Part 2 / Book 6 — Book VI (continued 2)

At Chapter XVII of the seventh book of the above-mentioned treatise, Browne makes allusion to “the story of Frier Bacon that made a Brazen Head to speak these words: “Time is....”

References.—“Library of Literary Criticism,” Chas. Wells Moulton, Vol. II. p. 339–345; “Fortnightly Review,” for Oct. 1905, pp. 616–626, “Sir Thomas Browne and his Family”; Edmund Gosse, in the “English Men of Letters Series”; Browne’s “Letter” inserted in the “Biographia Britannica,” also his entire works, recognized as an encyclopædia of contemporary knowledge, and which were published in four octavo volumes by Simon Wilkins, F.S.A., London, 1836.

A.D. 1653.—In the third edition of “The Jewell House of Arte and Nature,” by Sir Hugh Plat, originally published in 1594, and wrongly attributed in Weston’s “Catalogue” to Gabriel Plattes, is to be found the following allusion to the loadstone: “And though the adamant be the hardest of all stones, yet is it softened with Goa’s blood and there is a special antipathy between that and the loadstone, which is of the colour of rusty iron, and hath an admirable vertue not onely to draw iron to it self, but also to make any iron upon which it is rubbed to draw iron also, it is written notwithstanding that being rubbed with the juyce of Garlick, it loseth that vertue and cannot then draw iron, as likewise if a Diamond be layed close unto it.”

This “special antipathy” of garlick, and of the diamond—whether or not the latter be softened with Goa’s (goat’s) blood—is treated of very fully by many other authors, notably:

Pliny, “Nat. Hist.,” Holland tr. 1601, Chap. IV. p. 610; Plutarch, “Quæstones Platonicæ,” lib. vii. cap. 7; Claudius Ptolemæus, “Opus Quadripartitum,” lib. i. cap. 3; St. Augustine, “De Civitate Dei,” lib. xxi.; Bartholom. de Glanvilla, “Liber de Proprietatibus Rerum,” lib. xvi.; Pietro di Abano, “Conciliator Differentiarum,” 1520, pp. 72–73, or the Venice edition of 1526, cap. 51; Joannes Ruellius, “De Natura Stirpium,” 1536, pp. 125, 530; Ibn Roschd’s “Comment on Aristotle,” 1550, T. IV. p. 143t; Cardinal de Cusa, “Opera,” 1565, p. 175; C. Julius Solinus, “De Memorabilibus,” cap. 64; Walter Charleton, “A Ternary of Paradoxes,” London, 1650, pp. 40–41; Thomas Browne, “Pseudodoxia Epidemica,” 1658, p. 74; G. B. Porta, “Naturall Magick,” 1658, Chap. XLVIII and Chap. LIII—from both of which chapters extracts appear at the A.D. 1558 entry; “Journal des Savants” for January 1894; Chas. de Rémusat, “Hist. de la Philos.,” Paris, 1878, Vol. II. p. 187.

Rohault—at p. 186 of his 1728 “Syst. of Nat. Phil.”—says: “As to what some writers have related, that a loadstone will not attract iron if there be a diamond near and that onions and garlic will make it lose its vertue; these are contradicted by a thousand experiments which I have tried. For I have shown that this stone will attract iron through the very thickest diamonds and through a great many thick skins which an onion is made up of.”

References.—“Dict. of Nat. Biography,” Vol. XLV. pp. 407–409, giving many particulars; J. B. J. Delambre, at A.D. 1635. For Gabriel Plattes, see the same “Dict. of Nat. Biography,” Vol. XLV. p. 410.

A.D. 1657.—Schott (Gaspar)—P. Gaspar Schott—a German Jesuit who was sent to teach natural philosophy and mathematics at Palermo, Sicily, is the author of several very curious works on physics, of which the most important alone will here be noted.

“Magiæ Universalis Naturæ et Artis,” etc., appeared at Herbipoli in 1657, 1658, 1659. In the first book of the fourth volume (or part) he indicates, according to Kircher, whom he had met while in Rome, the means of conveying one’s thoughts at a distance by the loadstone, and he alludes to the speaking head constructed by Albertus Magnus, while, in the third and fourth books of the same volume, he gives a long treatise on the loadstone as well as an account of numerous experiments made with it.

“De Arte Mechanica,” etc. (“Mechanicæ,” etc.), Herbipoli, 1657–1658, contains, in Part II. class i. p. 314, the first published notice of Von Guericke’s experiments.

“Physica Curiosa sive Mirabilia Naturæ,” etc., Herbipoli, 1662 (which may justly be considered a continuation of the “Magiæ Universalis”), treats in the eleventh book of St. Elmo’s fire, thunder and meteors in general.

“Technica Curiosa sive Mirabilia Naturæ,” etc., Herbipoli, 1664, alludes, in the first two books, to the experiments made by Von Guericke and by Boyle, and gives the contents of eight letters written him by the first named.

“Schola Steganographica,” etc., Norimbergæ, 1665, gives, at pp. 258–264, a description of the dial telegraph of Daniell Schwenter.

“Jocoseriorum Naturæ et Artis,” etc., published about 1666, alludes to the “Thaumaturgus Mathematicus” of Gaspar Ens, published at Cologne, 1651, as well as to the “Deliciæ Physico-Mathematicæ” of Daniell Schwenter and Geo. Philippi Harsdoerffer (Senator of Nuremberg), to “La Récréation Mathématique” of Jean Leurechon, and to the works of Cardan, Mizauld, Aldrovandi and others.

References.—“Notice Raisonnée des Ouvrages de Gaspar Schott,” par M. L’Abbé Mxxx de St. Léger de Soissons, Paris, 1785, pp. 6, 31, 32, 37, 44, 70; Muirhead’s translation of Arago’s Eloge de James Watt, London, 1839, p. 51.[46]

A.D. 1660.—Guericke (Otto von), a burgomaster of Magdeburg, Prussian Saxony, constructs the first frictional electric machine. It consisted of a globe of sulphur, cast in a glass sphere, and mounted upon a revolving axis, which when rubbed by a cloth pressed against it by the hand, emitted both sound and light. It was Guericke who “heard the first sound and saw the first light in artificially excited electricity.” He proved that light bodies, when attracted by an excited electric, were immediately repelled by the latter and became incapable of a second attraction until touched by some other body; also that light bodies develop electrical excitation when suspended within the sphere of an excited electric.

References.—“Experimenta Nova Magdeburgica,” 1672, lib. iv, cap. 15, p. 147, also all relating to the sulphur globe reproduced from the “Experimenta Nova” at end of Figuier’s “Exposition et Histoire,” etc., Vol. IV. Paris, 1857; Moncony, Voyages, 1665; Schott (Gaspar), “Technica Curiosa,” etc., Norimbergæ, 1664; “Abhandlungen zur Geschichte der Mathem.,” Leipzig, 1898, Vol. VIII. pp. 69–112, for the two articles by Ferdinand Rosenberger on the development of the electric machine, etc., from the time of Von Guericke.

A.D. 1660.—At the meeting of the English Royal Society, held June 5, 1660, Magnetical Remedies were discoursed of. Sir Gilbert Talbot promised to bring in what he knew of sympatheticall cures, and those who possessed any powder of sympathy were requested to fetch some at the next meeting.

A.D. 1661.—Somerset (Edward), second Marquis of Worcester, an English inventor, announces, in his “Century of Inventions” that he has discovered “a method by which at a window as far as the eye can discover black from white, a man may hold discourse with his correspondent, without noise made or notice taken; being, according to occasion given, or means afforded, ex re nata, and no need of provision beforehand: though much better if foreseen, and course taken by mutual consent of parties.” This method, he asserts, he can put into practice “by night as well as by day, though as dark as pitch is black.”

References.—Dircks’ “Life of Worcester,” p. 357; “Dictionary of National Biography,” Vol. LIII. pp. 232–237.

