Bibliographical history of electricity & magnetism, chronologically arranged

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Book VI

Throughout this last Book, Gilbert glories in the Copernican theory, the open, unquestioned, advocacy and endorsement of which according to many seems, after all, to have been the object of the work. He maintains that the magnetic axis of the earth remains invariable; he treats of the daily magnetic revolution of the globes, as against the time-honoured opinion of a primum mobile, the fixed stars being at different distances from the earth; of the circular motion of the earth and of its primary magnetic nature, whereby her poles are made different from the poles of the ecliptic, as well as of the precession of the equinoxes and of the obliquity of the zodiac.

According to Humboldt,[37] Gilbert was the first to make use of the words electric force, electric emanations, electric attraction, but, he says, there is not found in “De Magnete” either the abstract expression electricitas or the barbarous word magnetismus introduced in the seventeenth century. We likewise owe to Gilbert the words equator, magneticum, terrella, versorium and verticitas, but not the word pole, which had before been used by P. Peregrinus and others.

The second edition of “De Magnete” appeared at Stettin in 1628, “embellished with a curious title-page in the form of a monument ... and a fantastic indication of the earliest European mariner’s compass, a floated lodestone, but floating in a bowl on the sea and left behind by the ship sailing away from it.”[38]

The third edition was also published at Stettin during 1633. Gilbert left, besides, a posthumous work, “De Mundo Nostro Sublunari Philosophia Nova,” Amsterdam, 1651, which latter, says Prof. Robison, consists of an attempt to establish a new system of natural philosophy upon the ruins of the Aristotelian doctrine.[39]

To give here such an analysis as Gilbert’s admirable work merits would be impracticable, but the short review of it made by Prof. Robison (at p. 209 of his “System of Mechanical Philosophy,” London, 1822) deserves full reproduction, as follows: “In the introduction, he recounts all the knowledge of the ancients on the subject treated, and their supine inattention to what was so entirely in their hands, and the impossibility of ever adding to the stock of useful knowledge, so long as men imagined themselves to be philosophizing, while they were only repeating a few cant words and the unmeaning phrases of the Aristotelian school. It is curious to mark the almost perfect sameness of Dr. Gilbert’s sentiments and language with those of Lord Bacon. They both charge, in a peremptory manner, all those who pretend to inform others, to give over their dialectic labours, which are nothing but ringing changes on a few trite truths, and many unfounded conjectures, and immediately to betake themselves to experiment. He has pursued this method on the subject of magnetism, with wonderful ardour, and with equal genius and success; for Dr. Gilbert was possessed both of great ingenuity, and a mind fitted for general views of things. The work contains a prodigious number and variety of experiments and observations, collected with sagacity from the writings of others, and instituted by himself with considerable expense and labour. It would, indeed, be a miracle if all of Dr. Gilbert’s general inferences were just, or all his experiments accurate. It was untrodden ground. But, on the whole, this performance contains more real information than any writing of the age in which he lived, and is scarcely exceeded by any that has appeared since. We may hold it with justice as the first fruits of the Baconian or experimental philosophy.” Elsewhere, Prof. Robison remarks: “It is not saying too much of this work to affirm that it contains almost everything we know of magnetism. His unwearied diligence in searching every writing on the subject and in getting information from navigators, and his incessant occupation in experiments, have left very few facts unknown to him. We meet with many things in the writings of posterior inquirers, some of them of high reputation and of the present day, which are published and received as notable discoveries, but are contained in the rich collection of Dr. Gilbert.”

The Rev. Wm. Whewell says in his “History of the Inductive Sciences” (Vol. III. p. 49) that in the “De Magnete,” a book of only 240 pages, upon which Dr. Gilbert has been engaged for nearly eighteen years, are contained “all the fundamental facts of the science, so fully examined, indeed, that, even at this day, we have little to add to them.”

