Bibliographical history of electricity & magnetism, chronologically arranged

by Unknown

Bernoulli Family

The Bernoulli family is as well known in the history of mathematics, by the distinguished services of eight of its members, as is the Cassini family through the successes achieved by four of its representatives in the development of astronomical studies.

Daniel Bernoulli (1700–1782), second son of John I, constructed a dipping needle, which is described on p. 85 of the Eighth “Britannica,” Vol. XIV, and with which he observed the dip to diminish half a degree during an earthquake in the year 1767. Before Daniel was twenty-four years old he had declined the Presidency of the Academy of Sciences at Genoa, and, at the age of twenty-five, was appointed Professor of Mathematics at St. Petersburg.

John Bernoulli II (1710–1790), youngest of the three sons of John I, gained three prizes from the French Academy of Sciences for Memoirs on the Capstan, on the Propagation of Light and on the Magnet.

John Bernoulli III (1744–1807), grandson of John I, took the degree of Doctor of Philosophy at the age of thirteen, and, when nineteen years old, was appointed Astronomer Royal of Berlin. He published several volumes of travels, in one of which he relates (A. L. Ternant, “Le Télégraphe,” 1881, p. 32) that he saw, in the last-named city, an instrument constructed of five bells, with which all letters of the alphabet could be expressed.

James Bernoulli I (1654–1705), brother of John I, while at London, was introduced into the philosophical meetings of Boyle, Hooke, Edward Stillingfleet and other learned and scientific men. He opened, in 1682, the Collegium Experimentale Physico-Mechanicum for public instruction, but his lasting fame dates from the year 1684, when the great Von Leibnitz published his treatise “De Gravitate Ætheris.” Three years later, in 1687, James occupied the mathematical chair of the University of Basel, made vacant by the death of the learned Megerlin.

References.—Whewell, “Hist. of the Inductive Sciences,” 1859, Vol. I. pp. 358–366, 375–380, 393, 430, and Vol. II. pp. 32–39, 42; “Hist. de l’Acad. Royale des Sciences,” 1700–1707; Edin. “Encycl.,” 1813, Vol. III. pp. 464–470; “Med. Library and Historical Journal,” New York, 1903, Vol. I. pp. 270–277.

For Bernoulli family see “Histoire des Sc. Math. et Phys.,” Maxim. Marie, Paris, 1888, Vols. VII-XI; “Geschichte der Mathemathik,” Moritz Canton, Leipzig, 1898, Vol. III. pp. 207–261; “Histoire Générale des Mathématiques,” Chas. Bossut, Paris, 1810, Vol. II. s. 2, as at table, p. 512. See the family tree in “Eng. Cycl.,” Vol. VI. p. 972, and all the Bernoullis at p. 84 of Vol. II, Houzeau et Lancaster’s “Bibl. Gén.,” 1882.

A.D. 1700.—Morgagni (Giovanni Battista), while practising medicine at Bologna and at Venice, uses the magnet to remove particles of iron which had accidentally fallen into the eyes, exactly in the same manner as Kirkringius and Fabricius Hildanus had done before him.

References.—Maunder’s “Biog. Treasury”; also Beckmann’s “History of Inventions,” Vol. I. p. 44, and biography in Larousse, Vol. XI, as well as in Vol. XVI of the Ninth “Britannica.”

A.D. 1700.—Duverney (Joseph Guichard), an eminent French anatomist, knew at this date that the limbs of a frog are convulsed by the electric current (as shown in the “Histoire de l’Académie des Sciences,” 1700, p. 40, and 1742, vol. I. p. 187), and the Italian physician L. Marco Antonio Caldani, assistant to Morgagni, alludes to the “revival of frogs by electrical discharges.”

References.—“Ency. Metrop.,” Vol. IV. p. 220; Highton’s “Elect. Tel.”; Fahie, “Hist. of Elec. Tel.,” pp. 175 and 176 and notes; Knight’s “Mech. Dict.,” Vol. II. p. 936; G. H. Browne, London, 1704, and in “Phil. Mag.,” Vol. XVIII. p. 285, also note p. 83 of Ronalds’ “Catalogue.”

A.D. 1701–1702.—Le Brun (Pierre), French theologian (1661–1729), publishes his “Histoire Critique des Pratiques Superstitieuses,” wherein he makes mention (Vol. I. p. 294) of the possibility of transmitting intelligence in the manner indicated by the Jesuit Leurechon.

He is also the author of “Lettres qui découvrent l’illusion des philosophes sur la baguette divinatoire,” Paris, 1693 (Larousse’s “Dictionnaire,” Tome X. p. 292).

A.D. 1702.—Bion (Nicolas), French engineer and manufacturer of mathematical and astronomical instruments (1652–1733), is the author of “Usage des Astrolabes,” which was shortly after followed by his well-known “Traité de la construction et des principaux usages des instruments de mathématique.” In the preparation of the last named, which was translated into German (Leipzig, 1713, Nuremberg, 1721) as well as into English (London, 1723, 1738), Bion admits the assistance afforded him by Lahire, Cassini and Delisle the younger.

The whole of Book VII (pp. 267–290) of the “Traité,” is devoted to the description of instruments employed in navigation, the compass and the astrolabe in particular, with instructions for ascertaining the declination and variation.

Bion is also the author of “L’Usage des Globes Célestes et Terrestres et des sphères suivant les differents systèmes du monde,” Amsterdam, 1700. Much of the matter, however, is said to have been copied by Bion from Pierre Polinière’s “Expériences de Phisique,” of which latter five editions were printed respectively in 1709, 1718, 1728, 1734 and 1741.

References.—“La Grande Encycl.,” Vol. VI. p. 897; Michaud, “Biog. Univ.,” Vol. IV. p. 354; Dr. J. Thomas, “Univ. Pr. Dict.,” 1886, p. 386.

A.D. 1702.—Marcel (Arnold), Commissioner of the Navy at Arles, publishes a pamphlet dedicated to the King, and entitled “The Art of Making Signals, both by Sea and by Land,” wherein he affirms that he has “communicated frequently at the distance of two leagues (in as short a space of time as a man could write down and form exactly the letters contained in the advice he would communicate), an unexpected piece of news that took up a page in writing.” The particulars of this invention are, however, wanting.

Marcel reports many well-authenticated instances where, as already mentioned by Mæstro Giulio Cæsare (A.D. 1590), iron bars have become temporarily magnetic by position alone.

References.—Snow Harris, “Rudim. Mag.,” I and II. pp. 91, 92; also “Emporium of Arts and Sciences,” 1812, Vol. I. p. 301; Phil. Trans., Vol. XXXVII. p. 294, also the following abridgments: Baddam, Vol. IX, 1745, p. 278; Eames and Martyn, Vol. VI. part. ii. p. 270; Hutton, Vol. VII. p. 540.

A.D. 1702.—Kæmpfer (Engelbrecht), German physician and naturalist (1651–1716), describes in his “Amœnitates Exoticæ,” experiments made by him upon the electric torpedo (Leithead, 1837, Chap. XII). He insists that any person may avoid all sensation of the shock by merely holding the breath while touching the animal. This apparently improbable fact has since been confirmed, however, by many scientists; the accurate observations of Mr. Walsh (A.D. 1773) on the subject, reported in the Phil. Trans. for 1773–1774–1775, claiming especial attention (Larousse, “Dict.,” Vol. IX. p. 1144).

A.D. 1704.—Amontons (Guillaume), an ingenious mechanician and scientist, exhibits before the royal family of France, and before the members of the Académie des Sciences, his system of communicating intelligence between distant points through the agency of magnifying glasses—telescopes. The “Mémoires de l’Académie,” 1698–1705, contain an account of his many scientific productions.

References.—Larousse, “Dict.,” Vol. I. pp. 282–283; Appleton’s “Cyclop.,” Vol. I. p. 432.

A.D. 1705.—Witson (Nicholaes), Burgomaster of Amsterdam, announces at p. 56 of his “Noord en Oost Tartarye,” that the nautical compass was in use by the Coreans in the second half of the seventeenth century.

A.D. 1705.—Hauksbee (Francis), English natural philosopher and Curator of the Royal Society, makes, before the latter, several experiments on the mercurial phosphorus. He shows that a considerable quantity of light can be produced by agitating mercury in partly exhausted as well as in thoroughly exhausted glass vessels. When the mercury is made to break into a shower, flashes of light are seen to start everywhere “in as strange a form as lightning.”

He also showed light in vacuo produced by rubbing amber and by rubbing glass upon woollen. He says (Priestley, “Hist. and Present State of Electricity,” London, 1775, p. 19) that every fresh glass first gave a purple and then a pale light, and that woollen, tinctured with salt or spirits, produced a new, strong and fulgurating light.

Hauksbee constructed a powerful electrical machine wherein the Von Guericke sulphur globe was replaced by one of glass, as had already been done by Sir Isaac Newton (at A.D. 1675). With it he found that upon exhausting the air, whirling the globe rapidly and placing his hand upon the outside, a strong light appeared upon the interior, and that the light would show itself also upon the outside when air was let into the globe (“Physico-Mech. Exp.,” pp. 12, 14, 26, 32, 34).

The machine, which the celebrated mechanician Leupold had constructed at Leipzig for Mr. Wolfius, only differed from the original one made by Hauksbee in that the glass globe turned vertically instead of horizontally.

Other experiments with coated glass globes, globes of sulphur, etc., are detailed in the “Physico-Mech. Exp.,” as indicated at pp. 21–24 the Priestley work above alluded to. At the last-named page he says: “That Mr. Hauksbee, after all, had no clear idea of the distinction of bodies into electrics and non-electrics appears from some of his last experiments, in which he attempted to produce electrical appearances from metals, and from the reasons he gives for his want of success in those attempts.”

Hauksbee also gave some attention to the study of the laws of magnetic force, and the results published in the Phil. Trans., Vol. XXVII. for 1710–1712, p. 506, giving a law of force varying as the sesqui-duplicate ratio of the distances, were subsequently confirmed by Taylor and by Whiston in the Phil. Trans. for 1721 (Noad, “Manual of Elec.,” 1859, p. 579).

References.—Aglave et Boulard, “Lumière Electrique,” Paris, 1882, p. 18; Priestley, “Familiar Intr. to Study of Elec.,” London, 1786, p. 60; Phil. Trans., Vol. XXV. pp. 2327, 2332; Vol. XXVI, 1708–1709, pp. 82–92; Vol. XXIX, 1714–1716, p. 294 (with Brooke Taylor); also the following abridgments: Hutton, Vol. V. pp. 270, 307, 324, 344, 355, 411–416, 452, 509, 528, 696; Jones, Vol. IV. p. 295; Baddam, 1745, Vol. V. pp. 33–37, 41–43, 112, 114–117, 483; Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 430; Chemical News, Vol. II. p. 147; Nicolas Desmarets, “Expériences,” etc., Paris, 1754, in “Recueil des Mémoires de l’Acad. des Sciences.”

A.D. 1705.—Keill (John), M.A., F.R.S., Savilian Professor of Astronomy, is the author of “Introductio ad Veram Physicam, etc.,” of which other editions appeared in 1725, 1739 and 1741, and a good English translation of which was published at Glasgow in 1776.

The last named is entitled “An Introduction to Natural Philosophy, or Lectures in Physics read in the University of Oxford in the Year 1700.” In Lecture VIII he states: “It is certain that the magnetic attractions and directions arise from the structure of parts; for if a loadstone be struck hard enough, so that the position of its internal parts be changed, the loadstone will also be changed. And if a loadstone be put into the fire, insomuch that the internal structure of the parts be changed or wholly destroyed, then it will lose all its former virtue and will scarce differ from other stones.... And what some generally boast of, concerning effluvia, a subtile matter, particles adapted to the pores of the loadstone, etc., does not in the least lead us to a clear and distinct explication of these operations; but notwithstanding all these things, the magnetick virtues must be still reckoned amongst the occult qualities.”

A.D. 1706.—Hartsoeker (Nicolas), Dutch natural philosopher, friend of Christian Huyghens, while Professor of Mathematics at Düsseldorf, writes his “Conjectures Physiques,” four editions of which were published during the three years 1708, 1710 and 1712.

The Tenth Discourse of the Second Book (pp. 140–182) treats of the nature and properties of the loadstone and gives numerous observations concerning magnetical phenomena, which are well illustrated. He says that many ordinary stones have become magnetic after being long exposed to the air, in consequence of iron penetrating them. He believes that the native loadstone is made up of ordinary stone and of iron containing many small bodies through which run magnetic channels; that the latter are held together so strongly as to be disintegrated with difficulty, and that they are filled with a subtile matter which circulates incessantly through and around them.

The First Discourse of the Fourth Book treats of Meteors, and at pp. 91–99 of his “Eclaircissements, ...” published in 1710 he gives further reports of his curious observations on magnetic phenomena.

References.—“Journal des Sçavans,” Vol. XXIV for 1696, pp. 649–656.

For particulars of the very celebrated natural philosopher, Christian Huyghens—Hugenius van Zuglichen (1629–1695) above alluded to, consult: the “Vita Hugenii,” prefixed to his “Opera Varia,” published by Van ’Sgravesande in 1724; “Meyer’s Konversations-Lexikon,” Leipzig und Wien, 1895, Vol. IX. pp. 93–94, also the biography, embracing a detailed list of his geometrical, mechanical, astronomical and optical works at pp. 536–538 of the “English Cyclopædia”; Vol. II. of Houzeau et Lancaster, “Bibliog. Générale,” p. 169; “Le Journal des Savants” for May 1834, April 1846, July 1888, April 1896, Feb. 1898, Oct. 1899; “Histoire des Sciences Math. et Phys.,” Maximilien Marie, Paris, 1888, Vol. V. pp. 15–140; “Hist. et Mém. de l’Acad. Roy. des Sc.,” Vol. I. p. 307; Hartsoeker’s biography at pp. 307–308 of the “Engl. Cycl.,” Vol. III, 1867.[49]

A.D. 1707.—J. G. S. (not, as many suppose, Jean George Sulzer) publishes “Curious Speculations during Sleepless Nights” 8vo, Chemnitz, wherein appears the first account of the development, by heat, of electricity in the tourmaline, which latter, it is therein stated, was first brought from Ceylon by the Dutch in 1703. Another report of the above appears in the Mémoires de l’Académie des Sciences of Paris for 1717.

Reference.—Beckmann, Bohn, 1846, Vol. I. pp. 86–98.

A.D. 1708.—Wall (Dr. William), a prominent English divine, communicates to the Royal Society (Phil. Trans., Vol. XXVI. No. 314, p. 69) the result of his experiments, showing him to have been the first to establish a resemblance of electricity to thunder and lightning.

He found that, upon holding tightly in the hand a large bar of amber and rubbing it briskly against woollen cloths, “a prodigious number of little cracklings was heard, every one of which produced a small flash of light (spark); and that when the amber was drawn lightly through the cloth it produced a spark but no crackling.” He observed that “by holding a finger at a little distance from the amber a crackling is produced, with a great flash of light succeeding it, and, what is very surprising, on its eruption it strikes the finger very sensibly, wheresoever applied, with a push or puff like wind. The crackling is fully as loud as that of charcoal on fire.... This light and crackling seem in some degree to represent thunder and lightning.”

References.—Bakewell, “Electric Science,” p. 13; Aglave et Boulard, “Lumière Electrique,” 1882, p. 17; Thos. Thomson, “An Outline of the Sciences of Heat and Electricity,” London, 1830, pp. 314, 463; Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 431; see also the following abridgments of the Phil. Trans.; Hutton, Vol. V. p. 408 and Baddam of 1745, Vol. V. p. 111.

A.D. 1712.—The great Japanese Encyclopædia, Wa-Kan-san siü tson-ye, describes the compass, zi-siak-no-fari, at Vol. XV. folio 3, recto (Klaproth, “Lettre à M. de Humboldt,” etc., 1834, p. 107).

A.D. 1717.—Leméry (Louis), two years after the death of his distinguished father, Nicolas Leméry, exhibits a stone (the tourmaline) brought from Ceylon, and announces, to the French Académie des Sciences, that it possesses the electrical property of attracting and repelling light bodies after being warmed.

Carl Linnæus (1707–1777) alludes to the experiments of Leméry, in his Flora Zeylanica, and mentions the stone under the name of lapis electricus. (See, for Carl Linnæus, “Thesaurus Litteraturæ Botanicæ,” G. A. Pritzel, Lipsiæ, 1851, pp. 162–169, also “Guide to the Literature of Botany,” by Benj. Daydon Jackson, London, 1881, pp. xxxvi, etc.)

The first scientific examination of the electric properties of the tourmaline was, however, made by Æpinus in 1756, and published in the Memoirs of the Berlin Academy. Æpinus showed that a temperature of between 99½° and 212° F. was necessary for the development of its attractive powers.

Of the electricity of crystals, Gmelin, in his “Chemistry” (Vol. I. p. 319), names the following discoverers: Æpinus (tourmaline)—see A.D. 1759; Canton (topaz)—see A.D. 1753; Brard (axinite)—see A.D. 1787; Haüy (boracite, prehnite, sphene, etc.)—see A.D. 1787; Sir David Brewster (diamond, garnet, amethyst, etc.)—see A.D. 1820; and Wilhelm Gottlieb Hankel (borate of magnesia, tartrate of potash, etc.).

References.—Becquerel, “Résumé,” 1858, p. 11; Leithead, “Electricity,” p. 239; “Ph. Hist. and Mem. of Roy. Ac. of Sc. at Paris,” London, 1742, Vol. V. p. 216; “Journal des Sçavans,” Vol. LXX for 1721, pp. 572–573 on the tourmaline.

A.D. 1720.—Grey—Gray (Stephen), a pensioner of the Charter House and Fellow of the Royal Society, makes known through his first paper in the Phil. Trans. the details of the important line of investigation which finally led to the discovery of the principle of electric conduction and insulation as well as to the fact, not the principle, of induction (see Æpinus, A.D. 1759). Thus, to Grey is due the credit of having laid the foundation of electricity as a science.

He proved that electricity can be excited by the friction of feathers, hair, linen, paper, silk, etc., all of which attract light bodies even at a distance of eight or ten inches. He next discovered that electricity can be communicated from excited bodies to bodies incapable of ready excitation. When first suspending a hempen line with pack threads he could not transmit electricity, but when suspending the line with silken threads he transmitted the electrical influence several hundred feet. The latter he did at the suggestion of his friend Granville Wheeler—Wheler—(not Checler, as Aglave et Boulard have it in “Lumière Electrique,” p. 20), thinking that “silk might do better than pack thread on account of its smallness, as less of the virtue would probably pass off by it than by the thickness of the hempen line which had been previously used.” They both tried experiments with longer lines of pack thread, but failed, as they likewise did after substituting thin brass wire for the thread. This afterwards led to the discovery of other insulating substances, like hair, resin, etc. During the months of June 1729, and August 1730, Grey and Wheeler succeeded in transmitting electricity through pack thread supported by silken cords a distance of 765 feet, and through wire at a distance of 800–886 feet.

Grey demonstrated also that electric attraction is not proportioned to the quantity of matter in bodies, but to the extent of their surface, and he likewise discovered the conducting powers of fluids and of the human body. Of the cracklings and flashes of light he remarks: “And although these effects are at present but in minimis, it is probable, in time, there may be found out a way to collect a greater quantity of the electric fire, and consequently to increase the force of that power, which by several of those experiments, if we are permitted to compare great things with small, seems to be of the same nature with that of thunder and lightning” (Phil. Trans., abridgment of John Martyn, Vol. VIII. p. 401).

Stephen Grey may be said to have continued his experiments while lying upon his death-bed, for, unable to write, he dictated to the last, as best he could, the progress he had made in his studies to Dr. Mortimer, the Secretary of the Royal Society (Phil. Trans., 1735–1736, Vol. XXXIX. p. 400).

Grey’s own description of a new electric planetarium deserves reproduction here: “I have lately made several new experiments upon the projectile and pendulous motions of small bodies by electricity; by which small bodies may be made to move about larger ones, either in circles or ellipses, and those either concentric or excentric to the centre of the large body about which they move, so as to make many revolutions about them. And this motion will constantly be the same way that the planets move around the sun, viz. from the right hand to the left, or from west to east. But these little planets, if I may so call them, move much faster in their apogeon than in the perigeon part of their orbits, which is directly contrary to the motion of the planets around the sun.” To this should be added the following description of the manner in which these experiments can be made: “Place a small iron globe, of an inch or an inch and a half in diameter, on the middle of a circular cake of rosin, seven or eight inches in diameter, greatly excited; and then a light body, suspended by a very fine thread, five or six inches long, held in the hand over the centre of the cake, will, of itself, begin to move in a circle around the iron globe, and constantly from west to east. If the globe is placed at any distance from the centre of the circular cake, it will describe an ellipse, which will have the same excentricity as the distance of the globe from the centre of the cake. If the cake of rosin be of an elliptical form, and the iron globe be placed in the centre of it, the light body will describe an elliptical orbit of the same excentricity with the form of the cake. If the globe be placed in or near one of the foci of the elliptical cake, the light body will move much swifter in the apogee than in the perigee of its orbit. If the iron globe is fixed on a pedestal an inch from the table, and a glass hoop, or a portion of a hollow glass cylinder, excited, be placed around it, the light body will move as in the circumstance above mentioned, and with the same varieties.”

References.—Priestley, “Hist. and Present State of Elec.,” 1775, pp. 26–42, 55–63; and “A New Universal History of Arts and Sciences,” Electricity, Vol. I. p. 460; Saturday Review, August 21, 1858, p. 190; Wilson, “Treatise,” 1752, Section IV. prop. i. p. 23, note; Phil. Trans., Vol. XXXI. p. 104; Vol. XXXVII. pp. 18, 227, 285, 397; Vol. XXXIX. pp. 16, 166, 220, also the following abridgments: Hutton, Vol. VI. p. 490; Vol. VII. pp. 449, 536, 566; Vol. VIII. pp. 2, 51, 65, 316; Reid and Gray, London, 1733, Vol. VI. pp. 4–17 (Granville Wheler); Eames and Martyn, Vol. VI. part ii. pp. 7, 9, 15, and Part IV. p. 96; Vol. VII. pp. 18–20, 231; John Martyn, Vol. VIII. part ii. pp. 397, 403, 404 (Dr. C. Mortimer); Baddam, Vol. IX, 1745, pp. 145–160, 244, 272, 340, 497; “An Outline of the Sciences of Heat and Electricity,” Thomas Thomson, London, 1830, p. 344; and Thos. Thomson’s “Hist. of the Roy. Soc.,” London, 1812, p. 431; Weld, “Hist. of Roy. Soc.,” Vol. I. p. 466; “A course of lectures on Nat. Philos. and the Mechanical Arts,” by Thos. Young, London, 1807, Vol. II. p. 417; “Hist. de l’Académie des Sciences,” 1733, p. 31; “Jour. Litter.” de 1732, à la Haye, pp. 183, 186, 187, 197; “Hist. de l’Académie Royale de Berlin,” 1746, p. 11; “Journal des Sçavans,” Vol. CXXV for 1741, pp. 134–141, and Vol. CXXVI for 1742, pp. 252–263. For Granville Wheeler, consult Phil. Trans., Vol. XLI. pp. 98, 118, also the following abridgments: Hutton, Vol. VIII. pp. 306–320; John Martyn, Vol. VIII. part ii. pp. 406, 412, 415. For Dr. C. Mortimer, consult Phil. Trans., Vol. XLI. p. 112 and John Martyn’s abridgments, Vol. VIII. part ii. pp. 404–412.

A.D. 1721.—Taylor (Brooke), LL.D., F.R.S. (1685–1731), an eminent English mathematician, past Secretary of the Royal Society, and one of the ablest geometers of his time—“the only one who, after the retreat of Newton, could safely enter the lists with the Bernoullis”—publishes his “Experiments on Magnetism” in Phil. Trans., No. 368.

In order to arrive at a proper determination of the laws of magnetic force, Dr. Taylor—and also Whiston and Hauksbee—according to Sir David Brewster, considered “the deviation of a compass needle from the meridian, produced by the action of a magnet at different distances; and the conclusion which they all drew from their experiments was that the magnetic force was proportional to the sines of half the arcs of deviation, or nearly in the inverse sesqui-duplicate ratio of the distance, or as the square roots of the fifth powers of the distances. Dr. Taylor had already come to the conclusion that the force was different in various magnets, and decreased quicker at great distances than at small ones, an experimental fact, as shown by Sir W. S. Harris, ‘Rud. Mag.,’ Part III. p. 224.”

In Dr. Thomas Thomson’s “History of the Royal Society” we read, however (p. 461), that Brooke Taylor, and after him Musschenbroek, attempted without success to determine by experiment the rate at which the magnetic attractions and repulsions vary. This rate was successfully investigated by the subsequent experiments of Lambert, Robison and Coulomb. The nature of magnetic curves was first satisfactorily explained by Lambert, Robison and Playfair. Brooke Taylor gave four poles to a wire by touching it at one end or at various parts, as indicated in Phil. Trans., Vol. XXIX. p. 294, and Vol. XXXI. p. 204.

References.—Whewell, “Hist. of the Ind. Sciences,” 1859, Vol. I. pp. 359, 375; Vol. II. p. 31; “General Biog. Dict.,” London, 1816, Vol. XXIX. pp. 163–166; Phil. Trans. for 1714–1716, Vol. XXIX. p. 294 and the following abridgments: Hutton, Vol. VI. p. 528; Reid and Gray, Vol. VI. pp. 17, 159; Hy. Jones, Vol. IV. part ii. p. 297; Eames and Martyn, Vol. VI. part ii. p. 253.

A.D. 1722.—Graham (George), a celebrated optician and instrument maker in London, is the first to distinctly make known the diurnal and horary variations of the magnetic needle, traces of which had been merely recognized as facts by Gellibrand, in 1634, and by the Missionary Father Guy-Tachard at Louvo, in Siam, during 1682. He finds that its northern extremity begins to move westward at about seven or eight o’clock in the morning, and continues to deviate in that direction until about two o’clock in the afternoon, when it becomes stationary; it soon begins to return to the eastward and becomes again stationary during the night. Graham made nearly a thousand observations, between the 6th of February and the 12th of May, 1722, and found that the greatest westerly variation was 14° 45’, and the least 13° 50’; in general, however, it varied between 14° and 14° 35’, giving 35’ for the amount of the daily variation.

Graham’s discovery—afterwards amplified by Anders Celsius (A.D. 1740)—attracted but little attention until 1750, when the subject was ably taken up by Wargentin, Secretary to the Swedish Academy of Sciences. Between 1750 and 1759 Mr. John Canton made about 4000 observations on the same subject, and was followed by the Dutch scientist Gerard van Swieten, the favourite pupil of Boerhaave, with like results.

As Dr. Lardner states (“Lectures on Science and Art,” 1859, Vol. II. p. 115), the same phenomenon has been observed more recently by Col. Beaufoy (at A.D. 1813), by Prof. Hansteen (at A.D. 1819) and by many others. He further states that Cassini, who observed the diurnal variation of the needle at Paris, found that neither the solar heat nor light influenced it, for it was the same in the deep caves constructed under the Observatory in Paris, where a sensibly constant temperature is preserved, and from which light is excluded, as at the surface. In northern regions these diurnal changes are greater and more irregular; while, toward the line, their amplitudes are gradually diminished until at length they disappear altogether.

It was Graham who first entertained the idea of measuring the magnetic intensity through the vibrations of the needle, a method subsequently used by Coulomb, and which many believe was invented by the latter. From the observations made by Humboldt and by Gay-Lussac in this manner, Biot has reduced the variation of intensity in different latitudes.

References.—“Am. Journal Science,” Vol. XXX. p. 225; Walker, “Magnetism,” Chap. II; Fifth Dissertation of the Eighth “Britannica,” Vol. I. p. 744; also Phil. Trans. 1724–1725, Vol. XXXIII. p. 332, and pp. 96–107 (“An Account of Observations Made of the Horizontal Needle at London, 1722–1723, by Mr. George Graham”) and the following abridgments: Reid and Gray, Vol. VI. pp. 170, 187; Hutton, Vol. VII. pp. 27, 94; Vol. IX. p. 495; Eames and Martyn, Vol. VI. part ii. pp. 28, 280, 290; Baddam, 1745, Vol. VIII. p. 20; John Martyn, Vol. X. part ii. p. 698; An de chimie for 1749, Vol. XXV. p. 310.