A.D. 1662.—Rupert (Prince Robert), of Bavaria, son of Frederick V, elector palatine, and one of the founders of the Royal Society of London, is credited with the discovery of the curious glass bubbles called “Rupert’s drops.” These are merely drops of glass thrown, when melted, into water, and thus becoming suddenly consolidated into a shape somewhat resembling the form of a tear. The globular end may be subjected to quite a smart stroke without breaking, but if a particle of the tail is nipped off, the whole flies into fine powder with almost explosive violence.

“Mr. Peter did show us the experiment (which I had heard talked of) of the chymicall glasses, which break all to dust by breaking off a little small end; which is a great mystery to me” (Samuel Pepys, “Diary,” January 13, 1662).

Sir David Brewster discovered that the fracture of these unannealed drops was accompanied by the evolution of electrical light, which appears even when they are broken under water. Mr. Bennet observed that when one of the drops was placed upon a book, the latter was electrified negatively.

References.—The articles on “Annealing,” “Optics,” and “Electricity” in the “Encyclopædia Britannica”; also the biography in “Penny Cycl.,” Vol. XX. pp. 226–227; Le Cat, “Memoir,” London, 1749–1750, or Philos. Trans., XLVI. p. 175.

A.D. 1665.—Grimaldi (Francesco Maria), Italian philosopher (1618–1663), member of the Order of Jesuits and an associate of the astronomer Giovanni Battista Riccioli (at A.D. 1270) is the author of the important work “Physico mathesis de Lumine ...” which cites the discovery of magnetism produced by the perpendicular holding of an iron bar.

References.—Phil. Trans. for 1665; “Engl. Cycl.,” article “Biography,” Vol. CXI. p. 207; Larousse, “Dict.,” Vol. VIII, p. 1531. And, for Riccioli’s works, see Houzeau et Lancaster, “Bibliog. Gén.,” Vol. III. p. 238; “Journ. des Sçavans” pour 1665 et 1666, pp. 642–647.

A.D. 1665.—Glanvill (Joseph), an eminent English divine and philosopher, Chaplain to King Charles II and F.R.S., sometimes called “Sadducismus Triumphatus Glanvill,” endorses in his “Scepsis Scientifica” (“the vanity of dogmatizing recast”)—published originally in 1661—the views advanced previously by the Jesuit Leurechon, and, after discussing the objections of Sir Thomas Browne, expresses the belief that “to confer at the distance of the Indies by sympathetic conveyances may be as usual to future times as to us in literary correspondence.”

A writer in the “Bath Chronicle” reproduced a long extract from Glanvill’s work, the concluding sentence of which, he says, seems to have anticipated the electric telegraph. It is as follows: “But yet to advance another instance. That men should confer at very distant removes by an extemporary intercourse is a reputed impossibility; but yet there are some hints in natural operations that give us probability that ’tis feasible, and may be compassed without unwarrantable assistance from demoniack correspondence. That a couple of needles equally touched by the same magnet, being set in two dials exactly proportioned to each other, and circumscribed by the letters of the alphabet, may effect this ‘magnale’ (i. e. important result) hath considerable authorities to avouch it.

“The manner of it is thus represented: Let the friends that would communicate take each a dial, and, having appointed a time for their sympathetic conference, let one move his impregnate needle to any letter in the alphabet, and its affected fellow will precisely respect the same. So that, would I know what my friend would acquaint me with, ’tis but observing the letters that are pointed at by my needle, and in their order transcribing them from their sympathized index, as its motion directs; and I may be assured that my friend described the same with his, and that the words on my paper are of his inditing. Now, though there will be some ill-contrivance in a circumstance of this invention, in that the thus impregnate needles will not move to, but avert from each other (as ingenious Dr. Browne hath observed), yet this cannot prejudice the main design of this way of secret conveyance; since it is but reading counter to the magnetic informer, and noting the letter which is most distant in the Abecederian circle from that which the needle turns to, and the case is not altered.

“Now, though this desirable effect may possibly not yet answer the expectations of inquisitive experiment, yet ’tis no despicable item, that by some other such way of magnetick efficiency it may hereafter with success be attempted, when magical history shall be enlarged by riper inspections; and ’tis not unlikely but that present discoveries might be improved to the performance.”

Glanvill is also the author of “Philosophical Considerations Touching Witches and Witchcraft,” 1666, and of “The Sadducismus Triumphatus,” 1681.

References.—“Dict. of Nat. Biog.,” 1908, Vol. VII. pp. 1287–8; Larousse, “Dict.,” Vol. VIII. pp. 1294–1295; “Nature,” Vol. XVI. p. 269; “Histoire de la Philosophie,” par Charles de Rémusat, Paris, 1878, Vol. II. chap. xi. pp. 184–201; “The General Biog. Dict.,” Alex. Chalmers, London, 1811, Vol. XVI. pp. 12–17; “Joseph Glanvill,” by Ferris Greenslet, New York, 1905; “Imperial Dict. of Universal Biography,” Vol. II. p. 642.

A.D. 1666.—Denys (William), hydrographer, of Dieppe, observes that the compasses placed in different parts of a vessel give different indications (Becquerel, “Magnétisme,” p. 119; “Journal des Sçavans” pour 1665 et 1666, p. 538).

A.D. 1671.—Richer (T.), French philosopher, who was sent by the Paris Academy of Sciences to the island of Cayenne for the purpose of determining the amount of terrestrial refraction and for other astronomical objects, is the first to make known the electrical powers of the gymnotus electricus.

References.—Leithead, “Electricity,” Chap. XII; Fahie, “El. Tel.,” p. 171; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. p. 171; Mém. de l’Acad. des Sciences, 1677, Art. VI; Richer, “Observations,” etc., Paris, 1679; Bancroft, at A.D. 1769; “Cosmos,” 1859, Vol. V. pp. 23–24.

A.D. 1671.—Rohault (Jacques), a French philosophical writer, and one of the earliest, ablest and most active propagators of the Cartesian philosophy in France, publishes at Paris the first edition of his “Traité de Physique,” at Part III. chap. viii. pp. 198–236 of which he treats especially of amber and of the loadstone. The same passages can be seen at Vol. II. part iii. chap. viii. pp. 163, etc., of Rohault’s “System of Natural Philosophy,” published in London during the year 1723, and at the same chapter, pp. 388, etc., of “Jacobi Rohaulti Physica,” Londini, 1718.

The latter is the last and best edition of the well-known classical translation, originally made in 1697, by Dr. Samuel Clarke, who was the friend of Sir Isaac Newton and chaplain to Bishop Moore, of Norwich. Through this work Clarke introduced very many critical notes exposing the fallacies of the Cartesian system. The “Physica” passed through four editions as the Cambridge University textbook before it was made to give way to the treatises of Newton.

A.D. 1672.—Sturm (John Christopher), a very able German mathematician, who was for thirty-four years professor of natural philosophy at the University of Altdorf (Franconia), and who, after vainly attempting to satisfactorily unite the Aristotelian and Cartesian doctrines finally adopted the Baconian philosophy, establishes the “Collegium Curiosum” on the plan of the celebrated Italian “Accademia del Cimento,” alluded to under the A.D. 1609 date.

The society was founded for the purpose of studying, repeating and even modifying the most notable philosophical experiments of the day, such as those made by Von Guericke, Boyle, Hooke and others, and its proceedings were published in 1676 and 1685 under the title of “Collegium Experimental sive Curiosum, etc.”

A.D. 1673.—Hevelius—Hevel—Hovel—Hövelke (Joannes), an eminent Polish astronomer, member of the English Royal Society, and a great friend more particularly of le Père M. Mersenne, of Gassendi and of Kircher, publishes during 1673 the first part of his great work “Machina Cœlestis”—dedicated to Louis XIV—the entire second part of which, issued in 1679, was destroyed by fire with the exception of seven copies. This explains its extreme scarcity. It was this work which led to the public controversy between Hevelius and Dr. Hooke who published, in London, during 1674 his “Animad. in Mach. Celest. Hevelii.”

