Chapter XVIII: Book I: chap. i. Therein, he says that Baptista Porta, who has made the (3)

=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.