Dr. John Davy remarks (“Memoirs of the Life of Sir Humphry Davy,” London, 1836, Vol. I. p. 309): “Gilbert’s work is worthy being studied, and I am surprised that an English Edition (translation) of it has never been published.” He also alludes to the well-known reproach thrown upon Gilbert’s philosophy by Francis Bacon, who, in his “De Augmentis Scientiarum,” observes that “Gilbert has attempted to raise a general system upon the magnet, endeavouring to build a ship out of materials not sufficient to make the rowing-pins of a boat.” On the other hand, Digby and Barlowe place Gilbert upon a level with Harvey, Galileo, Gassendi and Descartes (“Nouvelle Biographie Générale,” 1858, Vol. VIII. p. 494) while the celebrated historian of the Council of Trent, Fra Paolo Sarpi—who will not be thought an incompetent judge—names Gilbert, with Francis Vieta (the greatest French mathematician of the sixteenth century) as the only original writer among his contemporaries (“Lettere di Fra Paolo,” p. 31; Hallam, “Intro. to Lit.,” 1859, Vol. II. p. 464).

In Thos. Thomson’s “History of the Royal Society,” London, 1812, the “De Magnete” is thus alluded to: “Dr. Gilbert’s book on magnetism, published in 1600, is one of the finest examples of inductive philosophy that has ever been presented to the world. It is the more remarkable because it preceded the ‘Novum Organum’ of Bacon, in which the inductive method of philosophizing was first explained.” How far Gilbert was ahead of his time is best proven by the works of those who wrote on magnetism during the first few decades after his death. They contributed in reality nothing to the extension of this branch of physical science. Poggendorff, from whose “Geschichte der Physik,” p. 286, this is extracted, as already stated, calls Gilbert “the Galileo of Magnetism.” By Dr. Priestley, he was named “the Father of Modern Electricity.”

The tribute of Henry Hallam is to the following effect: “The year 1600 was the first in which England produced a remarkable work in physical science; but this was one sufficient to raise a lasting reputation for its author. Gilbert, a physician, in his Latin treatise on the magnet, not only collected all the knowledge which others had possessed on the subject, but became at once the father of experimental philosophy in this island, and, by a singular felicity and acuteness of genius, the founder of theories which have been revived after a lapse of ages, and are almost universally received into the creed of science. Gilbert was one of the earliest Copernicans, at least as to the rotation of the earth, and, with his usual sagacity, inferred, before the invention of the telescope, that there are a multitude of fixed stars beyond the reach of our vision” (“Introduction to the Literature of the Fifteenth, Sixteenth and Seventeenth Centuries,” London, 1859, Vol. II. p. 463).

In the “Principal Navigations ...” Edinburgh, 1889, Vol. XII. p. 10, Richard Hakluyt speaks of “... my worshipfull friend M. douctour Gilbert, a gentleman no lesse excellent in the chiefest secrets of the Mathematicks (as that rare iewel lately set forth by him in Latine doeth euidently declare) then in his oune profession of physicke.”

We conclude this account of Gilbert in the quaint words of old Dr. Fuller: “He has (said my informer[40]) the clearness of Venice Glass without the Brittleness thereof, soon Ripe and long lasting is his Perfection. He commenced Doctor in Physick, and was Physician to Queen Elizabeth, who stamped on him many marks of her Favour, besides an annuall Pension to encourage his studies. He addicted himself to Chemistry, attaining to great exactness therein. One saith of him that he was Stoicall, but not Cynicall, which I understand Reserved; but not Morose, never married, purposely to be more beneficial to his brethren. Such his Loyalty to the Queen that, as if unwilling to survive, he dyed in the same year with her, 1603. His Stature was Tall, Complexion Chearful, an Happiness not ordinary in so hard a student and so retired a person. He lyeth buried in Trinity Church in Colchester under a plain monument.”

“Mahomet’s Tombe, at Mecha, is said strangely to hang up, attracted by some invisible Loadstone, but the memory of this Doctor will never fall to the ground, which his incomparable book ‘De Magnete’ will support to eternity” (“The History of the Worthies of England Endeavoured by Thomas Fuller, D.D.,” London, 1662, p. 332—Essex).