A.D. 1725.—Horrebow—Horreboe—(Peter), was a Danish physicist (1679–1764), who studied medicine for a time and then became a pupil of the celebrated mathematician and astronomer Olaus Rœmer (1644–1710, best known by his discovery of the finite velocity of light), whom he succeeded in the University of Copenhagen.

His earliest work, “Clavis Astronomiæ,” first appeared during 1725, but it is only in the second and enlarged new edition of it in Horrebow’s “Operum Mathematico-Physicorum,” Havn. 1740, Vol. I. p. 317, that will be found the passage (s. 226) in which the luminous process of the sun is characterized as a perpetual northern light. Humboldt, who mentions the fact (“Cosmos,” 1859, Vol. V. p. 81) suggests that a comparison be made of Horrebow’s statement with the precisely similar views held by Sir William Herschel (1738–1822) and Sir John Frederick William Herschel (1792–1871). He says that Horrebow, who did not confound gravitation with magnetism, was the first who thus designated the process of light produced in the solar atmosphere by the agency of powerful magnetic forces (“Mémoires de Mathématiques et de Physique, présentés à l’Académie Royale des Sciences,” Vol. IX. 1780, p. 262; Hanow, in Joh. Dan. Titius’s “Gemeinützige Abhand. über natür. Dinge,” 1768, p. 102), and, with reference to the Herschels he thus expresses himself: “If electricity, moving in currents, develops magnetic forces, and if, in accordance with an early hypothesis of Sir Wm. Herschel (Phil. Trans. for 1795, Vol. LXXXV. p. 318; John Herschel, “Outlines of Astronomy,” p. 238; also, Humboldt, “Cosmos,” Vol. I. p. 189), the sun itself is in the condition of a perpetual northern light (I should rather say of an electro-magnetic storm) we should seem warranted in concluding that solar light transmitted in the regions of space by vibrations of ether, may be accompanied by electro-magnetic currents” (“Dict. of Nat. Biog.,” for John and William Herschel, Vol. XXVI. pp. 263–274).

References.—Larousse, “Dict. Univ.,” Vol. IX. p. 397; Wolf, “Hist. Ordbog.,” Vol. VII. pp. 194–199; Nyerup, “Univ. Annalen”; Houzeau et Lancaster, “Bibliographie,” 1882, Vol. II. p. 166.

Three of the children of Peter Horrebow, almost equally distinguished for their learning, are: Nicolas Horrebow (1712–1760), who made physical and astronomical observations in Iceland and published an able report thereon during 1752; Christian Horrebow (1718–1776), who succeeded his father in 1753 as astronomer in the Copenhagen University and who wrote several important scientific treatises; and Peter Horrebow (1728–1812), who was professor of mathematics and philosophy, and published works on geometry, meteorology and astronomy.

Much of interest concerning the above will also be found in the “Abstracts of Papers ... Roy Soc.,” Vol. II. pp. 208, 249, 251, and in the “Catalogue of Sc. Papers ... Roy. Soc.,” Vol. III. pp. 322–328; Vol. VI. p. 687; Vol. VII. p. 965.

A.D. 1726.—Wood (John), an English architect of considerable repute, is said to have shown that the electric fluid could be conveyed through wires a long distance, and, during the year 1747, one of the earliest applications of Wood’s discovery was made by Dr. William Watson (see A.D. 1745), who extended his experiments over a space of four miles, comprising a circuit of two miles of wire and an equal distance of ground.

References.—Alexander Jones, “Sketch of the Elect. Teleg.,” New York, 1852, p. 7; Charles F. Briggs, “Story of the Telegraph,” 1858, p. 18.

A.D. 1729.—Hamilton (James), who became sixth Earl of Abercorn—also called Lord Paisley—publishes “Calculations and Tables relating to the attractive virtue of loadstones ...” containing very valuable data and wherein he is the first to give the true law of the lifting capacity of magnets, as follows: “The principle upon which these tables are formed is this: That if two loadstones are perfectly homogeneous, that is if their Matter be of the same specifick parity, and of the same virtue in all parts of one stone, as in the other; and that like parts of their surfaces are cap’d or arm’d with iron; then the weights they sustain will be as the squares of the cube roots of the weights of the loadstones; that is, as their surfaces.”

Gilbert treats of armed loadstones, Book II. chaps. xvii-xxii. In connection with the increased energy which magnets acquire by being armed, that is, fitted with a cap of polished iron at each pole, Dr. Whewell remarks that it is only at a later period any notice was taken “of the distinction which exists between the magnetical properties of soft iron and of hard steel; the latter being susceptible of being formed into artificial magnets, with permanent poles; while soft iron is only passively magnetic, receiving a temporary polarity from the action of a magnet near it, but losing this property when the magnet is removed. About the middle of the last century various methods were devised of making artificial magnets, which exceeded in power all magnetic bodies previously known” (“Hist. of the Ind. Sc.,” 1859, Vol. II. p. 220).

Hamilton alludes to a loadstone weighing 139 grains, with a lifting power of 23,760 grains! We have referred, amongst others, to the loadstone belonging to Sir Isaac Newton at A.D. 1675, and to the wonderful collection belonging to Mr. Butterfield at A.D. 1809. A loadstone weighing twelve ounces, capable of lifting sixty pounds of iron, is referred to in Terzagus, “Musæum Septalianum,” 1664, p. 42, while another weighing two and a half grains and lifting 783 grains is mentioned at p. 272, Vol. III. of the “Records of General Science”; and Salviatus (“Dialogues of Galileo,” Dial. III) alludes to one in the Academy of Florence which, unarmed, weighed six ounces and could lift but two ounces, but when armed had a lifting power of 160 ounces. At pp. 317–318, Part III of Nehemiah Grew’s “Musæum Regalis Societatis,” London, 1681—also 1686—allusion is made to a loadstone found in Devonshire, weighing about sixty pounds, which moved a needle nine feet distant. Grew then refers to Athan. Kircher and to Vincent Leotaud as having published what is said of the loadstone by Gilbert and others, and he likewise states: “Those that travail through the vast deserts of Arabia, have also a needle and a compass whereby they direct themselves in their way, as Mariners at sea [Majoli, ‘Colloquia’]; the power of the magnet dependeth not upon its bulk—the smaller being usually the stronger....”

References.—Phil. Trans. for, 1729–1730, No. 412, Vol. XXXVI. p. 245, and for July 1888, also Hutton’s abridgments, Vol. VII. p. 383; V. T. M. Van der Willigen, “Arch. du Musée Teyler,” 1878, Vol. IV; Jacobi Rohaulti, “Physica,” 1718, Part III. cap. 8, p. 403, or the English translation by Dr. Clarke, 1728, Vol. II. p. 181; P. W. Hacker, “Zur theorie des magnetismus,” Nürnberg, 1856; Ath. Kircher, “Magnes. ...” 1643, lib. i. part ii. p. 63; Daniel Bernoulli, “Acta Helvetica,” 1758, Vol. III. p. 223; Nic. Cabæus “Philosophia Magnetica,” 1629, lib. iv. cap. 42, p. 407; Kenelme Digby, “The Nature of Bodies,” 1645, Chap. XXII. p. 243; “Dict. of Nat. Biog.” Vol. XXIV. p. 185.

A.D. 1729–1730.—Savery (Servington), English mechanician, succeeds in imparting magnetism to hard steel bars three-fourths of an inch square and sixteen inches long, by fitting one bar with an armature at each end and touching other bars with it whilst held in the magnetic meridian in the line of the inclined needle.

It was shown by Savery that his artificial magnets were preferable to loadstones. The first recorded attempt to make artificial magnets is credited to one John Sellers, believed to be the author of “The Practical Navigator,” of which the earliest edition appeared in 1669, and of “The Coasting Pilot,” published about 1680. An “Answer to Some Magnetical Inquiries Proposed in (the preceding) No. 23, pp. 423–424,” will be found in Phil. Trans. for 1667, Vol. II. pp. 478–479 and in the following abridgments: Baddam, 1745, Vol. I. p. 86; Hutton, Vol. I. p. 166 (as of No. 26, p. 478); John Lowthorp, Vol. II. p. 601. Reference is likewise made to this invention of Sellers at Vol. I. p. 86 of the “Memoirs of the Royal Society,” London, 1739, and in a paper by Réaumur, in the “Mémoires de l’Académie Française” for the year 1723.

References.—Savery, “Magnetical Observations and Experiments,” also Phil. Trans., Vol. XXXVI. pp. 295–340; and the following abridgments: Hutton, Vol. VII. p. 400; Reid and Gray, Vol. VI. p. 166; Eames and Martyn, Vol. VI. p. 260; Baddam, 1745, Vol. IX. p. 57; Geo. Adams, “Essay on Electricity,” 1785, p. 451.

A.D. 1731.—On the 25th of November the Royal Society were honoured by a visit from the Prince of Wales and the Duke of Lorraine, the last named being enrolled as a member during the evening. Experiments were performed “On the strength of Lord Paisley’s loadstone,” “On Dr. Frobenius’s phlogiston,” and “On the electrical observations of Mr. Stephen Grey.” These experiments which, it is said, “succeeded notwithstanding the largeness of the company,” showed the facility with which electricity passes through great lengths of conductors and are worth noting as being the first of their nature.

A.D. 1732.—Régnault (Le Père Noël) gives in “Les Entretiens Physiques,” etc., Vol. I. Nos. 15 and 16, the tables of the declination at Paris from the years 1600–1730, and treats at length of the merits of the loadstone and of the magnetic needle.

In Vols. II, IV and V he discourses about the extent of the magnetic fluid and explains the phenomena of meteors, St. Elmo’s fire, thunder, etc., besides recording the experiments of Grey, Dufay and others.

A.D. 1733.—Dufay (Charles François de Cisternay), French scientist and superintendent of the Jardin du Roi, now the Jardin des Plantes, of Paris (in which latter position he was succeeded by Buffon), communicates to the French Academy of Sciences the history of electricity brought down to the year 1732 (Dantzig Memoirs, Vol. I. p. 195).

He is said to have originated the theory of two kinds of electricity permeating matter and producing all the known phenomena of attraction, repulsion and induction, though the honour of this important discovery should be shared by M. White, who was associated at one time with Stephen Grey and who, it appears, independently discovered the fact while in England. Dufay thus announces his discovery: “... there are two kinds of electricity, very different from one another, one of which I call vitreous (positive) and the other resinous (negative) electricity. The first is that of glass, rock crystal, precious stones, hairs of animals, wool and many other bodies. The second is that of amber, copal, gum-lac, silk, thread, paper and a vast number of other substances. The characteristics of these two electricities are that they repel themselves and attract each other. Thus a body of the vitreous electricity repels all other bodies possessed of the vitreous, and, on the contrary, attracts all those of the resinous electricity. The resinous also repels the resinous and attracts the vitreous. From this principle one may easily deduce the explanation of a great number of the phenomena; and it is probable that this truth will lead us to the discovery of many other things” (see Franklin, at A.D. 1752, and Symmer, at A.D. 1759).

Upon repeating Grey’s experiments, Dufay observed, amongst other things, that, by wetting pack thread, electricity was more readily transmitted through it, and he was enabled thus easily to convey the fluid a distance of 1256 feet, though the wind was high and although the line made eight returns.

References.—Fontenelle, “Eloge”; Priestley, “History and Present State of Electricity,” 1775, Period IV. pp. 43–54; Sturgeon, Lectures, 1842, p. 23; “An Epitome of El. and Mag.,” Philad., 1809, p. 29; Mém. de l’Acad. Royale des Sciences for 1733, pp. 23, 28, 76, 83, 233–236, 251, 252, 457; also for the years 1734, pp. 303, 341, and 1737, pp. 86, 307; Phil. Trans., Vol. XXXVIII. p. 258; also the following abridgments: Hutton, Vol. VII. p. 638; John Martyn, Vol. VIII. part ii. p. 393; Baddam, Vol. IX. p. 497; Thos. Thomson, “An Outline of the Sciences of Heat and Electricity,” London, 1830, p. 344 and Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 432; “Electricity in the Service of Man,” R. Wormell (from the German of Dr. Urbanitzky), London, 1900, p. 14; “Journal des Sçavans,” Vol. XCIII for 1731, pp. 383–388; Vol. C for 1733, p. 244; Vol. CIV for 1734, p. 479; Vol. CXII for 1737, p. 65; Vol. CXV for 1738, p. 173; Vol. CXXIX for 1743, p. 501.

A.D. 1733.—Winckler (Johann Heinrich), a philosopher of Wingendorf, Saxony, and Professor of Languages in the University of Leipzig, first uses a fixed cushion in the electric machine for applying friction instead of by means of the hand, and is, by many, believed to have been the first to suggest the use of conductors as a means of protection against lightning (see B.C. 600).

In March 1745, Winckler read a paper before the Royal Society, in which he describes machines for rubbing tubes and globes, also a contrivance with which he can give his globes as many as 680 turns in a minute. Priestley states that the German electricians generally used several globes at a time and that they could excite such a prodigious power of electricity from “globes, whirled by a large wheel and rubbed with woollen cloth or a dry hand, that, if we may credit their own accounts, the blood could be drawn from the finger by an electric spark; the skin would burst and a wound appear, as if made by a caustic.”

During the year 1746 Winckler made use of common electricity for telegraphic communications by the discharge of Leyden jars through very long circuits, in some of which the River Pleisse formed a part, and it may be added that Joseph Franz had previously discharged the contents of a jar through 1500 feet of iron wire while in the city of Vienna.

References.—Phil. Trans., Vol. XLIII. p. 307; Vol. XLIV. pp. 211, 397; Vol. XLV. p. 262; Vol. XLVII. p. 231; Vol. XLVIII. p. 772; also following abridgments: Hutton, Vol. IX. pp. 74, 109, 251, 345, 494; Vol. X. pp. 197, 529; John Martyn, Vol. X. part ii. pp. 269, 273, 327, 345, 399; Priestley, 1775, on the discoveries of the Germans, pp. 70–77; “Thoughts on the Properties,” etc., Leipzig, 1744, pp. 146, 149.

A.D. 1733.—Brandt (Georg), Swedish chemist, gives in the “Memoirs of the Academy” of Upsal an account of the experiments made by him to show the possibility of imparting magnetism to substances which are not ferruginous. He proved it in the case of the metal cobalt, and during the year 1750 the able discoverer of nickel, Axel. F. de Cronstedt, showed that the latter is likewise susceptible of this property.

References.—Thomas, “Dict. of Biog.,” 1871, Vol. I. p. 428; English Cyclopædia (Biography Supplement), 1872, p. 423.

A.D. 1734.—Polinière (Pierre), French physician and experimental philosopher (1671–1734), member of the Society of Arts, entirely revises the fourth edition of his “Expériences de Phisique” originally issued in 1709. While the second volume contains but a short chapter relative to electricity, meteoric disturbances, etc., the remainder of the work gives very curious and interesting experiments with the loadstone, making allusion to the observations of John Keill, besides treating of the declination of the needle, etc.

References.—“New Gen. Biog. Dict.,” London, 1850, Vol. XI. p. 177; Moréri, “Grand Dict. Hist.”; “Biog. Univ.” (Michaud), Vol. XXXIII. p. 637; “Nouv. Biog. Gén.” (Hœfer), Vol. XL. p. 614; Chaudon, “Dict. Hist. Univ.”

A.D. 1734.—Swedenborg (Emanuel), founder of the Church of New Jerusalem, details in his “Principia Rerum Naturalium,” etc., the result of experiments and sets forth the laws relating to magnetic and electric forces and effects. The first explicit treatise upon the close relationship existing between magnetism and electricity was, however, written fourteen years later by M. Laurent Béraud (1703–1777), Professor of Mathematics at the College of Lyons. Both Swedenborg and Béraud recognized the fact that it is, as Fahie expresses it, the same force, only differently disposed which produces both electric and magnetic phenomena.

In “Results of an Investigation into the MSS. of Swedenborg,” Edinburgh, 1869, p. 7, No. 16, Dr. R. L. Tafel makes following entry:

“A treatise on the magnet, 265 pages text and 34 pages tables, quarto. This work is a digest of all that had been written up to Swedenborg’s time on the subject, with some of his own experiments. According to the title page, Swedenborg had intended it for publication in London during the year 1722.”

The “Principia Rerum Naturalium” is the first volume of Swedenborg’s earliest great work, “Opera Philosophica et Mineralia,” originally published in Leipzig and Dresden 1734, which has justly been pronounced a very remarkable cosmogony. In the “Principia” Part I. chap. ix., is to be found his treatment of what he calls the second or magnetic element of the world; in Part III. chap. i. he gives a comparison of the sidereal heaven with the magnetic sphere, but he devotes the whole of Part II to the magnet in following chapters:

I. On the causes and mechanism of the magnetic forces;

II. On the attractive forces of two or more magnets, and the ratio of the forces to the distances;

III. On the attractive forces of two magnets when their poles are alternated;

IV. On the attractive forces of two magnets when their axes are parallel or when the equinoctial of the one lies upon the equinoctial of the other;

V. On the disjunctive and repulsive forces of two or more magnets when the cognomical or inimical poles are applied to each other;

VI. On the attractive forces of the magnet and of iron;

VII. On the influence of the magnet upon ignited iron;

VIII. On the quantity of exhalations from the magnet and their penetration through hard bodies, etc.;

IX. On the various modes of destroying the power of the magnet; and on the chemical experiments made with it;

X. On the friction of the magnet against iron, and on the force communicated from the former to the latter;

XI. On the conjunctive force of the magnet, as exercised upon several pieces of iron;

XII. On the operation of iron and of the magnet upon the mariner’s needle; and on the reciprocal operation of one needle upon another;

XIII. On other methods of making iron magnetical;

XIV. The declination of the magnet calculated upon the foregoing principles;

XV. On the causes of the magnetic declination;

XVI. Calculation of the declination of the magnet for the year 1722, at London.

References.—Béraud, “Dissertation,” etc., Bordeaux, 1748; also Priestley, 1775, p. 191; “Biographie Universelle,” Vol. III. p. 687; “Biog. Génér.,” Vol. XLIV. pp. 690–703; Daillant de la Touche, “Abrégé des ouvrages de Swedenborg,” 1788; J. Clowes, “Letters on the writings of Swedenborg,” 1799; “Svenskt Biografiskt Handlexikon,” Herm. Hofberg, Stockholm, pp. 368–369; “Swedenborg and the Nebular Hypothesis,” Magnus Nyrén, astronomer at Observatory of Pulkowa, Russia, translated from the “Viertel jahrschrift der Astronomischen Gesellschaft,” Leipzig, 1879, p. 81, by Rev. Frank Sewall.

A.D. 1735–1746.—Ulloa (Don Antonio de), Spanish mathematician, who left Cadiz May 26, 1735, for South America, whither he was sent with Condamine and other French Academicians, as well as with Spanish scientists, to measure a degree of the meridian, returned to Madrid July 25, 1746, and shortly after gave an account of his experiences during an absence of eleven years and two months.

In his “Voyage Historique de l’Amérique Méridionale,” Amsterdam and Leipzig, 1752, he speaks (Vol. I. pp. 14–18 and Vol. II. pp. 30–31, 92–94, 113, 123, 128) of the defective magnetic needles given him as well as of the means of correcting them, and he details at great length the variations of the needle observed during the voyage. He also alludes to the variation charts of Dr. Halley and to the alterations therein made by advice of William Mountaine and Jacob Dooson—James Dodson—of London, as well as to the methods of ascertaining the variation of the magnetic needle pointed out both by Manuel de Figueyredo, at Chaps. IX-X of his “Hidrographie ou Examen des Pilotes,” printed at Lisbon in 1608, and by Don Lazare de Flores at Chap. I, part ii. of his “Art de Naviguer,” printed in 1672. The latter, he says, asserts, in Chap. IX, that the Portuguese find his method so reliable that they embody it in all the instructions given for the navigation of their vessels.

At pp. 66, 67, Chap. X of vol. ii. Ulloa makes the earliest recorded reference to the aurora australis, as follows: “At half-past ten in the evening, and as we stood about two leagues from the island of Tierra de Juan Fernandez, we observed upon the summit of a neighbouring mountain a very brilliant and extraordinary light.... I saw it very distinctly from its inception, and I noticed that it was very small at first, and gradually extended until it looked like a large, lighted torch. This lasted three or four minutes, when the light began to diminish as gradually as it had grown, and finally disappeared.”

Incidentally, it may be stated here that the very learned Dr. John Dalton reported having seen the aurora australis in England, and to have besides observed the aurora borealis as far as 45° latitude south (see accounts in Philosophical Transactions, Philosophical Magazine, Manchester Transactions and Nicholson’s Journal), while Humboldt remarks (“Cosmos,” 1849, Vol. I. p. 192, note) that in south polar bands, composed of very delicate clouds, observed by Arago, at Paris, on the 23rd of June, 1844, dark rays shot upward from an arch running east and west, and that he had already made mention of black rays resembling dark smoke, as occurring in brilliant nocturnal northern lights.

References to the aurora australis are made by the naturalist John Reinhold Forster, in the article on “Aurora Borealis” of the “Encycl. Britannica.”

For Mountaine and Dodson, consult the Phil. Trans., Vol. XLVIII. p. 875; Vol. L. p. 329, also Hutton’s abridgments, Vol. XI. p. 149.

A.D. 1738.—Boze—Böse—(Georg Matthias) (1710–1761), Professor of Philosophy at Wittemburg, publishes his “Oratio inauguralis de electricitate,” which is followed, in 1746, by “Recherches sur la cause et sur la véritable théorie de l’électricité,” and, in 1747, by his completed “Tentamina electrica.”

To him is due the introduction in the electrical machine of the prime conductor, in the form of an iron tube or cylinder. The latter was at first supported by a man insulated upon cakes of resin and afterward suspended by silken strings. M. Boze discovered that capillary tubes discharging water by drops give a continuous run when electrified. He also conveyed electricity by a jet of water from one man to another, standing upon cakes of resin, at a distance of six paces, and likewise employed the jet for igniting alcohol as well as other liquids.

References.—Alglave et Boulard, 1882, p. 22, also Priestley, 1775, upon “Miscellaneous Discoveries,” likewise “Nouv. Biog. Générale” (Hœfer), Vol. VI. p. 772; “La Grande Encycl.,” Vol. VII. p. 454; “Journal des Sçavans,” Vol. LXIII for 1718, p. 485; Phil. Trans. for 1745, Vol. XLIII. p. 419, and for 1749, Vol. XLVI. p. 189; also Hutton’s abridgments, Vol. IX. pp. 127, 681; and J. Martyn’s abridgments, Vol. X. part ii. pp. 277, 329.

A.D. 1739.—Desaguliers (Jean Theophile), chaplain to his Grace the Duke of Chandos, gives an account of his first experiments on the phenomena of electricity at pp. 186, 193, 196, 198, 200, 209, 634, 637, 638 and 661 of Vol. XLI of the Phil. Trans. for 1739. Some of these experiments were made on the 15th of April, 1738, at H.R.H. the Prince of Wales’ house at Cliefden.

He was the first to divide bodies into “electrics,” or non-conductors, and “non-electrics,” or conductors. He ranked pure air amongst his electrics (Tyndall, Lecture I) and stated that “cold air in frosty weather, when vapours rise least of all, is preferable for electrical purposes to warm air in summer, when the heat raises the vapours” (Phil. Trans., John Martyn abridgment, Vol. VIII. p. 437). It was Desaguliers who announced that he could render bars of iron magnetic, either by striking them sharply against the ground while in a vertical position or by striking them with a hammer when placed at right angles to the magnetic meridian.

His “Dissertation Concerning Electricity” London, 1742, which won for him the grand prize of the Bordeaux Academy, is said to be the second work on the subject published in the English language, the first having been Boyle’s “Mechanical Origin and Production of Electricity,” mentioned at A.D. 1675.

Desaguliers was the second to receive the Copley medal, it having been previously bestowed by the Royal Society only upon Stephen Grey, who obtained it in 1731 and 1732 for his “New Electrical Experiments.” The list of recipients of this distinguished honour, given by C. R. Weld at p. 385, Vol. I of the “History of the Royal Society,” shows that Desaguliers received three Copley medals; these were awarded him during the years 1734, 1736 and 1741, for his “Experiments in Natural Philosophy.” John Canton was given two of the medals, in 1751 and 1764, the only other electrician similarly favoured being Michael Faraday, who received them during the years 1832 and 1838, while Sir Humphry Davy is credited with only one, conferred upon him in 1805.

“Can Britain ...

... Permit the weeping muse to tell

How poor neglected Desaguliers fell?

How he, who taught two gracious kings to view,

All Boyle ennobled, and all Bacon knew,

Died in a cell, without a friend to save,

Without a guinea, and without a grave?”

Cawthorn, “Vanity of Human Enjoyments,” V. 147–154.

In the year 1742, Desaguliers received the prize of the Académie Royale de Bordeaux for a treatise on the electricity of bodies, which latter was separately published at the time in a quarto volume of twenty-eight pages. The same Academy had previously conferred important prizes for dissertations, upon the nature of thunder and lightning by Louis Antoine Lozeran du Fech in 1726, upon the variations of the magnetic needle by Nicolas Sarrabat in 1727, and also subsequently decreed similar awards, to Laurent Béraud for an essay on magnets in 1748, to Denis Barberet for a treatise on atmospherical electricity in 1750, and to Samuel Theodor Quellmalz for a dissertation on medical electricity in 1753.

References.—Phil. Trans., Vol. XL. p. 385; Vol. XLII. pp. 14, 140; also the following abridgments: Hutton, Vol. VIII. pp. 246–248, 340, 346, 350–358, 470–474, 479, 546, 584; John Martyn, Vol. VIII. part ii. pp. 419, 422–444, 740. Very interesting reading is afforded by M. Desaguliers through the observations he made on the magnets having more poles than two. These will be found recorded in Phil. Trans. for 1738, p. 383 and in Hutton’s abridgments, Vol. VIII. p. 246; Thomson, “Hist. Roy. Soc.,” 1812, pp. 433, 434; “Gen. Biog. Dict.,” Alex. Chalmers, London, 1811, Vol. XI. pp. 489–493.

A.D. 1740.—Celsius (Anders), who filled the chair of astronomy at Upsal, is first to point out the great utility of making simultaneous observations over a large extent of territory and at widely different points. He states (Svenska Vetenskaps Academiens Handlingar for 1740, p. 44) that a simultaneity in certain extraordinary perturbations, which had caused a horary influence on the course of the magnetic needle at Upsal and at London, afforded proof “that the cause of these disturbances is extended over considerable portions of the earth’s surface, and is not dependent upon accidental local actions.”

In the following year (1741), Olav Hiörter, who was Celsius’ assistant, discovered and measured the influence of polar light on magnetic variation. His observations were subsequently carried on in conjunction with Celsius, and were improved upon by Wargentin (A.D. 1750) and by Cassini (A.D. 1782–1791).

References.—Walker, “Ter. and Cos. Magnetism,” p. 116; also Humboldt, “Cosmos,” re “Magnetic Disturbances,” and Vol. II. p. 438, of Weld’s “History of the Royal Society.”

A.D. 1742.—Gordon (Andreas), a Scotch Benedictine monk (1712–1757), Professor of Philosophy at Erfurt, abandons the use of glass globes (Newton, at A.D. 1675 and Hauksbee, at A.D. 1705), and is the first to employ a glass cylinder, the better to develop electricity. His cylinder, eight inches long and four inches wide, is made to turn by means of a bow with such rapidity that it attains 680 revolutions per minute.

Priestley says (“Discovery of Germans,” Part I. period vii.) that Gordon “increased the electric sparks to such a degree that they were felt from a man’s head to his foot, so that a person could hardly take them without falling down with giddiness; and small birds were killed by them. This he effected by conveying electricity, with iron wires, to the distance of 200 ells (about 250 yards) from the place of excitation.”