It is said that, next to John Flamsteed, Hevelius was the most accurate observer of the heavens in his day (“The Reliquary,” London, Vol. XIV. pp. 149–159 and Vol. XV. pp. 34–38; “Journal des Savants” for March, June and November 1836). He had already published “De Variatione acus magneticæ” (Opusc. Act. Erudit. Lips., Vol. I. p. 103), also a report of the variations of the magnetical needle during 1670, which can be found in the Phil. Trans., Vol. V. for 1670, p. 2059, or in Hutton’s abridgments, London, 1809, Vol. I. p. 514.

References.—Larousse, “Dict.,” Vol. IX. pp. 266–267; “Biog. Gén.,” Vol. XXV. pp. 285–294; Delambre, “Hist. de l’Astron. Mod.,” Vol. II. pp. 434–484; Weidler, “Hist. Astron.,” p. 485; “Mem. Roy. Soc.,” 1739, Vol. I. p. 274.

A.D. 1675.—Boyle (Robert), Irish natural philosopher and chemist, seventh son of Richard Boyle, Earl of Cork, and one of the first members of what he calls the “Invisible” or “Philosophical” College, which has since become the Royal Society,[47] gives, in his “Philosophical Works,” the result of his many experiments upon magnetism and electricity.

John Evelyn in his letter to Mr. Wotton, March 30, 1695 (“Memoirs, Diary and Correspondence,” by Wm. Bray, London, p. 716), says of Boyle: “It must be confess’d that he had a marvailous sagacity in finding out many usefull and noble experiments. Never did stubborn matter come under his inquisition but he extorted a confession of all that lay in her most intimate recesses; and what he discover’d he as faithfully register’d, and frankly communicated....”

Prof. Tyndall remarks (“Lecture,” February 4, 1875): “The tendency to physical theory showed itself in Boyle. He imagined that the electrified body threw out a glutinous or unctuous effluvium, which laid hold of small bodies, and, in its return to the source from which it emanated, carried them along with it.”

A few of his many characteristic remarks and observations are, however, best given in his own words, as extracted from the “Philosophical Works” above alluded to:

“The invention of the mariner’s needle, which giveth the direction, is no less benefit for navigation than the invention of the sails, which give the motion” (London, 1738, Vol. I. p. 62).

“I, with a certain body (rough diamond), not bigger than a pea, but very vigorously attractive, moved a steel needle, freely poised, about three minutes after I had left off rubbing it” (Vol. I. p. 508). Speaking elsewhere of his experiments with diamonds, he says: “But when I came to apply it (the loadstone) to one more, which look’d somewhat duller than almost any of the rest, I found that it had in it particles enough of an iron nature to make it a magnetical body and observed without surprise that not only it would suffer itself to be taken up by the strongest pole of the loadstone, but when the pole was offer’d within a convenient distance it would readily leap through the air to fasten itself to it.”

“I removed a piece of amber in the sunbeams till they had made it moderately hot and then found it would attract those light bodies it would not stir before” (Vol. I. p. 400, and Vol. III. p. 52).

“Whether from such experiments one may argue that it is but, as it were, by accident that amber attracts another body, and not this the amber; and whether these ought to make us question, if electrics may, with so much propriety, as has been generally supposed, be said to attract, are doubts, that my design does not oblige me to examine” (Vol. IV. p. 350).

References.—John Evelyn’s “Diary,” Letter to Mr. Wotton, March 30, 1696; Libes’ “Histoire Phil. du Progrès de la Physique,” Paris, 1810; Boyle’s “Mechanical Origine or Production of Electricity,” 1675; Birch, “Life of Hon. R. Boyle,” 1743–1744; Secondat’s “Histoire d’Electricité” (Observations physiques), 1750, p. 141; Whewell, “Hist. of Ind. Sciences,” 1859, Vol. I. pp. 395, 396. Priestley’s “History of Electricity,” 1775, pp. 5–8; M. Reael, “Observ. a. d. Magnectsteen,” 1651, alluded to at note, p. 486, Vol. I. of Van Swinden’s 1784 “Recueil,” etc.; Van Swinden, Vol. II. pp. 353, 359–361; “Biblioth. Britan.” (Authors), Robt. Watt, Edinburgh, 1824, Vol. I. pp. 142–3; Aikin’s “G. Biography,” and Martin’s “Biog. Philosophica,” in “General Biog. Dict.,” by John Gorton, London, 1833, Vol. I; Phil. Trans., Vol. VIII for 1673, p. 6101 and Hutton’s abridg., Vol. II. p. 90; Boyle, London, 1673, “Essays of the ... Effluviums” (Subtility), pp. 38–42, 52–53; (Efficacy) pp. 18, 19, 32, 33; (Determinate Nature) pp. 21, 57; “An Essay ... of Gems,” London, 1672, pp. 108–129; Ch. W. Moulton, “Library of Literary Criticism,” Vol. II. pp. 416–420; “Critical Dict. of Engl. Lit.,” S. Austin Allibone, Philad., 1888, Vol. I. pp. 232–233; “Essays in Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 1–27; Eighth “Britannica,” V. p. 259 for notes of Boerhaave, also the “Britannica” 1st Dissertation, p. 47, and 4th Dissertation p. 597; “History and Heroes of the Art of Medicine,” J. Rutherfurd Russell, London, 1861, pp. 233–246.

Consult also Boyle’s “New Exper. Physico-Mechanical,” etc., in which the 16th Exp. is “concerning the operation of the loadstone”; Boyle’s “A Continuation of New Exp.,” etc., in which the 31st Exp. is “about the attractive virtue of the loadstone in an exhausted receiver,” and in which are “Notes, etc., about the atmospheres of consistent bodies,” etc., as well as “Observations about the exciting of the electricity of bodies,” and concerning the electrical emanations and effluviums. Boyle’s “Tracts Containing Some Suspicions Concerning some Occult Qualities of the Air; with an Appendix Touching Celestial Magnets,” etc. His “Phil. Works,” London, 1744, Vol. III. pp. 65, 67 and 70, 647, etc., give “Experiments and Notes about the Mechanical Origin or Production of Electricity.”

For full accounts of the Royal Society, alluded to above, see the histories written by Thomas Sprat (1667), by Thomas Birch (1756), by Thomas Thomson (1812), and by Chas. Richard Weld (1847–1848).

A.D. 1675.—Picard (Jean), eminent astronomer, who succeeded Gassendi (A.D. 1632) as professor of astronomy at the Collège de France, is the first to observe electric light in vacuo. According to Tyndall (“Lessons in Electricity,” p. 88) it was while carrying a barometer from the Observatory to the Porte Saint-Michel in Paris that he noticed light in the vacuous portion. Sebastien and Cassini observed it afterwards in other barometers (see Tyndall’s “Lecture V.” p. 91, for Priestley’s description of the electric light in vacuo).

It was this same scientist who had already given, in his “Mesure de la Terre,” 1671, Article IV, the description of the measurement of a degree of latitude made with instruments of his own manufacture.

References.—Humboldt, “Cosmos,” 1859, Vol. V. pp. 23, 24; Larousse, “Dict.,” Vol. XII. p. 937; “Phil. Hist. and Mem. of the Roy. Acad. at Paris,” London, 1742, Vol. I. pp. 208–221.

A.D. 1675.—Newton (Sir Isaac), prominent English mathematician and natural philosopher, of whom Macaulay says that “in no other mind have the demonstrative faculty and the inductive faculty coexisted in such supreme excellence and perfect harmony,” communicates to the Royal Society his discovery that excited glass will attract any light bodies even to the surface opposite to that upon which it has been rubbed. This was successfully demonstrated by the Society, January 31, 1676.

He improved the electric machine by substituting a glass globe for the globe of sulphur made use of by both Von Guericke and Boyle, the rubbers in every case being the hands of the operator.

