in another very scarce work, translated into Dutch during 1775 by the celebrated physicist, J. R. Deimann, under the title of “Geneeskundige Proefneeming met den door Koast gemaakten Magneet, door den Heere T. C. Unzer.”

References.—Magnetical cures by different processes are treated of more particularly by Goclenius R., Jr., “Tract. de Mag. Curatione ...” Marp., 1609; J. Robertus, “Curationis Magneticæ ...” Luxemb., 1621, Coloniæ, 1622; Charlton, “A Ternary of Paradoxes ...” London, 1650; G. Mascuelli, “De Medicina Magnetica,” Franckfort, 1613, translated by W. Maxwell (Maxvellus), 1679–1687; Tentzelius, “Medicina Diastatica ...” 1653; A. Van Leuwenhoeck (Phil. Trans., Vol. XIX for 1695–1697, as shown below); J. N. Tetens, “Schreiben ... Magnetcuren,” Bützow and Wismar, 1775; Jacques de Harsu, “Receuil des Effets ...” Geneva, 1783; W. Pigram, “Successful Application ...” (Phil. Mag., Vol. XXXII. p. 154); Kloerich, F. W., “Versuche ...” (“Götting. Anzeigen,” 1765), “Von dem Medicin ...” Göttingen, 1766; M. Mouzin, “De l’emploi ... Maladies,” Paris, 1843. See likewise A.D. 450, and Hell at A.D. 1770.

For Anthony Van Leuwenhoeck, consult the Phil. Trans. for 1695–1697, Vol. XIX. No. 227, p. 512; Vol. XXXII. p. 72; also the abridgments of Reid and Gray, Vol. VI. p. 170, and of Eames and Martyn, Vol. VI. part. ii. pp. 277–278.

A.D. 1775.—Volta (Alessandro), an Italian natural philosopher and Professor at the University of Pavia, who had already, in 1769, addressed to Beccaria a Latin dissertation, “De Vi Attractivâ ignis electrici,” etc., makes known his invention of the electrophorus, a sort of perpetual reservoir of electricity. This consists of two circular metallic plates having between them a round disc of resin, which is excited by being struck a number of times with either a silk kerchief or pieces of dry warm fur or flannel. During 1782 he discovered what he called an electrical condenser, wherein the disc of resin is replaced by a plate of marble or of varnished wood. With this he is reported (Philosophical Transactions, Vol. LXXII) to have ascertained the existence of negative electricity in the vapour of water, in the smoke of burning coals, and in the gas produced by a solution of iron in weak sulphuric acid. An account of the above named and of other discoveries, as well as of various experiments, appears in letters addressed by him to Prof. Don Bassiano Carminati, of the Pavia Medical University, April 3, 1792, and to Tiberius Cavallo, Sept. 13, and Oct. 25, 1792, as shown in the Philosophical Transactions of the Royal Society, which institution gave him its gold Copley medal.

Volta’s crowning effort lies in the discovery of the development of electricity in metallic bodies and in the production of the justly famous pile which bears his name. The latter consisted of an equal number of zinc and copper discs separated by circular plates of cloth, paper or pasteboard soaked in salt-water or dilute acid, all being suitably connected to develop a large quantity of the electric fluid. Thus, says Dr. Dickerson in his address at Princeton College, Volta gave to the world that new manifestation of electricity called Galvanism. In that form this subtle agent is far more manageable than in the form of static electricity; and by the use of galvanic batteries a current of low tension, but of enormously greater power, can be maintained with little difficulty; whereas static electricity is like lightning, and readily leaps and escapes on the surfaces on which it is confined.

“It was Volta who removed our doubtful knowledge. Such knowledge is the early morning light of every advancing science, and is essential to its development; but the man who is engaged in dispelling that which is deceptive in it, and revealing more clearly that which is true, is as useful in his place and as necessary to the general progress of science as he who first broke through the intellectual darkness and opened a path into knowledge before unknown” (Faraday’s “Researches”).

The last mentioned discovery, though made in 1796, was first announced only on the 20th of March, 1800, in a letter written from Como to Sir Joseph Banks, by whom it was communicated to the Royal Society. It was publicly read June 26, 1800 (Phil. Trans. for 1800, Part II. p. 408).

At pp. 428–429 of “La Revue Scientifique,” Paris, April 8, 1905, will be found a review of J. Bosscha’s work entitled “La correspondance de A. Volta et de M. Van Marum,” published at Leyden. Bosscha calls especial attention to letters numbered XIII and XIV, dated respectively August 30 and October 11, 1792, wherein Volta describes his construction of the apparatus which, as already stated, was not made known until March 20, 1800. M. Bosscha’s work is also referred to in the “Journal des Savants” for August 1905.

Volta, at about the same period, constructed an electrical battery, which has been named La Couronne de Tasses (the crown of cups), and which consisted of a number of cups arranged in a circle, each cup containing a saline liquid and supporting against its edges a strip of zinc and one of silver. As the upper part of each zinc strip was connected by a wire with a strip of silver in the adjoining cup, the silver strip of the first cup and the zinc strip of the last cup formed the poles of the battery. It is said that twenty such combinations decomposed water, and that thirty gave a distinct shock.

On the 16th, 18th and 20th of November 1800 (Brumaire an. IX), Volta, who had obtained permission of the Italian Government to go to Paris with his colleague Prof. Brugnatelli, delivered lectures and experimented before the French National Institute (Sue, “Histoire du Galvanisme,” Vol. II. p. 267). As a member of the latter body, Bonaparte, the First Consul, who had attended the second lecture and witnessed the electro-chemical decomposition of water, proposed that a gold medal be stuck to commemorate Volta’s discovery, and that a commission be formed to repeat all of Volta’s experiments upon a large scale. The commission embraced such prominent men as Laplace, Coulomb, Hallé, Monge, Fourcroy, Vauquelin, Pelletan, Charles, Brisson, Sabathier, Guyton De Morveau and Biot. Biot, the chairman of the commission, made a report December 11, 1800, which appears in Vol. V of the Mémoires de l’Institut National de France, as well as in the Annales de Chimie, Vol. XLI. p. 3. In addition to the gold medal, Volta received from Bonaparte the sum of six thousand francs and the cross of the Legion of Honour.

To Volta has been attributed the fact of having, as early as 1777, entertained the idea of an electric telegraph, although nothing more appears to be on record in relation to the matter. Fahie quotes a letter of Sir Francis Ronalds, alluding to an autograph manuscript, dated Como, April 15, 1777, and gives its translation by César Cantu, wherein Volta states that he does not doubt the possibility of exploding his electrical pistol at Milan, through wires supported by posts, whenever he discharges a powerful Leyden jar at Como.