References.—Dantzig Memoirs, Vol. II. pp. 358, 359, and Nollet, “Recherches,” etc., p. 172. See also Gordon’s “Phenomena Electricitatis Exposita,” Erford, 1744 and 1746; “Philosophia,” 1745; “Tentamen ... Electricitatis,” 1745; “Versuche ... einer Electricität.,” 1745–1746.

A.D. 1743.—Hausen (Christian Augustus), Professor of Mathematics at Leipzig, publishes his “Novi profectus in historia electricitatis,” and is the first to revive the use of the glass globe introduced by Newton (A.D. 1675) and employed with great effect by Hauksbee (A.D. 1705).

In Watson’s “Expériences et observations sur l’électricité,” is shown an electrical machine constructed by Hausen and differing but slightly from the one alluded to herein at A.D. 1705 as made for M. Wolfius. In this illustration a lady is pressing her hand against the glass globe, which is being rotated rapidly, thus developing upon its surface the vitreous electricity, while the resinous electricity passes through her body to the earth. The young man who is suspended and insulated by silken cords, represents the prime conductor introduced by Prof. Boze (A.D. 1738). The vitreous electricity passes from the surface of the glass globe, through his feet and entire body, and is communicated by his hand to the young girl, who stands upon a large section of resin, and is able to attract small parcels of gold leaf by means of the electric fluid. Another machine, taken from the same French work (originally published at Paris in 1748), is said to have been at that time much in use throughout Holland and principally at Amsterdam. The man rotates a glass globe, against which the operator presses his hand, and the electricity is conveyed through the metallic rod supported by silk-covered stands and held by a third party, who is igniting spirits in the manner indicated at the A.D. 1744 date.

Reference.—Dantzig Memoirs, Vol. I. pp. 278, 279.

A.D. 1743.—Boerhaave—Boerhaaven—(Hermann), illustrious physician, mathematician and natural philosopher (1668–1738), who held the chairs of theoretical medicine, practical medicine, botany and chemistry at the University of Leyden, F.R.S. and member French Academy of Sciences, writes an Essay on the virtue of Magnetical Cures, of which there were subsequently many editions and translations in different languages.

One of his biographers calls him “the Galen, the Ibn Sina, the Fernel of his age.” Another remarks that he was, perhaps, the greatest physician of modern times: “A man who, when we contemplate his genius, his erudition, the singular variety of his talents, his unfeigned piety, his spotless character, and the impress which he left not only on contemporaneous practice, but on that of succeeding generations, stands forth as one of the brightest names on the page of medical history, and may be quoted as an example not only to physicians, but to mankind at large. No professor was ever attended, in public as well as at private lectures, by so great a number of students, from such distant and different parts, for so many years successively; none heard him without conceiving a veneration for his person, at the same time that they expressed their surprise at his prodigious attainments; and it may be justly affirmed, that none in so private a station ever attracted a more universal esteem.”

References.—“Biographica Philosophica,” Benj. Martin, London, 1764, pp. 478–483; “Eloge de Boerhaave,” by Maty, Leyde, 1747, and by Fontenelle, 1763, T. VI; his life, written by Dr. Wm. Burton, London, 1736; Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. p. 354, note; “La Grande Encyclopédie,” Tome VII. p. 42; “Biographie Générale,” Tome VI. pp. 352–357; “Biographie Universelle,” Vol. IV. pp. 529–555; Ninth “Encycl. Britannica,” Vol. III. p. 854; “Histoire Philosophique de la Médecine,” Etienne Tourtelle, Paris, An. XII. (1807), Vol. II. pp. 404–446; “Bibl. Britan.” (Authors), Rob. Watt, Edinburgh, 1824, Vol. I. p. 127; “The Edinburgh Encyclopædia,” 1830, Vol. III. pp. 628–630 or the 1813 ed., Vol. III. pp. 612–614; G. A. Pritzel, “Thesaurus Literaturæ Botanicæ,” Lipsiæ, 1851, p. 26.

A.D. 1744.—Ludolf—Leudolff—(Christian Friedrich), of Berlin, first exhibits, January 23, the ignition of inflammable substances by the electric spark. This he does in the presence of hundreds of spectators, on the occasion of the opening of the Royal Academy of Sciences by Frederick the Great of Prussia, when fire is set to sulphuric ether through a spark from the sword of one of the court cavaliers (see notes on Tyndall’s second lecture, 1876, p. 80).

It was likewise at this period Ludolf the younger demonstrated that the luminous barometer is made perfectly electrical by the motion of the quicksilver, first attracting and then repelling bits of paper, etc., suspended by the side of the tube, when it was enclosed in another tube out of which the air was extracted (Dantzig Memoirs, Vol. III. p. 495).

A.D. 1744–1745.—Waitz (Jacob Siegismund von), a German electrician, writes three essays in Dutch and one in French, and is given the prize of fifty ducats proposed by the Berlin Academy of Sciences for the best dissertation on the subject of electricity. In the following year he makes experiments, with Etienne François du Tour, to show the destruction of electricity by flame, and, later on, with Prof. Georg Erhard Hamberger, he proves conclusively that the motion of quicksilver in a glass vessel out of which the air is extracted has the power of moving light bodies. Jean Nicolas Sebastien Allamand subsequently found that it was immaterial whether the vessel had air in it or not.

References.—Tyndall’s Notes on Lecture II, also Dantzig Memoirs, Vol. II. pp. 380, 426, and M. du Tour’s “Recherches sur les Différents Mouvements de la Matière Electrique,” Paris, 1760.

A.D. 1745.—Kratzenstein (Christian Gottlieb), Professor of Medicine at Halle, author of “Versuch einer Erklarung,” etc., and of “Theoria Electricitatis,” etc., is said to have first successfully employed electricity in the relief of sprains, malformations, etc. He observed that a man’s pulse, which had beat eighty in a second before he was electrified, immediately after beat eighty-eight, and was soon increased to ninety-six.

Kratzenstein is reported (Mary Somerville, “Physical Sciences,” Section XVII.) to have made instruments which articulated many letters, words and even sentences, and somewhat similar in construction to those alluded to at A.D. 1620 (De Bergerac), and A.D. 1641 (John Wilkins), some of which may truly be said to strongly suggest the modern phonograph.

Albertus Magnus constructed, after thirty years of experimentation, a curious machine which sent forth distinct vocal sounds, at which the very learned scholastic philosopher Saint Thomas Aquinas (“Angel of the Schools”) was so much terrified that he struck the contrivance with his stick and broke it. Bishop Wilkins alludes to this machine as well as to a brazen head devised by Friar Bacon, which could be made to utter certain words (“Journal des Savants” for 1899, and J. S. Brewer, “F. Rog. Bacon,” 1859, p. xci; also, “How Fryer Bacon made a Brasen Head to Speake,” at pp. 13–14 of the “Famous Historie of Fryer Bacon published at London for Francis Groue”).

Incidentally, it may be mentioned that Wolfgang von Kempelen, Aulic Counsellor to the Royal Chamber of the Domains of the Emperor of Germany, after witnessing some magnetic games shown to the Empress Maria Theresa at Vienna, constructed, during the year 1778, a speaking machine which “gave sounds as of a child three or four years of age, uttering distinct syllables and words” (Wm. Whewell, “Hist. of the Inductive Sciences,” Vol. II. chap. vi.; J. E. Montucla, “Hist. des Mathém,” Vol. III. p. 813).

La Nature, Paris, May 6, 1905, pp. 353–354, illustrates the speaking head of l’Abbé Mical presented by him to the French Academy of Sciences July 2, 1783, and alludes to those of Albertus Magnus, Wolfgang von Kempelen, C. G. Kratzenstein, etc.

Two more curious productions, in pretty much the same line as Bergerac’s, can, with equal propriety, be inserted here.

The first is taken from the April number, 1632, of the Courier Véritable, a little monthly publication in which novel fancies were frequently aired: “Captain Vosterloch has returned from his voyage to the southern lands, which he started on two years and a half ago, by order of the States-General. He tells us, among other things, that in passing through a strait below Magellan’s, he landed in a country where Nature has furnished men with a kind of sponge which holds sounds and articulations as our sponges hold liquids. So, when they wish to dispatch a message to a distance, they speak to one of the sponges, and then send it to their friends. They, receiving the sponges, take them up gently and press out the words that have been spoken into them, and learn by this admirable means all that their correspondents desire them to know.”

The second is the production of one Thomas Ward, theological poet, who was born in 1640 and died in 1704. In the second canto of one of his poems occur these words:

“As Walchius could words imprison

In hollow canes so they, by reason,

Judgment and great dexterity,

Can bottle words as well as he;

And can from place to place convey them,

Till, when they please, the reed shall say them;

Will suddenly the same discharge,

And hail-shot syllables at large

Will fly intelligibly out

Into the ears of all about:

So that the auditors may gain

Their meaning from the breach of cane.”

References.—Priestley, “History,” etc., 1775, p. 374, and Dantzig Memoirs, Vol. I. p. 294.

A.D. 1745.—Grummert (Gottfried Heinrich), of Biala, Poland, first observes the return of the electric light in vacuo. In order to ascertain whether an exhausted tube would give light when it was electrified, as well as when it was excited, he presented one eight inches long and a third of an inch wide, to the electrified conductor, and was surprised to find the light dart very vividly along the entire length of the tube. He likewise observed that some time after the tube had been presented to the conductor, and exposed to nothing but the air, it gave light again without being brought to an electrified body (see Dantzig Memoirs, Vol. I. p. 417).

A.D. 1745.—Dr. Miles (Rev. Henry), of Tooting, D.D. (1698–1763) reads, March 7, before the English Royal Society a paper indicating the possibility of kindling phosphorus by applying to it an excited electric without the approach of a conducting body. This gentleman’s tube happening to be in excellent order upon this occasion, he observed, and doubtless was the first to notice, pencils of luminous rays, which he called coruscations, darting from the tube without the aid of any conductor approaching it.

In a paper which Dr. Miles read before the same Society on the 25th of January, 1746, he gave an account of other equally interesting experiments, one of which was the kindling of ordinary lamp spirits with a piece of black sealing wax excited by dry flannel or white and brown paper.

References.—“Dict. Nat. Biog.,” Sidney Lee, Vol. XXXVII. p. 378; Phil. Trans., Vol. XLIII. pp. 290, 441; Vol. XLIV. pp. 27, 53, 78, 158, and the following abridgments: Hutton, Vol. IX. pp. 107, 136, 191, 198, 207, 213, 232; John Martyn, Vol. X. part ii. pp. 272, 277, 317, 319, 322–323, 325.

A.D. 1745.—This period was to witness a discovery which, according to Professor Tyndall, “throws all former ones in the shade,” and which Dr. Priestley calls “the most surprising yet made in the whole business of electricity.” This was the accumulation of the electric power in a glass phial, called the Leyden jar after the name of the place where the discovery was made. It was first announced in a letter to Von Kleist, dean of the cathedral of Kamin—Cammin—in Pomerania, dated the 4th of November, 1745, and addressed to Dr. Lieberkühn, who communicated it to the Berlin Academy. The following is an extract: “When a nail or a piece of thick brass wire is put into a small apothecary’s phial and electrified, remarkable effects follow; but the phial must be very dry or warm; I commonly rub it over beforehand with a finger, on which I put some pounded chalk. If a little mercury, or a few drops of spirit of wine, be put into it, the experiment succeeds the better. As soon as this phial and nail are removed from the electrifying glass, or the prime conductor to which it has been exposed is taken away, it throws out a pencil of flame so long that, with this burning machine in my hand, I have taken above sixty steps in walking about my room; when it is electrified strongly I can take it into another room and there fire spirits of wine with it. If while it is electrifying I put my finger, or a piece of gold which I hold in my hand, to the nail, I receive a shock which stuns my arms and shoulders.”

It is said that Cunæus, rich burgess of Leyden, accidentally made the same discovery in January 1746. It appears that Pieter Van Musschenbroek, the celebrated professor, while experimenting with his colleagues, Cunæus and Allamand, observed that excited bodies soon lost their electricity in the open air, attributable to the vapours and effluvia carried in the atmosphere, and he conceived the idea that the electricity might be retained by surrounding the excited bodies with others that did not conduct electricity. For this purpose he chose water, the most readily procured non-electric, and placed some in a glass bottle. No important results were obtained until Cunæus, who was holding the bottle, attempted to withdraw the wire which connected with the conductor of a powerful electric machine. He at once received a severe shock in his arms and breast, as did also the others upon renewing the experiment. In giving an account of it to the great scientist, René de Réaumur, Musschenbroek remarked: “For the whole kingdom of France, I would not take a second shock.” Allamand states that when he himself took the shock “he lost the use of his breath for some minutes, and then felt so intense a pain along his right arm that he feared permanent injury from it.”

In his “Cours Elémentaire de Physique,” Musschenbroek describes one of the peculiar electrical machines then being constructed by the well-known London instrument maker, George Adams, and a cut of it can be seen at p. 353, Vol. I. of the translation made by Sigaud de la Fond at Paris during 1769. Another of Adams’ machines is described and illustrated at p. 126 of the French translation of Cavallo’s “Complete Treatise,” published at Paris in 1785.

The invention of the Leyden jar is claimed with equal pertinacity for Kleist, Musschenbroek and Cunæus. While it is necessarily conceded that Von Kleist first published his discovery, it cannot be denied that his explanation of it is so obscure as, for the time, to have been of no practical use to others. It is stated by Priestley: “Notwithstanding Mr. Kleist immediately communicated an account of this famous experiment (which indeed it is evident he has but imperfectly described) to Mr. Winckler, at Leipzig, Mr. Swiettiki, of Denmark, Mr. Kruger, of Halle, and to the professors of the Academy of Lignitz, as well as to Dr. Lieberkühn, of Berlin, above mentioned, they all returned him word that the experiment did not succeed with them. Mr. Gralath, of Dantzig, was the first with whom it answered; but this was not till after several fruitless trials, and after receiving further instructions from the inventor. The Abbé Nollet had information of this discovery, and, in consequence of it says, in a letter to Mr. Samuel Wolfe, of the Society of Dantzig, dated March 9, 1746, that the experiment at Leyden was upon principles similar to that made with a phial half full of water and a nail dipped in it; and that this discovery would have been called the Dantzig experiment if it had not happened to have got the name of that of Leyden.”

In the thirty-eighth volume of the Philosophical Transactions, No. 432, p. 297, is given an abstract of a letter (dated Utrecht, January 15, 1733, O. S.), from Petrus Van Musschenbroek, M.D., F.R.S., to Dr. J. T. Desaguliers, concerning experiments made on the Indian Magnetic Sand, chiefly gathered along the seashore in Persia. After detailing his many observations, Van Musschenbroek asks: “And, now, what can this sand be? Is it an imperfect magnet, or Subtile Powder of it, which, when it is grown up into a greater lump, makes the vulgar Loadstones? So I conjectured at first; but when I found by experience that common Loadstones, exposed to the fire, according to some of the methods above-mention’d, did rather lose of their force than gain, I alter’d my opinion; and now confess that I have not yet penetrated into the knowledge of the nature of this matter.”

References.—Dalibard, “Histoire Abrégée,” p. 33; Dantzig Memoirs, Vol. I. pp. 407, 409, 411; Johann Gottlob Kruger, “Dissert. de Elect.,” Helmstadt, 1756 (Poggendorff, I. p. 1323); Priestley, 1777, “The Hist. and Pres. State of Electricity,” pp. 82–84; Opuscoli Scelti, 4to, xviii, 55; Pierre Massuet, “Essais,” Leide, 1751; Musschenbroek’s “Epitome elementorum,” etc., 1726, “Tentamina Experimentorum Naturalium,” 1731, and his “Disertatio Physica experimentalis de Magnete,” as well as his “Elementa Physicæ,” 1734, and the “Introductio ad Philosophiam Naturalem,” 1762, the last-named two works being greatly amplified editions of the “Epitome.” For Musschenbroek—Musschenbrock—consult also Phil. Trans., Vol. XXXII. p. 370; Vol. XXXVII. pp. 357, 408, also the following abridgments: Baddam, 1745, Vol. VIII. p. 42; Reid and Gray, Vol. VI. p. 161 (Musschenbroek to Desaguliers); Hutton, Vol. VII. pp. 105, 647 (magnetic sand); Eames and Martyn, Vol. VI. part ii. p. 255; John Martyn, Vol. VIII. p. 737 (magnetic sand). For this magnetic sand, consult also Mr. Butterfield’s article in Phil. Trans. for 1698, p. 336 and in the abridgments of Hutton, Vol. IV. p. 310.

A.D. 1745.—Watson (William), M.D., F.R.S., an eminent English scientist, bears “the most distinguished name in this period of the history of electricity.” His first letters, treating of this science, are addressed to the Royal Society between March 28 and October 24, 1745, and, on the 6th of February and the 30th of October, 1746, he communicated other similar papers to the same Society, all which, like his subsequent treatises, are to be found in the Philosophical Transactions.

Dr. Watson, like most scientists at the time, made numerous experiments with the Leyden jar, and he was the first to observe the flash of light attending its discharge. He says: “When the phial is well electrified, and you apply your hand thereto, you see the fire flash from the outside of the glass wherever you touch it, and it crackles in your hand.” It is to him that we owe the double coating of the jar, as well as the plus and minus of electricity.

He also shows conclusively that glass globes and tubes do not possess in themselves the electrical power, but only serve “as the first movers or determiners of that power,” and he also proves that the electric fluid takes the shortest course, passing through the substance of the best medium of connection and not along its surface. This, he demonstrated by discharging a phial through a wire covered with a mixture of wax and resin.

In order to ascertain the velocity of the electric fluid from the Leyden phial and the distance at which it could be transmitted (John Wood, at A.D. 1726), Watson directed a series of experiments upon a very grand scale, with the assistance of Martin Folkes, President of the Royal Society, Lord Charles Cavendish, Dr. Bevis, Mr. Graham, Dr. Birch, Peter Daval and Messrs. Trembley, Ellicott, Robins and Short. On the 14th and 18th of July, 1747, they experimented upon a wire carrying the electricity from the Thames bank at Lambeth to the opposite bank at Westminster, across Westminster Bridge, and, on the 24th of July, at the New River, Stoke Newington, they sent a shock through 800 feet of water and 2000 feet of land, as well as through 2800 feet of land and 8000 feet of water. Other experiments followed on the 28th of July and the 5th of August, as well as on the 14th of August of the same year, proving the instantaneous transmission of the fluid; while a year later, August 5, 1748, additional observations were made, through 12,276 feet of wire, at Shooter’s Hill, showing again that the time occupied in the passage of the electricity was “altogether inappreciable.” Regarding these experiments, Prof. Musschenbroek wrote to Dr. Watson, “Magnificentissimis tuis experimentis superasti conatus omnium.”

Watson’s experiments were repeated, notably by Franklin, across the Schuylkill at Philadelphia, in 1748; by Deluc, across the Lake of Geneva, in 1749; and by Winckler, at Leipzig, in 1750. It is said that Lemonnier (A.D. 1746) produced shocks at Paris through 12,789 feet of wire and that Bétancourt (A.D. 1795) discharged electric jars through a distance of twenty-six miles.

To Dr. Watson is also due the first demonstration of the passage of electricity through a vacuum. Noad tells us that he caused the spark from his conductor to pass in the form of coruscations of a bright silver hue through an exhausted tube three feet in length, and he discharged a jar through a vacuum interval of ten inches in the form of “a mass of very bright embodied fire.” These demonstrations were repeated and varied by Canton, Smeaton and Wilson.

His experiments in firing gunpowder, hydrogen, etc., by the electric spark, are detailed at p. 78 of Priestley’s “History,” etc., London, 1775.

Watson was rewarded with the Copley medal for his researches in electricity, which brought him also honorary degrees from two German universities. He was knighted in 1786, one year before his death.

References.—“Watson’s Experiments and Observations on Electricity,” 1745, also his “Account of the Experiments made by some gentlemen of the Royal Society,” etc., 1748; Phil. Trans., Vol. XLIII. p. 481; Vol. XLIV. pp. 41, 388, 695, 704; Vol. XLV. pp. 49–120, 491–496; Vol. XLVI. p. 348; Vol. XLVII. pp. 202, 236, 362, 567; Vol. XLVIII. p. 765; Vol. LI. p. 394 (lyncurium of the ancients); Vol. LIII. p. 10; also the following abridgments: Hutton, Vol. IX. pp. 151, 195, 308, 368, 408, 410, 440, 553; Vol. X. pp. 12, 189, 197, 227, 233, 242, 303, 372–379, 525; Vol. XI. p. 419 (lyncurium of the ancients), 580, 660, 679; Vol. XII. p. 127; John Martyn, Vol. X. part ii. pp. 279–280, 290, 294, 329, 339, 347, 368, 407, 410. See likewise, Scientific American Supplement of Oct. 5, 1889, No. 718, pp. 11, 471, for an interesting engraving of Dr. Watson’s experiment made through the water of the Thames, as well as for a detailed account of Lemonnier’s experiment above referred to. For Mr. A. Trembley, consult Phil. Trans., Vol. XLIV. p. 58, and John Martyn’s abridgments, Vol. X. part ii. p. 321.

A.D. 1746.—Lemonnier (Pierre Claude Charles), a distinguished savant, who was member of the French Academy as adjunct geometrician before he had attained his twenty-first year and became foreign member of the English Royal Society three years later, was the first scientist who drew electricity from the narrow domain of the laboratory.

He confirmed the result previously obtained by Grey (A.D. 1720) that electric attraction is not proportioned to the mass or quantity of matter in bodies, but only to the extent of their surface, length having greater effect than breadth (Phil. Trans., Vol. XLIV for 1746, p. 290; Snow Harris, “Treatise on Frict. Elect.,” London, 1867, p. 239, and “Hist. de l’Acad.,” 1746). He found that an anvil weighing two hundred pounds gives but an inconsiderable spark, while the spark from a tin speaking-trumpet eight or nine feet long, but weighing only ten pounds, is almost equal to the shock of the Leyden phial. A solid ball of lead, four inches in diameter, gives a spark of the same force as that obtained from a thin piece of lead of like superficies bent in the form of a hoop. He took a thin and long piece of lead, and noticed that when it was electrified in its whole length it gave a very strong spark, but a very small one when it was rolled into a lump (Ac. Par., 1746, M. p. 369). It had likewise been shown by Le Roi and D’Arcy that a hollow sphere accepted the same charge when empty as when filled with mercury, which latter increased its weight sixtyfold; all proving the influence of surface as distinguished from that of mass (Tyndall, Notes on Lecture IV).

Lemonnier discovered that electricity is ever present in the atmosphere, that it daily increases in quantity from sunrise till about three or four o’clock in the afternoon, diminishing till the fall of dew, when it once more increases for a while, and finally diminishes again before midnight, when it becomes insensible. He observed a continual diminution of electricity as the rain began to fall, and he says: “When the wire was surrounded with drops of rain, it was observed that only some of them were electrical, which was remarkable by the conic figure they had; whilst the others remained round as before. It was also perceived that the electrical and non-electrical drops succeeded almost alternately; this made us call to mind a very singular phenomenon which happened some years before, to five peasants who were passing through a cornfield, near Frankfort upon the Oder, during a thunderstorm; when the lightning killed the first the third and the fifth of them, without injuring the second or the fourth” (Phil. Trans., Vol. XLVII. p. 550).

References.—Le Monnier, “Lois du Magnétisme,” Paris, 1776–1778; Phil. Trans., Vol. XLIV. p. 247; Vol. XLVIII. part i. p. 203; “Journal des Sçavans,” Vol. CXII for 1737, p. 73; also Hutton’s abridgments, Vol. IX. pp. 275, 308, 368, 591 (biogr.); John Martyn’s abridgments, Vol. X. part ii. pp. 329–348; “Philosophical Magazine,” Vol. VI. for 1800, p. 181, “Some Account of the Late P. C. Le Monnier,” 1715–1799; “Mémoires de l’Institut Nat. des Sc. et des Arts,” Hist. An. IX. p. 101; Mémoires de l’Acad. Royale des Sciences, 1746, pp. 14–24, 447, 671–696; 1752, Tome I. pp. 9–17, Tome II. 233–243, 346–362; 1770, p. 459; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 10–14; Harris, “Frict. Elec.,” p. 239; Sc. American Supplement, for Oct. 5, 1889, No. 718, pp. 11, 471. See also reports of the experiments of G. B. Beccaria, G. F. Gardini (“De inflexu,” etc., ss. 50, 51), Andrew Crosse and others at “Bibl. Britan. Sc. et Arts,” 1814, Vol. LVI. p. 524.

A.D. 1746.—Bevis (John), English astronomer and Secretary of the Royal Society, first suggested to Dr. Watson the external coating of the Leyden jar with tinfoil or sheet-lead, and was likewise the first to observe that the force of the charge increases as larger jars are employed, but not in proportion to the quantity of water they contain. As water only played the part of a conductor, he rightly thought that metal would do equally well, and he therefore filled three jars with leaden shot instead of with water. When the metallic connection was made it was found that the discharge from three jars was greater than that from two and the discharge from two much greater than that from one. This showed that the seat of the electric force is the surface of the metal and the glass, and proves that the force of the charge is in proportion to the quantity of coated surface.

Thus to Dr. Bevis belongs the credit of having constructed the first electric battery, although the honour has been claimed by the friends of Daniel Gralath (A.D. 1747).

References.—Phil. Trans., abridged, Vol. X. pp. 374, 377; Wilson, “Treatise,” London, 1752, Prop. XVII. p. 107.

A.D. 1746.—Le Cat (Claude Nicolas), a physician of Rouen, observed, when suspending several pieces of leaf gold at his conductor, that they hung at different distances according to their sizes, the smallest pieces placing themselves nearest the conductor and the largest farthest from it.

Le Cat (1700–1768) became celebrated for his surgical operations and succeeded in carrying off all the first prizes offered by the Royal Academy of Surgeons between the years 1734 and 1738 inclusively. Consult his different works named at p. 292 of Ronalds’ “Catalogue”; “Histoire de l’Electricité,” pp. 84 and 85; “Biographie Générale,” Vol. XXX. pp. 179–182.

A.D. 1746.—Maimbray (M.), of Edinburgh, electrified two myrtle trees, during the entire month of October 1746, and found that they put forth small branches and blossoms sooner than other shrubs of the same kind which had not been electrified. This result was confirmed by the Abbé Nollet, who filled two pots with vegetating seeds and found that the pot which he had constantly electrified for fifteen consecutive days put forth earlier sprouts as well as more numerous and longer shoots than did the other.

Like experiments were at the same time carried on with equal success by M. Jallabert and M. Boze, as well as by the Abbé Menon, Principal of the College of Bueil at Angers, France. The last named also found that electricity increases the insensible perspiration of animals. He chose cats, pigeons and chaffinches, and observed after they were electrified, that one cat was sixty-five or seventy grains lighter than the other, the pigeon from thirty-five to thirty-eight grains, and the chaffinch had lost six or seven grains. He also electrified a young person between the ages of twenty and thirty, for five hours and found a loss in weight of several ounces.

With reference to the effect of electricity on different varieties of growing plants, a paper in Boston not long ago published the following:

“In the last few years some very interesting experiments in gardening by electricity have been made by Prof. Selim Lemström, of the University of Helsingfors. These have been carried out both upon the potted plants in the hot-house and upon plants in the open field, the insulated wires in the latter case being stretched upon poles over the plot of ground, and provided with a point for each square metre of area. The current has been supplied by Holtz machines run from eight to eighteen hours daily, the positive pole being connected with the network of wires and the negative with a zinc plate buried in the ground. The electric influence was scarcely perceptible in the growing plants, but was very marked in the yield of many species, especially of barley and wheat, of which the crop was increased by half in some cases. In the hot-house the maturity of strawberries was greatly advanced. The results have shown that plants may be divided into two groups: one, the development of which is favoured by electricity, comprising wheat, rye, barley, oats, red and white beets, parsnips, potatoes, celeriac, beans, raspberries, strawberries and leeks; and the other, whose development is more or less interfered with by electricity, including peas, carrots, kohlrabi, rutabagas, turnips, white cabbages and tobacco. The more fertile the soil, and consequently the more vigorous the vegetation, the greater has been the excess of the crop under electric influence. Prof. Lemström’s experiments up to 1887 were carried on in Finland, but he has since repeated his work in France, and demonstrated that the electric influence is the same in any climate, though likely to be injurious under a scorching sun.”