In his Epistle to Dr. Walter Charleton, physician in ordinary to King Charles I (Epist. III. p. 15, Vol. XI of the Works of Dryden, London, 1803) the celebrated English poet predicts that:

“Gilbert shall live till loadstones cease to draw

Or British fleets the boundless ocean awe.”

References.—“La Grande Encyclopédie,” Vol. XVIII. p. 930; “Dictionary of National Biography,” London, 1890, Vol. XXI. p. 338; “Bibliographica Britannica,” London, 1757, Vol. IV. p. 2202; Larousse, “Dict. Univ.,” Vol. VIII. p. 123; “Freeman’s Historic Towns” (Colchester), by Rev. E. L. Cutts, 1888, p. 172; “Beauties of England and Wales,” by E. W. Brayley and John Britton, 1810, Vol. V. (Colchester) pp. 318–319; Cooper, “Athenæ Cantabrigienses,” Cambridge, 1858; Anthony à Wood, “Athenæ Oxonienses,” London, 1813, Vol. I; Thomas Wright, “Hist. and Top. of the County of Essex,” 1866, Vol. I; “Journal des Savants” for June 1859, Sept. 1870; Wm. Munk, “The Roll of the Royal College of Physicians of London,” 1878, Vol. I. p. 77; Humboldt, “Cosmos,” 1859–1860, Vol. I. pp. 158–159, note, 177, 179, 182, note; Vol. II. pp. xvii, 279–281, 334–335, 341–342; Vol. V. p. 58 for references to and extracts from Dr. Gilbert’s work; Wm. Whewell, “Hist. of the Ind. Sciences,” Vol. I. pp. 274–275, 394; Vol. II. pp. 192, 217–220, 224, 225, and “Philosophy of the Ind. Sciences,” London, 1840, Vol. II. pp. 374–379; “Mémoires de Physique,” Lausanne, 1754, pp. 123, etc.; “U.S. Magnetic Tables and Isogonic Charts for 1902,” L. A. Bauer, pp. 1–77; “Popular Science Monthly,” August 1901, pp. 337–350 for “Gilbert of Colchester,” by Bro. Potamian, also its translation in “Ciel et Terre” for Dec. 1, 1902, pp. 472–480 and for Dec. 16, 1902, p. 489; “New International Encyclopædia,” New York, 1903, Vol. VIII. p. 368; “William Gilbert of Colchester,” by Conrad Wm. Cooke, London, 1890 (reprinted from “Engineering,” 1889); “William Gilbert of Colchester,” by Dr. Silvanus P. Thompson, London, 1891; “William Gilbert of Colchester,” a translation by P. Fleury Mottelay, New York and London, 1893; “William Gilbert of Colchester,” a translation by members of the Gilbert Club, London, 1900, to which is appended a valuable collection of “Notes on the De Magnete” of Dr. William Gilbert, by Dr. Silvanus P. Thompson, who therein also gives an interesting bibliography of this great work; “William Gilbert of Colchester,” a sketch of his magnetic philosophy by Chas. E. Benham, Colchester, 1902; “Zur bibliographie von W. Gilbert’s De Magnete,” Von. G. Hellmann (“Terrestrial Magnetism and Atmospheric Electricity” for June 1902); “Terr. Magn. and Atm. Elect.,” Vol. II. p. 45 for “The Earth a Great Magnet,” by J. A. Fleming; “The Earth a Great Magnet,” by Prof. Alfred M. Mayer, New York, 1872; Philip Morant, “History and Antiquities of Colchester,” London, 1748; Bacon, “Novum Organum,” Leyden, 1650, pp. 263–265; Rees’ “Encyclopædia,” 1819, Vol. XVI. article “Gilbert”; “A Course of Lectures on Natural Philosophy and the Mechanical Arts,” by Thos. Young, London, 1807, Vol. I. pp. 686, 747, 756; Vol. II. pp. 111, 324, 436; “Critical Dictionary of Engl. Literature,” S. Austin Allibone, Philad., 1888, Vol. I. p. 668; “General Biographical Dictionary,” John Gorton, London, 1833, Vol. II, mentioning Wood’s “Athen. Ox.,” Hutchinson’s “Biog.-Med.,” and Aikin’s “G. Biography”; Phil. Trans. for 1667, Vol. II. pp. 527–531, also Baddam’s abridgments, London, 1739, Vol. III. p. 129 and London, 1745, Vol. I. p. 97.