References.—Arago, “Eloge Historique de Volta” and “Notices Biographiques,” Tome I. p. 234 (“Raccolta Pratica di Scienze,” etc. for March and April 1835); London Times of January 26, 1860; the eulogies pronounced by Giorn. Fogliani at Como and by G. Zuccala at Bergamo, the year of Volta’s death, 1827; P. Sue, “Histoire du Galvanisme,” Tome II. p. 267; Journal de Leipzig, Tome XXXIV; Scelta d’ Opuscoli, Vols. VIII. p. 127; IX. p. 91; X. p. 87; XII. p. 94; XIV. p. 84; XXVIII. p. 43; XXXIV. p. 65; Opuscoli Scelti, Vols. I. pp. 273, 289; VII. pp. 128, 145; XV. pp. 213, 425; XXI. p. 373; “Mem. dell’ I. R. Istit. Reg. L. V.,” Vol. I. p. 24; “Mem. dell’ Istit. Nazion. Ital.,” Vol. I. p. 125; “Memor. Soc. Ital.,” Vols. II., pp. 662, 900; V. p. 551; “Bibl. Fisica d’Europa” for 1788; “Giornale Fis.-Med.,” Vols. I. p. 66; II. pp. 122, 146, 241, 287; III. p. 35; IV. p. 192; V. p. 63; “Giornale dell’ Ital. Lettera,” etc., Vol. VIII. p. 249; L. V. Brugnatelli, “Annali di Chimica,” etc., Vols. II. p. 161; III. p. 36; V. p. 132; XI. p. 84; XIII. p. 226; XIV. pp. 3, 40; XVI. pp. 3, 27, 42; XVIII. pp. 3, 7; XIX. p. 38; XXI. pp. 79, 100, 163; XXII. pp. 223–249 (Aless. Volta and Pietro Configliachi); Aless. Volta and Angelo Bellani, “Sulla formazione,” etc., Milano, 1824; F. A. C. Gren, Neues Journal der Physik, Vols. III and IV for 1796 and 1797; Rozier, Observ., Vols. VII, XXII and XXIII for 1776, 1873; J. B. Van Mons, Journal de Chimie, No. 2, pp. 129, 167; Sédillot, “Receuil Per. de la Soc. de Méd. de Paris,” IX. pp. 97, 231; Journal de Phys., Vols. XXIII. p. 98; XLVIII. p. 336; LI. p. 334; LXIX. p. 343; Annales de Chimie, Vols. XXX. p. 276; XLIV. p. 396; Nicholson’s Journal, Vol. XV. p. 3; Phil. Tr. for 1778, 1782 and 1793; “Soc. Philom.,” An. IX. p. 48, An. X. p. 74; “Bibl. Brit.,” Vol. XIX. p. 274; Le Correspondant for August, 1867, p. 1059, and Les Mondes, December 5, 1867, p. 561; Highton, “The Elec. Tel.,” 1852, pp. 13 and 28; Robertson, “Mémoires Récréatifs,” 1840, Vol. I. chaps, x. and xiii.; Miller, “Hist. Philos. Illustrated,” London, 1849, Vol. IV. p. 333, note; Achille Cazin, “Traité théorique et pratique des piles électriques,” Paris, 1881; “Mémoires de l’lnstitut” (Hist.) An. XII. p. 195; Andrew Crosse, “Experiments in Voltaic Electricity,” London, 1815 (Phil. Mag., Vol. XLVI. p. 421, and Gilbert’s “Annalen,” Bd. s. 60); “Lettere sulla Meteorol.,” 1783; Theod. A. Von Heller, in Gilb. “Annal.,” Vols. IV and VI, 1800; and Gren’s Neues Journ., 1795, 1797; “L’Arc Voltaique,” by M. Paul Janet, in “Revue Générale des Sciences,” May 15, 1902, pp. 416–422; “L’Académie des Sciences,” par Ernest Maindron, Paris, 1888, pp. 245–251; “Philosophical Magazine,” Vol. IV. pp. 59, 163, 306; Vol. XIII. pp. 187–190 [re prize founded by Napoleon); Vol. XXI. p. 289 (electrophorus); Vol. XXVIII. p. 182 (theory of Pierre Hyacinthe Azais), and p. 297 (Paul Erman on “Voltaic Phenomena”); Thomson, “Hist. of Chemistry,” Vol. II. pp. 251–252; “Dict. de Gehler,” Vols. III. p. 665; VI. pp. 475, 484; Thomas Thomson, “Hist. of the Royal Soc.,” London, 1812, p. 451; Young’s “Lectures,” Vol. I. pp. 674, 677, 678, 683; see likewise the “Theory of the Action of the Galvanic Pile,” as given by Dr. Wm. Henry at s. 5 Vol. I. of his “Elements of Experimental Chemistry,” London, 1823; also Nicholson’s Journal for Henry’s essay in Vol. XXXV. p. 259; M. De Luc’s papers in Vol. XXXII. p. 271, and Vol. XXXVI. p. 97; Mr. Singer on the “Electric Column” in Vol. XXXVI. p. 373; Dr. Bostock’s essay in Thomson’s “Annals,” Vol. III. p. 32; Sir H. Davy’s chapter on “Electrical Attraction and Repulsion,” in his “Elements of Chem. Philos.,” p. 125; the first volume of Gay-Lussac and Thénard’s “Recherches”; Johann Mayer, “Abhandlungen ... Galvani, Valli, Carminati u. Volta,” etc., Prague, 1793; Lehrbuch der Meteor., von L. F. Kaemtz, Halle, 1832, Vol. II. pp. 398, 400, 418; M. Detienne et M. Rouland in Jour. de Phys., Vol. VII. for 1776; J. N. Hallé, “Exposition Abrégée,” etc. (“Bull. des Sc. de la Soc. Philom.,” An. X. No. 58); C. B. Désormes’ very extended observations recorded in the An. de Ch., Vol. XXXVII. p. 284; Volta’s letter to Prof. F. A. C. Gren in 1794, and Wilkinson, “El. of Galv.,” Vol. II. pp. 314–325; J. F. Ackerman (“Salz. Mediechirurg,” 1792, p. 287); Cadet (An. de Ch., Vol. XXXVII. p. 68); letter written by Volta to M. Dolomieu (“Bull. de la Société Philom.,” No. 55, p. 48); Friedlander’s “Experiments” (Jour. de Phys., Pluvoise, An. IX. p. 101); Paul Erman (Jour. de Phys., Thermidor, An. IX. p. 121); Gilbert’s “Annalen,” VIII, X, XI, XIV); Jour. de Phys., Tome LIII p. 309; Jour. de Médecine, Nivose, An. IX. p. 351; P. C. Abilgaard,“Tentamina Electrica”; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, 2 vols. passim; A. W. Von Hauch’s Memoir read before the Copenhagen Acad. of Sc. (Sue, “Hist. du Galv.,” 1802, Vol. II. p. 255); Alexander Nicoläus Scherer’s Journal, 31st book; “Abstracts of Papers of Roy. Soc.,” Vol. I. p. 27; also Hutton’s abridgments of the Phil. Trans. Vol. XV. p. 263; Vol. XVII. p. 285; Vol. XVIII. pp. 744, 798; Phil. Magazine, Vol. IV. pp. 59, 163, 306; “Bibliothèque Britannique,” Genève, 1796, Vol. XV. an. viii. p. 3; Vol. XIX for 1802, pp. 270, 274, 339; Vol. XVI, N.S. for 1821, pp. 270–309; account of the immense electrophorus constructed for the Empress of Russia, in Vol. I. of “Acta Petropolitana” for 1777, pp. 154, etc. In the Philosophical Transactions for 1778, pp. 1027, 1049, will be found Ingen-housz’s paper relating to the then recent invention of Volta’s electrophorus and to Mr. Henley’s experiments. It is said that at about this time (1778), John Jacob Mumenthaler, Swiss mechanic, constructed very effective electrophori and electric machines out of a very peculiar kind of paper. M. F. Vilette also made a paper electrophorus which is alluded to by J. A. Nollet (“Experiments Letters,” Vol. III. pp. 209, etc.). Consult, besides, Carlo Barletti, “Lettera al Volta ...” Milano, 1776; W. L. Krafft, “Tentatem theoriæ ...” Petropol, 1778; J. C. Schäffer, “Abbild. Beschr. d. elek. ...” Regensberg, 1778; Georg Pickel, “Experimenta physico-medica ...” Viceburgi, 1778–1788; J. A. Klindworth, “Kurze Beschr. ...” Gotha, 1781–1785; (Lichtenberg’s “Magazin,” I. 35–45;) while for Klindworth, M. Obert and M. Minkeler, see the “Goth. Mag.,” I. ii. p. 35; V. iii. pp. 96, 110; E. G. Robertson, “Sur l’électrophore résineux et papiracé,” Paris, 1790; (Journal de Physique, Vol. XXXVII;) M. Robert on the electrophorus (Rozier, XXXVII. p. 183); S. Woods, “Essay on the phenomena ...” London, 1805; (Phil. Mag., Vol. XXI. p. 289;) M. Eynard’s “Mém. sur l’electrophore,” Lyon, 1804; John Phillips, “On a modification of the electrophorus,” London, 1833 (Phil. Mag., s. 3, Vol. II); G. Zamboni, “Sulla teoria ...” Verona, 1844 (“Mem. Soc. Ital.,” Vol. XXIII); F. A. Petrina, “Neue theorie d. elect. ...” Prag., 1846.

A.D. 1776.—Borda (Jean Charles), French mathematician and astronomer, improves upon the work of Mallet (at A.D. 1769), and is the first to establish accurately the knowledge of the third and most important element of terrestrial magnetism, viz. its intensity.

To him is exclusively due the correct determination of the difference of the intensity at different points of the earth’s surface by measuring the vibrations of a vertical needle in the magnetic meridian. This he determined during his expedition to the Canary Islands, and his observations were first confirmed through additional experiments which the companion of the unfortunate La Pérouse, Paul de Lammanon, made during the years 1785–1787, and which were by him communicated from Macao to the Secretary of the French Academy.

References.—Borda’s biography in the “Eng. Cycl.,” and in the eighth “Britannica”; Walker, “Magnetism,” p. 182; Humboldt on magnetic poles and magnetic intensity, embracing the observations of Admiral de Rossel, and “Cosmos,” Vol. V. 1859, pp. 58, 61–64, 87–100; also Vol. I. pp. 185–187, notes, for the history of the discovery of the law that the intensity of the force increases with the latitude; Norman (A.D. 1576).