He appears to have somewhat anticipated Franklin’s great discovery, judging by the following letter he addressed, December 15, 1716, to the Rev. Dr. Law, in Suffolk:

“Dear Doctor,” it begins, “He that in ye mine of knowledge deepest diggeth, hath, like every other miner ye least breathing time, and must sometimes at least come to terr; alt (terra alta) for air. In one of these respiratory intervals I now sit doune to write to you, my friend. You ask me how, with so much study, I manage to retene my health. Ah, my dear doctor, you have a better opinion of your lazy friend than he hath himself. Morpheus is my best companion; without eight or nine hours of him ye correspondent is not worth one Scavenger’s peruke. My practizes did at ye first hurt my stomach, but now I eat heartily enow, as y’ will see when I come down beside you. I have been much amused by ye singular φενομενα resulting from bringing a needle into contact with a piece of amber or resin fricated on silke clothe. Ye flame putteth me in mind of sheet lightning on a small—how very small—scale. But I shall in my epistles abjure philosophy, whereof when I come down to Sakly I’ll give you enow. I begin to scrawl at five mins. from nine of ye clk, and have in writing consumed ten mins. My Lord Somerset is announced.”

Æther, according to Sir Isaac Newton, is a thin subtile matter much finer and rarer than air. Sometimes, it is termed by him, a subtil spirit, as in the latter part of his “Principia,” and sometimes a subtil ætherial medium, as in his “Optics.” By many it is supposed to pervade all space, also the interior of solid bodies, and to be the medium of the transmission of light and heat. The æther of Descartes was his materia subtilis or his First Element: by which he understood a “most subtil matter very swiftly agitated, fluid, and keeps to no certain figure, but which suits itself to the figure of those bodies that are about it. His Second Element consists of small Globules; that is, bodies exactly round and very solid, which do not only, like the First Element, fill up the pores of bodies but also constitute the purest substance of the Æther and Heaven” (Blome’s translation of Descartes’ “Philosophy,” p. 101; R. Lovett, “The Subtil Medium Prov’d”; Phil. Mag., Vol. XVIII. p. 155).

During the years 1686 and 1687 Newton composed his “Principia,” a work which Lagrange pronounced “la plus haute production de l’esprit humain”: “the greatest work on science ever produced” (Sir Robt. Ball), and “which will be memorable not only in the annals of one science or of one country, but which will form an epoch in the history of the world.” This was published at Halley’s expense. As Brewster says (1686, Chap. XII): “It is to Halley alone that science owes this debt of gratitude. It was he who tracked Newton to his college, who drew from him his great discoveries, and who generously gave them to the world.”

In the twenty-third proposition of the second book, fifth section, Newton says: “The virtue of the magnet is contracted by the interposition of an iron plate and is almost terminated at it, for bodies further off are not so much attracted by the magnet as by the iron plate.” And in Book III. prop. vi. he thus expresses himself: “The magnetic attraction is not as the matter attracted; some bodies are attracted more by the magnet, others less; most bodies not at all. The power of magnetism in one and the same body may be increased and diminished, and is sometimes far stronger for the quantity of matter than the power of gravity; and in receding from the magnet decreases, not in the duplicate, but almost in the triplicate proportion of the distance, as nearly as I could judge from some rude observations.”

Newton is said to have carried in his ring a magnet weighing but three grains, which could raise 746 grains, or nearly 250 times its own weight. This magnet naturally excited much admiration, but is greatly surpassed in power by that formerly belonging to Sir John Leslie, and now in the Physical Collection at Edinburgh, weighing three and one-half grains, and having a carrying power of 1560 grains.

References.—Brewster’s “Life of Sir I. Newton,” pp. 307, 308; “Dict. of Nat. Biog.,” Vol. XL. pp. 370–393; Ch. W. Moulton, “Library of Literary Criticism,” Vol. II. pp. 710–726; “Bibl. Britan.” (Authors), Robt. Watt, Edinburgh, 1824, Vol. II., p. 701; Harris, “Magnetism,” Vol. III. p. 11; Ninth “Britannica,” Vol. XV. p. 274; Whewell, “Hist. of the Ind. Sciences,” 1858, Vol. I. pp. 385–488; the interesting note at foot of p. 683 of the Fourth Dissertation in the “Encyclopædia Britannica”; “Muspratt’s Chemistry,” Vol. II. p. 255; the English “Chemical News” for November 1867, and January 1868, reproducing Sir David Brewster’s letters to the London “Athenæum” and London “Times,” likewise Dr. Crompton’s paper read before the Manchester Literary and Philosophical Society in October 1866; Phil. Trans., Vol. LXIV. Part I for 1774, p. 153: “Remarks of John Winthrop upon ... Castillione’s Life of Sir Isaac Newton”; Dr. Geo. Miller, “Hist. Phil. Ill.,” London, 1849, Vol. III. pp. 414–415; “Newton, sa vie et ses œuvres” in “Cosmos,” September 27, 1890 to December 13, 1890; “Journal des Savants” for April, May and June 1832; for April 1846, March, April, May, June, July and August 1852, October, November 1855; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II, 1882, pp. 213–214, 1586; “Hist. de la Philosophie,” par Chas. de Rémusat, Paris, 1878, Vol. II. chap. xii. pp. 202–222.

A.D. 1676.—Haward, master of several sailing vessels, and a man of good credit (Phil. Trans., Vol. XI. No. 127, p. 647, of July 18, 1676), states that “being on board of the ship Albemarle, July 24, 1641 ... in latitude of Bermuda ... after a terrible clap of thunder ... it was found that the compass card was turned around, the N. and S. points having changed positions and, though Mr. Grofton brought with his finger the flower-de-lys to point directly N., it would immediately, as soon as at liberty, return to this new unusual posture, and upon examination he found every compass (three) in the ship of the same humour; which ... he could impute to nothing else but the operation of the lightning or thunder mentioned.” The above is also alluded to at p. 33 of Vol. III. of Boyle’s “Phil. Works,” London, 1738, with this addition: “One of the compasses, pointing West, was brought to New England, where, the glass being broke and the air gaining entrance, it lost its virtue. But one of the others is in that country possess’d by Mr. Encrease Mather, the North point of the needle remaining South to this day.”

A.D. 1677.—At p. 14 of an exceedingly curious publication entitled “A Rich Cabinet with a Variety of Inventions,” etc., written by J. W. (i. e. John White, of London), who calls himself “a lover of artificial conclusions,” will be found an article on “Divers rare, conceited motions performed by a magnet or loadstone.”

A.D. 1678.—Redi (Francesco), well-known Italian scientist, physician to the Grand Duke Ferdinand II, publishes his “Experimenta circa res diversas Naturales,” wherein he is first to communicate the fact that the shock of the raia torpedo can be transmitted to the fisherman through the line and rod connecting him with the fish.

References.—Leithead, “Electricity,” Chap. XII; the Firenze, 1671 ed. of Redi’s “Esperienze,” etc., pp. 47–54; Phil. Trans. for 1673, Vol. VIII. p. 6003; Sci. Am. Supp., No. 457, pp. 7300–7302; Matteucci, “Recherches,” 1837 and 1867; Eschinardi (F. della Compagnia di Gesü), “Lettera al S. Francesco Redi,” Roma, 1681, wherein are detailed many curious experiments, including some treating of the magnetic needle by which agency are foretold sudden attacks of earthquakes, etc. etc.

A.D. 1679.—Maxwell (William)—Guillelmo Maxvello—native of Scotland, author of “Medicina Magnetica,” offers to prove to various medical faculties that, with certain magnetic means at his disposal, he could cure any of the diseases abandoned by them as incurable (Blavatsky, “Isis,” Vol. I. p. 215).

Reference.—J. H. Van Swinden, “Recueil de Mémoires,” etc., La Haye, 1784, Vol. II. p. 367.