References.—Nollet, “Recherches sur l’Electricité,” pp. 366, 382; Phil. Trans., abridged, Vol. X. p. 384; Electrical Review, London, June 5, 1891, p. 707.

A.D. 1746.—Knight (Gowan or Gowin), F.R.S., an English physician, is the first to make very powerful steel magnets. The method, which he long succeeded in keeping secret, was described after his death, in the Phil. Trans. for 1746–1747, Vol. XLIV. It consists of placing two magnets in the same straight line, with their opposite poles close to or very near each other, and in laying under them the bar to be magnetized after having it tempered at a cherry-red heat. The magnets are then drawn apart in opposite directions along the bar, so that the south pole of one magnet passes over the north polar half, and the north pole of the other magnet passes over the south polar half of the bar.

This was how Dr. Knight made the bars of the two great magnets of the Royal Society. Each magnet contained two hundred and forty bars, fifteen inches long, one inch wide and half an inch thick. Dr. Robison described, in 1800, the effect of pressing together the dissimilar poles of the two magnets, and, thirty years later, Prof. Faraday, upon placing a soft iron cylinder, one foot long and three-quarters of an inch in diameter, across the dissimilar poles, found that he required a force of one hundred pounds to break down the attractive power.

Previously to Dr. Knight’s discovery, the method of making artificial magnets most in use was by simply rubbing the bar to be magnetized upon one of the poles of a natural magnet in a plane at right angles to the line joining its two poles.

Another secret of Dr. Knight was also, after his death, made known to the Royal Society by its secretary, Mr. Benjamin Wilson. It was the mode of making artificial paste magnets. He collected a large quantity of iron filings, which he cleansed and made into a fine powder under water and afterward dried and mixed, preferably with linseed oil. This was baked into cakes, which were magnetized by placing them between the ends of his magazine of artificial magnets.

To Dr. Knight was given the first English patent in the Class of Electricity and Magnetism. It bears date June 10, 1766, No. 850, and is for the construction of “Compasses so as to prevent them being affected by the motion of the ship,” etc.

References.—Phil. Trans., Vol. XLIII. pp. 161, 361; Vol. XLIV. p. 656; Vol. XLIX. p. 51; Vol. LXVI. p. 591; C. R. Weld, “Hist. of Roy. Soc.,” Vol. I. p. 511; Noad, “Manual,” 1859, p. 593; Sturgeon, “Sc. Researches,” Bury, 1850, p. 249; also the abridgments by Hutton, Vol. IX. pp. 71, 74, 122, 390 (Folkes), 653; Vol. X. pp. 64, 67; Vol. XIV. pp. 117, 480; and by John Martyn, Vol. X. part ii. pp. 678–698.

A.D. 1746.—Gravesande (Wilhelm Jacob), celebrated Dutch mathematician and natural philosopher (1688–1742), whose family name was Storen Van ’Sgravesande, is the author of “Eléments de physique démontrés mathématiquement ... ou introduction à la philosophie Newtonienne,” which was translated from the Latin and published at Leyden in 1746.

At p. 87 of the second volume of the last-named work he gives a description of an electrical machine constructed on the plan of that of Hauksbee. It consisted merely of a crystal globe, which was mounted upon a copper stand, and against which was pressed the hand of the operator while it was made to revolve rapidly by means of a large wheel.

Gravesande taught publicly on the Continent the philosophy of Newton, and, by so doing, was one of the first to bring about a revolution in the domain of physical sciences generally. His original “Physices Elementa Mathematica,” as well as his “Philosophiæ Newtonianæ,” etc., and “Introductio ad Philosophiam,” etc., were respectively published at Leyden in 1720, 1723 and 1736.

Reference.—Houzeau et Lancaster, “Bibl. Générale,” Vol. II. p. 252.

A.D. 1746.—Nollet (Jean Antoine), a distinguished French philosopher (1700–1770), to whom was given the title of Abbé while holding deacon’s orders, is the first in France to make experiments with the Leyden jar.

While in Paris he applied himself to electrical studies in company with Charles Dufay (already noticed at A.D. 1733), and made such ingenious experiments that René de Réaumur allowed him the free use of his extensive apparatus and laboratory. During the month of April 1746, he transmitted, in the presence of the French King, an electrical shock from a small phial through a chain of one hundred and eighty of the Royal Guards, and at the Carthusian Convent, not long afterward, he sent a shock through a line of monks stretched a distance of over a mile, causing them all to experience instantaneously the same sensation.

Nollet’s work, “Essai sur l’électricité des corps,” was originally published at Paris in 1746. He was the first to observe that pointed bodies electrified give out streams of light (the smallest points displaying “brushes of electric light”), but that they do not exhibit as powerful indications of electricity as are shown by blunt bodies. He also found that glass and other non-conductors are more strongly excited in air than in vacuo; that the electric spark is more diffuse and unbroken in vacuo; and that an excited tube loses none of its electricity by being placed in the focus of a concave mirror when the sunlight is therein concentrated.

His experiments upon the evaporation of fluids by electricity, as well as upon the electrification of capillary tubes full of water (observed also by Boze), and upon the electrification of plants and animals, are detailed in his “Recherches,” etc., pp. 327, 351, 354–356, while his observations upon the electrical powers of different kinds of glass are given in the sixth volume of the “Leçons de Physique Expérimentale,” issued in 1764.

As has been truly said, it is no easy matter to form an adequate idea of Nollet’s theory of electricity, which was opposed at the time by almost all the eminent electrical philosophers of Europe. He asserted that when an electric is excited, electricity flows to it from all quarters, and when it is thus affluent, it drives light bodies before it. Hence the reason why excited bodies attract. When the electricity is effluent the light bodies are of course driven from the electric, which in that condition appears to repel. He therefore believed every electric to be possessed of two different kinds of pores, one for the emission of the electric matter, and the other for its reception.

Nollet is the first one who published the close relationship existing between lightning and the electric spark. This he did during the year 1748, in the fourth volume of his “Leçons,” already alluded to and from which the following is extracted: “If any one should undertake to prove, as a clear consequence of the phenomenon, that thunder is in the hands of nature what electricity is in ours—that those wonders which we dispose at our pleasure are only imitations on a small scale of those grand effects which terrify us, and that both depend on the same mechanical agents ... I confess that this idea, well supported, would please me much.... The universality of the electric matter, the readiness of its actions, its instrumentality and its activity in giving fire to other bodies, its property of striking bodies, externally and internally, even to their smallest parts ... begin to make me believe that one might, by taking electricity for the model, form to one’s self, in regard to thunder and lightning, more perfect and more probable ideas than hitherto proposed.”

For a memoir treating of the cause of thunder and lightning, written by the Rev. Father de Lozeran de Fech, of Perpignan, the Bordeaux Academy of Sciences had in 1726 awarded him its annual prize; and the same institution conferred a similar award, in August 1750, upon M. Bergeret, a physician of Dijon, whose memoir admitted the close analogy between lightning and electricity.

References.—Ronalds’ “Catalogue,” pp. 369–371; Jean Morin, “Réplique,” Paris, 1749; A. H. Paulian, “Conjectures,” 1868; “Abrégé des transactions philosophiques,” Vol. X. p. 336; “Mémoires de mathématique,” etc., pour 1746, p. 22; “Journal des Sçavans,” Vol. CXVII. for 1739, pp. 111–115, and Vol. CXLII for 1747, pp. 248–265; “Medical Electricity,” by Dr. H. Lewis Jones, Philad., 1904, p. 2; “Mémoires de l’Acad. Royale des Sciences” pour 1745, p. 107; 1746, p. 1; 1747, pp. 24, 102, 149, 207; 1748, p. 164; 1749, p. 444; 1753, pp. 429, 475; 1755, p. 293; 1761, p. 244; 1762, pp. 137, 270; 1764, pp. 408–409; 1766, p. 323; “Leçons,” eighth edition, Vol. IV. p. 315; Phil. Trans., Vol. XLV. p. 187; Vol. XLVI. p. 368; Vol. XLVII. p. 553; also the following abridgments: Hutton, Vol. X. pp. 20, 295, 372–379, 446 (Dr. Birch); Vol. XI. p. 580; John Martyn, Vol. X. part ii. pp. 277–333, 382 (Folkes), 414. See the experiments of Etienne François du Tour, “Sur la manière dont la flamme agit sur les corps electriques,” in a letter addressed by him to Nollet in 1745, and in “Mém. de Mathém. et Phys.,” Vol. II. p. 246, Paris, 1755; also Zantedeschi and Faraday on the “Magnetic Condition of Flame” (Faraday’s “Exper. Res.,” Vol. III. pp. 490–493).

A.D. 1746.—Wilson (Benjamin) (1721–1788), Secretary to the Royal Society, writes his “Essay toward an explication of the phenomena of Electricity deduced from the ether of Sir Isaac Newton.” In the chapter of Priestley’s “History” treating of the Theories of Electricity, he says: “With some, and particularly Mr. Wilson, the chief agent in all electrical operations is Sir Isaac Newton’s ether, which is more or less dense in all bodies in proportion to the smallness of their pores, except that it is much denser in sulphureous and unctuous bodies. To this ether are ascribed the principal phenomena of attraction and repulsion, whereas the light, the smell, and other sensible qualities of the electric fluid are referred to the grosser particles of bodies, driven from them by the forcible action of this ether. Many phenomena in electricity are also attempted to be explained by means of a subtile medium, at the surface of all bodies, which is the cause of the refraction and reflection of the rays of light, and also resist the entrance and exit of this ether. This medium, he says, extends to a small distance from the body, and is of the same nature with what is called the electric fluid.[50] On the surface of conductors this medium is rare and easily admits the passage of the electric fluid, whereas on the surface of electrics it is dense and resists it. This medium is rarefied by heat, which converts non-conductors into conductors.”

At pp. 71 and 88, 1746 edition, and at p. 88, Prop. XI. of the 1752 edition of this same “Essay,” Wilson says that during the year 1746 he discovered a method of giving the shock of the Leyden jar to any particular part of the body without affecting any other portion; that he increased the shock from the jar by plunging it into water, thereby giving it a coating of water on the outside as high as it was filled on the inside; and that the accumulation of electricity in the Leyden jar is always in proportion to the thinness of the glass, the surface of the glass and that of the non-electrics in contact with the inside and outside thereof.

It was in this same year, 1746, that Wilson first observed the lateral shock or return stroke, which was not, however, explained until Lord Mahon, third Earl of Stanhope, published his “Principles of Electricity,” in 1779.

On the 13th of November, 1760, a paper of Mr. Wilson’s was read before the Royal Society, in which he detailed several of his ingenious experiments on the plus and minus of electricity, and showed that these can be produced at pleasure by carefully attending to the form of bodies, their sudden or gradual removal and the degrees of electrifying. He had previously noticed that when two electrics are rubbed together, the body whose substance is hardest and electric power strongest is always electrified positively and the other negatively. Rubbing the tourmaline and amber together he produced a plus electricity on both sides of the stone and a minus on the amber; but, rubbing the diamond and the tourmaline, both sides of the tourmaline were electrified minus and the diamond plus. When insulated silver and glass were rubbed, the silver became minus and the glass plus.

He further observed that when directing a stream of air against a tourmaline, a pane of glass or a piece of amber, these were electrified plus on both sides. Prof. Faraday subsequently showed that no electrical effect is produced in these cases unless the air is either damp or holds dry powders in suspension, the electricity being produced by the friction of particles of water in the one case and by the particles of powder in the other. Sir David Brewster, who thus mentions the latter fact, likewise singles out two more of Mr. Wilson’s observations, viz. that when a stick of sealing-wax is broken across or when a dry, warm piece of wood is rent asunder, one of the separated surfaces becomes vitreously and the other resinously electrified.

References.—De La Rive, “Electricity,” Vol. I. p. 203; Wilson, “Treatise on Electricity”; Wilson and Hoadley, “Observations on a Series of Electrical Experiments”; Phil. Trans., Vol. XLVIII. p. 347; Vol. XLIX. p. 682; Vol. LI. part i. pp. 83, 308, 331, part ii. p. 896; Vol. LIII. pp. 436, etc.; Vol. LXVIII. p. 999; Vol. LXIX. p. 51; also Hutton’s abridgments; Vol. X. p. 420; Vol. XI. pp. 15, 396, 504; Vol. XII. pp. 44, 147; Vol. XIII. p. 374; Vol. XIV. pp. 334, 337, 458, 480; “The Electrical Researches of the Hon. Henry Cavendish,” Cambridge, 1879, No. 125; L. E. Kaemtz, “Lehrbuch der Meteor,” Halle, 1832, Vol. II. p. 395.

A.D. 1746.—Ellicott (John), of Chester, suggests a method of estimating the exact force of the electric charge contained in the Leyden jar by its power to raise a weight in one scale of a balance while the other scale is held over and attracted by the electrified body. This was the principle upon which Mr. Gralath constructed the electrometer shown in Dantzig Memoirs, Vol. I. p. 525.

With reference to the experiments of Boze (A.D. 1738) and of Nollet (A.D. 1746) made with capillary tubes, he says that the siphon, though electrified, will only deliver the water by drops if the basin containing the water is also electrified. He explains Nollet’s observation, that the electric matter issues more sensibly from the point at the extremity of the conductor, by saying that the effluvia, in rushing from the globe along the conductor, as they approach the point are brought nearer together, and therefore are denser there, and if the light be owing to the density and velocity of the effluvia it will be visible at the point and nowhere else. Ellicott’s theory of electricity is founded upon the following data: (1) electrical phenomena are produced by effluvia; (2) these effluvia repel each other; (3) they are attracted by all other matter. If the word fluid is substituted for effluvia, these data absolutely agree with those adopted by Æpinus and Cavendish, forming the basis of the only satisfactory theory of electricity hitherto proposed.

References.—Boulanger, “Traité de la Cause et des phénomènes de l’électricité,” Paris, 1750, p. 324; Phil. Trans. for 1746, Vol. XLIV. p. 96, and for 1748, Vol. XLV. pp. 195–224, 313; also the abridgments of John Martyn, Vol. X. part ii. pp. 324, 386, 389, 394; Hutton, Vol. IX. p. 475.

A.D. 1747.—Pivati (Johannes Francisco), a Venetian physician, relates in his “Lettere della elettricita medica,” that if odorous substances are confined in glass vessels and the latter excited, the odours and other medical virtues will transpire through the glass, infect the atmosphere of a conductor, and communicate the virtue they may possess to all persons in contact therewith; also, that those substances held in the hands of persons electrified will communicate their virtue to them so that medicines can thus be made to operate without being taken in the usual manner.

This appears to have been likewise asserted especially by M. Veratti, of Bologna, and by M. Bianchi, of Turin; also by Prof. Winckler, of Leipzig, who satisfied himself of the power of electricity on sulphur, cinnamon, and on balsam of Peru even at a distance.

By the above-named means of applying the electric fluid Pivati is reported to have effected cures of ordinary pains and aches, and to have even relieved of gout the old Bishop Donadoni, of Sebenico, who had long been a sufferer, and who was at the time seventy-five years of age. This pretended transudation and its medical effects could not, however, be verified, even with the directions asked of and given by Prof. Winckler, when very careful and exhaustive experiments were made, on the 12th of June, 1751, at the house of Dr. Watson, in presence of the president and other officers as well as friends of the Royal Society. Nor could Dr. Bianchini, Professor of Medicine at Venice, succeed any better. At a later date, Franklin asserted that it was impossible to combine the virtues of medicines with the electric fluid.

References.—Franklin’s Letters, p. 82; Phil. Trans. for 1748, Vol. XLV. pp. 262, 270; for 1750, Vol. XLVI. pp. 348, 368; for 1751, Vol. XLVII. p. 231; for 1753, Vol. XLVIII. pp. 399, 406, and Vol. X. abridged, pp. 400–403.

A.D. 1747.—Louis (Antoine), eminent French surgeon (1723–1792), publishes “Observations sur l’électricité,” of which the first issue appeared in 1747 and wherein he indicates the employment of electricity in medical practice. This he did again in his “Recueils,” upon a more pretentious scale, six years later, 1753.

References.—N. F. J. Eloy, “Dict. de la Médecine,” Mons, 1778, Vol. III. p. 206; “Gen. Biog. Dict.” of Alex. Chalmers, 1815, Vol. XX. p. 419; Hœfer, “Nouv. Biog. Gén.,” Vol. XXXI. p. 1033; Quérard, “La France Littéraire”; “Biog. Univ.,” de Michaud, Vol. XXV. pp. 319–325.

A.D. 1747.—Gralath (Daniel) publishes in the Dantzig Memoirs his “Geschichte der Electricität.”

He is the first to construct a Leyden phial with a long, narrow neck, through which is passed an iron wire bearing a tin knob in place of the iron nail theretofore used; and, with several of these phials joined together in the form of a battery, he had, during the previous year, transmitted a shock through a chain of twenty persons. His observations are recorded in the above-named Memoirs at pp. 175–304 and 506–534, Vol. I.; pp. 355–460, Vol. II.; pp. 492–556, Vol. III. Gralath’s “Electrische Bibliothek” is in Vols. II. and III.

A.D. 1747.—The Swedish mathematician and philosopher, Samuel Klingenstierna, and his pupil, M. Stroemer, were the first who properly electrified by the rubber, and their experiments were published in the Acts of the Royal Academy of Sciences at Stockholm for the year 1747 (see Priestley’s “History of Electricity,” Part I. period viii. s. 3, wherein he alludes to Wilcke’s “Herrn Franklin’s briefe,” etc., p. 112).

A.D. 1748.—Morin (Jean), French physicist, publishes at Chartres “Nouvelle dissertation sur l’électricité des corps,” etc., in which he details many of his experiments, and endeavours to give a correct explanation of all the extraordinary electrical phenomena hitherto observed. He is also the author of a “Reply to Mr. Nollet upon Electricity,” published in 1749 at Chartres and at Paris, as well as of a treatise upon Universal Mechanism, which latter, according to the Journal des Savants, contained more information upon Nature generally, and expressed in fewer words, than was embraced in any previous work.

References.—“Dict. Univ.,” Vol. XI. p. 568; “Biog. Générale,” Vol. XXXVI. p. 599.

A.D. 1749.—Stukeley (the Rev. William), M.D., is the first who advanced that earthquakes are probably caused by electricity. This he did in a paper read before the Royal Society, March 22, 1749, having reference to the subterranean disturbances noticed in London, February 8 and March 8 of the same year. In this communication, as well as in a subsequent one read to the same Society, December 6, 1750, bearing upon a similar disturbance observed throughout England during the previous month of September, he explains why earthquakes are not the result of subterraneous winds, fires, vapours, etc.

One of his strongest arguments is that no such vapours could instantaneously have destroyed thirteen great cities as did the earthquake which occurred in Asia Minor, A.D. 17, and which is reckoned to have shaken a cone of earth three hundred miles diameter in base and two hundred miles in the axis. This quantity of earth, he says, “all the gunpowder which has ever been made since the invention of it would not have been able to stir, much less any vapours, which could be supposed to be generated so far below the surface,” and, he adds, “if the concussion depended upon a subterraneous eruption the shock would precede the noise.”

He observes that the earth for months prior to the afore-named disturbances “must have been in a state of electricity ready for that particular vibration in which electrification exists”; that all the vegetation had been “uncommonly forward ... and electricity is well known to quicken vegetation”; that the aurora borealis had been very frequent about the same time and had been twice repeated just before the earthquake, “of such colours as had never been seen before,” there being, one evening, “a deep red aurora borealis covering the cope of heaven very terrible to behold”; that the whole year had been “remarkable for fire-balls, thunder, lightning and coruscations, almost throughout all England,” all which “are rightly judged to proceed from the electrical state of the atmosphere”; and, finally, that, a little before the earthquake, “a large and black cloud suddenly covered the atmosphere, which probably occasioned the shock by the discharge of a shower.” He adds that, according to Dr. Childrey, earthquakes are always preceded by rain and sudden tempests of rain in times of great drought.

Dr. Stephen Hales (1677–1761), who was Stukeley’s classmate at Bennet College, Cambridge, and later his chief assistant in the study of the natural sciences, and who afterward became celebrated for his physical investigations and discoveries, arrives at a like conclusion. He thinks that “the electric appearances were only occasioned by the great agitation which the electric fluid was put into by the shock of so great a mass of the earth.” The great noise which attended the disturbance of March 8, 1749, he conjectured was “owing to the rushing or sudden expansion of the electric fluid at the top of St. Martin’s spire, where all the electric effluvia, which ascended along the large body of the tower, being strongly condensed, and accelerated at the point of the weathercock, as they rushed off made so much the louder expansive explosion.” It may be added here that Dr. Hales is the one who, at a previous date, had communicated to the Royal Society his observation of the fact that the electric spark proceeding from warm iron is of a bright, light colour, while that from warm copper is green, and the colour from a warm egg of a light yellow. In his opinion, these experiments appeared to argue that some particles of those different bodies are carried off in the electric flashes wherein those different colours are exhibited.

For Stephen Hales, consult the Phil. Trans., Vol. XLV. p. 409, as well as the abridgments of Hutton, Vol. IX. p. 534, and for his portrait see “Essays in Historical Chemistry,” by T. E. Thorpe, London, 1894.

For Stukeley and for Stephen Hales: consult “General Biographical Dictionary,” Alex. Chalmers, London, 1814, Vol. XVII. pp. 41–43.

References.—Priestley, “History of Electricity,” Part I. period x. s. 12; Phil. Trans., abridged by John Martyn, Part II. of Vol. X. pp. 406–526, 535, 540, 541, 551; Vol. XLIV-XLV, p. 409; Appendix to the Phil. Trans. for 1750, Vol. XLVI; Hale, “Statical Essays,” II. p. 291; Thomson, “Hist. Roy. Soc.,” 1812, p. 197.

A.D. 1749.—Jallabert (Jean Louis), Professor of Philosophy and Mathematics at Geneva, is the author of “Expériences sur l’électricité, avec quelques conjectures sur la cause de ses effets,” of which a smaller edition had appeared at Geneva in 1748.

He confirms the result obtained by Dr. Watson (A.D. 1745) that the electric fluid takes the shortest course by passing through the substance of a conducting wire instead of along its surface. By making his Leyden experiments with a jar in which the water is frozen, he shows that ice is a conductor of electricity. He improves upon Nollet’s experiments, and demonstrates conclusively that plants which are electrified grow faster and have finer stems, etc., than those not electrified. He is the first to observe that a body pointed at one end and round at the other produces different appearances upon the same body, according as the pointed or the rounded end is presented to it. The Dantzig Memoirs, Vol. II. p. 378, tell us that Carolus Augustus Van Bergen, Professor of Medicine at Frankfort on Oder, had previously noticed, “as a small step toward discovering the effect of pointed bodies,” that sparks taken from a polished body are stronger than those from a rough one. With the latter he found it difficult to fire spirits, but he could easily do it with a polished conductor.

M. Jallabert is also known to have effected some medical cures through the agency of the electric fluid, as related in the “Expériences” above alluded to.

References.—“Biog. Univ.,” Vol. XX. p. 535; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 260, 292, 299, 334, 413, and Vol. II. p. 291; Beccaria, “Dell’ Elettricismo Naturale,” etc., p. 125; “Journal des Sçavans,” Vol. CXLIX. for 1749, pp. 1–18, 441–461; “Medical Electricity,” by Dr. H. Lewis Jones, Philad. 1904, p. 2.

A.D. 1749.—Mines are fired by electricity (S. P. Thompson, lecture delivered October 7, 1882, at the University College, Bristol).

A.D. 1749.—Through the important work entitled “Traité sur l’Electricité,” Louis Elisabeth de la Vergne Tressan secures, a year later, admission to both the French Académie des Sciences and the English Royal Society. During 1786, three years after his death, the above-named work was merged into a publication in two volumes under the title of “Essai sur le fluide électrique considéré comme agent universel.”

References.—“Biographie Générale,” Vol. XLV. pp. 623–626; Larousse, “Dictionnaire Universel,” Vol. XV. p. 474.

A.D. 1749.—Duhamel (Henri Louis, du Monceau) (1700–1782), member of the French Royal Academy of Sciences, develops, in conjunction with M. Antheaulme, the method introduced by Gowin Knight (A.D. 1746) for making artificial magnets, which latter process was found to be defective when applied to very large bars. To Le Maire, however, is due (Mem. de l’Acad. de Paris, 1745 and 1750), the notable improvement which consists in magnetizing at the same time two steel bars of any shape by placing them parallel to each other and connecting their extremities, with pieces of soft iron placed at right angles, in order to form a closed rectangular parallelogram. Two strong magnets, or two bunches of small magnetic bars, with their similar poles together, are then applied to the centre of one of the bars to be magnetized and are drawn away from each other, practically as in Dr. Knight’s method, while being held at an inclination of about forty-five degrees. The operation is repeated upon the other bar and continued alternately until sufficient magnetism is imparted to both, it being borne in mind that before the treatment is given to the second bar the poles must in each instance be reversed, i. e. the pole which was to the right hand should be turned to the left. The entire operation is to be repeated upon the reverse side of both bars.

References.—Harris, “Rudim. Magn.,” I. and II. pp. 85 and 86; P. Larousse, “Dict. Univ.,” Vol. VI. p. 1363; “Biog. Générale,” Vol. XV. pp. 106–107; Condorcet, “Eloge de Duhamel”; I. M. Des Essarts, “Siècles littéraires”; Georges Cuvier, “Hist. des Sc. Naturelles,” Vol. V; Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 45.

A.D. 1750–1753.—In M. Arago’s “Historical Eloge of James Watt,” translated by James P. Muirhead and published in London during the year 1839, it is said, at p. 6, that Watt constructed, at about the period first mentioned herein, a small electrical (his earliest) machine, the brilliant sparks from which became a subject of much amusement and surprise to all the companions of the poor invalid (“James Watt,” by Andrew Carnegie, New York, 1905).

A.D. 1750.—Wargentin (Pierre Guillaume—Perh Vilhelm—) (1717–1783), Secretary to the Swedish Academy of Sciences and a distinguished astronomer, addresses, on the 21st of February, a letter to the Royal Society, of which a copy is to be found in Vol. XLVII. p. 126 of the Phil. Trans. In this he gives his observations of the result produced on the magnetic needle by the aurora borealis.

We have already seen (under the A.D. 1683 date), that the discovery of the fact that magnets are affected by the polar lights has been ascribed to Wargentin, and we have also learned (A.D. 1722) that he ascertained the diurnal changes of the magnetic needle with more precision than had been done by George Graham.

References.—Walker, “Magnetism,” p. 116; American Journal Science and Arts, 1841, Vol. XXX. p. 227; Celsius, A.D. 1740, and the abridgments of Hutton, Vol. X. p. 165.

A.D. 1750.—Michell (John), an eminent English man of science, Professor at Queens’ College, Cambridge, publishes “A treatise of Artificial Magnets, in which is shown an easy and expeditious method of making them superior to the best natural ones.”

The process introduced by this work is known as that of the “double touch.” This consists in first joining, at about a quarter of an inch distance, two bundles of strongly magnetized bars, having their opposite poles together, and in drawing these bars backward and forward upon and along the entire length of the bars to be magnetized, which latter have already been laid down end to end and in a straight line. The operation is to be repeated upon each side of the bars. The central bars of a series thus acquire at first a higher degree of magnetism than do the outer ones, but by transposing the latter and treating all alike the magnetic virtue is evenly distributed. In this process the external bars act the same part as do the pieces of soft iron employed in the Duhamel method.

At Chap. VI. p. 20 of the third volume of his “Rudimentary Magnetism,” Harris thus expresses himself: “Michell advanced the idea that in all the experiments of Hauksbee, Dr. Brooke Taylor, William Whiston and Musschenbroek, the force may really be in the inverse duplicate ratio of the distances, proper allowance being made for the disturbing changes in the magnetic forces so inseparable from the nature of the experiment. He is hence led to conclude that the true law of the force is identical with that of gravity, although he does not set it down as certain.”