A.D. 1777.—Lichtenberg (Georg Christoph), Professor of Experimental Philosophy at the University of Göttingen, reveals the condition of electrified surfaces by dusting them with powder.

The figures, which bear his name, are produced by tracing any desired lines upon a cake of resin with the knob of a Leyden jar and by dusting upon the cake a well-triturated mixture of sulphur and of red lead. These substances having been brought by friction into opposite electrical conditions, the sulphur collects upon the positive and the lead upon the negative portions of the cake: positive electricity producing an appearance resembling feathers, and negative electricity an arrangement more like stars.

References.—Harris, “Frict. Elect.,” p. 89; eighth “Britannica,” Vol. VIII. p. 606; E. Reitlinger, “Sibven Abh. ...” (Wien Acad.); illustrations in Sc. Am. Suppl., No. 207, p. 3297; Noad, “Manual,” p. 132; Erxleben’s “Physikalische Bibliotek,” s. 514; L. F. F. Crell, Chemische Annalen for 1786; “Göttingisches Magazin,” J i., S ii., pp. 216–220; Lichtenberg’s “Math. u. Phys. Schriften,” etc., Vol. I. p. 478. See also Dr. Young’s “Lectures on Nat. Phil.,” London, 1807, Vol. II. pp. 119, 419 for additional references, and p. 426 for Lichtenberg’s “Table of Excitation.”

A.D. 1777.—Pringle (Sir John), a man of great scientific attainments—who was physician to the Duke of Cumberland as well as to the Queen’s household, became a baronet in 1766, and afterward received many distinguished honours from foreign learned bodies—resigns the Presidency of the English Royal Society, which he had held since the year 1772. In this, as will be seen at a later date, he was succeeded by Sir Joseph Banks (at A.D. 1820), who continued in the office a period of over forty-two years. The cause which led to his resignation is best given in the following extract from his biography in the English Cyclopedia:

“During the year 1777 a dispute arose among the members of the Royal Society relative to the form which should be given to electrical conductors so as to render them most efficacious in protecting buildings from the destructive effects of lightning. Franklin had previously recommended the use of points, and the propriety of this recommendation had been acknowledged and sanctioned by the Society at large. But, after the breaking out of the American Revolution, Franklin was no longer regarded by many of the members in any other light than an enemy of England, and, as such, it appears to have been repugnant to their feelings to act otherwise than in disparagement of his scientific discoveries. Among this number was their patron George III, who, according to a story current at the time, and of the substantial truth of which there is no doubt, on its being proposed to substitute knobs instead of points, requested that Sir John Pringle would likewise advocate their introduction. The latter hinted that the laws and operations of nature could not be reversed at royal pleasure; whereupon it was intimated to him that a President of the Royal Society entertaining such an opinion ought to resign, and he resigned accordingly.”

In Benjamin Franklin’s letter to Dr. Ingen-housz, dated Passy, Oct. 14, 1777, occurs the following: “The King’s changing his pointed conductors for blunt ones is therefore a matter of small importance to me. If I had a wish about it, it would be that he had rejected them altogether as ineffectual.” It was shortly after the occurrence above alluded to that the following epigram was written by a friend of Dr. Franklin:

“While you Great George, for knowledge hunt,

And sharp conductors change for blunt,

The nation’s out of joint:

Franklin a wiser course pursues,

And all your thunder useless views,

By keeping to the point.”

Thomson informs us (“Hist. Roy. Soc.” pp. 446–447) that the Board of Ordnance having consulted the Royal Society about the best mode of securing the powder magazine, at Purfleet, from the effects of lightning, the Society appointed Mr. Cavendish, Dr. Watson, Dr. Franklin, Mr. Robertson and Mr. Wilson a committee to examine the building and report upon it. These gentlemen went accordingly, and the first four recommended the erecting of pointed conductors in particular parts of the building, as a means which they thought would afford complete security. Mr. Wilson dissented from the other gentlemen, being of the opinion that the conductors ought not to be pointed but blunt, because pointed conductors solicit and draw down the lightning which might otherwise pass by. He published a long paper on the subject, assigning a great variety of reasons for his preference (Philosophical Transactions, Vol. LXIII. p. 49). It was this dissent of Mr. Wilson which produced between the electricians of the Royal Society a controversy respecting the comparative merits of pointed and blunt conductors, which continued a number of years, and a variety of papers in support of which made their appearance in the Philosophical Transactions. The controversy, in fact, engaged almost the exclusive attention of the writers on electricity for several successive volumes of that work.

References.—William Henley, “Experiments ... pointed and blunted rods ...” in Phil. Trans, for 1774, p. 133; P. D. Viegeron, “Mémoire sur la force des pointes ...”; Edward Nairne, “Experiments ... advantage of elevated pointed conductors,” in Phil. Trans. for 1778, p. 823; Lord Mahon, “Principles ... superior advantages of high and pointed conductors,” London, 1779; Hale’s “Franklin in France,” 1880, Part I. p. 91, and Part II. pp. 254–256, 279, for some of his other correspondence with Dr. Ingen-housz; likewise Part II., pp. ix, 273, 441–451, regarding the first publication of copies of letters written by Franklin to Sir Joseph Banks, which “for some curious reason,” Mr. Hale remarks, were not publicly read and were never included in the Philosophical Transactions, as Franklin intended they should be. Consult also Thomas Hopkinson on “The Effects of Points,” etc., in Franklin’s “New Experiments,” etc., London, 1754; Tilloch’s Philosophical Magazine for 1820; Hutton’s abridgments, Vol. XIII. p. 382; “Memoir of Sir J. Pringle” in Weld’s “Hist. of Roy. Soc.,” Vol. II. pp. 58–67, 102; Jared Sparks’ edition of Franklin’s “Works,” and Sir John Pringle’s discourse delivered at the Anniversary Meeting of the Royal Society, Nov. 30, 1774, a translation of the last named appearing at p. 15, Vol. XV of the “Scelta d’ Opuscoli.” J. Clerk Maxwell, “Electrical Researches of the Hon. Henry Cavendish,” 1879, pp. 52–54.

A.D. 1778.—Martin (Benjamin), English artist and mathematician, who had already written an “Essay on Electricity” and a prominent supplement thereto (1746–1748), publishes an enlarged edition in three volumes of his “Philosophia Britannica,” originally produced in 1759. At Vol. I. p. 47 of the last-named work, he states that his experiments indicate a magnetic force inversely as the square roots of the cubes of the distances. Noad, treating of the laws of magnetic force, says (“Electricity” p. 579) that Martin and Tobias Mayer both came to the conclusion that the true law of the magnetic force is identical with that of gravitation, and that, in the previous experiments of Hauksbee and others, proper allowance had not been made for the disturbing changes in the magnetic forces so inseparable from the nature of the experiments.

His first Lecture explains all the phenomena of electricity and magnetism, the appendix thereto detailing numerous experiments of Mr. John Canton, and giving many additional facts concerning the manufacture of artificial magnets. From his preface the following extracts will, doubtless, prove interesting: “We are arrived at great dexterity since Sir Isaac Newton’s time; for we can now almost prove the existence of this aether by the phenomena of electricity; and then we find it very easy to prove that electricity is nothing but this very aether condensed and made to shine. But I believe, when we inquire into the nature and properties of this aether and electricity, we shall find them so very different and dissimilar, that we cannot easily conceive how they should thus mutually prove each other.... I see no cause to believe that the matter of electricity is anything like the idea we ought to have of the spiritus subtilissimus of Sir Isaac.... The smell also of electrical fire is so very much like that of phosphorus, that we may be easily induced to believe a great part of the composition of both is the same.”

References.—“Encycl. Britan.,” 1857, Vol. XIV. p. 320; Antoine Rivoire (Rivière), “Traité sur les aimants ...” Paris, 1752; Nicolaus von Fuss, “Observations ... aimants ...” Petersburg, 1778; Le Noble, “Aimants artificiels ...” Paris, 1772, and “Rapport ... aimants,” 1783 (Mém. de Paris); Wens, “Act. Hill,” Vol. II. p. 264; C. G. Sjoestén (Gilbert, Annalen der Physik, Vol. XVII. p. 325); Rozier, IX. p. 454.

A.D. 1778.—Toaldo (Giuseppe) Abbé, celebrated Italian physicist, who had in 1762 been made Professor at the Padua University and was the first one to introduce the lightning rod in the Venetian States, makes known the merits of the last-named invention through his “Dei conduttori per preservare gli edifizj,” etc., which work embraces most of his previous treatises on metallic conductors as well as the translation of H. B. de Saussure’s “Exposition abrégée,” etc., Geneva, 1771, and of M. Barbier de Tinan’s “Considérations sur les conducteurs en général.”