A.D. 1683.—Arrais (Edoardo Madeira), who had been physician to—João—John IV, the first Portuguese king of the house of Braganza, is the author of this much-delayed edition of a book entitled “Arbor Vitæ, or a physical account of the Tree of Life in the Garden of Eden.” It treats of occult qualities under the headings of “Doubts,” of which latter there are eight separate ones which constitute as many different chapters, from which the following extracts will prove interesting:

“Doubt” 5, p. 45. “Doth not the fish called Torpedo render the fishes that swim over it immovable, and stupefy the fisher’s arm with its virtue diffused along his spear?”

“Doubt” 5, p. 46. “... as also there are divers sorts of fishes that bring numness, as our Torpedo doth.”

“Doubt” 5, p. 49. “And those that travail the coasts of Brasile make mention of another fish, which causeth numness as our Torpedo doth: whence it becomes sufficiently manifest that there are many kinds of Torpedoes to be found. But this kind lives especially in the river Itapecuro, in the country of the Maragnani, and it is called Perache, or, as Gaspar Barlæus observed, Puraquam, among those Barbarians. In shape and greatness it resembles a kind of lamprey (or Muræna); they use to kill it by striking it with staves; but the arm of him that strikes and then his whole body is stupefied, and shakes presently. Of which thing, Frier Christopher Severineus, Bishop elect of Angola is my ocular witness....”

“Doubt” 7, p. 93. “For it is evident from experience that iron is so indisposed by some qualities that it cannot be moved by the magnet. That fishes swimming over the Torpedo, enclosed in the mud or sand for the purpose, when they come to the places whereto the virtue of the Torpedo is extended can stir no further; by which art she catches and eats them, as Aristotle relates (6 ‘de Hist. Animal.,’ cap. 10; and 9 ‘de Hist.,’ cap. 37).”

“Doubt” 7, p. 94. “For if amber be dulled by moisture, its virtue cannot produce motion in straws. If the virtue of the Torpedo reach the fishes swimming over her, or the fisher’s arm their motive power cannot produce motion.”

“Doubt” 7, p. 96. “And for this cause, the virtue of the magnet can produce motion in iron, not in other bodies, because it finds in it Dispositions necessary on the part of the agent which, being present, it can operate; not in other things. And, for the same reason, amber moves straws, not iron nor stones.”

The preface to the “Arbor Vitæ ...” is written by Richard Browner M.L. Coll. Med., London, who translated out of Latin “The Cure of Old Age,” by Roger Bacon, wherein he gives quite a good account of the latter’s life and writings, and from which we extract but one passage likely here to be of some little interest, viz. at p. 155, regarding the component parts of a medicine: “By Amber here our author intends Amber Gryse (a bituminous body found floating on the sea): For he calls it Ambra and not Succinum (which is solid Amber). Besides, Succinum was never reckoned a spice as Amber is here. And though both Ambra and Succinum be great restorers of the animal spirits, yet the former is more efficacious.”

The “Biographie Générale,” Vol. III. p. 348, says that Duarte Madeyra Arraess, who died at Lisbon in 1652, was the author also of “Apologia,” 1638, of “Methodo,” 1642, and of “Novæ Philosophiæ,” 1650.

A.D. 1683.—Halley (Edmund), LL.D., who became English astronomer royal, makes known his theory of four magnetic poles and of the periodical movement of the magnetic line without declination. He states that the earth’s magnetism is caused by four poles of attraction, two of them being in each hemisphere near each pole of the earth. By the word pole he means a point where the total magnetic force is a maximum, or, as he himself styles it, “a point of greatest attraction” (Walker, “Magnetism,” p. 317, etc.).

One of the magnetic poles he places near the meridian of Land’s End, not above 7 degrees from the North Pole, the other being about 15 degrees from the North Pole in the meridian of California, while the two south magnetic poles are placed respectively about 16 and about 20 degrees from the South Pole of the earth, and 95 degrees west, 120 degrees east of London.

In order to test Halley’s theory, the English Government permitted him to make three voyages in the Atlantic Ocean (1698, 1699, 1702), in vessels of which he had the command as post-captain. Humboldt states that these were the first expeditions equipped by any government for the establishment of a great scientific object—that of observing one of the elements of terrestrial force on which the safety of navigators is especially dependent.

The result of these voyages was the construction of the first accurate Magnetic Chart, whereon the points at which navigators have found an equal amount of variation were connected together by curved lines. This was the model of all charts of a similar nature since constructed. Halley remarked upon its completion: “The nice determination of the variation, and several other particulars in the magnetic system, is reserved for a remote posterity. All that we can hope to do is to leave behind us observations that may be confided in, and to propose hypotheses which after-ages may examine, amend or refute.”

See copy of his chart in Vol. I. No. I of “Terrestrial Magnetism,” also in Musschenbroek’s “Essais de Physique,” or, preferably, in Bouguer’s “Traité de Navigation,” where the lines for 1700 are in red ink, while those for 1744 are traced in black, thus readily indicating the changes in the declination.

References.—Cavallo, “Magnetism,” and “Nat. or Exp. Phil.,” Vol. II. p. 273; Lloyd, “Treatise on Magnetism,” 1874, p. 102; Sci. Am. Suppl., No. 224, pp. 3570, 3571; Whewell, “Hist. of the Inductive Sciences,” 1859, Vol. I. pp. 396–8, 435–7, 450, 451, 480, 481, and Vol. II. p. 225; Giambattista Scarella, “De Magnete,” 1759, Vol. II; also G. Casali, “Sopra la Grandine,” etc., 1767; “The Phil. Hist. and Mem. of the Roy. Ac. of Sciences at Paris,” London, 1742, Vol. I. p. 245; Vol. II. pp. 240–244, 270, 349; “Magnetic Results of Halley’s Expedition (1698–1700)” in “Terrestrial Magnetism,” September 1913, pp. 113–132; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 156–7; Dr. G. Hellmann “Neudrucke von schriften,” Nos. 4 and 8; Humboldt, “Cosmos,” 1859, Vol. V. pp. 59–60; John Wallis’s letters to Halley, London (Phil. Trans. for 1702–1703), p. 106; Phil. Trans. for 1667, 1683, 1692; “Memoirs of the Roy. Soc.,” 1739, Vol. II. p. 195; “A Bibliography of Dr. Edmund Halley,” by Alex. J. Rudolph, in the “Bulletin of Bibliography” for July 1905; “Old and New Astronomy,” by Richard A. Proctor, 1892, pp. 37–38; Phil. Trans. Vol. XIII for 1683, No. 148, p. 208; Vol. XVII. p. 563; Vol. XXIII. p. 1106; Vol. XXIX. p. 165; Vol. XLII. p. 155; Vol. XLVIII. p. 239, also the following abridgments: Hutton, Vol. II. p. 624; Vol. VI, pp. 99, 112; J. Lowthorp, Vol. II. p. 285; Reid and Gray, Vol. VI. p. 177; Eames and Martyn, Vol. VI. pp. 28, 286; Baddam, 1745, Vol. II. pp. 195–202; Vol. III. pp. 25–32.

Aurora Borealis, or Northern Polar Light

Dr. Halley was the first to give (Phil. Trans., No. 347) a distinct history of this phenomenon, which has certainly an electric as well as magnetic origin, and to which Gassendi originally gave the name it now bears, as has been stated at A.D. 1632.

According to Dr. Lardner (“Lectures,” Vol. I. p. 137), Prof. Eberhart, of Halle, and Paul Frisi, of Pisa, first proposed an explanation of the aurora founded upon the following: 1. Electricity transmitted through rarefied air exhibits a luminous appearance, precisely similar to that of the aurora borealis. 2. The strata of atmospheric air become rarefied as their altitude above the surface of the earth is increased, a theory which has since been countenanced by many scientists. It has been observed, notably by Dalton, of Manchester, that the primitive beams of the aurora are constantly in a direction parallel to that of the dipping needle, and that the latter appears most affected when the aurora is the brightest. Arago noticed that the changes of inclination amounted, upon one occasion to 7’ or 8’. The discovery that the magnetic needle was agitated during the presence of an aurora has been ascribed to Wargentin (Am. Journal Sc., Vol. XXX. p. 227), though it is claimed by the friends of Olav Hiörter (see A.D. 1740), that it was independently ascertained by the latter during the year 1741.