References.—Harris, “Rud. Mag.,” I. and II. pp. 94–95; C. R. Weld, “Hist. Roy. Soc.,” Vol. I. p. 512; Phil. Trans., Vol. LI. pp. 390, 393, and Hutton’s abridgment, Vol. XI. p. 418; Gaugain’s observations in “Sc. Am. Suppl.,” No. 7, p. 99.

A.D. 1750.—Boulanger—not Boullangère—(Nicholas Antoine) (1722–1759), a well-known French writer, whose extensive studies were interrupted by his death, in 1759, at the early age of thirty-seven, gives, in this “Traité de la cause et des phénomènes de l’électricité,” accounts of many important observations made in the electrical field.

His attention was carefully given to ascertaining the degrees in which different substances are capable of being excited, and he gives several lists of such, inferring therefrom that the most transparent and the most brittle are always the most electric.

At pp. 64 and 124 of the above-named “Traité” he states that electricity affects mineral waters much more sensibly than common water; that black ribbons are more readily attracted than those of other colours, next to the black being the brown and deep red; and that, of two glass cylinders exactly alike, except that one is transparent and the other slightly coloured, the transparent one will be the more readily excited.

References.—The “Traité,” notably at pp. 135 and 164; “Biog. Générale,” Vol. VI. p. 939; Le Bas, “Dict. Encycl. de la France”; Quérard, “La France Littéraire”; Chaudon et Delandine, “Dict. historique.”

A.D. 1751.—Adanson (Michael), a French naturalist of very high reputation, who, before the age of nineteen, had actually described four thousand species of the three kingdoms of nature, introduces in his “History of Senegal” the silurus electricus, a large species of eel originally brought from Surinam. Sir John Leslie states that the silurus is furnished with a very peculiar and complex nervous apparatus which has been fancifully likened to an electrical battery, and that, from a healthy specimen exhibited in London, vivid sparks were drawn in a darkened room. M. Broussonet alludes to the silurus as Le Trembleur in the “Hist. de l’Acad. Royale des Sciences” for 1782, p. 692.

Adanson also called attention, in 1756, to the electrical powers of the malapterus electricus, but, according to the able naturalist, James Wilson (“Ichthyology,” Encycl. Brit.), there is a much earlier account of the fish extracted from the narrative of Baretus and Oviedo dated 1554.

The Swedish scientist, Karl A. Rudolphi, pupil of Linnæus, called the princeps helminthologorum, has given a detailed description as well as illustrations of the electric organs of the malapterus in “Ueber den Zitter-wels,” Abh. Berl. Acad. VII.... This fish, which the Arabs call Raad or Raash (thunder), gives its discharge chiefly when touched on the head, but is powerless when held by the tail, the electrical organs in fact not reaching the caudal fin.

To Adanson has been attributed the authorship of an essay on the “Electricity of the Tourmaline” Paris, 1757, which bears the name of the Duke de Noya Caraffa.

References.—Spreng, “Hist. R. Herb.,” Vol. II; and “Adanson’s Biog.,” Vol. II. “Encycl. Britannica,” Rees’ “Cycl.” Supplement and in “Bibl. Universelle,” Vol. I; Chambers’ “Encyl.” for 1868, Vol. III. p. 822; Cavallo, “Nat. Phil.,” Philad., 1825, Vol. II. p. 237; Scientific American Supplement, No. 457, pp. 7300, 7301; Rozier, Vol. XXVII. p. 139, and W. Bryant in Trans. Am. Phil. Soc. II. p. 166, O. S.

A.D. 1752.—Franklin (Benjamin) (1706–1790), an able American editor, philosopher and statesman, crowns his many experiments with the brilliant discovery of the identity of electricity and lightning. Humboldt says: “From this period the electric process passes from the domain of speculative physics into that of cosmical contemplation—from the recesses of the study to the freedom of nature” (“Cosmos,” Vol. II. 1849, p. 727). Wall (A.D. 1708) had only alluded to the resemblance of electricity to thunder and lightning; Grey (A.D. 1720) had conjectured their identity and implied that they differed only in one degree, while Nollet (A.D. 1746) pointed out a closer relationship than ever before adduced between lightning and the electric spark; but it was left for Franklin to prove the fact with empirical certainty.

Franklin’s attention was first directed to electrical studies in 1745, by a letter from Peter Collinson, Fellow of the Royal Society of London, to the Literary Society of Philadelphia, and he first wrote on the subject to that gentleman on the 28th of July, 1747. This was followed by several other similar communications up to April 18, 1754, the whole of which comprise most of what subsequently appeared under the title “New Experiments and Observations on Electricity, made at Philadelphia, in America, by Benjamin Franklin, LL.D. and F.R.S.”

Franklin first entertained the idea that lightning was not likely to be attracted by a pointed rod unless the latter was placed at a great height, and he therefore waited for the erection of a tall spire in Philadelphia which he intended to utilize for his observations, but delay in its completion led him to use a kite pointed with an iron rod, not doubting that the electric fluid could, during a thunderstorm, be drawn from it through a string.

The manner of constructing and employing the kite, and the attending results, are thus given in a letter dated Oct. 19, 1752 (Letter XII, “Experiments and observations on Electricity”): “Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief when extended. Tie the corners of the handkerchief to the extremities of the cross, so you have the body of a kite which, being properly accommodated with a tail, loop and string, will rise in the air like those made of paper; but, this being made of silk, is fitter to bear the wet and wind of a thunder-gust without tearing. To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood. In the end of the twine, next the hand, is to be held a silk ribbon, and where the silk and twine join a key may be fastened. This kite is to be raised when a thunder-gust appears to be coming on, and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet, and care must be taken that the twine does not touch the frame of the door or window. As soon as any of the thunder clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite with all the twine will be electrified, and the lose filaments of the twine will stand out every way and be attracted by an approaching finger. And when the rain has wetted the kite so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. At this key, the phial (Leyden jar) may be charged, and from electric fire thus obtained spirits may be kindled, and all the other electric experiments be performed which are usually done by the help of a rubber glass globe or tube, and thereby the sameness of the electric matter with that of lightning completely demonstrated.”

It was during the month of June 1752, on the approach of a storm, that he and his son walked out upon the Philadelphia Commons and first raised the kite. At the outset no important results were obtained, but as soon as the cord became wet by the shower that followed, the electric sparks were easily drawn from the key and enabled Franklin to charge and give shocks from a Leyden jar.

Thus, says Sabine, was Benjamin Franklin successful in one of the boldest experiments ever made by man upon the powers of nature, and from that moment he became immortal.

He had already, in 1749, made public the following, which is embodied in one of his letters to Mr. Collinson: “The electrical spark is zigzag, and not straight; so is lightning. Pointed bodies attract electricity; lightning strikes mountains, trees, spires, masts and chimneys. When different paths are offered to the escape of electricity, it chooses the best conductor; so does lightning. Electricity fires combustibles; so does lightning. Electricity fuses metals; so does lightning. Lightning rends bad conductors when it strikes them; so does electricity when rendered sufficiently strong. Lightning reverses the poles of a magnet; electricity has the same effect.”

Franklin had, likewise, published at about the same period the plan for an experiment to ascertain from elevated structures whether the clouds that contain lightning are electrified or not. He himself had proposed to put the plan to execution; but he was led to try the kite experiment, and, meanwhile, his suggestions had been successfully acted upon, in France, by M. Dalibard and de Lor, as will be shown later on.

“The lightning, which doth cease to be, ere one can say, ‘it lightens.’”—Shakespeare.

“First let me talk with this philosopher; what is the cause of thunder?”—Shakespeare.

“... a way for the lightning of the thunder.”—Job xxviii. 26, and xxxviii. 25.

“It related not to the instances of the magneticalness of lightning.”—“Hist. of Roy. Soc.,” by Thomas Birch, Vol. IV. p. 253.

When specifying the great points of coincidence existing between the ordinary electric discharge and lightning, Franklin, as already partly stated, had remarked that flashes of lightning are frequently waving and crooked, of a zigzag or forked appearance, sometimes diffused and sometimes coloured (“On the Nature of Thunderstorms,” W. Snow Harris, London, 1843, p. 24; Priestley, “History and Present State of Electricity,” London, 1769, p. 166; “Encycl. Metropol.,” article “Electricity”; Biot, “Traité de Physique,” Vol. II). In treating of the subject of lightning flashes, Dr. L. D. Gale (trans. of M. F. J. F. Duprez’s paper on “Atmospheric Electricity,” taken from the memoirs of the Royal Academy of Brussels) alludes to the attempts made by C. G. Helvig to determine the velocity of the linear flashes (Gilbert’s Annalen, Vol. LI. pp. 136 and 139, ss. 2, 10) which he estimated to be 40,000 to 50,000 feet in a second, and states that M. Weigsenborn, of Weimar (Comptes Rendus, Vol. IX. p. 218), calculated the velocity of a flash observed in 1839 to be more than two leagues, while M. François Arago (“Annuaire,” etc., pour l’année 1838, pp. 249, 255, 257, 459, estimated the lengths of certain flashes to be 3·3, 3·6, 3·8 leagues. The views of Messrs. Logan (Phil. Trans., 1735, Vol. XXXIX. p. 240), L. J. Gay-Lussac (Ann. de Chim. et de Phys., 1805, Vol. XXIX. p. 105), H. W. Brandes (“Beiträge zur Witterungskunde,” etc., 1820, p. 353), C. H. Pfaff and L. E. Kaemtz (J. S. T. Gehler, “Dict. de Phys.,” Vol. I. p. 1001, and “Lehrbuch d. Meteor,” Vol. II. p. 430), Gabriel Lamé (“Cours. de Phys. de l’Ecole Polytech.,” Tome II. 2^e partie, p. 82), Becquerel (Comptes Rendus, 1839, Tome VIII. p. 216), Faraday (Philos. Magazine, 1841, Vol. XIX. p. 104), Pouillet (“Eléments de Phys. et de Météor,” Tome II. p. 808), Parrot (J. S. T. Gehler, “Dict. de Phys.,” Vol. I. p. 999), are also set forth in the above-named translation of M. Duprez’s valuable work.

Humboldt informs us that “the most important ancient notice of the relations between lightning and conducting metals is that of Ctesias, in his Indica, Cap. IV. p. 169. He possessed two iron swords, presents from the King Artaxerxes Mnemon, and from his mother Parysatis, which, when planted in the earth, averted clouds, hail and strokes of lightning. He had himself seen the operation, for the king had twice made the experiment before his eyes” (“Cosmos,” Vol. II. N. 186). Ctesias was a man of great learning. He was a contemporary of Xenophon, and lived for a number of years at the Court of Artaxerxes Mnemon as private physician to the king. Diodorus states that Ctesias was highly honoured at the Persian court. An abridged edition of the Indica was printed by Stephens in 1594 (“Hist. Roy. Soc.,” C. R. Weld, London, 1848, Vol. II. p. 93; “La Grande Encyclopédie,” Vol. XIII. p. 536; “Biographie Générale,” Vol. XII. p. 568).

In imitation of Franklin, Doctor Lining, of Charleston, in South Carolina, sent a kite into a thunder cloud, and by that means dissipated the lightning (Philosophical Transactions for 1754, Vol. XLVIII. p. 757).

The opinion entertained by Franklin regarding the nature of electricity differs from that previously submitted by Dufay (A.D. 1733), in the manner shown by Noad at p. 6 of his Manual, London, 1859 edition.

What Dufay considered to be two distinct species of electricities, vitreous and resinous, Franklin conceived to be two different states of the same electricity, which he called positive and negative. This, which constitutes the foundation of the present theory of electricity, is usually called the Franklinian theory, but it can be said to belong equally to Dr. Watson, for he had communicated it to the Royal Society before Franklin’s opinion on the subject was known in England (Phil. Trans. for 1748, Vol. XLV. pp. 49, 491; Thomson, “Hist. Roy. Soc.,” p. 436). Noad, in paragraph 12, applies the latter theory to the case of a charged Leyden jar, alluding to Franklin’s discovery of the location of electricity in the jar, wherefrom is drawn the conclusion that it is upon the glass that the electricity is deposited, and that the conducting coatings serve “only, like the armature of the loadstone, to unite the forces of the several parts and bring them at once to any point desired” (see “Œuvres de Franklin,” trans. of Barbeu-Dubourg, Tome II. p. 16, 3^e lettre).

Of his plus and minus theory, Franklin thus wrote to Mr. Collinson: “To electrise plus or minus no more needs to be known than this, that the parts of the tube or sphere that are rubbed do, in the instant of the friction, attract the electrical fire, and therefore take it from the thing rubbing; the same parts, immediately as the friction upon them ceases, are disposed to give the fire they have received to any body that has less.”

In an appendix to his official report as U.S. Commissioner at the Paris Universal Exposition of 1867, entitled “Franklin and Electrical Semaphores,” Professor Samuel F. B. Morse, LL.D., expressed himself as follows:

“It has frequently been asserted (on what authority I know not) that the first idea of an electric semaphore originated with Franklin. I have sought in vain in the publication of Franklin’s experiments and works for anything confirmatory of this assertion. On mentioning the subject to my friend Professor Blake, he kindly proposed examining the writings of Franklin in order to elicit the truth. From him I have received the following:

“‘I consulted several works for the purpose of ascertaining, if possible, the foundation for the statement that Franklin suggested the idea of semaphores by static electricity. I have not yet found any such suggestion, but I have noted that, following the experiments by Dr. Watson and others, in England, to determine the velocity of the electric discharge, and the time supposed to be required for the electrical discharges across the Thames, by which spirits were kindled, etc. (in 1747), Dr. Franklin (in 1748) made some similar experiments upon the banks of the Schuylkill, and amused his friends by sending a spark “from side to side through the river without any other conductor than the water” (vide Priestley’s “History of Electricity”). This was in 1748, at the end of the year. In 1756 “J. A., Esq.,” of New York (James Alexander), presented to the Royal Society a proposition “to measure the time taken by an electric spark in moving through any given space” by sending the discharge or spark down the Susquehanna or Potomac, and round by way of the Mississippi and Ohio rivers, so that the “electric fire” would have a circuit of some thousands of miles to go. All this was upon the supposition or assumption that the electric fire would choose a continuous water conductor rather than to return or pass through the earth. Franklin presented a paper in reply, in which he says “the proposed experiment (though well imagined and very ingenious) of sending the spark round through a vast length of space, etc. etc., would not afford the satisfaction desired, though we could be sure that the motion of the electric fluid would be in that tract, and not underground in the wet earth by the shortest way”’ (‘Franklin’s Experiments on Electricity, and Letters and Papers on Philosophical Subjects,’ 4to, London, MDCCLXIX, pp. 282, 283).

“Can it be possible that Franklin’s experiment of firing spirits and showing the spark and the effects of the electric discharge across the river originated, or forms the foundation for, the statement that he suggested the semaphoric use of electricity?”

After speaking of the experiments, to which allusion was made (at Watson, A.D. 1745), Franklin writes: “... It is proposed to put an end to them for this season, somewhat humorously, in a party of pleasure, on the banks of the Schuylkill. Spirits at the same time are to be fired by a spark sent from side to side through the river without any other conductor than the water—an experiment which we some time since performed to the amazement of many. A turkey is to be killed for our dinner by the electrical shock, and roasted by the electrical jack, before a fire kindled by the electrified bottle, when the healths of all the famous electricians in England, Holland, France and Germany are to be drank in electrified bumpers under the discharge of guns from the electrical battery.”

It was toward the close of the year 1750 that Franklin entertained the practicability of a lightning conductor (see Winckler, A.D. 1733), and, for this, he says, he was indebted to an experiment made by his friend Mr. Thomas Hopkinson (vide Franklin’s “Complete Works,” London, 1806, Vol. I. p. 172). In his “Poor Richard’s Almanac” for 1753, he refers to the lightning rod as security for “habitations and other buildings from mischief by thunder and lightning.”

References.—J. B. Le Roy, “Lettera al Rozier,” etc., Milano, 1782; “Rec. de Mém. de l’Acad. des Sc.” for 1770 and 1773; Jour. de Phys., 1773, Vol. II; Memoirs of M. Beyer, Paris, 1806–1809, and Delaunay’s explanation of his theories at pp. 193–198 of his 1809 Manuel.

The many notable observations, experiments and discoveries of Franklin are nowhere more ably reviewed than by his great admirer Dr. Priestley, who devotes much space thereto in his justly celebrated work on electricity.

At p. 92 of his “New Experiments,” etc., London, 1774, Franklin alludes to the failure of many European electricians in firing gunpowder by the electric spark, and gives his own method by using a battery of four large glass jars, while at p. 423 of the London edition of his “Letters and Papers,” etc., Franklin relates curious observations which are worth mentioning here. He says that he sent a charge of electricity “through a small glass tube that had borne it well when empty, but when filled with water was shattered to pieces and driven all about the room. Finding no part of the water on the table, I suspected it to have been reduced to vapour. I was confirmed in that suspicion afterward when I had filled a like piece of tube with ink and laid it on a sheet of paper, whereon after the explosion I could find neither any moisture nor any sully from the ink. This experiment of the explosion of water, which I believe was first made by that most ingenious electrician, Father Beccaria, may account for what we sometimes see in a tree struck by lightning, when part of it is reduced to fine splinters like a broom; the sap vessels being so many tubes containing a watery fluid, which, when reduced to vapour, sends every tube lengthways. And, perhaps it is this rarefaction of the fluids in animal bodies killed by lightning or electricity, that by separating its fibres renders the flesh so tender and apt so much sooner to putrefy. I think, too, that much of the damage done by lightning to stone and brick walls may sometimes be owing to the explosion of water found during showers, running or lodging in the joints or small cavities or cracks that happen to be in the walls.”

References.—Majus—May—(Heinrich), “Disp. de fulmine” and “Disp. de tonitru,” Marp., 1673, as at Pogg., Annalen, Vol. II. p. 21; Giuseppe Saverio Poli, “La formazione del Tuono,” etc., 1772, and his other works on the same subject which appeared during the years 1773, 1779 and 1787; Phil. Trans. for 1751, Vol. XLVII. pp. 202, 289, 362; W. de Fonvielle, “Eclairs et Tonnerres”; “Terrestrial Magn.” for June 1903; Jour. of the Franklin Institute for 1836, Vol. XVII., p. 183; M. le Docteur Sestier, “De La Foudre”; “Lightning-Rod Conference,” Reports of Delegates, by G. J. Symons, 1882; Chap. III. s. 3, vol. i. of Van Swinden’s “Recueil,” etc., 1784; Lumière Electrique, Tome XL. No. 23, p. 497; Giovanni Cardan’s work, Lyons, 1663; “Library of Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 79–106; “An Outline of the Sciences of Heat and Electricity,” by Thos. Thomson, London, 1830, pp. 347, 423, 432–433; “The Electrical Researches of the Hon. Henry Cavendish,” Cambridge, 1879, Nos. 350, note, 363; “Works of Benj. Franklin,” Jared Sparks, London, 1882; Phil. Trans., Vols. XLVII. p. 565; XLIX. pp. 300, 305,; L. p. 481; LI. p. 525; LII. 456; also Hutton’s abridgments, Vol. X. pp. 189, 212, 301, 629, 632; Vol. XI. pp. 189, 435, 609; “Bibliothèque Britannique,” Genève, 1796, Vol. LI. p. 393 (letter to M. Marc Auguste Pictet); Stuber, “Continuation of the Life of Dr. Franklin”; “An Essay on the Nature of Heat, Light and Electricity” (on the Franklinian hypothesis), by Chas. Carpenter Bompass, London, 1817, Chap. III. s. 3, p. 217; “List of Books written by or relating to Franklin,” by Paul L. Ford, 1889; L. Baldwin, “Mem. of Amer. Acad.,” O. S. I. part i. p. 257; Sturgeon’s “Researches,” p. 524; J. Bart. Beccari, “De Artif. elect ...”; likewise all the references that are given at pp. 26–27 of Ronalds’ “Catalogue”; “Journal des Savants” for June 1817, pp. 348–356.

A.D. 1752.—Dalibard (Thomas François), French botanist and amateur in physics, carries out very carefully the suggestions embodied in Franklin’s printed letters and constructs an atmospherical conductor at Marly-la-Ville, about eighteen miles from Paris, where Nollet likewise experimented. Dalibard’s apparatus consisted of a pointed iron rod, one inch in diameter and about forty feet long, which was protected from the rain by a sentry box and attached to three long wooden posts insulated by silken strings.

On the 10th of May, 1752, during Dalibard’s absence, an old soldier by the name of Coiffier, who was at the time employed as a carpenter and who had been left in charge, on observing the approach of a storm, hurried to the apparatus prepared to carry out the instructions previously given him. It was not long before he succeeded in obtaining large sparks on presenting a phial to the rod, and these sparks, which were all accompanied by a large snapping noise, were likewise obtained by the curate of Marly, M. Raulet, whom he had sent for and with whose aid Coiffier subsequently succeeded in charging an electric jar. On the 13th of May, Dalibard made, to the French Academy of Sciences, a report of the results thus obtained by Coiffier, to whom, it may be said, properly belongs the distinction of having been the first man who saw the electric spark drawn from the atmosphere.

On the 18th of the same month of May, M. de Lor, of the French University, drew similar sparks from a rod ninety-nine feet high at his house in the Estrapade, at Paris, and the same phenomenon was afterward exhibited to the French King. It is said that the conductor afforded sparks even when the cloud had moved at least six miles from the place of observation. Other experiments of a like nature were made a few days later by Buffon at Montbar, and, during the ensuing months of July and August, in the vicinity of London, by Canton, who, it is said, succeeded in drawing atmospheric electricity by means of a common fishing rod (Dissertation Fifth, Eighth “Britannica,” Vol. I).

An account of the Dalibard and de Lor experiments was transmitted by the Abbé Mazéas, on the 20th of May, to the Royal Society of London.

Mazéas erected, in the upper section of his residence, a magazine consisting of several insulated iron bars connected with the pointed rod. The lightning was brought into the house by means of a projecting wooden pole, having at its extremity a glass tube filled with resin which received a pointed iron rod twelve feet long. This apparatus was, however, too much exposed to afford reliable observations, and Mazéas therefore arranged to make more accurate experiments at the Château de Maintenon, during the months of June, July and October 1753. The results he obtained were communicated to the English Royal Society by Dr. Stephen Hales. The letters of the Abbé Mazéas to the Rev. Stephen Hales, detailing some of M. Le Monnier’s experiments as well as observations made by M. Ludolf at Berlin and transmitted by M. Euler, are to be found at pp. 354–552, Vol. XLVII. Phil. Trans. for 1753. For Mazéas, see also Phil. Trans., Vol. XLVII. p. 534, Vol. XLVIII. part i. p. 377, and Hutton’s abridgments, Vol. X. pp. 289, 434.

Thomas Ronayne in Ireland, and Andrew Crosse[51] in England (see “Account of an apparatus for ascertaining and collecting the electricity of the atmosphere”) made use of long wires in horizontal positions insulated by being attached to glass pillars, but Mazéas, in his Maintenon experiments, attached the iron wire by a silken cord to the top of a steeple ninety feet in height, whence it entered an upper room of the castle, a total distance of 370 feet. With this, Mazéas ascertained that electric effects are produced at all hours of the day during clear, dry and particularly hot weather, the presence of a thunderstorm not being requisite for the production of atmospheric electricity. In the driest summer nights he could discover no signs of electricity in the air, but when the sun reappeared the electricity accompanied it, to vanish again in the evening about half an hour after sunset.

References.—W. Sturgeon, “Lectures,” London, 1842, pp. 182, 183; Phil. Trans., Vol. XLVIII. part i. pp. 370, 377, etc.; Dalibard’s “Franklin,” Vol. II. p. 109, etc.; “Mém. de l’Acad. des Sciences,” for May, 1762; Nollet, “Letters,” Vol. I. p. 9; Franklin’s Works, Vol. V. p. 288; English Cyclopædia, “Arts and Sciences,” Vol. III. pp. 804–805; “Letters of Thomas Ronayne, to Benjamin Franklin,” at p. 137 of Vol. LXII of Phil. Trans., likewise Ronayne both in Journal de Physique, Tome VI, and in the Phil. Trans. for 1772, Vol. LII. pp. 137–140; also Hutton’s abridgments, Vol. XIII. p. 310; Geo. Adams, “Essay on Elect.,” London, 1785, p. 259.

A.D. 1752.—Freke (John), surgeon to St. Bartholomew’s Hospital, London, gives, in the Second Part of “A Treatise ... of Fire,” the third edition of his “Essay to Show the Cause of Electricity,” etc., originally published in 1746, while in the Third Part of the same work he shows the “Mechanical Cause of Magnetism, and why the compass varies in the manner it does.”

He says (pp. 90–91): “It had been impossible that this wonderful Phenomenon of Electricity should ever have been discovered, if there had not been such things as are non-electricable; for, as fast as this Fire had been driven on anything its next neighbour would have carried it farther; but, when it was most wonderfully found, that anything which was suspended on a silk cord (that being non-electricable) was obliged to retain the Fire, which by Electrical Force was driven on it; and when, moreover, it appeared, that any person or thing, being placed on a cake of beeswax (which is also a non-electricable) could no more part with its Fire than when suspended in [sic] a silk cord; I think it will become worthy of inquiry, why they are not electricable.” And, at p. 136, he adds: “I think it a great pity that the word Electricity should ever have been given to so wonderful a Phenomenon, which might properly be considered as the first principle in nature. Perhaps the word Vivacity might not have been an improper one; but it is too late to think of changing a name it has so long obtain’d.” In the Third Part, he explains that “by the Fire passing from and to the Sun, it so pervades iron aptly placed, as to make it attractive and produce the various operations of magnetism.”

Reference.—“Gentleman’s Magazine,” London, Vol. XVI for 1746, pp. 521, 557.

A.D. 1752.—In this year was published at Leipzig the “Biblia Naturæ,” written by John Swammerdam, a celebrated Dutch natural philosopher (1637–1682), all of whose works were translated into English and published in folio during the year 1758.

In the second volume of the Biblia, he thus alludes to one of many experiments made by him in 1678, before the Grand Duke of Tuscany: “Let there be a cylindrical glass tube in the interior of which is placed a muscle, whence proceeds a nerve that has been enveloped in its course with a small silver wire, so as to give us the power of raising it without pressing it too much or wounding it. This wire is made to pass through a ring bored in the extremity of a small copper support and soldered to a sort of piston or partition; but the little silver wire is so arranged that on passing between the glass and the piston the nerve may be drawn by the hand and so touch the copper. The muscle is immediately seen to contract.”

Through Swammerdam, the Germans lay claim to the origin of what has been called galvanism. It certainly cannot be denied that the above-described experiment closely resembles that which made Galvani famous (A.D. 1786).

References.—Swammerdam’s Biography, also Dissertation Fifth, in the eighth edition “Encycl. Brit.”; the note at p. 491 of Ronalds’ “Catalogue”; “Gen. Biog. Dict.,” London, 1816, Vol. XXIX. pp. 45–47; Eloy, “Dict. Hist. de la Méd.,” Vol. IV; “Biog. Générale,” Vol. XLIV. pp. 706–708; Cuvier, “Hist. des Sc. Naturelles,” Vol. II. pp. 427–433; Schelhorn, “Amænitates liter.,” Vol. XIV; “Biblioth. Hulthemiana,” Gand, 1836, Vol. II; Boerhaave, Preface to “Biblia Naturæ.”

A.D. 1752.—On the 16th of April, 1752, is read before the Royal Society a letter written by John Smeaton, a very prominent English engineer and inventor (1724–1792), to Mr. John Ellicot, giving an account of the electrical experiments in vacuo made with his improved air pump at the request of Mr. Wilson. This account, fully illustrated, appears in the Society’s Vol. LXVII for the years 1751 and 1752, pp. 415–428.

He observes that, upon heating the middle of a large iron bar to a great heat, the hot part can be as strongly electrified as the cold parts on each side of it. He also finds that if anybody who is insulated presses the flat part of his hand heavily against the globe, while another person standing upon the floor does the same, in order to excite it, the one who is insulated will hardly be electrified at all; but that, if he only lays his fingers lightly upon the globe, he will be very strongly electrified.