The above was followed by many highly interesting memoirs containing valuable meteorological observations, notably those in continuation of the work of J. Poleni, made close up to the time of Toaldo’s sudden death at Padua, Dec. 11, 1798. His complete works, covering the period 1773–1798, were published in Venice through M. Tiato, with the assistance of Vincenzo Chiminello, during the year 1802.

References.—In addition to the last-named publication (entitled “Completa Raccolta d’ Opuscoli,” etc.), “Mem. della Soc. Ital.,” Vol. VIII. pt. i. p. 29 (“Elogio ... da A. Fabbroni,” 1799); note at Beccaria, p. 42 of Ronalds’ “Catalogue”; Larousse, “Dict. Universel,” Vol. XV. p. 251; “Biographie Générale,” Vol. XLV. p. 450; “Biografia degli Italiani Illustri,” etc., by E. A. Tipaldo, Vol. VIII; “Padua Accad. Saggi,” Vol. III. p. cv; “Opusc. Scelti,” Vol. VI. p. 265; Vol. VII. p. 35; “Nuovo Giornale Enciclopedico di Vicenza” for 1784; Antonio Maria Lorgna, “Lettera ... parafulmini,” 1778; G. Marzari (Vol. II. p. 73, of “Treviso Athenæum”); Fonda “Sopra la maniera ...” Roma, 1770; G. Marzari e G. Toaldo, “Memoria Descrizione ...” 25 Aprile, 1786; Barbier de Tinan, “Mémoire sur la manière d’armer,” etc., Strasbourg, 1780; F. Maggiotto’s letter to Toaldo upon a new electrical machine; Sestier et Méhu, “De la foudre,” etc., Paris, 1866.

Vincenzo Chiminello, nephew of Giuseppe Toaldo, whom he succeeded at the Padua Observatory and who continued the Giornale Astro-meteorologico after his uncle’s death, is the author of works on the magnetic needle, on lightning conductors, etc., which are treated of in the columns of the Mem. Soc. Ital., Vols. VII and IX; the Giornale Astro-met. for 1801, 1804, 1806, as well as in the Saggi ... dell’Accad. di Padova, Nuova Scelta d’Opuscoli, and Opuscoli Scelti sulle scienze e sulle arti.

References.—Chiminello’s biography, Giorn. dell’Ital. Lettera, etc., Serie II. tome xvii. p. 164, and in “Atti della Soc. Ital.,” Modena, 1819.

A.D. 1778.—Dupuis (Charles François), eminent French writer who, at the age of twenty-four, became Professor of Rhetoric at the College of Lisieux, constructs a telegraph upon the plan suggested by Amontons (at A.D. 1704). By means of this apparatus he exchanged correspondence with his friend M. Fortin, then residing at Bagneux, until the commencement of the Revolution, when he deemed it prudent to lay it permanently aside (Encyclopædia Britannica, 1855, Vol. VIII. p. 263).

A.D. 1778.—Brugmans—Brugman (Anton), who was Professor of Philosophy at the University of Francker between 1755 and 1766, publishes his “Magnetismus, seu de affinitatibus magneticis.” He is, besides, the author of several works upon magnetic matter and the magnetic influence, which appeared 1765–1784 and are alluded to by Poggendorff (“Biog.-Liter. Hand.,” Vol. I. p. 316), as well as in the “Vaderlandsche Letter” for 1775 and 1776, and at p. 34, Vol. I of Van Swinden’s “Recueil de Mémoires ...” La Haye, 1784.

It was in this same year, 1778, that Sebald Justin Brugmans—Brugman—son of Anton Brugmans, a distinguished physician, naturalist and author who was the successor of Van Swinden at the Francker University, and became Professor of Botany at Leyden, discovered that cobalt is attracted while bismuth and antimony are repelled by the single pole of a magnet, thus laying the foundation of the science of diamagnetism.

Humboldt remarks: “Brugmans, and, after him, Coulomb, who was endowed with higher mathematical powers, entered profoundly into the nature of terrestrial magnetism. Their ingenious physical experiments embraced the magnetic attraction of all matter, the local distribution of force in a magnetic rod of a given form, and the law of its action at a distance. In order to obtain accurate results the vibrations of a horizontal needle suspended by a thread, as well as deflections by a torsion balance, were in turn employed.”

References.—“Biographie Générale,” Vol. VII. p. 582; Larousse, “Dict. Univ.,” Vol. II. p. 1334; “Catalogue Sc. Papers Roy. Soc.,” Vol. I. p. 672; W. H. Wollaston, “Magnetism of ... Cobalt and Nickel” (Edin. Phil. Jour., Vol. X. p. 183); Kohl on pure cobalt (L. F. F. Crell’s “Neusten Ent.,” Vol. VII. p. 39); Tyndall, “Researches on Dia-Magnetism,” London, 1870, pp. 1, 90, etc.; Appleton’s Encyclopædia, 1870, Vol. IV. p. 10; Humboldt’s “Cosmos,” 1859, Vol. V. p. 61; Augustin Roux, “Expériences nouvelles ...” (Journal de Médecine, for November 1773). Consult also, for Sebald J. Brugmans, “Biog. Générale,” Vol. VII. p. 582; Bory de Saint Vincent, in the “Annales Générales de Sciences Physiques,” Vol. II.

A.D. 1779.—Lord Mahon, afterward third Earl of Stanhope, an Englishman of great ingenuity and fertility in invention and a pupil of Lesage of Geneva (at A.D. 1774), publishes his “Principles of Electricity,” in which he explains the effects of the return stroke or lateral shock of an electrical discharge which was first observed by Benjamin Wilson (at A.D. 1746).

He imagined that when a large cloud is charged with electricity it displaces much of that fluid from the neighbouring stratum of air, and that when the cloud is discharged the electric matter returns into that portion of the atmosphere whence it had previously been taken. According to Lord Cavendish, the theory developed in the above-named work is that “A positively electrified body surrounded by air will deposit upon all the particles of that air, which shall come successively into contact with it, a proportional part of its superabundant electricity. By which means, the air surrounding the body will also become positively electrified; that is to say, it will form round that positive body an electrical atmosphere, which will likewise be positive.... That the Density of all such atmospheres decreases when the distance from the charged body is increased.”

Tyndall says (Notes on Lecture VII) that Lord Mahon fused metals and produced strong physiological effects by the return stroke.

In 1781, the English scientist, John Turberville Needham (1713–1781), published at Brussels his French translation of Lord Mahon’s work under the title of “Principes de l’Electricité.” Needham was the first of the Catholic clergy elected to a fellowship of the English Royal Society, to whose Transactions he made several contributions. His numerous works include “A letter from Paris concerning some new electrical experiments made there,” London, 1746, also a volume of researches upon the investigations of Spallanzani. The list of his communications to the Phil. Trans. and to the “Mém. de l’Acad. de Bruxelles” will be found in Watt’s “Bibliotheca Britannica” and in Namur’s “Bibl. Acad. Belge” (“Dict. Nat. Biog.,” Vol. XL. p. 157; Phil. Trans., 1746, p. 247, and Hutton’s abridgments, Vol. IX. p. 263).

References.—“Electrical Researches” of Lord Cavendish, pp. xlvi-xlvii; Phil. Trans. for 1787, Vol. LXXVII. p. 130; Dr. Thomas Young, “Course of Lectures,” London, 1807, Vol. I. p. 664; Dr. Thomas Thomson, “History of the Royal Society,” London, 1812, p. 449; Sturgeon, “Researches,” Bury, 1850, p. 398.

A.D. 1779.—Ingen-housz (Johan), distinguished English physician and natural philosopher, native of Breda, publishes, Phil. Trans., p. 661, an account of the electrical apparatus which is by many believed to have led to the invention of the plate electrical machine, although the same claim has been made in behalf of Jesse Ramsden (at A.D. 1768). Dr. Priestley states that Ingen-housz and Ramsden invented it independently of one another. He describes a circular plate of glass nine inches in diameter turning vertically and rubbing against four cushions, each an inch and a half long and placed at the opposite ends of the vertical diameter. The conductor is a brass tube bearing two horizontal branches extending to within about half an inch of the extremity of the glass, so that each branch takes off the electricity excited by two of the cushions (Dr. Thomas Young, “Course of Lectures,” Vol. II. p. 432).