A.D. 1601.—Brahé (Tycho—Tygge—Thyghe—Tyge), who has been several times mentioned in this compilation and is referred to by Gilbert (“De Magnete,” Book IV. chap. xii. also Book VI. chap. v.), was a distinguished Danish astronomer (b. 1546, d. 1601), the founder of modern astronomical calculations, whose investigations and records of the positions of the stars and planets made possible the brilliant discoveries of Kepler and Newton. As Humboldt expresses it, the rich abundance of accurate observations furnished by Tycho Brahé, himself the zealous opponent of the Copernican system, laid the foundation for the discovery of those eternal laws of planetary movements which prepared imperishable renown for the name of Kepler, and which, interpreted by Newton, proved to be theoretically and necessarily true, have been now transferred into the bright and glorious domain of thought as the intellectual recognition of nature (“Cosmos,” 1860, Vol. II. p. 313).

As his very able biographer, Dr. J. L. E. Dreyer, of the Armagh Observatory, remarks in his admirable work (Edinburgh, 1890): “Without Brahé, Kepler never could have found out the secrets of the planetary motions, and, in the words of Delambre, ‘Nous ignorerions peut être encore le véritable système du monde.’ The most important inheritance which Tycho left to Kepler and to posterity was the vast mass of observations all which, Kepler justly said, ‘deserved to be kept among the royal treasures, as the reform of astronomy could not be accomplished without them ...’ at one breath blowing away the epicycles and other musty appendages which disfigured the Copernican system.... Tycho Brahé had given Kepler the place to stand on and Kepler did move the world!”

Brahé was the first to recognize the variation, i. e. the inequality, in the moon’s motion. In opposition to the opinion of Sédillot, M. Biot maintains that this fine discovery of Tycho by no means belongs to Abul-Wefa, and that the latter was acquainted not with the “variation” but only with the second part of the “evection” (“Cosmos,” 1860, Vol. II. p. 222, wherein are many references to the Comptes Rendus and to the “Journal des Savants”).

The biographical division of the “English Cyclopædia,” 1866, Vol. I. pp. 898–903, gives a list of Brahé’s numerous writings, headed by his earliest publication, “De Nova Stella,” 1573, which is so extremely rare that, until 1890, when Dr. Dreyer gave a description of it, not a single historian of astronomy had ever seen it or been able to even give its title correctly (“Journal of Br. Astron. Assoc.,” Vol. XII. No. 2, p. 95; Houzeau et Lancaster, Vol. II. p. 598). A detailed account of its contents is given at pp. 44–56 of Dr. Dreyer’s 1890 work above alluded to, wherein we are further told of the protection given Brahé by the Landgrave William of Hesse-Cassel, as well as of the consequent aid so liberally extended by King Frederick II. Reference is likewise made to the fact that in December 1584 the King turned to Tycho for help, writing that he was under the impression he had returned a compass made by Tycho, believing there was something wrong with it; that, if this proved to be the case, Tycho was to send back the compass, but, if not, he was to make two new ones similar to the old one (F. R. Friis, “Tyge Brahé,” p. 147).