References.—Wilson, “Treatise on Electricity,” pp. 129–216; Phil. Trans. XLVI. p. 513; “Dict. of Nat. Biography,” Vol. LII. pp. 393–395; “Biog. Univ.” (Michaud), Vol. XXXIX. p. 445; Smile’s “Lives of the Engineers—Smeaton and Rennie”; Flint’s “Mudge Memoirs,” Truro, 1883.

A.D. 1752–1753.—M. de Romas, Assessor to the Presideal of Nerac, in France, repeats the experiment of Benjamin Franklin, and succeeds finally in bringing from the clouds more electricity than had before been taken by any apparatus.

He constructed a kite seven feet five inches high and three feet wide, with a surface of eighteen square feet, and, having wound fine copper wire around a strong cord through its entire length of about eight hundred feet, he raised the kite to a height of five hundred and fifty feet on the 7th of June, 1753. Sparks two inches in length were at first drawn by a discharging rod, and, when the kite was afterwards allowed to reach an elevation of six hundred and fifty feet, he received many flashes one foot long, three inches wide and three lines diameter, accompanied by a noise audible at as great a distance as five hundred feet.

On the 16th of August, M. de Romas raised the kite with about one thousand feet of string and obtained thirty beams of fire, nine or ten feet long and about an inch thick, accompanied by a noise similar to that of a pistol shot (“Encycl. Britannica,” eighth edition, Vol. VIII. p. 582). Three years later, August 26, 1756, and also during the year 1757, De Romas obtained similar results from numerous experiments. He finally apprehended much danger from the raising of the kite and thereafter coiled the string upon a small carriage, which he drew along by means of silken lines as the cord was being unwound.

The researches of De Romas concerning the electricity of isolated metallic bars are embraced in six letters addressed by him to the Bordeaux Academy of Sciences between July 12, 1752, and June 14, 1753. It is reported that they have never been printed and that they are kept, together with other manuscript matter of the same physicist, in the private archives of the institution.

The experiments of De Romas upon isolated bars were first repeated by Boze at Wittenberg, by Gordon at Erfurt, and by Lomonozow in Russia (Phil. Trans., Vol. XLVIII. part ii. p. 272). M. Veratti, of Bologna, obtained the electric spark in all weathers, through a bar of iron resting in sulphur, and Th. Marin, of the same city, by means of a long iron pole erected upon his dwelling, studied the relationship of rain and atmospheric electricity (Musschenbroek, “Cours de Physique” Vol. I. p. 397).

References.—Journal des Sçavans for October, 1753, p. 222; “Mémoire sur les moyens,” etc., par De Romas, Bordeaux, 1776; Sturgeon’s “Annals,” etc., Vol. V. p. 9; Harris, “Electricity,” p. 176; Priestley, “History,” etc., 1775, pp. 326–329; “Mémoires de Mathématique,” etc., Vol. II. p. 393, and Vol. IV. p. 514; “Etude sur les travaux de De Romas,” p. 491, by Prof. Mergey, of Bordeaux, which latter work won a prize for its author in 1853; Becquerel, “Traité expérimental,” etc., 1834, Vol. I. pp. 42–43; likewise the results obtained by Prof. Charles in “Traité de Physique Expérimentale,” etc., par Biot, Paris, 1816, Vol. II. pp. 444, 446, and in Peltier’s Introduction to his “Observations et Recherches Expérimentales,” etc., Paris, 1840, p. 7, as well as Brisson’s “Dict. de Phys.,” Paris, 1801, Vol. II. p. 174, and “Mémoires des Savants Etrangers,” 1755, Vol. II. p. 406.

A.D. 1753.—M. Deslandes, member of the French Royal Academy of Sciences, is the author of “Recueil de Différents traités de Physique,” the third volume of which contains his memoir on the effects of thunder upon the mariner’s compass. He alludes to the observations made thereon by Dr. Lister of London (well known by his “Historiæ Animalium Angliæ,” Lugd., 1678), as well as to many experiments made by Musschenbroek and by others noted in the Philosophical Transactions.

A.D. 1753.—Prof. George William Richmann (1711–1753), native of Sweden and member of the Imperial Academy of St. Petersburg, who had already constructed an apparatus for obtaining atmospherical electricity according to Franklin’s plans, was attending a meeting of the Russian Academy of Science, on the 6th of August, 1753, when his ear caught the sound of a very heavy thunder clap. He hastened away in company with his engraver, M. Sokolow, and upon their arrival home they found the plummet of the electrometer elevated four degrees from the perpendicular. Richmann stooped toward the latter to ascertain the force of the electricity, and “as he stood in that posture, a great white and bluish fire appeared between the rod of the electrometer and his head. At the same time a sort of steam or vapour arose, which entirely benumbed the engraver and made him sink on the ground.” Sokolow recovered, but Richmann had met with instant death.

References.—“Library of Useful Knowledge,” London, 1829; “Electricity,” p. 59, also p. 33; “Lettre sur la mort de Richmann,” par C. A. Rabiqueau, Paris, n. d.; “Comment. Acad. Petrop.,” XIV. pp. 23, 301–302, also the “Novi Comment.,” IV. pp. 25, 235 and 299; “Biog. Générale,” Vol. XLII. p. 258; “Gentleman’s Magazine,” London, Vol. XXIII., 1753, p. 431 and Vol. XXV. for 1755, p. 3; Singer, “Electricity,” p. 217; Harris, “Electricity,” p. 177; Phil. Trans., Vol. XLVIII. part ii. pp. 763–765, 772; also Vol. XLIX. part i. pp. 61, 67, and the abridgments by Hutton, Vol. X. pp. 525, 574–577; “La physique à la portée de tout le monde,” par le Père Paulian, Vol. II. p. 357; “Hist. de l’Acad. des Sciences,” pour 1753, p. 78; “Franklin in France,” 1888, Part. I. p. 5.

A.D. 1753.—Canton (John), an English savant (1718–1772), announces his most important discovery that vitreous or resinous electricity may be produced at will in the same tube. This he proves on taking a tube, which had been roughened by grinding it with thin sheet-lead and flour-of-emery mixed with water, and which developed vitreous electricity when rubbed with dry oil silk, and resinous or negative electricity when rubbed with new flannel. Rough quartz will, it is said, show like results. He also took a tube, of which only one-half had been made rough while the other half was polished, and he demonstrated that the different electricities are produced at a single stroke with the same rubber.

He likewise discovered that the exciting power of the rubber or cushion of the electrical machine will be very greatly increased by applying to it an amalgam of mercury and tin mixed with a little chalk or whiting (see Winckler, at A.D. 1733, for the introduction of the cushion).

His very remarkable experiments upon many descriptions of tourmaline, reported to the Royal Society in December 1759, were followed by many others detailed by Priestley, at pp. 298–301 of his “History of Electricity,” London, 1775, and Canton was the first to discover the electrical properties of the topaz, which latter were made known during the early part of the year 1760. (Consult Wilhelm Hankel, “Uber die therm. eigen. des Topases,” Leipzig, 1870.)

He was also the first to establish properly the fundamental fact of electrification by induction, or, as he terms it, “relating to bodies immerged in electric atmospheres,” which afterward led Wilcke (A.D. 1757) and Æpinus (A.D. 1759) to the method of charging a plate of air like a plate of glass, and to make the most perfect imitation of the phenomena of thunder and lightning (George Adams, “Essay on Electricity,” London, 1799, pp. 351–356; Noad, “Manual,” Chapter I, and Priestley, “History,” etc., s. 5). The paper containing an account of Canton’s experiments was read before the Royal Society, December 6, 1753. The principle enounced is that “the electric fluid, when there is a redundancy of it in any body, repels the electric fluid in any other body when they are brought within the sphere of each other’s influence and drives it into the remote parts of the body; or quite out of it, if there be any outlet for that purpose. In other words, bodies immerged in electric atmospheres always become possessed of the electricity contrary to that of the body in whose atmosphere they are immerged.”

Canton is the first to show that the air of a room can be electrified either positively or negatively, and can be made to retain the electricity when received. He thus explains his method: “Take a charged phial in one hand and a lighted candle insulated in the other, and, going into any room, bring the wire of the phial very near to the flame of the candle and hold it there about half a minute, then carry the phial and candle out of the room and return with the pith balls (suspended by fine linen threads) held out at arm’s length. The balls will begin to separate on entering the room and will stand an inch and a half or two inches apart when brought near the middle of it.”

The construction of artificial magnets by Canton, through the combination of the Duhamel (A.D. 1749) and the Michell (A.D. 1750) methods, as well as without the aid of natural loadstones or artificial magnets, is detailed by Noad at Chapter XV of his “Manual,” London, 1859.

References.—Phil. Trans., Vol. XXXV. p. 137 (Berlinghieri, V. L.); Vol. XXXVII. p. 294 (Marcel, A.); Vol. XLVII. p. 31; Vol. XLVIII. part i. pp. 350, 356, and Part II. pp. 780, 782 and 784, also Vol. XLIX. part i. p. 300; Vol. LI. pp. 398, 403, and Vol. LII. part ii. pp. 457, 461; and the abridgments of Hutton, Vol. X. pp. 131, 421, 532; Vol. XI. pp. 421, 609; A.D. 1722, and A.D. 1752; “A Course of Lectures on Nat. Philos. and the Mechanical Arts,” by Thos. Young, London, 1807, Vol. I. p. 372; II. pp. 64, 243; “The Electrical Researches of Hon. Hy. Cavendish,” 1879, Nos. 117, 205; Descriptions and Drawings of the various electric friction machines can be seen in Priestley’s “History,” Plates IV-VIII, and in Albrecht’s “Geschichte d. Electricität,” 1885, pp. 20–30; Acta Acad. Petr., I., 1778; “Gentleman’s Magazine” for Sept. 1759. See likewise the Phil. Trans. for Monday, January 21, 1666, p. 375, and George Adams’ “Essay on Electricity,” etc., London, 1799, p. 579, for method of making the artificial Bolonian stone or Canton’s phosphorus.

A.D. 1753.—Beccaria (Giovanni Baptista) (1716–1781), a very ingenious and industrious Italian electrician and astronomer, is the author of several quite important works on electricity.

Father Beccaria, as he is sometimes called from having been a member of the religious order of the Pious Schools, proved at the time to be the most indefatigable follower of Franklin in the study of atmospheric electricity. He was the first who recorded the phenomena of thunderstorms, and his many observations thereon are detailed throughout Part I. period x. and s. 10 of Priestley’s great work on electricity. Beccaria says that all clouds, whether of thunder, rain, snow or hail, are formed by the electric fluid; that the electric matter is continually darting from the clouds in one place at the same time that it is discharged from the earth in another; and that the clouds serve as conductors to convey the electric fluid from those places of the earth which are overloaded with it to those which are exhausted of it. Having shown that the polarity of the magnetic needle is determined by the direction in which the electric current has passed through it, he suggests taking the polarity acquired by ferruginous bodies as a test for ascertaining the kind of electricity with which the thunder cloud is charged.

He also shows that the meteor called a falling star is an electrical appearance, explains the cause of the peculiar noise attending the electric spark, and states that the passage of electricity is not instantaneous through the best conductors. He found a spark to occupy at least half a second in passing through 500 feet of wire, and six and a half seconds through a hempen cord of the same length, although when the cord was dampened it passed through it in two or three seconds.

He was the first to show the electric spark while in its passage through water, and he observed that the water sank in the tubes whenever a spark passed from one to the other as the air was repelled by the electric fluid. He found the effect of the electric spark upon water greater than the effect of common fire on gunpowder, and says he does not doubt that, if a method could be found of managing them equally well, a cannon charged with water would be more effective (“dreadful”) than one charged with gunpowder.

He demonstrates that air, contiguous to an electrified body, gradually acquires the same electricity; that the electricity of the body is diminished by that of the air; that there is mutual repulsion between air and the electric fluid, and that the latter, in passing through any portion of air, creates a temporary vacuum.

The production of what he calls his new inventive phosphorus and the method he employs for revivifying metals, are described, respectively, at pp. 365 and 282 of his “Lettere dell’ elettricismo.”

References.—Beccaria, “Lettere,” etc., Bologna, 1758, pp. 146, etc., 193, 266, 268, 290, 310, 345; likewise his “Elettricismo Artificiale,” Turin, 1753, pp. 110, 114, 227; Phil. Trans. for 1760, Vol. LI. p. 514; 1762, p. 486; 1766, Vol. LVI. p. 105; 1767, Vol. LVII. p. 297; 1770, Vol. LX. p. 277; 1771, p. 212, also Hutton’s abridgments, Vol. XI. p. 435; Vol. XII, pp. 291, 445; Vol. XIII. p. 50; Wartmann, “Mém. sur les Etoiles filantes”; Humboldt, “Relation historique,” Tome I; Lardner, “Lectures,” Vol. I. pp. 429–444; Sturgeon’s Annals, Vol. VI. pp. 415–420, 425–431, and Vol. VIII. p. 180; Noad, “Manual,” London, 1859, p. 197; Louis Cotte, “Observation ...” Paris, 1769 and 1772; “Mém. de Paris” for the same years and Jour. de Phys. for 1783; Ant. Maria Vassalli-Eandi, “Notizia sopra la vita ... di Beccaria,” 1816; Carlo Barletti, “Nuove Sperienze ...” Milano, 1771; “Biog. Générale,” Vol. V. pp. 77–78; “The Electrical Researches of Hon. Henry Cavendish,” Cambridge, 1879, No. 136; Hale, “Franklin in France,” Boston, 1888, Part I. p. 447; Humboldt, “Cosmos,” London, 1859, Vol. I. pp. 113–136, 202, 337; Vol. V. pp. 217–219, for the observations of Beccaria, Rozier, Kepler, Benzenberg, Brandes, Bogulawski, Nicholson, Arago and others on atmospheric electricity, aerolites, etc. See likewise Beccaria’s letters to Jean Claude Fromond, the Italian physicist (1703–1795), relating his experiments tending to prove that electric motions do not occur in vacuo, also his letters to the Princess Giuseppina di Carignano on the electricity of the moon, as well as to Jean Baptiste Le Roy and to Jacopo Bartolommeo Beccari relative to experiments with his kite; “Scelta di Opuscoli,” of Amoretti, Campi, Fromond and Soave, Vols. XIX. XXI. XXXII.; “Opuscoli Scelti,” II. 378; III. 243, 284, 377; V. 19.

A.D. 1753.—Bazin (Gilles Augustin), French physician and naturalist, publishes, at Strasbourg, an illustrated treatise on Magnetic Currents (“Description des Courants Magnétiques,” etc.), which also contains his observations upon the magnet, and a supplement to which appears during the year 1754.

References.—“La Grande Encyclopédie,” Vol. V. p. 974; Michaud, “Biog. Univ.,” Vol. III. p. 353; Ninth “Britannica,” Vol. XV. p. 242.

A.D. 1753.—C. M., i. e. Charles Morrison and not Charles Marshall, of Greenock, Scotland, writes, from Renfrew, February 1, 1753, to the Scots’ Magazine, a letter entitled “An Expeditious Method of Conveying Intelligence,” wherein is first suggested a practical manner of transmitting messages by frictional electricity.

A full copy of this letter appears at pp. 7–9 of Robert Sabine’s “Electric Telegraph,” London, 1872, and at p. 9, 103, No. 570, of the Scientific American Supplement for December 4, 1886, the last-named also reproducing some correspondence establishing the identity of Charles Morrison which was found in the papers of Sir David Brewster.

In the article of Auguste Guérout, which appeared in La Lumière Electrique early in 1883, C. M. is alluded to as Charles Marshall. This is likewise the case in Johnson’s Encyclopædia, 1878, Vol. IV. p. 757. Fahie gives (“History of the Electric Telegraph,” London, 1884, pp. 68–77) a full account of the many inquiries instituted to establish the identity of C. M., which he admits to stand for Charles Morrison, although, at p. 81 of the same work, is given a letter of Sir Francis Ronalds alluding to Charles Marshall, of Renfrew. An article in Cornhill Magazine, Vol. II for 1860, pp. 65–66, speaks of an elderly Scotch lady who remembered a very clever man named Charles Marshall, who could make “lichtnin’ write an’ speak” and who could “licht a room wi’ coal-reek” (coal-smoke).

In his remarks upon the afore-named letter, made during the year 1859, Sir David Brewster says: “Here we have an electric telegraph upward of a hundred years old, which at the present day would convey intelligence expeditiously, and we are constrained to admit that C. M. was the inventor of the electric telegraph.... Everything done since is only improvement.”

References.—Scots’ Magaz., XV. p. 73; “Le Cosmos,” Paris, Feb. 17, 1854; “Dict. of Nat. Biog.,” Vol. XXXIX. p. 107; Athenæum of Nov. 5, 1864; Lesage, at A.D. 1774; Th. Du Moncel, “Exposé des applications de l’électricité,” Paris, 1874, Vol. III. pp. 1 and 2.

A.D. 1754.—Diwish (Prokop), Diviss—Divisch (Procopius), a monk of Seuftenberg, Bohemia (1696–1765), erects, June 15, 1754, a lightning protector upon the palace of the curator of Prenditz, Moravia. The apparatus was composed of a pole surmounted by an iron rod supporting twelve curved up branches and terminating in the same number of metallic boxes filled with iron ore and closed by a boxwood cover traversed by twenty-seven sharp iron points which plunged at their base in the ore. All the system of wires was united to the earth by a large chain. The enemies of Diwish, jealous of his success at the court of Vienna, excited the peasants of the locality against him, and, under the pretext that his lightning rod was the cause of the great drought, they made him take down the lightning rod which he had utilized for six years and then imprisoned him. What is most curious is the form of this first lightning rod, which is of multiple points, like the one M. Melseu afterward invented.

References.—Poggendorff, Vol. I. p. 580, for Procopius Divisch’s “Erfand einen Wetter Ableiter”; Scientific American, Sept. 10, 1887, p. 160; “Kronika Prace,” by Pokorny, of Prague; “Historical Magazine,” Feb. 1868, Art. XII. p. 93; “Prague News,” for 1754, art. of Dr. Scrinci.

A.D. 1754.—Ammersin (Rev. Father Windelinus), of Lucerne, Switzerland, announces in his “Brevis relatio de electricitate,” etc., that wood properly dried till it becomes very brown is a nonconductor of electricity. We have already mentioned the observation made by Benjamin Wilson (A.D. 1746) that, when a dry, warm piece of wood is broken across, one of the pieces becomes vitreously and the other resinously electrified.

Ammersin advises boiling the dried wood in linseed oil or covering it with varnish to prevent the possible return of moisture, and he states that wood thus treated seems to afford stronger appearances of electricity than does even glass (Phil. Trans., Vol. LII. part i. p. 342).

References.—Ammersin, “Kurze Nachricht,” etc., pub. at Basel, 1771, and translated the same year by Jallabert, who embodied it in his “Versuche über die Elektricität,” etc.

A.D. 1754.—In his “Dissertations sur l’incompatibilité de l’attraction,” etc., Le Père Gerdil, Professor of Philosophy in the Royal University of Turin, speaks of agencies of which we shall never know anything and of others with which we shall inductively become acquainted, although we shall always ignore many of their respective quantities, qualities and differences. He says that the electric fluid explains the sympathy known to exist between amber and straws—shown by the analogy observed between electricity and magnetism to be the same as that existing between iron and the loadstone.

A.D. 1754.—Mr. Strype produces the sixth and last edition of the original “Survey of London” by John Stow, which first appeared during the year 1598.

In his account of Cornehill Ward, allusion is made to the “fair new steeple” of the Church of Saint Michael th’ Archangel, “begun to be built in the year 1421,” and, at p. 74, occurs the following: “As I have oft heard my father report, upon St. James’ night, certain men in the loft next under the bells, ringing of a peal, a tempest of lightning and thunder did arise, an ugly shapen sight appeared to them, coming in at the South window and lighted on the North, for fear whereof they all fell down and lay as dead for the time, letting the bells ring and cease of their own accord; when the ringers came to themselves, they found certain stones of the North window to be razed and scratched, as if they had been so much butter, printed with a lion’s claw; the same stones were fastened there again and so remain to this day.”

In one of the notes to William T. Thoms’ reprint of the above-named “now perfectly invalyable” work, he says: “It is quite clear from the tone in which Stow speaks of this ‘ugly shapen sight’ and the marks ‘printed with a lion’s claw,’ that he suspected this instance of the power of the electric fluid to be nothing less than a visitation from the foul fiend himself.”

Speaking of St. Paul’s Cathedral, Stow tells us that its pulpit cross “was by tempest of lightning and thunder defaced,” and that “on Wednesday, the fourth of June (in the year 1561), betweene three, four and five of the clock, in the after-noone, the steeple of Paule’s in London, being fired by lightning brast forth (as it seemed to the beholders) two or three yards beneath the foote of the crosse, and from thence burnt downe the speere to the stone worke and bels, so terribly, that within the space of foure houres, the same steeple with the roofes of the church ... were consumed.” Very curious and interesting reading will be found in the “Burnynge of Paule Church, London, in 1561, and the iiii day of June, by lyghtnynge at three of the clocke ...” by Wyllyam Seres, London, 1563; as well as in his previous work on like subject, published in 1561. See Report in “Archæologia,” London, 1794, Vol. XI. pp. 72–86; likewise the entry at A.D. 1769, relative to another lightning stroke in 1772.

Stow is perhaps best known by his “Annales, or a Generalle Chronicle of England.” In that portion of the latter work devoted to “the life and raigne of Queene Elizabeth” he states (London ed., 1631, p. 809) “that the knowledge and use of the sea compasse or needle was neither familiar nor understood but few yeeres before” the time of the navigators John Hawkins, Francis Drake, Martin Frobisher and Thomas Candish, and he adds (at p. 810) “that the honour of that invention, as touching the propertie of the Magneticall needle in pointing towards the Poles is attributed by (Flavius) Blondus in his Italia Illustrata (in the description of Campadia Felix) and by the great writer Paulus Jovius in lib. xxv. of his History in the end [sic], to the citizens of Amalfi.... The author’s name is no more particularly recorded, then [sic] to be one Flavio ... for to him that honour is given by Francis Lopez, of Gomara, in his West Indian History, lib. i. cap. 9, and by Peter Ciezius, in lib. ii. cap. 9, of his Indian Story, and by Pandulph: Collenutius in his History of Naples, who, three hundred yeeres since, namely in the yeere of our Saviour 1305, discovered that propertie in the Magnes and applied it to navigation” (see, for Flavius Blondus: George Hakewill, “An apologie,” etc., Oxford, 1635, lib. iii. s. 4, and lib. v. p. 60; “Blondi Flavii Fortiriensis ... Italia Illustrata,” 1531, folio; Flavius Blondus (Flavio Biondo), “Roma Ristaurata et Italia Illustrata,” Vinezia, 1558, 12mo; Niceron, “Mémoires ... des hommes illustres,” Paris, 1731, Vol. XVI. pp. 274–281).

A contemporary of Flavius Blondus, by name Michael Angelus Blondus (1497–1560), author of “De Ventis et Navigatione,” published at Venice in 1546, likewise alludes to the polarity of the needle, and gives a curious illustration of a mariner’s compass at Chap. XXIV. p. 15, of the last-named work. (For M. A. Blondus, see “La Grande Encyclopédie,” Vol. VI. p. 899.)

Stow makes reference (p. 810) to Dr. Gilbert’s De Magnete, to the “diuision of the plot or playne of the compasse into the thirty-two points,” considered by “Goropius in his lib. iii. De Origin. Hispanicis, to have been the inuention of some Germane,” and to the manner and “meanes saylers vsed to sayle, before they atteined the knowledge of the compasse.”

A.D. 1755.—Eeles—Eales (Henry), a prominent scientist of Lismore, Ireland, communicates to the Royal Society, on the 25th of April, 1755, a paper concerning the electrical property of steam and exhalations of all kinds. Eeles’ theory of the electricity of vapour (“On Vesicles and Atmospheres of Electricity”), afterward developed by Sir John Herschel, is fully explained in the “Encycl. Brit.” article on “Meteorology” (par. 135, etc.), and is also alluded to at p. 43 of Harris’ “Electricity” as well as at p. 153, Vol. XLIX. part i. of the Philosophical Transactions.

Mr. Eeles showed, that while the Leyden jar is being charged, both the inside and the outside have the same kind of electricity and that the negative electricity does not appear until the machine has ceased turning. Eeles’ hypothesis, extracted from his “Philosophical Essays,” and from the analysis of a course of lectures delivered at Trinity College, Cambridge, by Mr. Atwood, is treated of at length by George Adams in the fourth chapter of his “Essay on Electricity,” wherein pertinent allusion is also made to the fact of Mr. Eeles having been purposely shut out of Priestley’s “History and Present State of Electricity.”

References.—Philosophical Transactions, Vol. XLVII. p. 524; Phil. Mag. and Journal, Vol. XLIV. p. 401 (1814).

A.D. 1756.—Le Chevalier Jacques C. F. de la Perriere de Roiffé (not Reiffé) is the author of “Méchanismes de l’Electricité et de l’Univers,” published at Paris, wherein he pretends to account for all electrical phenomena.

At p. 12 of his Préface, he curiously states that as everybody comprehends the distinction between elastic and non-elastic bodies, likewise the existence, nature and diversity of the properties of atmospheric fluids, with which all bodies are impregnated and by which they are surrounded, also the various expansive modes of activity to which they are subject, as well as their immiscibility as regards the surrounding air, without which latter they could not, however, subsist, he will in his new theory apply these principles to the mechanisms of electricity and of the universe as affected by the general laws and the invariable results attaching to shock and motion.

A.D. 1756.—In the “Subtil Medium Proved,” etc., of Mr. R. Lovett, lay-clerk of the cathedral church at Worcester, England, are shown numerous medical cures successfully made by electricity. He asserts that the electric fluid is almost a specific in all cases of violent pains, like obstinate headache, the toothache, sciatica, etc., but that it has not succeeded so well in rheumatic affections. He states that electricity properly administered has never caused injury, and he alludes to equally successful cures made by the Rev. John Wesley and by Dr. Wetzel, of Upsal.

The well-known physician, Antonius de Haen, during several years’ experience, made many cures of paralysis, St. Vitus’ dance, etc., by the agency of electricity, as related in his Ratio Medendi, Vol. I. pp. 199, 200, 233, 234 and 389. Allusion has been made in these pages to the employment of electricity for medical purposes by Kratzenstein (A.D. 1745) and by Jallabert (A.D. 1749), and Priestley named many others who have likewise used it successfully in their practice.

References.—“Subtil Medium Proved,” etc., pp. 76, 101 and 112; also his “Philosophical Essays,” Worcester, 1761 and 1766, and his “Electrical Philosopher,” 1774; Wesley’s “Desideratum, or Electricity made Plain and Useful,” p. 3; Joseph Veratti, “Observations ... pour guérir les paralytiques....” La Haye, 1750.

A.D. 1757.—Dr. Darwin, of Lichfield, addresses to the Royal Society of London a paper which is read May 5, 1757, and in which he gives an account of experiments to prove that the electric atmosphere does not displace air, and that all light, dry, animal and vegetable substances, in particular, are slow to part with the electricity with which they have been charged (Phil. Trans., Vol. L. part i. pp. 252 and 351).

A.D. 1757.—Euler (Leonard), a native of Switzerland, who studied under the Bernoullis, and who succeeded Daniel Bernoulli as Professor of Mathematics at St. Petersburg, was undoubtedly one of the greatest analysts the world has ever produced (“Encycl. Brit.,” Fifth Dissertation of the eighth edition, Vol. I. p. 742).

He adopted the theory of Descartes that the magnetic fluid moves from the equator to the poles, and he endeavoured to determine mathematically the course of the magnetic needle over the earth’s surface. He announces that “the magnetic direction on the earth follows always the small circle which passes through the given place and the two magnetic poles of the earth,” or, as worded by Sir David Brewster, that “the horizontal needle is a tangent to the circle passing through the place of observation and through the two points on the earth’s surface where the dipping needle becomes vertical or the horizontal needle loses its directive power.”