The plate machine of Dr. Ingen-housz is illustrated at p. 16 of “Electricity” in the “Library of Useful Knowledge.” For other plate machines see, more particularly, Dr. Young’s “Course of Lectures,” Vol. II. p. 431; Phil. Trans. 1769, p. 659; Geo. K. Winter’s apparatus with ring conductor and peculiar-shaped rubbers, as well as the great machine at the Royal Polytechnic, and that of Mr. Snow Harris, illustrated and described in Vol. III. p. 787, “Eng. Ency.—Arts and Sciences,” and at pp. 223, 224 of J. H. Pepper’s “Cyclopædic Science,” London, 1869; “Allg. deutsche Biblioth.,” B. XXIV. Anh. 4, Abth., p. 549, 1760 (Poggendorff, Vol. II. p. 465), relative to the machines of Martin Planta, Ingen-housz and Ramsden; Reiser’s plate machine (Lichtenberg and Voigt’s “Magazin für das Neueste aus der Physik,” Vol. VII. St. 3, p. 73); Ferdinando Elice, “Saggio sull’Elettricita,” Genoa, 1824 (for two electricities); J. J. Metzger’s machine (Elice, “Saggio,” second edition, p. 55); Marchese C. Ridolfi, for a description of Novelluccis’ plate electrical machine (“Bibl. Italiana,” Vol. LXIII. p. 268; “Antologia di Firenze,” for August 1824, p. 159); Robert Hare, “Description of an Electrical Plate Machine,” London, 1823 (Phil. Mag., Vol. LXII. p. 8). See, besides, the machines of Bertholon (rubber in motion) in Lichtenberg and Voigt’s “Magazin,” Vol. I. p. 92 and Rozier XVI. p. 74; of Brilhac (Rozier, XV. p. 377); of Saint Julien (Rozier, XXXIII. p. 367); of Van Marum (Rozier, XXXVIII. p. 447).

Dr. Ingen-housz also constructed a small magnet, of several laminæ of magnetised steel firmly pressed together, capable of sustaining one hundred and fifty times its own weight, and he found that pastes into the composition of which the powder of the natural magnet entered were much superior to those made with the powder of iron; the natural magnet, he observed, having more coercitive force than iron.

References.—Journal de Physique for February 1786, and for May 1788, containing the letters of Dr. Ingen-housz, which show that the vegetation of plants is in no sensible degree either promoted or retarded by common electricity. An account is also given of his experiments in “Versuche mit Plantzen,” Vienna, 1778, in the “Catalogue of the Royal Society,” p. 313, in “Goth. Mag.,” Vol. V. iii. 13; Rozier, XXXII. p. 321; XXXIV. p. 436; XXXV. p. 81; Journal de Physique, Vol. XXXV for 1789. See also, Journal de Physique, XLV (II), 458; Rozier, XXVIII. p. 81; M. Nuneberg, “Osservazioni ...” Milano, 1776 (“Scelta d’Opuscoli,” XVII. p. 113); Pietro Moscati, “Lettera ...” Milano, 1781 (“Opus Scelti,” IV. p. 410); H. B. de Saussure (Journal de Physique, Vol. XXV for 1784); G. da San Martino, “Memoria ...” Vicenza, 1785; M. Schwenkenhardt, “Von dem Einfluss ...” (Rozier, XXVII. p. 462; Journal de Physique for 1786, Vol. I); A. M. Vassalli-Eandi in the “Mem. della Soc. Agr. di Torino,” Vol. I for 1786, particularly regarding the experiments of Ingen-housz and Schwenkenhardt; also in the “Giornale Sc. d’una Soc. Fil. di Torino,” Vol. III; N. Rouland, “Elec. appliquée aux vegétaux” (Journal de Physique, 1789–1790); Ingen-housz, Rouland, Dormoy, Bertholon and Derozières (Rozier, XXXV. pp. 3, 161, 401; XXXVIII. pp. 351, 427, and in Journal de Physique, Vols. XXXII, XXXV, XXXVIII); M. Carmoy, on the effects of electricity upon vegetation, in Rozier, XXXIII. p. 339; Jour. de Physique 1788, Vol. XXXIII; M. Féburier, “Mémoire sur quelques propriétés ...”; G. R. Treviranus, “Einfluss ...” Kiel, 1800 (Gilbert’s Annalen, Vol. VII for 1801 and “Nordisches Arch. f. Nat. u. Arzneiw.,” 1st Band, 2tes Stück); C. G. Rafn (“Mag. Encyclopédique,” No. 19, Ventose An. X. p. 370), Paris, 1802; J. P. Gasc, “Mémoire sur l’influence ...” Paris, 1823; E. Solly, “On the influence ...” London, 1845 (“Journ. of the Hortic. Society,” Vol. I. part ii.); E. Romershausen, “Galv. El. ... Vegetation,” Marburg, 1851; M. Menon, “Influence de l’électricité sur la végétation,” and his letters to R. A. F. de Réaumur. Consult likewise J. Browning’s letter to H. Baker, Dec. 11, 1746 (Phil. Trans. for 1747, Vol. XLIV. p. 373); G. Wallerius, “Versuch ...” Hamb. and Leipzig, 1754; (“K. Schwed. Akad. Abh.,” XVI. p. 257; also “Vetensk Acad. Handl.,” 1754;) L. F. Kamtz (Kaemtz), “Über d. Elek ...” Nürnberg, 1829; (Schweigger’s Journal f. Chemie u. Physik, Vol. LVI;) Bartolomeo Zanon, “Intorno un punto ...” Belluno, 1840; Francesco Zantedeschi “Dell influsso ...” Venezia, 1843; (“Mem. dell Instit. Veneto,” I. p. 269;) E. F. Wartmann, “Note sur les courants ...” Genève, 1850; (“Bibl. Univ. de Genève,” for Dec. 1850;) T. Pine, “Connection between Electricity and Vegetation,” London, 1840; (“Annals of Electricity,” Vol. IV. p. 421.) For the effects of galvanism on plants, see Giulio in “Bibl. Ital.,” Vol. I. p. 28; also E. J. Schmuck “On the Action of Galvanic Electricity on the Mimosa Pudica,” and M. Rinklake, as well as Johann W. Ritter, “Elektrische versuche an der Mimosa Pudica.” For an account of M. P. Poggioli’s observations on the influence of the magnetic rays on vegetation, and the reply of F. Orioli thereto, see Vol. I of the “Nuova collezione d’opuscoli scientifici ...” Bologna, 1817. Dr. Thomas Young’s “Course of Lectures,” Vol. II. pp. 432–433; N. K. Molitor’s “John Ingen-housz. Anfangsgrunde ...” 1781; Geo. Adams, “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. I. pp. 512–515; John Senebier, “Expériences,” etc., 1st and 2nd Memoirs, Genève and Paris, 1788; Becquerel in the Comptes Rendus for November 1850, also Tome XXXI. p. 633; M. Buff (Phil. Mag. N. S. Vol. VII. p. 122); Priestley’s “History ...” 1775, p. 487; Walsh at A.D. 1773; Cavallo’s “Exper. Philosophy,” 1803, Vol. III. p. 357; Pouillet (Poggendorff’s Annalen, Vol. XI. p. 430); Reiss, in Poggendorff’s Annalen, Vol. LXXIX. p. 288; G. F. Gardini, “De inflvxu ...” s. 7, p. 10; Philosophical Transactions for 1775, 1778, p. 1022; 1779, p. 537; Journal de Physique, Vol. XVI for 1780; “Erxleben’s phys. bibliothek,” s. 530; papers relative to the effects of electricity upon vegetation alluded to in “Le Moniteur Scientifique,” more particularly at pp. 904, 907, 1026, Vol. XX for 1878, and at p. 23, Vol. XXI for 1879.

A.D. 1780.—Spallanzani (Lazaro), celebrated Italian naturalist, to whom the French Republic vainly offered the Professorship of Natural History at the Paris Jardin des Plantes, and who has been already particularly alluded to in connection with John Walsh, at A.D. 1773, writes a second treatise upon the operations of Charles Bonnet, of Geneva, as regards the effects of electricity upon nerves and muscles. He is also the author of works upon electrical fishes as well as upon meteors, etc., which will be found detailed in Vol. VII of the “Biographie Médicale,” as well as at Vol. XLIII. p. 246, of the “Biographie Universelle.”

References.—Alibert’s Eloge in Vol. III of the “Mém. de la Soc. Médicale d’Emulation”; “Catal. Roy. Soc. Sc. Papers,” Vol. V. p. 767; “Opus. Scelti,” Vols. VII. pp. 340, 361; VIII. p. 3; XIV. pp. 145, 296; Brugnatelli, “Ann. di chimica” for 1793 and 1795; “Mem. Soc. Ital.,” Vols. II. p. 11; IV. p. 476.