References.—“Life of Tycho Brahé,” by Gassendi, containing the “Oratio Funebris,” etc., of John Jessenius; Tessier “Eloges des hommes illustres,” Vol. IV. p. 383; Blount, “Censura,” etc.; “Epistolæ ad Joh. Keplerum,” 1718; Riccioli, “Chronicon in Almagesto Novo,” Vol. I. p. 46; the biography by Malte-Brun in the “Biog. Univ.,” wherein is to be found the list of all of Tycho Brahé’s writings; “English Cycl.,” Supplement to Biography, p. 376, at Scipione Chiaromonti, for “Anti-Tycho”; “Bulletin de la Société Astronomique de France,” Janvier 1903; “Journal des Savants,” Juin 1864; Humboldt, “Cosmos,” 1860, Vol. III. pp. 158, 160, 162; “Nature” of Dec. 27, 1900, p. 206, and “Nature,” Vol. LXV. pp. 5–9, 104–106, 181, as well as the “Bulletin Astronomique,” Paris, Avril 1902, pp. 163–166, for account of the celebrations of the Tercentenary of Tycho-Brahé’s death, held at Prague and elsewhere, on Oct. 24, 1901, with illustrations of his observatory, etc. etc.; “Geschichte der Mathem. von Abraham G. Kästner,” Vol. II. pp. 376, etc., 613, etc.; R. A. Proctor, “Old and New Astronomy,” 1892 passim; “Biog. Génér.,” 1890, Vol. XLV. pp. 750, 755; “La Grande Encycl.,” Vol. VII. pp. 962–963; Larousse, “Dict. Univ.,” Vol. XV. pp. 613–614; “Encycl. Brit.,” Edin., 1876, Vol. IV. p. 200.

Consult likewise for Abul Wefa: “Le Journal des Savants,” for Nov. 1841, Sept. 1843, Mar. 1845 and Oct. 1871; Houzeau et Lancaster, “Bibliog. Gén.,” 1887, Vol. I. pp. 598–600, and Vol. II. pp. 92–93; “Bull. de la Soc. Acad. de Laon,” Janvier 1903, pp. 40–48; Leopold Von Ranke, “History of England,” Vol. I. p. 367 and notes; Wm. Whewell, “Phil. of the Ind. Sc.,” London, 1840, Vol. II. pp. 386–388; Harold Höffding, “A Hist. of Mod. Phil.,” translated by B. E. Mayer, London, 1900, Vol. I. p. 428.

A.D. 1602.—Blundeville (Thomas) publishes at London, “The Theoriques of the Seuen Planets,” etc., which, as the lengthy title goes to show, indicates “the making, description and vse of two ingenious and necessarie instruments for sea men to find out thereby the latitude of any place upon the sea or land, in the darkest night, that is, without the helpe of sunne, moone or starre; first invented by M. Dr. Gilbert, a most excellent philosopher, and one of the ordinarie physicians to Her Majestie.”

He had previously published, in 1589, “A briefe description of universal mappes and cardes and of their use; and also the use of Ptolemy his Tables,” which was followed, during 1594, by his well-known work on navigation. From the rare sixth edition of the latter (London, 1622) the curious title page is worth reproducing as follows: “M. Blundeville, His Exercises, contayning eight treatises, the titles whereof are set down in the next printed page: which treatises are very necessary to be read and learned of all Young Gentlemen that haue not beene exercised in such Disciplines and yet are desirous to haue knowledge as well in Cosmographie, Astronomie and Geographie, as also in the art of navigation, in which art it is impossible, to profit without the helpe of these or such like Instructions. To the furtherance of which Art of Navigation the sayd Master Blundeville especially wrote the said Treatises and of meere good will doth dedicate the same to all Young Gentlemen of this Realme.” The contents of this curious work treat of Arithmetic, Cosmography, Terrestrial and Celestial Globes, Peter Plancius, his Universal Map, Mr. Blagrau, his Astrolabe, The First Principles of Navigation, etc. etc.

The Mr. Blagrau here mentioned is John Blagrave, eminent English mathematician, author of “The Mathematical Jewel,” as well as of “The making and use of the familiar staffe,” of “The Art of Dialling,” and of “Astrolabium Uranicum Generale, a necessary and pleasunt solace and recreation for Navigators in their long journeying, containing the use of an instrument or astrolabe.” From the last named, it appears that Blagrave was a convert to the heliocentric theory of Copernicus (“New Gen. Biog. Dict.,” by Rev. H. J. Rose, London, 1850, Vol. IV. p. 277). The invention of the dipping needle by Mr. Blagrave was before the discovery of the change of the needle’s variation by Mr. Gellibrand (“Philos. Britan.,” Benj. Martin, London, 1771, Vol. I. p. 46).