The well-known Swiss chemist Auguste Arthur De la Rive has made many important observations upon the electric character of the aurora, the experiments carried on by him in the mountains of Finland being thus described: “We surrounded the peak of a mountain with copper wire, pointed at intervals with tin nibs. We next charged the wire with electricity, and nearly every night during our stay produced a yellowish white light on the tin points, in which the spectroscope analysis revealed the greenish yellow rays so characteristic of the aurora borealis. On the peak of Pietarintumturi we were especially successful, an auroral ray making its appearance directly over and about 150 yards above the copper coil.”

A complete list of all auroras appearing prior to 1754 is to be found in Jean Jacques d’Ortons de Mairan’s, Paris, 1731, “Traité Physique de l’Aurore Boréale,” and a catalogue of auroræ observed, 1800–1877, has been made up by M. Zenger (Sci. Am. Supp., p. 10915). One of the most interesting displays is known as the purple aurora, alluded to in the Annals of Clan-mac-noise as having appeared A.D. 688 (Biot “Note sur la direction,” etc., Comptes Rendus, Tome XIX for 1844, p. 822). Between September 19, 1838, and April 8, 1839, Lottin, Bravais, Lilliehöök and Siljeström observed 160 auroras at Bossekop (69° 58’ N. lat.) in Finmark and at Jupvig (70° 6’ N. lat.); they were most frequent during the period the sun remained below the horizon, that is, from November 17 to January 25. During this night of 70 times 24 hours there were 64 auroras visible (Comptes Rendus, Tome X. p. 289; Martin, “Météorologie,” 1843, p. 453; Argelander, in the “Vorträgen geh. in der Königsberg Gesellschaft,” Bd. I. s. 259).

A Finnish physicist, named S. Lenström, who had been attached to the Nordenskjold Polar Expedition of 1868, visited Lapland in 1871, and, after a series of important observations, constructed an apparatus that permitted him to “artificially reproduce the light of the aurora.” The intensity of this light is so great at times that Lowenörn perceived the coruscations in bright sunshine on the 29th of January, 1786, and Parry saw the aurora throughout the day during the voyage of 1821–1823.

The height of the aurora has been variously estimated, but it is seldom found to be less than forty-five miles above the surface of the earth. Father Boscovich estimated at 825 miles the height of the one observed by the Marquis of Poleni on the 16th of December, 1737. The extent of the aurora, according to Dalton, has been known to cover an area of 7000 or 8000 square miles.

References.—“Mem. de Turin,” An. 1784–5, Vol. I. part ii. pp. 328, 338; Young, “Lectures,” Vol. I. pp. 687, 716; Herschel, “Prelim. Discourse,” pp. 93, 329, 330; Phil. Trans., 1753, p. 350; Müller’s “Kosmischen Physik”; Noad, “Manual,” pp. 225–237; also all the references at pp. 187–196, Vol. I of Humboldt’s “Cosmos,” Bohn, London, 1849, as well as in Ronalds’ “Catalogue,” pp. 23–24; Mairan, at Vol. X. p. 961, “Dict. Univ.,” and Vol. XXVI. p. 161, of the “Biog. Universelle”; Trans. Cambridge Phil. Soc., Vol. I; “Isis Unveiled,” Vol. I. pp. 417, 418.

See likewise the “Pharsalia” of Marcus Annæus Lucanus, translated by J. Krais, I. pp. 518–527; Plutarchus, “De facie in orbe lunæ,” cap. 26; the “Annals” of Caius Cornelius Tacitus, Germania, XLV. 1st ed., Venice, 1470; “Das Polarlicht,” H. Fritz, Leipzig, 1881, pp. 4–6, 332; Mairan’s “Traité Physique,” etc., 1731, pp. 179–181; Grégoire du Tour, Lumière Electrique, 1882, Vol. VII. p. 389; Elias Loomis, “The Aurora Borealis,” etc., p. 220 of the Reports of Smiths. Inst., 1865; A. M. Mayer, “Observations,” etc., Amer. Jour. of Sc., February 1871; “A copy of the Catalogue of Aurorae Boreales observed in Norway from the earliest times to June 1878” (“Nature,” December 4, 1902, p. 112); “La cause de l’aurore boréale,” Claudius Arrhenius, in the Revue Générale des Sciences for January 30, 1902, pp. 65–76; “Les Années Météores,” in “Le Cosmos,” Paris, May 25, 1889, etc.; “Terrestrial Magnetism,” March 1898, p. 7 for Chronological Summary of Authors re Aurora; Rev. Jas. Farquharson in “Abstracts of Sc. Papers Roy. Soc.,” Vol. II. p. 391; Wm. Dobbie, Phil. Mag., Vol. LXI for 1823, p. 252; W. Derham, for description of Auroras (in Phil. Trans. for 1728, p. 453); see, for Boscovitch, “Journal des Savants,” February 1864; “Journal des Savants,” for August 1820; C. H. Wilkinson, “Elements,” 1804; Vol. II. p. 279 and note; Calogera’s “Raccolta,” XVII. 47, Proc. of the Royal Soc. of Edinburgh for the observations of J. A. Brown and others on the aurora; F. C. Meyer, De luce boreali, 1726; Poggendorff, I. 135; Sturgeon, “Sc. Res.” 4th Sec. p. 489; Phil. Trans., Vol. XXXVIII. p. 243; Vol. XLVI. p. 499; F. Zöllner’s paper in “L. E. and D. Philos. Mag.,” for May and July, 1872; C. A. Young, Amer. Jour. of Sc., Vol. III., 3rd s., p. 69; Baron Karl Von Reichenbach’s “Physico-Physiological Researches,” trans. of Dr. John Ashburner, London, 1851, pp. 5–36, also pp. 445, etc., of the translation of Dr. W. Gregory, London, 1850; J. H. Van Swinden, “Recueil de Mémoires,” etc., La Haye, 1784, Vol. III. p. 187, etc.; J. E. B. Wiedeburg, “Beobachtungen und Muth.,” etc., 1771; G. W. Krafft, “Observ. Meteor,” etc., in Novi Com. Acad. Petrop., Vol. V. p. 400; Giuseppe Toaldo, “Descrizione,” etc., in Saggi ... Accad. di Padova, Vol. I. p. 178; Louis Cotte, “Table of Auroræ, Observed ... 1768–1779,” Paris, 1783; Journal de Physique for 1775; Recueil de Mem. de l’Acad. des Sciences for 1769; A. S. Conti, “Rifflessioni sull’ Aurora Boreale.”[48]

For Auguste Arthur De la Rive, consult “Bibl. Britan.,” Vol. XVI, N.S., 1821, p. 201, likewise the “Annales de Chimie et de Physique,” Phil. Mag., Phil. Trans., Comptes Rendus, more especially, as well as the “Bibl. Univ.” and the “Mem. de la Soc. de Genève,” at which latter place he was born in 1801.

For Jean Jacques d’Ortons de Mairan, consult “Mém. de Paris” for the years 1726, 1731–1734, 1747, 1751, also abridgments of the Phil. Trans. by Hutton, Vol. VII. p. 637, and by Baddam, 1745 ed., Vol. IX. pp. 490–497.

For W. Derham (1657–1735) consult also “Nouv. Biog. Gen.” (Hœfer), Vol. XIII. p. 712; the Phil. Trans. unabridged, Vol. XXIV. for 1704–1705, pp. 2136–2138; Vol. XXXVI. pp. 137, 204, also the following abridgments: Hutton, Vol. V. pp. 258–263; Hy. Jones, Vol. IV. part ii. pp. 290–291; Baddam, Vol. IV. pp. 473–478. In the last-named volume is thus given an account of Mr. Derham’s experiments: “He shows (Phil. Trans., No. 303, p. 2136) that, having consulted what others had writ of magnets, he finds in Grimaldi’s De Lumine et colore that both he and M. De la Hire (Phil. Trans., No. 188) had hit upon the same discovery before him.” Mr. Derham also alludes, more particularly, to the observations of Ridley, Barlow and Dr. Gilbert.