A.D. 1780–1781.—Bertholon de Saint Lazare (Pierre), French physician and Professor of Natural Philosophy, and a great friend of Dr. Franklin, publishes at Paris his “Electricité du Corps Humain ...” in which he relates more particularly his general observations upon atmospheric electricity as affecting the human body while in a healthy state and while in a diseased condition. He likewise treats of the effects of electricity upon animals, and details very interesting experiments upon the torpedo, which latter, he remarks, establishes the closest possible resemblance to the Leyden phial.

He is also the author of “Electricité des Végétaux” (1783), as well as of “Electricité des Météores” (1787), and of a volume entitled “Electricité des Métaux.” J. C. Poggendorff says (“Biog.-Lit. Handw. ...” Vol. II. p. 102) that J. Ferd. Meidinger (1726–1777) had previously written concerning the action of electric fire upon metals and minerals. Johann Jacob Hemmer published, at Mannheim in 1780, “Sur l’Electricité des Métaux” (“Ob. sur la Physique,” July 1780, p. 50), and A. A. De La Rive wrote in 1853 “De l’Elect. Développée ...” (“Bibl. Univ.,” Vol. LIX).

References.—Young’s “Course of Lectures,” Vol. II. p. 431; Ingen-housz at A.D. 1779; Journal de Physique, Vol. XXXV; “Biographie Universelle,” Vol. IV. p. 149; “Biographie Générale,” Vol. V. p. 722; Larousse, “Dict. Univ.,” Vol. II. p. 618; “La Grande Encyclopédie,” Vol. VI. p. 450. See also Bertholon’s “Nouvelles Preuves ...” pp. 18–19; Arago, “Notices Scientifiques,” Vol. I. pp. 338–340, 386; “Mercure de France,” 1782, No. 52, p. 188; Abbé d’Everlange de Wittry, “Mém. sur l’Elec. ... dans les végétaux et le corps humain,” read June 24, 1773—“Anc. Mém. de l’Acad. Belge,” Vol. I. p. 181; Vassalli-Eandi, “Esame della Elett. delle Meteore del Bertholon,” Torino, 1787; account of the experiments to ascertain the effects of electricity on vegetation, made in France during the summer of 1878 by MM. Grandeau, Celi and Leclerc; and a curious publication, “Les Animaux et les Métaux deviennent ils Electriques par communication,” by L. Béraud (Bérault), alluded to in Poggendorff, Vol. I. p. 146.

A.D. 1780–1783.—Prof. Samuel Williams, at Cambridge, Mass., makes the earliest known observations of the magnetic dip in the United States, and publishes them in the “Memoirs of the American Academy of Arts,” Vol. I. pp. 62, 68. According to this authority, the dip in 1783 was 69° 41’. The next dip observations are those made during Long’s expedition to the Rocky Mountains in 1819.

References.—“American Journal of Science,” Vol. XLIII. pp. 93, 94; “Trans. Amer. Phil. Soc.,” O. S., Vol. III. p. 115.

A.D. 1780–1794.—Le Père Amyot (Amiot), learned French Jesuit, who was sent in 1751 as a missionary to Pekin, where he resided till his decease in 1794, writes, on the 26th of July 1780, and also on the 20th of October 1782 that, as a result of a great number of observations, he finds no change in the variation of the magnetic needle, i. e. that “the point which indicates the north declines westerly from 2 to 2½ degrees, rarely more than 4½ degrees, and never less than 2 degrees.”

References.—“Mémoires concernant l’histoire,” etc., Saillant et Nyon, Vol. X. p. 142; Davis, “The Chinese,” Vol. III. p. 13.

A.D. 1781.—The so-called compass plant (Silphium lancinatum) is first introduced from America into Europe by M. Thouin and blooms for the first time in the Botanic Gardens of Upsala, Sweden.

In the “Scientific American” of February 26, 1881, reference is made to the interesting account of this plant given by Sir J. D. Hooker in Curtis’ “Botanical Magazine,” as well as to the following extract from Prof. Asa Gray’s report concerning it: “The first announcement of the tendency of the leaves of the compass plant to direct their edges to the north and south was made by General (then Lieutenant) Alvord, of the U.S. Army, during the year 1842, and again in 1844, in communications to the American Association for the Advancement of Science.... The lines in “Evangeline” (familiar to many readers):

“Look at this delicate plant that lifts its head from the meadow,

See how its leaves all point to the north as true as the magnet;

It is the compass plant that the finger of God has suspended,

Here on its fragile stalk, to direct the traveller’s journey,

Over the sealike, pathless, limitless waste of the desert——”

were inspired through a personal communication made by General Alvord to the poet Longfellow.

In this connection, the following article, headed “A Wonderful Magnetic Plant,” translated from La Nature by the London Court Journal, will prove interesting: “There has been discovered in the forests of India a strange plant (Philotacea electrica) which possesses to a very high degree astonishing magnetic power. The hand which breaks a leaf from it receives immediately a shock equal to that which is produced by the conductor of an induction coil. At a distance of six metres a magnetic needle is affected by it, and it will be quite deranged if brought near. The energy of this singular influence varies with the hours of the day. All powerful about two o’clock in the afternoon, it is absolutely annulled during the night. At times of storm its intensity augments to striking proportions. While it rains the plant seems to succumb: it bends its head during a thunder-shower and remains without force or virtue even if one should shelter it with an umbrella. No shock is felt at that time in breaking the leaves, and the needle is unaffected by it. One never by any chance sees a bird or insect alight on this electric plant; an instinct seems to warn them that in so doing they would find sudden death. It is also important to remark that where it grows none of the magnetic metals are found, neither iron, nor cobalt, nor nickel—an undeniable proof that the electric force belongs exclusively to the plant. Light and heat, phosphorescence, magnetism, electricity, how many mysteries and botanical problems does this wondrous Indian plant conceal within its leaf and flower!”

The results of some interesting researches on plant-electricity have been reported by A. D. Waller, who finds that whenever a plant is wounded, a positive electric current is established between the wounded part and the intact parts. This may start with an electromotive force of 0·1 volt, but it afterward diminishes. He writes further:

“Actual wounding is not necessary to obtain this manifestation; an electro-positive current is set up when there is mechanical excitation, but it is much weaker (0·02 volt). And light acts like mechanical excitation with certain plants, such as the leaves of the iris, of tobacco, of the begonia, etc. From the illuminated to the darkened part flows a positive electric current that may be as strong as 0·02 volt. A similar reaction in the petals is not always observed. There is a certain correlation between the vigour of a plant and the electric reaction. The more vigorous the plant is, the stronger the current. Plants grown from fresh seeds give a more powerful current than those from old seeds. A bean a year old gave a current of 0·0170 volt; one five years old, a current of 0·0014; and the reaction is inversely and regularly proportional to the age of the seed from which the plant springs. There is observed in vegetable tissues, subjected to an excitation of the same intensity at regular intervals, the characteristic changes of reaction that are present in animal tissues—fatigue, recuperation, etc. Temperature plays a part in all these phenomena; below -4° to -6° C. [+° to + 25° F.] and above 40° C. [108° F.] there is no reaction.”

A.D. 1781.—Lavoisier (Antoine Laurent), an eminent French natural philosopher, the chief founder of modern chemistry as well as of the prevailing system of chemical nomenclature which ended in the expulsion of the phlogistic theory, demonstrates by experiments made in conjunction with Volta and Laplace that electricity is developed when solid or fluid bodies pass into the gaseous state. Sir David Brewster says that the bodies to be evaporated or dissolved were placed upon an insulating stand and were made to communicate by a chain or wire with a Cavallo electrometer, or with Volta’s condenser, when it was suspected that the electricity increased gradually. When sulphuric acid, diluted with three parts of water, was poured upon iron filings, inflammable air was disengaged with a brisk effervescence; and, at the end of a few minutes, the condenser was so highly charged as to yield a strong spark of negative electricity. Similar results were obtained when charcoal was burnt on a chafing dish, or when fixed air or nitrous gas was generated from powdered chalk by means of the sulphuric and nitrous acids.