References.—“Gen. Biogr. Dict.” (Gorton), London, 1833, Vol. I; Hutton’s abridgments of the Phil. Trans., London, 1739, Vol. IV. p. 103; “Dict. of Nat. Biog.,” Leslie Stephen, London, 1886, Vol. V. pp. 157 and 271–272; “Gen. Biog. Dict.,” Alex. Chalmers, London, 1812, Vol. V. pp. 370–371; “Biog. Univ.,” Paris, 1843, Vol. IV. p. 397; “Nouv. Biog. Générale” (Hœfer), Paris, 1853, pp. 170–171; Baddam’s abridgments of the Phil. Trans., London, 1739, Vol. IV. p. 103; “Ames’ Typog. Antiq.” (Herbert), pp. 693, 694, 697–701; Bloomfield’s “Norfolk,” Vol. LXIV. pp. 68–70; Cooper’s “Athenæ Cantab.”; Davy’s “Suffolk Coll.,” Vol. LXXXIX. p. 215; Hazlitt, “Coll. and Notes,” 1876, also the second series.

A.D. 1609.—Kepler (Johann), who succeeded Tycho Brahé in 1601 as astronomer to the German Emperor Rudolph II, is the author of a treatise “On the Magnet,” which was followed, during 1609, by his greatest work, the “Astronomia Nova.” The latter was deemed by Lalande of such importance that he considered it the duty of every astronomer to read it from beginning to end at least once in his lifetime.

The “Astronomia” contains the extraordinary book “on the motion of Mars,” and is said to hold the intermediate place, besides being the connecting link between the discoveries of Copernicus and those of Newton. Kepler’s doctrine is thus enunciated by Dr. Whewell (“Physical Astronomy,” Chap. I): “A certain Force or Virtue resides in the sun by which all bodies within his influence are carried around him. He illustrates (‘De Stella Martis,’ Chap. XXXIV. p. 3) the nature of this Virtue in various ways, comparing it to Light and to the Magnetic Power, which it resembles in the circumstances of operating at a distance, and also in exercising a feebler influence as the distance becomes greater.” In the Table of Contents of the work on the planet Mars, the purport of the chapter to which allusion has been made is stated as follows: “A Physical speculation, in which it is demonstrated that the vehicle of that virtue which urges the planets, circulates through the spaces of the universe after the manner of a river or whirlpool (vortex), moving quicker than the planets.” It will doubtless be found by any one who reads Kepler’s phrases concerning the moving force—the magnetic nature—the immaterial virtue of the sun, that they convey no distinct conception, except so far as they are interpreted by the expressions here quoted: “A vortex of fluid constantly whirling around the sun, kept in this whirling motion by the rotation of the sun himself and carrying the planets around the sun by its revolution, as a whirlpool carries straws, could be readily understood; and though it appears to have been held by Kepler that this current and vortex was immaterial, he ascribes to it the power of overcoming the inertia of bodies, and of putting them and keeping them in motion, the only material properties with which he had anything to do. Kepler’s physical reasonings, therefore amount, in fact, to the doctrine of vortices around the central bodies and are occasionally so stated by himself; though by asserting these vortices to be ‘an immaterial species,’ and by the fickleness and variety of his phraseology on the subject, he leaves his theory in some confusion; a proceeding, indeed, which both his want of sound mechanical conceptions and his busy and inventive fancy might have led us to expect. Nor, we may venture to say, was it easy for any one at Kepler’s time to devise a more plausible theory than the theory of vortices might have been made. It was only with the formation and progress of the science of mechanics that this theory became untenable.”