He entertained very peculiar ideas regarding the source of power in the loadstone, the pores of which he imagined were filled with valves admitting of the entrance of the current and preventing its return. His notions on this subject are best given in his own words: “Non-magnetic bodies are freely pervaded by the magnetic matter in all directions; loadstones were pervaded by it in one direction only ... water, we know, contains in its pores particles of air ... air, again, it is equally certain, contains in its pores a fluid incomparably more subtile, viz. æther, and which, on many occasions, is separated from it, as in Electricity; and now we see a still further progression, and that ether contains a matter much more subtile than itself—the magnetic matter which may, perhaps, contain in its turn others still more subtile.... The loadstone, besides a great many pores filled with ether, like all other bodies, contains some still much more narrow into which the magnetic matter alone can find admission. These pores are disposed in such a manner as to have communication with each other, and constitute tubes or canals through which the magnetic matter passes from the one extremity to the other. Finally, this matter can be transmitted through these tubes only in one direction, without the possibility of returning in the opposite direction.... As we see nothing that impels the iron toward the loadstone, we say that the latter attracts it. It cannot be doubted, however, that there is a very subtile, though invisible matter, which produces this effect by actually impelling the iron towards the loadstone.”

References.—“Journal des Savants” for March and April 1868; Euler’s “Letters,” translated into English, 1802, Vol. I. p. 214, and Vol. II. pp. 240, 242, 244; “Berlin Memoirs,” for 1746, p. 117; 1757, p. 175; 1766, p. 213; Poggendorff, Vol. I. p. 702; “Nova Act. Petropol.” for 1779, Vol. III; “Pièces de Prix de l’Acad. des Sc. de Paris,” Vol. V. Mém. II and IX, this last-named publication, containing likewise a joint Memoir of D. Euler, J. Bernoulli and E. F. Dutour upon the mariner’s compass, which appeared in Paris during 1748; Whewell, “History of the Inductive Sciences,” 1859, Vol. I. pp. 225, 367, 370; Vol. II. pp. 32, 40.

His son, Albert Euler, censured Halley’s magnetical hypothesis, and proposed, in 1766, a theory requiring the assumption of only two poles, distinct, however, from those of the terrestrial axis.

A.D. 1757.—Dollond (John), who was at first a silk weaver at Spitalfields, England, which occupation he abandoned in order to give his exclusive attention to scientific experimental studies, discovered the laws of the dispersion of light and constructed the first achromatic telescope as well as several improved instruments for magnetic observations. A full description of the most important of these, accompanied by illustrations, can be found in the articles of the “Encyclopædia Britannica” on magnetic instruments.

References.—Kelly’s “Life of John Dollond,” London, 1808; Phil. Mag., Vol. XVIII. p. 47; Thomas Thomson, “Hist. of Roy. Soc.,” London, 1812, pp. 379–382; “Directions for using the Electric Machine made by P. and J. Dollond,” London, 1761.

A.D. 1757.—Wilcke (Johann Karl), a very distinguished scientist of Stockholm (1732–1796), introduces new phenomena respecting the production of electricity produced by melting electrical substances, which he discovers in continuation of experiments begun by Stephen Grey. He gives the name of spontaneous to the electricity produced by the liquefaction of electrics, observing that the electricity of melted sulphur does not appear until it commences to cool and to contract, its maximum being reached at its point of greatest contraction. Melted sealing wax, he says, becomes negatively electrified when poured into glass, but, when poured into sulphur, it is positively electrified, leaving the sulphur negative (Sir Humphry Davy, “Bakerian Lectures,” London, 1840, p. 36 and notes).

While in Berlin, he and Æpinus investigate the subject of electric atmospheres, and they are led to the discovery that plates of air can be charged in the same manner as plates of glass. (See Canton, A.D. 1753.) This they did by suspending large wooden boards, which were covered with tin and whose flat surfaces were held parallel to and near each other. They found that upon electrifying one of the boards positively the other was always negative, and that with them could be given shocks like those produced by a Leyden jar. They likened the state of the boards to the condition of the clouds and the earth during a thunderstorm, the earth being in one state and the clouds in the opposite, the body of air between them answering the same purpose as the small plate of air between the boards or the plate of glass between the two metallic coatings of the Leyden jar.

In Wilcke’s treatise, alluded to below, he defines the two electricities much more clearly than had previously been done. He distinguishes three causes of excitation, viz. warming, liquefaction and friction; the spontaneous electricity already alluded to, he further says, is the result of the apposition or mutual action of two bodies, in consequence of which one of them is electrified positively and the other negatively; communicated electricity, on the other hand, is that which is superinduced upon the whole or part of a body, electric or non-electric, without the body having been previously heated, melted or rubbed, or without any mutual action between it and any other body. This distinction is, in general, very obvious, but Mr. Wilcke defines it throughout his work in a very clear manner, citing cases wherein they are frequently confounded.

Wilcke and Anton Brugmans (A.D. 1778) first propounded the theory of two magnetic fluids, which was afterward established by Coulomb (A.D. 1785) and perfected by the great mathematician Poisson (A.D. 1811). The hypothesis of the two fluids supposes that a magnet contains minute invisible particles of iron, each of which possesses by itself the properties of a separate magnet. It is assumed that there are two distinct fluids—the austral and the boreal—which reside in each particle of iron. These fluids are inert and neutral when combined, as in ordinary iron, but when they are decomposed the particles of the austral attract those of the boreal, and vice versa, while they each repel one another.

References.—Wilcke, “Disputatio inauguralis physica,” etc., published Rostock, 1757, also his “Herrn Franklin’s briefe von der electricitat,” etc., Leipzig, 1758, his “Jal om Magneten,” 1764, and his “Über den Magneten,” Leipzig, 1758; besides 1794–1795; likewise his different Memoirs in the “Swedisches Musæum,” Vol. I. p. 31, and in both the “Schwedischen Akad. Abhandlungen,” etc. (also Neue Abhand.) and the “Vetensk Acad. Handl.” for 1758, 1759, 1761–1763, 1766–1770, 1772, 1775, 1777, 1780, 1782, 1785, 1786, 1790; “The Electrical Researches of Hon. Hy. Cavendish,” 1879, No. 134.

A.D. 1759.—Hartmann (Johann Friedrich), of Hanover, is the author of three works on electricity, published in that city during 1759, 1764 and 1766, wherein he gives an account of several very curious electrical experiments. One of the most interesting of these demonstrates the progressive motion of the electrical discharge. When he passes the shock through many small cannon balls, sometimes to the number of forty, placed upon small drinking goblets close by one another, all the sparks are seen and all the cracklings are heard at the same moment; but when he substitutes eggs (preferably ten or twelve) for the balls, the progress of the explosion is visible, every two giving a flash and a report separately.

He remarks that upon one occasion, as he re-entered a room which he had just before left, after making therein a number of experiments, he observed a small flame following him as he walked about swiftly while holding a lighted candle in his hand. The flame vanished whenever he stopped to examine it, and he attributed its appearance to the presence of sulphur thrown into the air by continued violent electrification.

References.—Hartmann, “Abhandlung von der verwandschaft,” etc., Hanover, 1759, pp. 58, etc., and 135; also his “Electrische experimente,” etc., Hanover, 1766, and his “Anmerkungen,” etc., 1764, 4to, p. 38; Friedrich Saxtorph, “Elektricitätsläre,” Vol. II; Hamburgisches Magazin (also Neues Hamb. Mag.) for 1759, Vol. XXIV, and for 1761, Vol. XXV; “Nov. Acta Acad. Nat. Curios,” Vol. IV. ss. 76–82, 126; “Göttingischen gemein. Abhand.,” von Jahr 1775.

A.D. 1759.—Wesley (John), the founder of Methodism (1703–1791) and the most eminent member of a very distinguished English family, publishes “The Desideratum; or Electricity made Plain and Useful, by a Lover of Mankind and of Common-sense.” In this, he relates at great length the cures of numerous physical and moral ailments, attributed to the employment of the electric fluid, under such curious headings as “Electricity, the Soul of the Universe,” “Electricity, the Greatest of all Remedies,” etc. (“The Library of Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 110–129).

A.D. 1759.—Æpinus (Franz Maria Ulrich Theodor) (1724–1802), celebrated German natural philosopher, member of the Scientific Academies of Berlin and St. Petersburg, publishes in the latter city his most important work, “Tentamen Theoriæ Electricitatis et Magnetismi,” wherein he adopts, as did Wilcke, all the general principles of Franklin’s theory of positive and negative electricities. Therein he also shows that the phenomena of electricity depend mainly upon the tendency of the fluid to attain a state of equilibrium by passing from bodies containing an excess to others which have less than the natural quantity; that the electric fluid existing in the pores of all bodies moves without obstruction in non-electrics and with much difficulty in electrics; that all bodies contain a fluid whose particles mutually repel one another with forces decreasing as the distance between them increases, and, according to the same law, attract the particles of the bodies with which they are in combination.

It has already been shown that, in conjunction with Wilcke, he found the means of charging a plate of air. This experiment, suggested by some of the observations made by Canton and Franklin, led to what may be considered one of the greatest discoveries in the science of electricity, for in this was first demonstrated the grand principle of induction (see Grey at A.D. 1720), and the result led to Volta’s discovery of the electrophorus. Volta, also, was the first to apply to an electrometer the apparatus invented by Æpinus for condensing electricity.

Æpinus first discovers to its fullest the affinity existing between electricity and magnetism, explaining nearly all the phenomena of magnetism (“De Similitudine vis electricæ et magneticæ”; “Similitudinis effectuum vis magnet. et. elect.: novum specimen” in the “Novi Comment. Acad. Petrop.,” Vol. X. p. 296). He improves upon the methods employed by both Duhamel and Michell for the construction of artificial magnets in a different line from that employed by John Canton, A.D. 1753. He lays the bar to be magnetized upon the ends of the opposite poles of two powerful field magnets, and places two bunches of magnetic bars upon the middle of the bar, separating the bunches by a piece of wood and keeping together the poles of each of the same name as that of the powerful fixed magnet nearest to it. These two bunches are then held at an inclination of 15 to 20 degrees, and are drawn away from each other to the end of the bar which is to be magnetized, so that each half of the bar receives the same number of strokes. When the bar is very thick, the process should be repeated upon its reverse, and in order to make the result more effective, the united ends of the bars should at the outset be ground together, and pressure should be applied while the operation is going on.

Æpinus was the first to discover the polarity of the tourmaline. After M. Lechman acquainted him with its attractive power, he made many experiments, of which he communicated the very important results, during the year 1756, to the Academy of Sciences and Belles-Lettres at Berlin. Up to this time but little was known regarding the necessity of heat to excite the tourmaline. Æpinus found that he could electrify it to a high degree by placing the stone in boiling water, and that it was necessary to heat it to between 99½ degrees and 212 degrees Fahrenheit to develop its attractive powers. One of the extremities of the tourmaline terminated by the six-sided pyramid then becomes charged with positive electricity, while the other extremity is negative. When the stone is of considerable size, flashes of light can be seen along its surface.

M. De Romé Delisle, in his “Essai de Cristallographie,” Paris, 1772, p. 268, alludes to what has already been stated relative to the necessity of heating the tourmaline (see J. G. S. at A.D. 1707, and Leméry at A.D. 1717), and he gives an extract from the work attributed to Adanson, as mentioned at A.D. 1751. Delisle’s references embrace: “Act. Paris,” 1717, p. 9; “Act. Berolin,” 1756, p. 105; “Lettre du Duc de Noya Caraffa à M. de Buffon,” Paris, 1759; Ascendrecker, Aschentrecher, Aschenzicher (tire-cendre), “Trip: Tourmaline, Vog. min.” 191; “Act. Holmens,” 1768, p. 7; besides, at pp. 209, 233 and 245 he speaks of the electrical and phosphorescent properties of crystals, showing that the lapis lyncurius of the ancients is the hyacinth or zircon of to-day (see B.C. 321), and not, as many believe, either amber or belemnite (pierre de foudre, lapis fulminaris), while the hyacinth of old was a purple stone which, if now found, would be classed among the amethysts.

References.—“Allgemeine Deutsche Biographie,” Leipzig, 1875, Vol. I. p. 129; Æpinus, “Sermo Acad. de similitudine,” etc., 1758, and his “Recueil ... sur la tourmaline,” 1762; “Novi. Com. Petropol.,” for 1761, 1764, 1768; “Acta Acad. Moguntinæ,” Vol. II. p. 255; Leithead, “Electricity,” p. 289; Phil. Trans., Vol. LI. p. 394, and Vol. LVII. part i. p. 315; “Encycl. Brit.,” articles “Electricity” and “Magnetism”; Bigeon’s report in the “Annales de Ch. et de Phys.,” 2^e série, Tome XXXVIII. p. 150; Van Swinden, “Recueil,” etc., La Haye, 1784, Vols. I and II passim; Becquerel in Annales de Chimie et de Physique, Vol. XXXVI. p. 50; Thomson, “Hist. Roy. Soc.,” 1812, p. 184; “The Electrical Researches of the Hon. Henry Cavendish,” Cambridge, 1879, Nos. 1, 134, 340 and 549; Lord Kelvin (Sir Wm. Thomson), “Æpinus atomized,” in Phil. Mag. for March 1902, p. 257, etc., and in Journal de Physique for Sept. 1902, p. 605.

A.D. 1759.—Symmer (Robert) assails the theory announced by Dufay (see Franklin, A.D. 1752), and shows, in a paper submitted to the Royal Society, December 20, 1759, that all the electrical phenomena are produced by two distinct but coexistent fluids not independent of, but counteracting each other. He says that equal quantities of these fluids are contained in all bodies while in their natural condition; that when a body is positively electrified it does not hold a larger share of electric matter, but a larger portion of one of the active powers, and when negatively electrified a larger portion of the other, and not, as Franklin’s theory supposes, an actual deficiency of electric matter. Symmer’s theory is perhaps best explained in his own words, as follows: “It is my opinion that there are two electric fluids (or emanations of two distinct electric powers), essentially different from each other; that electricity does not consist in the efflux and afflux of these fluids, but in the accumulation of the one or the other in the body electrified; or, in other words, it consists in the possession of a larger portion of the one or of the other power than is requisite to maintain an even balance within the body, and lastly, that according as the one or the other power prevails, the body is electrified in one or the other manner.”

Very curious reading may be had by reference to the volumes of the Philosophical Transactions named below, in which Symmer details many experiments with pieces of silk, as well as with white and coloured, new and newly cleansed silk and worsted stockings. Therein he shows his ability to charge the Leyden jar with either positive or negative electricity, according as he presents a black or white stocking to the wire of the phial. These experiments, which Symmer admits to have made for the express purpose of proving the existence of two electricities, further illustrate the phenomenon of electrical cohesion, although the latter is still better demonstrated by means of panes of ordinary glass. He thus expresses himself: “Upon these considerations, we may expect, from the experiment in hand, the means of determining whether the distinction of electricity into two different kinds is merely nominal, or if there is an essential difference between them; for, after the glass plates have been electrified in one position, so as to be incapable of receiving any more electricity, if they be inverted, and in that new position presented to the chain and wire, and the globe again be put in motion, according as one or other of those opinions hold, corresponding effects will follow.”

Symmer also proves his two distinct powers of electricity by the experiment of passing the electric shock through a quire of paper instead of through a single card (“Lib. Useful Knowledge,” London, 1829, “Electricity,” p. 44).

References.—“Electricity in the Service of Man,” R. Wormell, London, 1900, p. xiv; Philosophical Transactions, Vol. LI. part i. pp. 171, 340, 366, 373, etc., 389, and Vol. LVII. p. 458; also Hutton’s abridgments, Vol. XI. p. 405; Nollet, “Lettres,” etc., Vol. III. p. 42; “Encycl. Brit.,” article “Electricity”; “Library of Useful Knowledge,” London, 1829, “Electricity,” Nos. 160 and 161.

A.D. 1760.—Mayer (Johann Tobias, Sen.) (1723–1762), one of the most celebrated German astronomers, director of the observatory at Göttingen, is the first to make known the law of the inverse square resulting from actual experimental investigation. This he does in a paper, “Inclination and Declination of the Magnetic Needle, as deduced from theory,” read before the Royal Society at Göttingen, wherein he states that the intensities of the magnetic attractions and repulsions vary inversely as the squares of the distances from the pole of a magnet. Consult “Magnetism,” in the ninth edition of the “Encyclopædia Britannica,” for additional reference to the above paper, also section 14 of the same work for an account of Mayer’s dipping needle as constructed by General Sabine.

References.—Delambre’s notice of the life of J. T. Mayer in the “Biographie Universelle”; Hutton’s “Mathem. Dict.”; Montucla, “Histoire des Mathématiques”; list of his works added to the éloge pronounced by Kaestner, Göttingen, 1762; “Abhandlungen von Galvani und andern,” Prague, 1793; Whewell, “History of the Inductive Sciences,” 1859, Vol. II. pp. 206, 221; Coulomb, “Mémoires Acad. Paris” for 1786 and 1787; “Royal Soc. Cat. of Sc. Papers,” Vol. IV. pp. 311–314; Lambert, “Reports of the Berlin Academy” for 1776.

Mayer (Johann Tobias, Jr.), 1752–1830, is the author of Memoirs on the magnetic needle as well as upon many electrical experiments, of which details may be found in the Journal der Physik of Friedrich A. C. Gren and in the “Comment Soc. Göttingen recent.”

A.D. 1760.—Delaval (E. H.) communicates between 1760 and 1764 several papers to the London Royal Society in reference to experiments made for the purpose of ascertaining the conducting powers of a body in different states. Therein, he shows that animal and vegetable substances lose their conducting powers when reduced to ashes, and that while metals are the best conductors, their oxides are non-conductors. His experiments made with island (Iceland) crystal (well known for its extraordinary property of double refraction), proved that it is affected by heat differently from other substances named, since the temperature necessary to render them electric makes the crystal non-electric. He had a piece of crystal of which, he said, one part became non-electric when greatly heated, while the other part, with the same or even a much greater heat, remained perfectly electric. These experiments did not, however, succeed with Sir Torbern Bergman, who repeated them with great care and who found that island crystal was a conductor in all cases, to whatever degree of heat it was exposed.

References.—Phil. Trans., Vol. LI. part i. p. 83; Vol LII. part i. pp. 353, etc., and part ii. p. 459; also Vol. LIII. part i. pp. 84–98; and Hutton’s abridgments, Vol. XI. pp. 334, 589; Vol. XII. p. 140; Thomas Thomson, “Hist. of Roy. Soc.,” p. 443; Thos. Young, “Course of Lectures,” 1807, Vol. II. p. 679, for notes on Dr. Wm. H. Wollaston’s paper concerning the double refraction of Iceland crystal.

A.D. 1760–1762.—Bergman—Bergmann—(Torbern Olof), celebrated Swedish astronomer, naturalist and chemist, writes several letters to Mr. Wilson, which are read before the Royal Society, Nov. 20, 1760, and March 18, 1762, wherein he alludes to the possibility of electrifying plates of ice in the same manner as plates of glass. In a subsequent letter he details experiments with silk ribbons of different colours, almost as curious as those of which an account has already been given (by Symmer at A.D. 1759), and from which he concludes that there is a certain fixed order regarding positive and negative electricity in which all bodies may be placed while other circumstances remain unchanged.

References.—Bergman’s “Bemerkung ... Isländischen Krystales,” “Comment ... electrica turmalini,” “Elektrische Versuche,” etc., and his other works referred to in the Philosophical Transactions, Vol. LI. p. 907; Vol. LIII. p. 97; Vol. LIV. p. 84; Vol. LVI. p. 236; also Hutton’s abridgments, Vol. XI. pp. 506, 705; Vol. XII. pp. 109, 343; “Nova Acta Soc. Upsal.,” “K. Schwedischen Akad. Abhand.,” “Aus dem Schwed. Magazine,” Phil. Mag., IX. p. 193; “Eng. Cycl.,” Vol. I. pp. 664–665; Gmelin’s “Chemistry,” Vol. I. p. 320; Thomas Thomson, “Hist. of the Royal Society,” London, 1812, pp. 444, 475–477.

A.D. 1761.—The many experiments made at this period by Ebenezer Kinnersley, of Philadelphia, relative to the two contrary electricities of glass and sulphur, are endorsed by his close friend Benjamin Franklin in his Letters at pp. 99, 100 and 102–105. He makes several curious observations on the elongation and fusion of fine iron wires whenever a strong charge is passed through them while in a state of tension, to which Dr. Watson makes special reference in a paper read before the Royal Society. He believes that lightning does not melt metal by a cold fusion, as Dr. Franklin and himself had formerly supposed, and that when it passes, for instance, through the blade of a sword, if the quantity is not very great, it may heat the point so as to melt it, while the broadest and the thickest part may not be sensibly warmer than before.

To ascertain the effects of electricity upon air, Kinnersley devised an instrument which he called an electrical air thermometer, and which is described at p. 626, Vol. VIII of the 1855 “Encyclopædia Britannica.” With this he could show the sudden rarefaction which air undergoes during the passage of the electric spark through it, heat being produced without accompaniment of any chemical change in the heated body.

Some other important observations made by Kinnersley, who, besides being an intimate friend, was the original associate of Ben. Franklin, are summed up as follows: A coated flask containing boiling water cannot be charged, the electricity passing off with the steam; but when the water gets cold the flask may be charged as usual. A person in a negative state of electricity standing upon an electric, and holding up a long sharp needle out of doors in the dark, observes light upon the point of it. No heat is produced by electrifying a thermometer, nor by passing shocks through large wire, but small wire is heated red-hot, expanded and melted (Phil. Trans. for 1763, Vol. LIII. p. 84; Thomson, “Hist. Roy. Soc.,” p. 445).

In the New York “Electrical Review” of May 13, 1905, will be found the following curious reference to the Boston Art Club exhibits of President R. H. W. Dwight:

“Among these is an interesting broadside, which gives a summary of two lectures on electricity by Ebenezer Kinnersley delivered in Faneuil Hall in September, 1751—the first lectures probably ever delivered on the then new subject of electricity. Kinnersley was an Englishman, who was head master in English literature in the College of Philadelphia, from 1753 to 1773, a student of science, who made a number of discoveries in electricity and invented a number of quaint electrical devices. He and Franklin were on intimate terms, and were closely associated in their electrical experiments. Kinnersley has been erroneously cited as an anticipator of Oersted’s discovery of the deflection of a magnetic needle by an electric current. The former’s experiment, however, was purely electrostatic. In the summary of these two lectures, among other things, it states that electricity ‘is an extremely subtile fluid; that it doth not take up any perceptible time in passing through large portions of space; that it is mixed with the substance of all other fluids and solids of our globe; that our bodies at all times contain enough of it to set a house on fire.’”

The exhibits of President Dwight are:

“An artificial spider animated by the electric fire so as to act like a live one; a shower of sand which rises again as fast as it falls; a leaf of the most mighty of metals suspended in the air, as is said of Mahomet’s tomb; electrified money which scarce anybody will take when offered to them; a curious machine, acting by means of the electric fire, and playing a variety of tunes on eight musical bells.”

This broadside of 1751 appears to antedate any other similar notice of electrical experiments.

The “Electrical Review” of April 23, 1904, p. 621, had published copy of an advertisement from the Massachusetts Gazette of March 7, 1765, giving notice of a course of lectures by David Mason, illustrated by “entertaining experiments on electricity similar to those cited in the broadside under date of 1751.” The advertisement of 1765, here referred to, appears at A.D. 1771.

References.—Sturgeon’s “Lectures,” London, 1842, p. 169; “The Electrical Researches of Hon. Henry Cavendish,” 1879, Nos. 125, 137, 213; Phil. Trans., Vol. LIII. part i. pp. 84–87; Vol. LIV. p. 208; Vol. LXIII, 1773, part i. p. 38; also the Hutton abridgments, Vol. XI. p. 702, and Vol. XIII. p. 370; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp. 23, 33, 214, 217, 220.

A.D. 1762.—Sulzer (Johann Georg), a Swiss philosopher, member of the Berlin Academy of Sciences, in his “Theory of Agreeable and Disagreeable Sensations” (“Theorie d. angenehmen u. unangenehmen Empfindungen,” Berlin, 1762), thus expresses himself: “When two pieces of metal, one of lead and the other of silver, are so joined together that their edges make one surface, a certain sensation will be produced on applying it to the tongue, which comes near to the taste of martial vitriol (vitriol of iron); whereas each piece by itself betrays not the slightest trace of that taste” (F. C. Bakewell, “Manual of Electricity” London, 1857, Chap. III. p. 28).

The passage in the edition “Nouvelle Théorie des Plaisirs,” published in 1767, is thus given by Sabine, “Electric Telegraph,” 1872, p. 15: “On taking two pieces of different metals—silver and zinc—and placing one of them above and the other underneath his tongue, he found that, so long as the metals did not make contact with each other, he felt nothing; but that when the edges were brought together over the tip of his tongue, the moment contact took place and during the time it lasted, he experienced an itching sensation and a taste resembling that of sulphate of iron....” Sulzer does not appear to have been much surprised at the result, thinking it “not improbable that, by the combination of the two metals, a solution of either of them may have taken place, in consequence of which the dissolved particles penetrate into the tongue; or we may conjecture that the combination of these metals occasions a trembling motion in the respective particles, which, exciting the nerves of the tongue, causes that peculiar sensation.”

And thus, remarks Pepper, a prominent fact has slept in obscurity from the time of Sulzer to the time of Galvani.

References.—Izarn, “Manuel,” Paris, 1804, p. 4; Sturgeon, Annals, Vol. VIII. p. 363; also note at p. 491 of Ronalds’ “Catalogue”; Mém. de l’Acad. de Berlin, “Théorie Générale du Plaisir”; also “Temple du Bonheur,” published at Bouillon (Pays Bas), 1769, Tome III. p. 124, this last-named work being alluded to in the Journal des Débats, 7 Vendémiaire, au X; Edm. Hoppe, “Geschichte,” 1884, p. 128; C. H. Wilkinson, “Elements of Galvanism,” Vol. I. p. 69, note; Albert’s “Amer. Ann. d. Artz,” Vol. II. Bremen, 1802.

A.D. 1762.—Ledru Comus, French Professor of Natural Philosophy, invents a mode of telegraphing which is described and fully illustrated in Vol. I of Guyot’s “Nouvelles Récréations Physiques et Mathématiques,” Paris, 1769; as well as at p. 278 of “Mémoires, Correspondance et Ouvrages Inédits de Diderot,” Paris, 1821, in one of the letters to Mlle. Voland dated July 28, 1762.

His apparatus consisted of two dials, each bearing upon it twenty-five letters of the alphabet, which were moved by the agency of magnets and of magnetized needles; but Auguste Guérout considers the contrivance to have been merely a speculative one, as will be seen by his article, reproduced from “La Lumière Electrique” of March 3, 1883, in No. 384 of the “Scientific American Supplement.”

References.—Journal de Physique for 1775, Vols. V and VI; for 1776, Vol. VII; and for 1778, Vol. I; “Scelta di Opuscoli,” Milano, 1776.

A.D. 1765.—Cigna (Giovanni Francesco), native of Mondovi, Italy, and nephew to the electrician Beccaria (A.D. 1753), became secretary to the society of savants who gave birth to the Royal Academy of Sciences at Turin, and whose Memoirs contain his work, “De novis quibusdam experimentis electricis,” 1765.

At pp. 31–65 of the above Memoirs is given a full account of Cigna’s many curious observations made with silk ribbons placed in various positions, and in contact with different surfaces, instead of with the silk stockings employed by Symmer (A.D. 1759). He thus supplies the main defect of Dufay’s theory (A.D. 1733) by proving that the two opposite electricities are produced simultaneously. On p. 47 of the same work will be found a report of Cigna’s experiment with ice to ascertain whether electric substances contain more electric matter than other bodies.