The phlogistic theory alluded to above, which was so named by George Ernest Stahl in 1697 after Johann Joachim Beccher (1635–1682) had pointed out its principle in 1669, had for its most energetic defender the editor of the Journal de Physique, M. J. C. De La Méthérie, who is entered at A.D. 1785, and it was in order to offset the influence which this gave him that the antiphlogistians established the Annales de Chimie, so frequently mentioned in these pages.[52]

References.—George Adams’ “Lectures on Nat. and Exp. Philosophy,” London, 1799, Vol. I. pp. 575–587, wherein Lavoisier’s system is confuted by the German chemist Wieglib, whose views are endorsed by Mr. Green, while for Stahl and Beccher, refer to Sir H. Davy, “Bakerian Lectures,” London, 1840, p. 102, note, to “Biog. Gén.,” Vol. V. pp. 85–87; “Meyer’s Konvers. Lexikon,” Vol. II. p. 654, and to Thomson’s “Hist. of Roy. Soc.,” London, 1812, p. 467. See also J. M. G. Beseke, “Ueber elementärfeuer ...” Leipzig, 1786; G. A. Kohlreif, “Sollte die elektricität ...” Weimar, 1787; Lavoisier and Laplace, in the “Mém. de l’Acad. Roy. des Sciences” for 1781, p. 292; Lavoisier’s “Opuscules ...” 1774, and his “Rapport ... mag. animal.,” Paris, 1784; Dr. Thomas Thomson, “Hist. Roy. Soc.,” pp. 479–486; Herschel’s “Nat. Phil.,” concerning the third age of chemistry; Grégoire, “Dict. d’hist.,” etc., p. 1171; Miller’s “Hist. Phil. Illus.,” London, 1849, Vol. IV. pp. 332–333, notes. Chap. IV of the “History of Chemistry,” Ernst Van Meyer, tr. by George McGowan, London, 1898, entitled “History of the Period of the Phlogiston Theory from Boyle to Lavoisier,” will prove interesting. “La chimie constituée par Lavoisier,” Jacob Volhard, in “Le Moniteur Scientifique,” du Dr. Quesneville, Vol. XIV for 1872, pp. 50–71; “Nouveau Larousse,” Vol. V. p. 608; “La Révolution chimique,” M. Berthelot, Paris, 1890; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 87, 110; “Journal des Savants” for Nov. 1859 and Feb. 1890; “Lives of Men of Letters and Science,” by Henry, Lord Brougham, Philadelphia, 1846, pp. 140–166.

A.D. 1781.—Achard (Franz Carl), able chemist and experimental philosopher, born in Prussia but of French extraction, communicates to the “Mém. de Berlin” a report of many very interesting experiments made by him, which are reviewed by Prince Dmitri Alexewitsch Fürst Gallitzin, in Vol. XXII of the Journal de Physique.

He had previously published essays upon the electricity of ice and the electricity developed on the surface of bodies, as well as upon terrestrial magnetism, the electrophorus, etc. He made many notable investigations to prove that fermentation is checked by electricity and that putrefaction is hastened both in electrified meats and in animals killed by the electric shock.

One of his experiments illustrating galvanic irritation so greatly interested Humboldt that the latter repeated it with different animals, not doubting but small birds might in many cases be brought back to life when they fall into a state somewhat resembling death. On one occasion, he took a linnet about to expire and, having established the necessary communication, perceived, the moment the contact took place, that the linnet opened its eyes, stood erect upon its feet and fluttered its wings; it breathed, he says, during six or eight minutes and then expired tranquilly.

It was a namesake of Achard who invented the electro-magnetic brake which will be found described and illustrated in articles from the London Engineer and Engineering, reproduced through the Scientific American Supplements, No. 111, p. 1760, and No. 312, p. 4974.

References.—Poggendorff, “Biog.-Lit. Hand. ...” Vol. I. p. 7; “Biographie Générale,” Vol. I. p. 176; “Cat. Roy. Soc. Sc. Papers,” Vol. I. p. 9; “Opus. Scelt.,” Vols. III. p. 313; V. p. 351; VI. p. 199; Reuss, Repertorium, Vol. IV. p. 351; Dr. G. Gregory, “Economy of Nature,” London, 1804, Vol. I. p. 317; Van Swinden, “Recueil ...” La Haye, 1784, Vol. I. p. 24; “Biographie Universelle,” Vol. I. p. 114; “Journal Lit. de Berlin,” for 1776; Cavallo, London, 1777, p. 403; “Mém. de Berlin” for 1776–1780, 1786, 1790–1791; Sturgeon, “Lectures,” London, 1842, p. 12; Geo. Adams, “Essay on Electricity,” etc., London, 1785, pp. 214–220, 277; “Gött. Mag.,” Vol. II. ii. 139; Rozier, VIII. p. 364; XV. p. 117; XIX. p. 417; XXII. p. 245; XXIII. p. 282; XXV. p. 429; XXVI. p. 378; Phil. Mag., Vol. III. p. 51.

A.D. 1781.—Kirwan (Richard), LL.D., F.R.S., an Irish chemical philosopher of great eminence, who became President of the Dublin Society and of the Royal Irish Academy, receives from the English Royal Society its gold Copley medal for the many valuable scientific papers communicated by him to the latter body. These papers embrace his “Thoughts on Magnetism,” wherein he treats at length of attraction, repulsion, polarity, etc., as shown in the review given at pp. 346–353 of the eighth volume of Sturgeon’s “Annals of Electricity,” etc.

It is said that Kirwan first suggested the notion of molecular magnets, but, according to Dr. J. G. M’Kendrick, it was not till a definite form was given thereto by Weber that it acquired any importance.

References.—Transactions Royal Irish Academy, Vol. VI; Ninth “Encycl. Britannica,” Vol. XV. p. 276; Phil. Mag., Vol. XXXIV. p. 247; Thomson, “Hist. of the Roy. Soc.,” p. 483; “Bibl. Britan.,” An. VII. vol. xii. p. 105.

A.D. 1781.—Mauduyt (Antoine René) (1731–1815), Professor at the Collège de France, publishes several observations from which he concludes that the application of electricity is favourable in cases of paralysis. He was in the habit of placing the patient upon an insulated stool, in communication with the conductor of an electrical machine. De La Rive, who mentions the fact (“Electricity,” Chap. III. pp. 586, 587), observes that the effect, if any, could only proceed from the escape of electricity into the air.

References.—Bertholon, Elec. du Corps. Humain, 1786, Vol. I. pp. 275–276, 302, 439, 447, etc., and Vol. II. pp. 7 and 296; “Mémoire sur les différentes manières d’administrer l’électricité,” etc., Paris, 1784; “Recueil sur l’électricité médicale,” etc., containing articles by G. F. Bianchini, De Lassoné, Deshais (see Sauvages), Dufay, Jallabert, Pivati, Quellmalz, Veratti, Zetzell, etc.; K. G. Kuhn’s works published at Leipzig, 1783–1797; E. Ducretet in “Le Cosmos,” Paris, Oct. 3, 1891, pp. 269–272; P. Sue, aîné, “Hist. du Galvan,” Paris, An. X-XIII, 1802, Vol. I. p. 40; and Vol. II. p. 382; “Grande Encyclop.,” Vol. XXIII. p. 415.

A.D. 1781–1783.—Don Gauthey—Gauthier or Gualtier—a monk of the Order of Citeaux, improved upon the invention of Dupuis (at A.D. 1778) and constructed a telegraph, which he submitted at the Académie des Sciences to Dr. Franklin as well as to Condorcet and De Milly, by whom it was recommended to the French Government. In his prospectus, published during 1783, he relates that he has discovered a new mode of rapid transmission enabling him to convey intelligence and sound, by means of water pipes, a distance of fifty leagues in fifty minutes. Ternant, who states this at pp. 33 and 34 of Le Télégraphe, Paris, 1881, adds that, as no action was taken at the time upon the prospectus, it doubtless still lies in the archives of the Academy.

References.—Laurencin, Le Télégraphe, p. 9; Eng. Cycl., “Arts and Sciences,” Vol. VIII. p. 65; “Penny Cycl.,” 1842, Vol. IV. p. 146.

A.D. 1782.—Nairne (Edward), an English mathematical instrument maker, publishes papers on electricity describing his invention of a cylinder machine which is illustrated and described at p. 15 of the chapter on “Electricity” in “Library of Useful Knowledge,” 1829. In this, as has been truly said, are seen all the essential parts of the frictional apparatus now in use.

This machine, according to Cuthbertson, was originally constructed in 1774, and was far more powerful than any before made. Nairne also constructed the largest battery known up to that time. It contained 50 square feet of coated surface, and it could be given so high a charge as to ignite 45 inches of iron wire ¹⁄₁₅₀ of an inch diameter, which up to that period was the greatest length of wire ever ignited. Nairne, while improving upon some of Priestley’s experiments, found that a piece of hard drawn iron wire, ten inches long and one-hundredth of an inch diameter, after receiving successively the discharge of 26 feet of coated glass (nine jars), was shortened three-fortieths of an inch by such discharge. Dr. Priestley had previously observed that a chain 28 inches long was shortened one quarter of an inch after having had transmitted through it a charge of 64 square feet of coated glass, and Brooke Taylor found that by passing a charge of nine bottles of 16 feet of coated surface nine times in succession through a steel wire 12 inches long and one one-hundredth of an inch diameter, the wire was shortened one and one-half inches, or one-eighth its entire length.