References.—“Kepler, sa vie et ses ouvrages,” in the “Journal des Savants” for June, July and August 1847; Kepler’s manuscripts, “Phil. Trans.,” Vol. XI. p. 27; Wm. Whewell, “Phil. of the Ind. Sc.,” London, 1840, Vol. II. pp. 383–386; “Epistolæ ad J. Keplerum,” published by M. G. Hansch in 1718; Houzeau et Lancaster, “Bibliogr. Générale,” 1887, Vol. I. part i. pp. 612–614, detailing the contents of Kepler’s “Opera Omnia,” also Vol. I. part ii. pp. 1315–1316, 1330–1331, 1383, and Vol. II. pp. 175–176, 456–462 and 1581; Robert Small, “An Account of the Astronomical Discoveries of Kepler,” London, 1804; Humboldt, “Cosmos,” 1860, Vol. II. p. 710, notes, for Laplace, Chasles and Brewster on the writings and theories of Kepler; “Jour. des Savants” for June, July and August 1847; “Geschichte der Mathem.,” Vol. III. p. 318, and Vol. IV. pp. 216, 311; Dr. Geo. Miller, “Hist. Phil. Ill.,” London, 1849, Vol. III. notes at pp. 134–135; Fourth Dissert. of “Encycl. Brit.”; Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. I. pp. 291–311, 320, 386, 387, 415, 462, 532–534, and Vol. II. pp. 55, 56.

It will be well to look at the last-named work of Dr. Whewell for references to Jeremiah Horrox—Horrockes—(1619–1641), the celebrated young English scientist, who wrote in defence of the Copernican opinion in his “Keplerian Astronomy defended and promoted” (“Hist. of the Ind. Sc.,” Vol. I. Book V. chap. iii. p. 276, and Chap. V. p. 303), as well as for references to Giovanni Alfonso Borelli (1608–1679). Borelli, who has by many been erroneously called a pupil of Galileo, was a distinguished Italian physicist and astronomer, born at Naples in 1608, who founded what has been called the iatromathematical school, which, under the protection of Leopold of Tuscany, became known as the Accademia del Cimento. Whewell speaks of him in Vol. I. at Book VI. chap. ii. p. 323, at Book VII. chap i. pp. 387, 393, 394, and at Chap. II. pp. 303, 395, 405, 406. Horrox is mentioned, more particularly, by Houzeau et Lancaster (“Bibliog. Générale,” Vol. II. p. 167), also at pp. 12 and 220, Vol. II of Hutton’s abridgments of the Phil. Trans.; while full accounts of the many important works of Borelli are to be found in “Biogr. Générale,” Vol. VI. pp. 700–701; Ninth “Britannica,” Vol. IV. p. 53; Larousse, “Dict. Univ.,” Vol. II. p. 1003; “Chambers’ Encycl.,” 1888, Vol. II. p. 328; “La Grande Encycl.,” Vol. VII. p. 405; Nicéron, “Mémoires,” Vol. VIII. p. 257; Vigneul-Marville, “Mélanges,” Vol. II. p. 122; Sachs, “Onomasticon Literarium,” V. 40; Hagen, “Memoriæ Philosophorum,” Frankfort, 1710.

A.D. 1613.—Ridley (Marke), “Doctor in physicke and philosophie, latly physition to the Emperour of Russia and one of ye eight principals or elects of the College of Physitions in London,” is the author of a small quarto entitled “A Short Treatise of Magnetical Bodies and Motions,” published in London, 1613. Of this treatise, Libri says that the author, in his preface, deals tolerantly with the many and varied theories concerning magnetic bodies, instancing many of the most notable from those of Pliny and Nicander to those of Robert Norman. He is particularly emphatic concerning the production of perpetual motion by means of the loadstone, finding it “by the experience of many ingenious practices ... impossible to be done.”

From the notice given him in “Dict. of Nat. Biog.,” 1896, Vol. XLVIII. pp. 285–286, we learn that in the above-named work, he claims acquaintance with William Gilbert, whom he commends as the greatest discoverer in magnetical science, and that after giving twenty-four chapters on the properties and description of the magnet, he discusses the variation of the compass and methods of estimating it in eight chapters, the inclinatory needle in eight others, concluding with a chapter on finding the longitude and one “of the matter of the magnetical globe of the earth by the needle.”

In 1617, he published “Animadversions on a late work entitled Magnetical Advertisement; or, Observations on the Nature and Properties of the Loadstone.”