References.—Vol. III. p. 168 of Nollet’s “Letters,” for an account of his observations upon the electric attraction and repulsion between conducting substances immersed in oil; as well as Chap. II. s. 3., vol. i. of Van Swinden’s “Receuil,” etc., published at La Haye, 1784. Should also be consulted: Cigna’s “Memoirs on Electricity and Magnetism” in the “Miscellanea ... Taurinensia,” and the several communications made by him to Priestley, Lagrange and others in 1775 concerning Volta’s electrophorus; likewise “Memorie istorische ... di Gianfrancesco Cigna de Antonmaria Vassalli Eandi,” Torino, 1821.

A.D. 1766–1776.—Lambert (Johann Heinrich), a profound German mathematician, native of Upper Alsace, publishes in Vol. XXII of the “Reports of the Berlin Academy” two beautiful Memoirs upon the “Laws of Magnetic Force” and upon the “Curvature of the Magnetic Current,” both of which, according to Dr. Robison, would have done credit to Newton himself.

In the first Memoir, says Harris, the author endeavours to determine two very important laws; one relating to the change of force as depending upon the obliquity of its application, the other as referred to the distance. In the second Memoir the curves of the magnetic current are investigated by the action of the directive or polar force of a magnet upon a small needle. Lambert concludes that the effect of each particle of the magnet on each particle of the needle, and reciprocally, is as the absolute force or magnetic intensity of the particles directly, and as the squares of the distances inversely.

Noad states (“Manual,” London, 1859, p. 580) that Lambert’s deductions were confirmed twenty years later by Coulomb, through the agency of his delicate torsion balance, and more recently (about the year 1817) by Prof. Hansteen, of Christiania.

Previous to the above-named date, in 1760, Lambert had published, both at Leipzig and at Augsburg, his “Photometria, sive de Mensura et Gradibus Luminis, Colorum et Umbræ,” the sequel to a tract printed two years before, wherein he indicates the mode of measuring the intensity of the light of various bodies. The celebrated mathematician and astronomer, Pierre Bouguer (1698–1758), who had published, in 1729, his “Essai d’Optique,” etc., which was greatly enlarged in his “Traité,” etc., brought out by La Caille in 1760, may be considered the founder of this branch of the science of optics, to which the name photometry has been given by English writers. The photometer designed by Sir Benjamin Thompson, Count Rumford (entered at A.D. 1802), has been described in Phil. Trans. for 1794, Vol. LXVII. His method is to cast two shadows of a given object near each other on the same surface, the lights being removed to such distances that the shadows appear equally dark.

References.—Sir John Leslie’s “Fifth Dissertation” in the eighth “Encycl. Brit.”; Count Rumford’s photometer illustrated at Plate XXVII. figs. 387, 388, vol. i. of Dr. Thomas Young’s “Course of Lectures,” London, 1807; also Vol. II. pp. 282 and 351 of the same work, concerning photometry generally; Dredge and others, “Electric Illumination,” etc. (chiefly compiled from London Engineering), Vol. II. pp. 101–117; Brewster’s “Edin. Jour. of Sc.,” 1826, Vol. II. p. 321; Vol. III. p. 104; Vol. V. p. 139, for William Ritchie’s articles on the photometer of Mr. Leslie, and relative to an improved instrument upon the principles of Bouguer (Edin. Transactions, Vol. X. part. ii.); Lambert’s biography and the article “Magnetism” in the “Encycl. Brit.”; Harris, “Rudim. Magn.,” Part III. pp. 20, 33, 191–203.

It may be added that all the valuable manuscripts left by Lambert were purchased by the Berlin Academy, and were afterward published by John Bernoulli, a grandson of the celebrated John Bernoulli alluded to at A.D. 1700.

A.D. 1766.—Lullin (Amadeus), in his “Dissertatio physica de electricitate,” Geneva, 1766, at p. 26, alludes to Beccaria’s experiments, saying that he produced much greater effects with the electric spark by passing the latter through oil instead of water: oil being a much worse conductor, the spark in it is larger. At p. 38 of the same work he details the experiments made to prove the correctness of Mollet’s doctrine regarding the constant motion of electrical atmospheres, and at p. 42 are given his experiments to show the production of electricity in the clouds. With a long insulated pole projecting from the mountain side he observed, among other effects, that when small clouds of vapour produced by the sun’s heat touched only the end of the pole the latter was electrified, but that it was not affected if the entire pole was covered by the vapour (“Lib. Useful Knowledge,” “Electricity,” Chap. XI. Nos. 154, etc.).

Lullin, it is said, proposed a modification of Reusser’s plan of telegraphing, in manner stated at p. 69 of Reid’s 1887 “Telegraph in America.”

A.D. 1766.—L’Abbé Poncelet, a native of Verdun, France, publishes at Paris “La Nature dans la formation du Tonnerre,” etc., wherein he indicates a method of protecting from lightning residences, pavilions and other structures, by constructing them of resinous woods and lining them with either silk or waxed cloths. He quaintly remarks that as they thus present “on all sides resinous surfaces, which never receive phlogiston by communication, the latter (thunder and lightning), after having leaped lightly around the pavilion and finding itself unable to attack it, will probably depart in order to pursue its ravages elsewhere.”

References.—Scientific American Supplement, No. 66, p. 1053, for a copy of the frontispiece of the above-named work; also Figuier, “Exposition et Histoire,” etc., 1857, Vol. IV. pp. 234, 235.

A.D. 1767.—Bozolus (Joseph), an Italian Jesuit, Professor of Natural Philosophy at Rome, is the first (and not Cavallo, A.D. 1775) to suggest employing the active principle of the Leyden jar for the transmission of intelligence.

His plan is to place underground two wires which are to be brought at each station close enough to admit of the passage of a spark. One of the wires is to be connected with the inner coating and the other with the outer surface of a Leyden phial; the sparks observed at the opening between the wires being there made to express any meaning according to a preconcerted code of signals.

References.—Latin poem entitled “Mariani Parthenii Electricorum,” in six books, Roma, 1767, lib. i. p. 34 (describing the telegrafo elettrico scintillante); also Saturday Review, August 21, 1858, p. 190, and Cornhill Magazine for 1860, Vol. II. p. 66.

A.D. 1767.—Priestley (Joseph), the earliest historian of electrical science, publishes, by advice of Benjamin Franklin, the first edition of his great work, “The History and Present State of Electricity,” of which there were four other separate enlarged issues, in 1769, 1775, 1775 and 1794. During the year 1766 he had been given the degree of Doctor of Laws by the Edinburgh University and he had also, at the instance of Franklin, Watson and others, been made a member of the English Royal Society, which, a few years later, bestowed upon him the Copley medal.

Speaking of the above-named work, Dr. Lardner says (“Lectures, 1859, Vol. I. p. 136): “This philosopher did not contribute materially to the advancement of the science by the development of any new facts; but in his ‘History of Electricity’ he collected and arranged much useful information respecting the progress of the science.” Nevertheless, to him is due the first employment of the conductor supported by an insulating pillar, as described by Noad, who gives an account of Priestley’s electrical machine at Chap. IV of his “Manual”; and he is also the first to investigate upon an extensive scale the chemical effects of ordinary electricity. The observations of M. Warltire, a lecturer on natural philosophy, and Priestley’s own experiments in this line, made by passing the electric spark through water tinged blue by litmus, also through olive oil, turpentine, etc., as well as his researches more particularly upon the gases and upon the influence of the electric fluid in expanding solid bodies, are detailed at the “Electricity” chapter of the “Encycl. Brit.”

At pp. 660–665 of the fourth edition of his “History,” Priestley describes the experiments he made to illustrate what he called the lateral force of electrical explosions; that is, the tendency of the fluid to diverge, as is the case with lightning when any material obstruction lies in its path.

Perhaps the most important of all Dr. Priestley’s electrical discoveries (Thomson, “Hist. Roy. Soc.,” p. 445) was that charcoal is a conductor of electricity, and so good a conductor that it vies even with the metals themselves. When the conducting power of charcoal was tried by succeeding electricians, it was found to vary in the most unaccountable manner, sometimes scarcely conducting at all, sometimes imperfectly and sometimes remarkably well; a diversity naturally indicating some difference in the nature of the different specimens of English charcoal (Priestley’s “History,” etc., Part VIII. s. 3). Charcoal being examined by Mr. Kinnersley (at A.D. 1761), was also by him observed to vary in its conducting power. Oak, beech and maple charcoal he found to conduct satisfactorily; the charcoal from the pine would not conduct at all, while a line drawn upon paper by a heavy black lead pencil conducted pretty well (Phil. Trans., 1773, Vol. LXIII. p. 38).

References.—Priestley’s letter to Dr. Franklin (Phil. Trans., Vol. LXII. p. 360) concerning William Henley’s new electrometer and experiments; likewise the Phil. Trans., Vol. LVIII. p. 68; Vol. LIX. pp. 57, 63; Vol. LX. p. 192; Vol. LXII. p. 359; and the abridgments by Hutton, Vol. XII. pp. 510, 600, 603; Vol. XIII. p. 36; “Trans. of the Amer. Phil. Soc.,” O. S., Vol. VI. part i. p. 190, containing proceedings of the Society on the death of Joseph Priestley; Wilkinson’s “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 74–80; Noad’s Lectures, No. 4, Knight’s edition, pp. 182, 183; “Library of Useful Knowledge,” London, 1829, Chap. “Electricity,” pp. 41 and 45; “Library of Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 444–456; “Essays, Reviews and Addresses” by James Martineau, London, 1890, Vol. I. pp. 1–42; “Mém. de l’Institut” (Histoire), Tome VI. 1806, p. 29 for Elogium; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 28, 110; “Science and Education,” by Thos. Henry Huxley, New York, 1894, pp. 1–37; “Scientific Correspondence of Jos. Priestley,” by H. C. Bolton, New York, 1902; Dr. Thos. H. Huxley, “Science Culture,” 1882, p. 102; Warltire, in Muirhead’s translation of Arago’s “Eloge de James Watt,” pp. 99, 100; also the appendix to the last-named work, p. 157 and note.

A.D. 1767.—Lane (Thomas—Timothy), a medical practitioner of London, introduces his discharging electrometer, which is now to be found described and illustrated in nearly all works on electricity.

It consists of a bent glass arm, one end of which is attached to a socket in the wire of the Leyden jar, while the other end holds a horizontal sliding brass rod, or spring tube, which bears a ball at each extremity. The rod is usually divided into inches and tenths, indicating the force of the discharge which takes place when the knob of the jar is placed in contact with the prime conductor of an electrical machine, and the charge is strong enough to leap from one to the other. In Mr. Lane’s experiments the shocks were twice as frequent when the interval between the balls was one twenty-fourth of an inch as when twice as much: from which he concluded that the quantity of electricity required for a discharge is in exact proportion to the distance between the surfaces of the balls.

A combination of the Lane and other electrometers was made by Mr. Cuthbertson, as shown at p. 528, Vol. II of Nicholson’s Journal of Natural Philosophy, and at p. 451, Vol. LVII of the Philosophical Transactions.

References.—Phil. Trans. for 1805; Hutton’s abridgments, Vol. XII; p. 475; Cavallo, “Elements ... Phil.” 1825, Vol. II. p 197; Harris, “Electricity,” p. 103; Monthly Magazine, December 1805, and Tilloch’s Philosophical Magazine, Vol. XXIII. p. 253.

The Hutton abridgments contain, at p. 308, Vol. XV, the description of a new electrometer by Abraham Brook.

A.D. 1768.—Ramsden (Jesse), a very capable English manufacturer of mechanical instruments, member of the Royal Society and of the Imperial Academy of St. Petersburg, is said to be the first to construct an electrical machine wherein a plate of glass is substituted for the glass globe of Newton and of Hauksbee and for the glass cylinder of Gordon (at A.D. 1675, 1705 and 1742). The same claim which has been made for Martin de Planta, Swiss natural philosopher, appears to have no foundation. (See note at p. 401 of Ronalds’ “Catalogue.”)

References.—Journal des Sçavans, November 1788, p. 744; Phil. Trans., 1783; “Chambers’ Encyclopædia,” 1868, Vol. III. p. 812; Mme. Le Breton, “Hist. et app. de l’Electricité,” Paris, 1884, pp. 61, 62.

A.D. 1768.—Molenier (Jacob), physician to the French King, Louis XV, writes “Essai sur le Mécanisme de l’Electricité” for the purpose of showing the utility of the application of the electric fluid in medical practice. At p. 60 he explains the effects and results when applications are made more particularly to the nerves, and at pp. 65–67 he gives certificates of many of the cures he has effected of gout, rheumatism, tumours, cancers, loss of blood, as well as of pains and aches of various descriptions.

References.—Jallabert (A.D. 1749); Lovett (A.D. 1756); Bertholon (A.D. 1780–1781); Mauduyt (A.D. 1781); Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. pp. 122–129 for the experiments of Sauvages, De La Croix, Joseph Elder von Herbert, H. Boissier and others; Thomas Fowler, “Med. Soc. of London,” Vol. III; M. Tentzel, “Collection Académique,” Tome XI; the works of L’Abbé Sans, Paris, 1772–1778; M. de Cazèles Masar’s “Mémoires et Recueils,” published 1780–1788, and reproduced in Vols. II and III of the “Mémoires de Toulouse”; Jacques H. D. Petetin, “Actes de la Soc. de Lyon,” p. 230; M. Partington, Jour. de Phys., 1781, Vol. I; Dr. Andrew Duncan’s “Medical Cases,” Edinburgh, 1784, pp. 135, 191, 235, 320; C. A. Gerhard, “Mém. de Berlin,” 1772, p. 141; Jour. de Phys., 1783, Vol. II; J. B. Bohadsch, “Dissertatio,” etc., Prague, 1751; Phil. Trans. for 1752; Patrick Brydone, Phil. Trans. for 1757; Geo Wilkinson, of Sunderland, “An account of good effects,” etc., in Medical Facts, etc., 1792, Vol. III. p. 52; M. Carmoy, “Observ. sur l’El. Med.,” Dijon, 1784; M. Cosnier, M. Maloet, Jean Darcet, etc.; “Rapport,” etc., 1783; Le Comus, “Dissertatio,” etc., 1761; Le Comus, “Osservazioni,” etc., 1776 (Jour. de Phys., 1775, Vols. V and VI; 1776, Vol. VII; 1778, Vol. I; 1781, Vol. II); Ledru, “Sur le traitement,” etc., 1783; Le Dr. Boudet, “De l’Elec. en Médecine,” conférence faite à Vienne le 6 Octobre, 1883.

A.D. 1769.—Bancroft (Edward Nathaniel), a resident physician of Guiana, openly expresses the belief that the shock of the torpedo is of an electrical nature. He alludes (“Natural History of Guiana”) also to the gymnotus electricus, which, he says, gives much stronger strokes than the torpedo; the shocks received from the larger animals being almost invariably fatal.

The discharge of the gymnotus has been estimated to be equal to that of a battery of Leyden jars of three thousand five hundred square inches, fully charged. At a later date, the American physicians, Garden and Williamson, showed that as the fluid discharged by that fish affects the same parts that are affected by the electric fluid; as it excites sensations perfectly similar; as it kills and stuns animals in the same manner; as it is conveyed by the same bodies that carry the electric fluid and refuses to be conveyed by others that refuse to take the fluid, it must be the electric fluid itself, and the shock given by the eel must be the electric shock.

Humboldt, speaking of the results obtained by M. Samuel Fahlberg, of Sweden, says: “This philosopher has seen an electric spark, as Walsh and Ingen-housz had done before him at London, by placing the gymnotus in the air and interrupting the conducting chain by two gold leaves pasted upon glass and a line distant from each other” (Edinburgh Journal, Vol. II. p. 249). Faraday, who gives this extract at paragraph 358 of his “Experimental Researches” says he could not, however, find any record of such an observation by either Walsh or Ingen-housz and does not know where to refer to that by Fahlberg. (See the note accompanying afore-named extract.)

References.—Annales de Chimie et de Physique, Vol. XI; Phil. Trans. for 1775, pp. 94, 102 (letter of Alexander Garden, M.D.), 105, 395; “Acad. Berlin,” 1770, 1786; fifteenth series Faraday’s “Exper. Researches,” read December 6, 1838; Wheldon’s “Catalogue,” No. 74, 1870; Sir David Brewster’s “Edin. Jour. of Science,” 1826, Vol. I. p. 96, for the observations of Dr. Robert Knox; G. W. Schilling: at Ingen-housz, “Nouvelles Expériences,” p. 340, as well as at note, p. 439, Vol. I. of Van Swinden’s “Recueil,” etc., La Haye, 1784; also G. Schilling’s “Diatribe de morbo in Europâ penè ignoto,” 1770; article “Physiology” in the “Encycl. Brit.,” 1859, Vol. XVII. p. 671; Aristotle (B.C. 341), Scribonius (A.D. 50), Richer (A.D. 1671), Redi (A.D. 1678), Kaempfer (A.D. 1702), Adanson (A.D. 1751); Sc. Am. Suppl., No. 24, p. 375 (for M. Rouget’s observations on the gymnotus) and No. 457, p. 7300; M. Bajon, “Descrizione di un pesce,” etc., Milano, 1775 (Phil. Trans., 1773, p. 481); M. Vanderlot’s work on the Surinam eel, alluded to at p. 88 of “Voyage Zoologique,” by Humboldt, who published in Paris, during 1806 and also during 1819 special works on the gymnotus and upon electrical fishes generally.

A.D. 1769.—Cuthbertson (John), English philosophical instrument maker, issues the first edition of his interesting work on electricity and galvanism.

He is the inventor of the balance electrometer, employed for regulating the amount of a charge to be sent through any substance, as well as of an electrical condenser and of an apparatus for oxidating metals, all of which are respectively described at pp. 593, 614 and 620, Vol. VIII. of the 1855 “Encycl. Brit.”

At the end of Part VI of his “Practical Electricity and Galvanism,” Cuthbertson gives the conclusions he reached from his numerous experiments with wire. These, as well as Mr. George Adams’ own observations (“Essay,” etc., 1799, p. 285), proved that the quantity of electricity necessary to disperse a given portion of wire will be the same, even though the charged surface be greatly varied; and that equal quantities of electricity in the form of a charge will cause equal lengths of the same steel wire to explode, whether the jar made use of be of greater or less capacity (Nicholson’s Journal, Vol. II. p. 217).

During his many experiments Cuthbertson made the very extraordinary discovery that a battery of fifteen jars and containing 17 square feet of coated glass, which, on a very dry day in March 1796 could only be made to ignite from 18 to 20 inches of iron wire of ¹⁄₁₅₀ part of an inch in diameter, took a charge which ignited 60 inches when he breathed into each jar through a glass tube (Noad, “Manual,” p. 122; also Cuthbertson, “Prac. Elec. and Magnetism,” 1807, pp. 187, 188).

References.—Cuthbertson’s communication to the “Emporium of Arts,” Vol. II. p. 193, regarding his experiments on John Wingfield’s “New Method of Increasing the Charging Capacity of Coated Electric Jars”; Cuthbertson’s “Electricity,” Parts VIII, IX and XI; Cuthbertson’s letter addressed to Nicholson’s Journal, Vol. II. p. 526, also Phil. Mag., Vol. II. p. 251. for electrometers; “Bibl. Britan.,” Vol. XXXIX. 1808, p. 97; Vol. XLVII. 1811, p. 233; Cuthbertson’s several works published at Amsterdam and Leipzig, 1769–1797, and alluded to in Phil. Mag., more particularly at Vols. XVIII. p. 358; XIX. p. 83; XXIV. p. 170; XXXVI. p. 259, as well as at p. 313, Vol. XII. of J. B. Van Mons’ Journal de Chimie; Nicholson’s Journal, Vols. II. p. 525; VIII. pp. 97, 205, and the New Series, Vol. II. p. 281; Gilbert’s Annalen, Vol. III. p. 1; “Bibl. Brit. Sc. et Arts,” Genève, 1808, Vol. XXXIX. p. 118; Noad’s “Manual,” p. 118; Van Marum (A.D. 1785); Harris, “Electricity,” p. 103, and his “Frictional Electricity,” p. 76; C. H. Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. II. pp. 242, 266–268; Phil. Trans., 1782, for A. Brook’s electrometer, which apparatus is described in the latter’s work published, under the head of “Miscellaneous Experiments,” at Norwich, 1789, as well as in the “Electricity” article of the “Encycl. Britannica.”

A.D. 1769.—St. Paul’s Cathedral, London, is first provided with lightning conductors. Dr. Tyndall, who mentions this fact (Notes of Lecture VI, March 11, 1875) likewise states that Wilson, who entertained a preference for blunt conductors as against the views of Franklin, Cavendish and Watson, so influenced King George III that the pointed conductors on Buckingham House were, during the year 1777, changed for others ending in round balls.

In 1772, St. Paul’s Cathedral was struck by lightning, which “heated to redness a portion of one of its conductors consisting of a bar of iron nearly four inches broad and about half an inch thick.” In 1764, the lightning had struck St. Bride’s Church, London, and “bent and broke asunder an iron bar two and a half inches broad and half an inch thick” (Sturgeon, “Sc. Researches,” Bury, 1850, p. 360; Phil. Trans. for 1764 and 1762).

The Rev. James Pilkington, Bishop of Durham, published in London a detailed account of the partial destruction of St. Paul’s Church by lightning, June 4, 1561, which is also to be found at pp. 53–55 of Strype’s “Life of Grindall,” published in London, 1710, and of which an abstract appears under the A.D. 1754 date.

References.—Sturgeon’s Annals, Vol. X. pp. 127–131; also, Biography of John Canton in “Encycl. Britannica”; Sir John Pringle, at A.D. 1777; Hutton’s abridgments of the Phil. Trans., Vol. XII. pp. 620–624.

A.D. 1769.—Mallet (Frederick) member of the Royal Society of Upsal and of the Stockholm Academy of Sciences, acting upon the observations of Anders Celsius (at A.D. 1740), is the first to make an attempt to determine the intensity of magnetism simultaneously at distant points. He ascertains that the number of oscillations in equal times at Ponoi, China (latitude, 67 degrees 4 minutes north; longitude, 41 degrees east) are the same as at St. Petersburg, Russia (59 degrees 56 minutes north latitude; 30 degrees 19 minutes east longitude).

References.—Walker, “Magnetism,” Chap. VI; “Novi Commen. Acad. Sc. Petropol.,” Vol. XIV for 1769, part ii. p. 33; Le Monnier, “Lois du Magnétisme,” etc., 1776, p. 50; “Biog. Univ.,” Vol. XXVI. p. 258.

A.D. 1770.—The well-known work of Jas. Ferguson, F.R.S., which first appeared under the title of “Introduction or Lectures on Electricity,” now becomes still more popular under the head of “Lectures on Select Subjects,” etc. (Consult likewise his “Lectures on Electricity,” corrected by C. F. Partington, with appendix, London, 1825.)

In his first lecture he says that the most remarkable properties of the loadstone are: (1) it attracts iron and steel only; (2) it constantly turns one of its sides to the north and the other to the south, when suspended to a thread that does not twist; (3) it communicates all its properties to a piece of steel when rubbed upon it without losing any itself. He cites the experiments of Dr. Helsham, according to whom, says he, the attraction of the loadstone decreases as the square of the distance increases. He also treats of electrical attraction generally, and reports in the sixth lecture having “heard that lightning, striking upon the mariner’s compass, will sometimes turn it round and often make it stand the contrary way, or with the north pole towards the south.”

A.D. 1770.—Hell—Hehl—Heyl—Höll (Maximilian), Hungarian scientist (1720–1792), member of the Order of Jesuits and Professor of Astronomy at Vienna, who had great faith in the influence of the loadstone, invented a singular arrangement of steel plates to which he afterward attributed the cure “with extraordinary success” of many diseases, as well as of a severe attack of rheumatism from which he himself had long suffered.

He communicated his discovery to Friedrich Anton Mesmer, who was so strongly impressed by Hell’s observations that he immediately procured every conceivable description of magnet, with which he made many experiments that led to his introduction of animal magnetism, or rather mesmerism.

He is the author of many works, the most important being “Elementa Algebræ Joannis Crivelii magis illustrata et novis demonstrationibus et problematibus aucta,” Vienna, 1745; “Observ. Astronomicæ,” 1768, and “Auroræ Boreales Theoria nova,” 1776.

References.—Beckmann, Bohn, 1846, Vol. I. p. 44; Practical Mechanic, Glasgow, 1843, Vol. II. p. 71; Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. pp. 303, 304, etc.; J. Lamont, “Handbuch,” etc., p. 436; M. V. Burq, “Métallo thérapie,” Paris, 1853; “Biog. Générale,” Vol. XXIII. pp. 836–839; Schlichtegroll, “Nekrol.,” 1792, Vol. I. pp. 282–303; “Journal des Sçavans,” for July 1771, p. 499; Meusel, “Gelehrtes Teutschl”; Jer. de la Lande, “Bibliogr. Astronomique,” Paris, 1803, pp. 721–722.

A.D. 1771.—Morveau (Baron Louis, Bernard Guyton de), a very prominent French chemist and scientist, publishes at Dijon his “Reflexions sur la boussole à double aiguille,” and, later on, communicates to the Annales de Chimie, Vol. LXI. p. 70, and Vol. LXIII. p. 113, very valuable papers treating on the influence of galvanic electricity upon minerals, which are read before the French Institute.

References.—Thomson, “Hist. of Chemistry,” Vol. II. 1831; the translation of Morveau’s letter to Guénaud de Montbéliard in Scelta d’ Opuscoli, Vol. XXXIII. p. 60; Berthollet, “Discours,” etc., 1816; “Biog. Univ.,” Tome XVIII. pp. 296–298; “Journal des Savants” for Jan. 1860; “Roy. Soc. Cat. of Sc. Papers,” Vol. III. pp. 99–102; Vol. VI. pp. 679–680; “Biog. Univ. et Portative,” etc., 1834, Vol. III. p. 701; Annales de Chimie, Vol. LXI. pp. 70–82; Sir Humphry Davy, “Bakerian Lectures,” London, 1840, p. 51.

A.D. 1771.—In a very interesting article published by the Gazette at Salem (Mass.), August 9, 1889, on the occasion of the formal opening of the new station of the Electric Lighting Company, the connection of that city with the progress of electricity was traced in the following manner:

“In 1771 Col. David Mason, a prominent figure among the patriots at Leslie’s Retreat, gave a course of lectures on ‘Electricity’ at his house near North Bridge. The Rev. John Prince, LL.D., minister of the First Church from 1779 to 1836, was especially interested in electricity, and is said to have made the first electrical machine in Salem, if not in the country. Col. Francis Peabody, assisted by Jonathan Webb, the apothecary, was much interested in the subject, and, in 1829, gave a series of lectures, illustrated with a machine made by himself, which had a glass plate wheel imported from Germany at a reported cost of $1500.

“Dr. Charles Grafton Page, another native of Salem, invented the first electric motor in which solenoids were used, and as early as 1850 constructed a motor which developed over 10 h.p. The next year he made a trial trip with his electro-magnetic locomotive over the Baltimore and Washington Railroad. Prof. Moses Gerrish Farmer lived in Pearl Street between the years 1850 and 1870, and, as far back as 1859, illuminated the house with divided electric lights—probably the first time that any house in the world was lighted by electricity. In 1847 Prof. Farmer had constructed and exhibited in public an electro-magnetic locomotive drawing a car holding two passengers, on a track one foot and a half wide.

“Many of Prof. Alexander Graham Bell’s early experiments were conducted in Salem, and the first lecture on the telephone in this country, if not in the world, was delivered by him before the Essex Institute in Lyceum Hall, February 12, 1877. The late Prof. Osbun, teacher of chemistry and physics at the Normal School in Salem, was also an electrical expert. He exhibited the first arc lights in Salem, and was the inventor of the storage battery system from which lights were exhibited.”

The advertisement of March 7, 1765, previously alluded to herein at Kinnersley, A.D. 1761, is as follows:

“A Course of Experiments on the

newly discovered Electrical Fire, to be accompanied with methodical Lectures on the Nature and Properties of that wonderful Element will be exhibited by David Mason, at his House opposite Mr. Thomas Jackson; Distiller, near Sudbury-Street.—To consist of two Lectures, at one Pistareen each Lecture.—The first Lectures to be on Monday and Thursday, and the Second on Tuesday and Friday Evenings every week, Weather permitting.