For Claudius—Claes—Arrhenius (1627–1694) Swedish scientist, professor at the Upsal University, consult “La Grande Encycl.,” Vol. III. p. 1107; “Dict. Biog. Suédois,” Vol. XXII. pp. 385–389.

For John Wallis, the celebrated English mathematician (1616–1703), in addition to the above-named Phil. Trans., Vol. XXIII for 1702–1703, p. 1106, consult Phil. Trans., Vol. XII for 1677, No. 135, pp. 863–866 (meteors), also the abridged editions as follows: Hutton, Vol. IV. pp. 196, 639, 655; Hy. Jones, Vol. IV. part ii. p. 286; Baddam, London, 1739, Vol. III. p. 228 and Vol. IV. pp. 100–104 (mariner’s compass); “Nouv. Biog. Gen.” (Hœfer), Vol. XLVI. p. 530.

Aurora Australis, or Southern Polar Light

The earliest account of this phenomenon was given by Don Antonio de Ulloa, as will be seen under date A.D. 1735–1746.

References.—W. L. Krafft, “Observation,” etc., in Acta Acad. Petropol. for 1778, Part I. Hist., p. 45; Phil. Trans., XLI. pp. 840, 843; XLVI. pp. 319, 345; Chr. Hansteen, “On the Polar Lights,” London, 1827.

Zodiacal Light

This phenomenon, from its occasional faint resemblance to and association with the auroras, would seem to deserve mention here, though none of the conjectures formed, more particularly by Cassini, Euler, Mairan, Kepler, Laplace, Fatio de Duiller, Schubert, Poisson, Olmsted, Biot, Herschel, Delambre, Olbers or Sir Wm. Thomson attribute to it any electric or magnetic origin.

In the Report of the Proceedings of the Reale Istituto Lombardo, 1876, however, appears the account of many observations confirmed by M. Serpieri which “demand absolutely” the conclusion that the zodiacal light “is an electrical aurora preceding and following the sun round the earth.”

Angstrom asserted that he observed the auroral line in the spectrum of the zodiacal light, and Lewis saw the latter during the aurora of May 2, 1877. Humboldt, who observed it (“Cosmos,” 1849, Vol. I. p. 126) in the Andes at an elevation of 13,000 to 15,000 feet, as well as on “the boundless grassy plains, the Llanos of Venezuela, and on the seashore, beneath the ever-clear sky of Cumana,” believes it to be caused by “a very compressed annulus of nebulous matter, revolving freely in space between the orbits of Venus and Mars.” In this connection he refers to Arago in the Annuaire for 1832, p. 246, and to a letter published in Comptes Rendus, XVI, 1843, p. 687, from which the following is extracted: “Several physical facts appear to indicate that, in a mechanical separation of matter into its smallest particles, if the mass be very small in relation to the surface, the electrical tension may increase sufficiently for the production of light and heat.”

In Chambers’ “Descript. Astronomy,” p. 257, the historian Nicephorus is credited with first calling attention to the existence of this phenomenon, to which Giovanni Domenico Cassini gave the name of Zodiacal Light, after determining its relations in space during the year 1683 (Mém. de l’Académie, 1730, Tome VIII. pp. 188 and 276), but to Childrey belongs the credit of having given to Europe the first explicit description of this phenomenon at p. 183 of his 1661 “Britannia Baconica.”

References.—Sturgeon’s Annals, etc., Vol. II. pp. 140–142; Prof. C. W. Prichett’s paper in Sci. Am. Supp., No. 126, p. 2008, and the conclusions reached by Herr Gronemann (Archives Néerlandaises) in Sci. Am. Supp., No. 327, p. 5221; Whewell, “Hist. of the Ind. Sciences,” 1859, Vol. I. p. 531, and Vol. II. p. 609; Tyndall, “Heat as a Mode of Motion,” 1873, pp. 57, 58, 497, 498; J. F. J. Schmidt, “Das Zodiacallicht,” Braunschweig, 1856; the very interesting abstract given in “The Journal of the Brit. Assoc.,” Vol. XII. No. 5, of paper read by Rev. J. T. W. Claridge, F.R.S., Jan. 9, 1902; Houzeau et Lancaster, “Bibl. Générale,” Vol. II. 1882, pp. 763–771; “Pr. Roy. Soc. of Edin.,” XX. pt. 3; C. Wilkes, “Theory of Zod. Light,” Philad., 1857; Phil. Trans., Vol. XXXVIII. p. 249; “Cosmos,” 1849, Vol. I. pp. 126–134; “Anc. Mém. de Paris,” I, VIII and X; J. J. de Mairan, Paris, 1733; “U. S. Japan Expedition,” Vol. III, Washington, 1856.

A.D. 1684.—Hooke (Dr. Robert), English natural philosopher (1635–1703), who, in 1677, had succeeded Oldenburg as Secretary to the Royal Society, gives the earliest well-defined plan of telegraphic transmission, in a paper addressed to the Royal Society “showing a way how to communicate one’s mind at great distances ... 40, 100, 120, etc., miles ... in as short a time almost as a man could write what he would have sent.” His apparatus consisted of an elevated framework supporting an open screen, behind which were suspended as many wooden devices, or symbols, such as circles, squares, triangles, etc., as there were letters in the alphabet. In the daytime these devices were drawn up by a rope behind the screen and made visible in the open space, while during the night use was made of torches, lanterns or lights.

Hooke also showed, in 1684, that iron and steel rods can be permanently magnetized by strongly heating them and by rapidly cooling them in the magnetic meridian (“Enc. Brit.” 1857, Vol. XIV. p. 3).

But, what is still more singular, he had, even previous to the above-named date (i. e. in 1667), alluded to the possibility of telephoning, that is, communicating sound through a wire. He thus expresses himself: “And as glasses have highly promoted our seeing, so it is not improbable that there may be found many mechanical inventions to improve our other senses—of hearing, smelling, tasting, touching.... ’Tis not impossible to hear a whisper a furlong’s distance, it having been already done; and perhaps the nature of the thing would not make it more impossible though that furlong should be ten times multiplied. And though some famous authors have affirmed it impossible to hear through the thinnest plates of Muscovy glass, I know a way by which it is easy to hear one speak through a wall a yard thick. It has not been examined how far acoustics may be improved, nor what other ways there may be of quickening our hearing, or conveying sound through other bodies than the air, for that is not the only medium. I can assure the reader that I have, by the help of a distended wire, propagated the sound to a very considerable distance in an instant, or with as seemingly quick a motion as that of light, at least, incomparably swifter than that which at the same time was propagated through the air; and this not only in a straight line, or direct, but in one bended in many angles.”

References.—Hooke’s entire paper in Derham’s “Phil. Exp. and Obs.” for 1726, pp. 142–150; Phil. Trans, for 1684; for his observations on atmospheric electricity consult Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 166; “Journal des Savants” for April 1846; “The Posthumous Works of Robert Hooke,” London, 1705, p. 424; “Revue Scientifique,” Mars 15, 1902, p. 351; for a complete list of all his works, consult Ward’s “Lives of the Gresham Professors”; for description of his telegraph and reference to Amontons, etc., see Phil. Mag., Vol. I. pp. 312–316.

A.D. 1684.—Sturmy’s “Mariner’s Magazine” for this year, of which a copy can be seen in the library of the British Museum, contains an account of the deviation of the compass and its tendency to give misleading directions on account of local attraction.