To Nairne was granted the third English patent in the Class of Electricity and Magnetism, the first having been issued to Gowin Knight in 1766 (see A.D. 1746) and the second to Gabriel Wright, June 25, 1779, for “a new constructed azimuth and amplitude compass.” Knight subsequently covered other similar inventions, July 5, 1791, and Jan. 19, 1796. Nairne’s patent bears date Feb. 5, 1782, No. 1318, and is for what he calls “The Insulated Medical Electrical Machine,” the conductors of which are so arranged as to readily give either shocks or sparks. He says that “by means of the conductors and jointed tubes, the human body can be in any part affected with either kind of electricity in any convenient manner.”

References.—Philosophical Transactions for 1772, 1774, 1778, 1780, 1783, Vol. LXIV. p. 79; Vol. LXVIII. p. 823; Vol. LXX. p. 334; also Hutton’s abridgments, Vol. XIII. pp. 360 (dipping needle), 498; Vol. XIV. pp. 427–446, 688; Vol. XV. p. 388; “General Biog. Dict.,” London, 1833, by John Gorton, Vol. I. (n. p.); Cuthbertson, “Practical Electricity,” London, 1807, pp. 165–168; article “Electricity,” in the “Encycl. Britannica”; “Description of ... Nairne’s ... Machine,” London, 1783 and 1787; Caullet de Veaumorel, “Description de la machine électrique négative et positive de Mr. Nairne,” Paris, 1784; Delaunay’s “Manuel,” etc., Paris, 1809, pp. 7, 12–14.

A.D. 1782–1783.—Linguet (Simon, Nicolas, Henri), French advocate (1736–1794), who was an associate of Mallet du Pan in the preparation of the Annales Politiques and who was later on committed to the Bastille in consequence of a visit which he imprudently made to Paris, writes a letter to the French Ministry proposing a novel method of transmitting messages of any length or description by means of some kind of a telegraph, “nearly as rapidly as the imagination can conceive them.” He adds, “I am persuaded that in time it will become the most useful instrument of commerce for all correspondence of that kind; just as electricity will be the most powerful agent of medicine; and as the fire-pump will be the principle of all mechanic processes which require, or are to communicate, great force.”

To Linguet has been attributed the authorship of the anonymous letter which appeared in the Journal de Paris of May 30, 1782, and in Le Mercure de France of June 8, 1782, wherein it is proposed to employ twenty-four pairs of gilt wires, placed underground in separate wooden tubes filled with resin and bearing a knob at each extremity. Between each pair of knobs was to be placed a letter of the alphabet, which would become discernible whenever the electric spark was passed through the wire by means of the Leyden phial.

References.—Ternant, Le Télégraphe, Paris, 1881, p. 11; Linguet, “Mém. manuscrit ... signaux par la lumière,” Paris, 1782; all about the “Mercure de France,” in “Bulletin du Bibliophile” No. 7 of July 15, 1902; “Biog. Dict.,” Alex Chalmers, 1815, Vol. XX. p. 290; “Nouv. Biog. Gén.” (Hœfer), Paris, 1860, Vol. XXXI. p. 279; “Biog. Univ.” (Michaud), Vol. XXIV. p. 565.

A.D. 1782–1791.—Cassini (Jean Jacques Dominique, Comte de), son of Cassini de Thury, eminent astronomer, makes the very important announcement that, besides the secular variation of the declination, the magnetic needle is subject to an annual periodical fluctuation depending on the position of the sun in reference to the equinoctial and solstitial points.

Cassini’s discovery is contained in a Memoir consisting of two parts, the first part being a letter addressed to L’Abbé Rosier and published by him in the Journal de Physique, while the second part, composed at request of the Académie des Sciences, is that which specially treats of the annual variation in declination.

Besides the last named, we have thus far learned of the secular variation discovered by Gellibrand (Hellibrand) in 1635, as well as of the diurnal and horary variations, first accurately observed by George Graham during the year 1722, and we have likewise been informed of the earliest observations of the dip or inclination, made independently by both Georg Hartmann (A.D. 1543–1544) and by Robert Norman (A.D. 1576), as well as of the determination of the intensity of the inclination by J. C. Borda (at A.D. 1776). For accounts of the secular and annual, as well as of the diurnal and horary variations of the dip, the reader should consult the First Section of Humboldt’s “Cosmos” treating of telluric phenomena and some of the very numerous references therein given.

Speaking of the influence of the sun’s position upon the manifestation of the magnetic force of the earth, Humboldt remarks that the most distinct intimation of this relation was afforded by the discovery of horary variations, although it had been obscurely perceived by Kepler, who surmised that all the axes of the planets were magnetically directed toward one portion of the universe. He says that the sun may be a magnetic body, and that on that account the force which impels the planets may be centred in the sun (Kepler, in “Stella Martis,” pp. 32–34—compare with it his treatise, “Mysterium Cosmogr.,” cap. 20, p. 71). He further observes that the horary variations of the declination, which, although dependent upon true time are apparently governed by the sun as long as it remains above the horizon, diminish in angular value with the magnetic latitude of place. Near the equator, for instance, in the island of Rawak, they scarcely amount to three or four minutes, whilst the variations are from thirteen to fourteen minutes in the middle of Europe. As in the whole northern hemisphere the north point of the needle moves from east to west on an average from 8½ in the morning until 1½ at midday, in the southern hemisphere the same north point moves from west to east (Arago, Annuaire, 1836, p. 284, and 1840, pp. 330–358). Attention has been drawn, with much justice, to the fact that there must be a region of the earth, between the terrestrial and the magnetic equator, where no horary deviations in the declination are to be observed. This fourth curve (in contradistinction to the isodynamic, isoclinic and isogonic lines, or those respectively of equal force, equal inclination and equal declination), which might be called the curve of no motion, or rather the line of no variation of horary declination, has not yet been discovered. No point has hitherto been found at which the needle does not exhibit a horary motion, and, since the erection of magnetic stations, the important and very unexpected fact has been evolved that there are places in the southern magnetic hemisphere at which the horary variations of the dipping needle alternately participate in the phenomena (types) of the hemispheres.

Humboldt also alludes, in the article on “Magnetic Variation,” to his recognition of the “four motions of the needle, constituting, as it were, four periods of magnetic ebbing and flowing, analogous to the barometrical periods,” which will be found recorded in Hansteen’s “Magnetismus der Erde,” 1819, s. 459, and he likewise refers to the long-disregarded nocturnal alterations of variation, for which he calls attention to Faraday “On the Night Episode,” ss. 3012–3024. (See also, Poggendorff’s Annalen der Physik, Bd. XV. s. 330, and Bd. XIX. s. 373.)

The Phil. Trans. for 1738, p. 395, contain the description of a new compass for ascertaining the variation “with greater ease and exactness than any ever yet contrived for that purpose.” This was devised by Capt. Christopher Middleton, whose many interesting observations are to be found in the same volume of the Phil. Trans., p. 310, as well as in the volumes for 1726, p. 73; 1731–1732, 1733–1734, p. 127; 1742, p. 157, and in John Martyn’s abridgment, Vol. VIII. part i. p. 374. Reference should also be made to the volumes for 1754 (p. 875) and 1757 (p. 329), giving the reports of W. Mountaine and J. Dodson upon the magnetic chart and tables of 50,000 observations, likewise to the volume for 1766 containing the report of W. Mountaine on Robert Douglass’ observation, as well as for the record of investigations of the variation made by David Ross on board the ship “Montagu” during the years 1760–1762.

References.—Sabine, “On the Annual and Diurnal Variations” in Vol. II of “Observations made ... at Toronto,” pp. xvii-xx, also his Memoir “On the Annual Variation of the Magnetic Needle at Different Periods of the Day,” in Phil. Trans. for 1851, Part II. p. 635, as well as the Introduction to his “Observations ... at Hobart Town,” Vol. I. pp. xxxiv-xxxvi, and his Report to the British Association at Liverpool, 1854, p. 11—Phil. Trans. for 1857, Art. 1, pp. 6, 7—relative to the lunar diurnal magnetic variation. See likewise C. Wolf, “Histoire de l’observatoire depuis sa fondation à 1793”; Houzeau et Lancaster, “Bibl. Gen.,” Vol. II. p. 102; “Mém. de Paris,” Vol. II. p. 74, and Vol. VII. pp. 503, 530; Walker, “Ter. and Cos. Magn.,” Chap. III; Mme. J. Le Breton, “Histoire et Applic.,” etc., Paris, 1884, p. 17; Robison, “Mech. Phil.,” Vol. IV. p. 356; Thos. Young, “Nat. Phil.,” 1845, p. 583.