References.—Chambers’ Journal, Vol. III. No. 60 for Feb. 24, 1855, p. 132, and Vol. XII. No. 300 for Oct. 1, 1859, p. 246; Capt. Sam. Sturmy’s “Magn. Virtues and Tides,” in Phil. Trans., No. 57, p. 726, or “Memoirs of the Roy. Soc.,” Vol. I. p. 134; Phil. Trans., abridgments: by Hutton, Vol. II. p. 560, and by Lowthorp, Vol. II. p. 609; “Journal des Sçavans” for 1683, Vol. XI. pp. 267–293.

A.D. 1684.—In the “Essayes of Natural Experiments made in the Accademia del Cimento” (Englished by Richard Waller), London, 1684, by direction of the Royal Society, there are given, respectively at pp. 53, 123 and 128–132, accounts of the operation of the magnet in vacuo, details of several magnetical experiments and experiments touching amber as well as other electrical bodies.

A.D. 1686.—Maimbourg (Louis), French historian, relates this instance of the employment of the magnet at Chap. VI of the Rev. W. Webster’s translation of his “Histoire de l’Arianisme”: “Whilst Valens (the Roman emperor) was at Antioch ... several pagans of distinction, with the philosophers ... not being able to bear that the empire should continue in the hands of the Christians, consulted privately the demons ... in order to know the destiny of the emperor and who should be his successor.... For this purpose they made a three-footed stool ... upon which, having laid a basin of divers metals, they placed the twenty-four letters of the alphabet around it; then one of these philosophers, who was a magician ... holding in one hand vervain and in the other a ring which hung at the end of a small thread, pronounced ... conjurations ... at which the three-footed stool turning around and the ring moving of itself, and turning from one side to the other over the letters, it caused them to fall upon the table ... which foretold them ... that the Furies were waiting for the emperor at Mimas; ... after which the enchanted ring, turning about again over the letters in order to express the name of him who should succeed the emperor, formed first of all these capital letters, T H E O. After adding a D, to form T H E O D, the ring stopped, and was not seen to move any more, at which one of the assistants cried out ... ‘Theodorus is the person whom the gods appoint for our emperor’” (“History of Christianity,” by the Rev. Henry Hart Milman, London, 1840, Vol. III. p. 120).

Maimbourg’s biography is given at p. 58, Vol. IV. of the “English Encyclopædia.”

A.D. 1692.—Dr. Le Lorrain de Vallemont relates, in “Description de l’Aimant,” etc., which he published at Paris, that, after a very severe wind and rain storm during the month of October 1690, the new steeple of the Church of Notre Dame de Chartres was found to be so seriously injured as to necessitate demolition. It was then observed that the iron cross was covered with a heavy coating of rust, which latter proved to be so highly magnetic that a special report upon it was made in the “Journal des Sçavans” by M. de la Hire, December 3, 1691, at the request of Giovanni Dom. Cassini, and of other members of the French Royal Academy.

References.—“Journal des Sçavans,” Vols. XX, 1692, pp. 357–364 and Vol. XXXV, 1707, pp. 493–494 for additional accounts of the Church of N. Dame de Chartres by M. de la Hire and M. de Vallemont, and for a review of M. de Vallemont’s work, of which latter pp. 4, 30, 66, 74, 89 to 90 merit special attention.

A.D. 1693.—Gregory (David), an eminent mathematician, who, in 1691, had been made Savilian Professor of Astronomy in Oxford mainly through the influence of Newton and Flamsteed, communicates the result of his observations on the laws of magnetic action.

References.—Noad, “Manual of Electricity,” 1859, p. 525, Phil. Trans., Vols. XVIII-XXV; “Biog. Générale,” Vol. XXI. p. 902; Ninth “Britannica,” Vol. XI. p. 182; J. J. Fahie, “A History of El. Tel. to the year 1837,” London, 1884, p. 24.

A.D. 1693.—In the first volume (Letter IV. pp. 25–28) of the “Memoirs for the Ingenious ...” by J. de la Crosse, are given accounts of several “New experiments on the loadstone; of a needle touch’d with it, and plac’d directly over the needle of a compass; of two Mariner’s Needles hang’d freely over one another, at several distances; of a touch’d steel-ring. Reasons of these experiments. The earth magnetical.”

In explanation of all this, M. de la Hire supposes “that the mass of the earth is a great loadstone, which directs the poles of the same name in all the loadstones and touch’d needles, towards the same place of the earth; so that the two hang’d needles do but remove from this natural position by the particular force they have of driving away each other’s poles of the same name; which force, in a certain degree, is not sufficient to overcome the power of the great loadstone of the earth.”

An account of M. P. de la Hire’s “new sort of a magnetical compass” had already appeared in the Phil. Trans. for 1686–1687, Vol. XVI. No. 188, p. 344.

References.—For De la Hire, the following abridgments of the Phil. Trans.: Lowthorp, London, 1722, Vol. II. pp. 620–622; Baddam, London, 1739, Vol. IV. pp. 473–478; Hutton, London, 1809, Vol. III. p. 381; also “The Phil. Hist. and Mem. of the Roy. Acad. at Paris,” by Martyn and Chambers, London, 1742, Vol. II. pp. 273–277; Vol. V. pp. 272–282 and the “Table Alphab. ... Acad. Royale,” by M. Godin, Paris, Vol. II. p. 16 and Vol. X. pp. 164 and 734.

A.D. 1696.—Zahn (F. Joannes), prebendary of the Prémontrés Order at Celle near Wurtzburg and provost of the convent of Niederzell, celebrated for his philosophical and mathematical studies, publishes his highly valued “Specula physico-mathematico-historica-notabilium ac mirabilium sciendorum ...” throughout the three folio volumes of which he treats extensively of the wonders of the entire universe.

In his tabulated list of the origin and properties of all the different known gems and stones (Vol. II. chap. vii. p. 55), he states that the loadstone, first discovered at Magnesia in Lydia (Caria—on the Mæander) is heavy, very well shaped, and of a dark colour verging upon blue. The marvellous properties of gems and stones are detailed at pp. 59–73 of the same volume, the fifth paragraph of Chap. VIII treating of the loadstone’s many virtues and admirable qualities, as exemplified in the writings of Guilielmus Gilbertus, Nicolaus Zucchius, Nicolaus Cabæus, Athanasius Kircherus, Eusebius Nierembergius, Laurentius Forerus, Hieronymus Dandinus, Jacobus Grandamicus, Ludovicus Alcazar, Claudius Franciscus Milliet de Chales, as well as of many others.

References.—Michaud, “Biog. Univ.,” Vol. XLV. p. 340; Dr. John Thomas, “Universal Pron. Dict.,” 1886, p. 2514; Brunet, “Manuel du Libraire,” Vol. V. p. 1519.

A.D. 1700.—Bernoulli (John I), son of Nicolas, the founder of the celebrated family of that name, improves upon Picard’s discovery of the electrical appearance of the barometer, made A.D. 1675, by devising a mercurial phosphorus or mercury shining in vacuo (“Diss. Physica de Mercurio Lucente,” etc., Basel, 1719). This procured the favourable notice of King Frederick I, of Prussia, who rewarded him with a medal. John Bernoulli I (1667–1748) was a member of nearly every learned society of Europe and “one of the first mathematicians of a mathematical age.” His exceedingly valuable memoirs, found in all the scientific transactions of the day, were first collected in their entirety during the year 1742, by Cramer, Professor of Mathematics, and published at Lausanne and Geneva.

“Is it not surprising,” remarks Prof. Robison, in his able article on “Dynamics” (Eighth “Britannica,” Vol. VIII. p. 363), “that, twenty-five years after the publication of Newton’s ‘Principia,’ a mathematician on the Continent should publish a solution in the Memoirs of the French Academy, and boast that he had given the first demonstration of it? Yet, John Bernoulli did this in 1710. Is it not more remarkable that this should be precisely the solution given by Newton, beginning from the same theorem, the 40th I., Prin., following Newton in every step and using the same subsidiary lines? Yet, so it is.” This was five years after he had accepted (1705) the chair of mathematics made vacant by the death of his brother, James I.

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....”