References.—A. Watt, “Bibliotheca Britannica,” Vol. II. p. 804, at p. 75g Vol. I. of which (article, “Wm. Barlowe”) is “A briefe discovery of the idle animadversions of Marke Ridley, M.D.,” upon a treatise entitled “Magneticall Advertisements,” London, 1618. Consult also “The Lancet” of August 7, 1897, p. 349; Munk’s “College of Phys.,” Vol. I. p. 106; Ridlon’s “Ancient Ryedales,” p. 425.

A.D. 1616.—Schouten (Guillaume Cornelissen—Willem Cornelisz), Dutch navigator, indicates points lying in the midst of the Pacific and south-east of the Marquesas Islands in which the variation is null. Humboldt alludes to this (“Cosmos,” 1859, Vol. I. p. 182, and Vol. V. p. 59) and says, “Even now there lies in this region a singular, closed system of isogonic lines, in which every group of the internal concentric curves indicates a smaller amount of variation.”

For Schouten, consult “Relation,” published by Aris Classen, Amst., 1617; Larousse, “Dict. Univ.,” Vol. XIV. p. 375.

Under this same date, A.D. 1616, Chas. Pickering tells us that Wm. Baffin (Churchill Coll. and Anders. II. 268) continued North to “seventy-eight degrees,” as far as a Sound called by him “Thomas Smith’s,” where the compass varied “fifty-six degrees to the westward,” making the true North bear N.E. by E. The northern expanse of water received the name of “Baffin’s Bay” (“Chron. Hist. of Plants,” Boston, 1879, p. 933).

A.D. 1617.—Strada (Famianus), an Italian author and Jesuit priest, publishes his curious “Prolusiones Academicæ,” wherein he describes (lib. ii. prol. 6) a contrivance consisting of two magnetic needles attached to two dials each bearing a circle of letters so arranged that when one needle is made to point to any letter on one dial, the other needle points to the same letter upon the other dial.

The description is best given in his own words taken from the original Latin (Stradæ, “Prol. Acad.,” Oxoniæ, 1662, “Magnes cur ferrum aut aurum trahat,” pp. 326–335): “... If you wish your distant friend, to whom no letter can come, to learn something, take a disc or dial, and write round the edge of it the letters of the alphabet in the order in which children learn them, and, in the centre, place horizontally a rod, which has touched a magnet, so that it may move and indicate whatever letter you wish. Then a similar dial being in the possession of your friend, if you desire privately to speak to the friend whom some share of the earth holds far from you, lay your hand on the globe, and turn the movable iron as you see disposed along the margin of all the letters which are required for the words. Hither and thither turn the style and touch the letters, now this one, and now that.... Wonderful to relate, the far-distant friend sees the voluble iron tremble without the touch of any person, and run now hither, now thither; conscious he bends over it and marks the teaching of the rod. When he sees the rod stand still, he, in his turn, if he thinks there is anything to be answered, in like manner, by touching the various letters, writes it back to his friend....”

References.—“The Student; or, Oxford and Cambridge Misc.,” 1750, Vol. I. p. 354; Abbé Moigno’s “Traité de Tel. Elec.,” p. 58; Addison (Joseph), “Spectator” for December 6, 1711, No. 241 (p. 273, Vol. II. London ed., 1854); the “Guardian” for 1713, No. 119, and “Nature,” Vol. XVI. pp. 268, 269. Also “Academy and Literature” of January 7, 1905. Zachary Grey, in 1744 edition of Butler’s “Hudibras,” quotes from the “Guardian.”

A.D. 1620.—Bacon (Sir Francis), by many considered the greatest of English philosophers and philosophical writers (1561–1626), who was knighted in 1603, became Earl of Verulam in 1618 and Viscount St. Albans in 1620, produces the masterpiece of his genius, the “Novum Organum,” after having twelve times copied and revised it. The last-named work, observes Macaulay, “takes in at once all the domains of science—all the past, the present and the future, all the errors of two thousand years, all the encouraging signs of the passing times, all the bright hopes of the coming age.” Prof. Playfair says of it that “the power and compass of the mind which could form such a plan beforehand, and trace not merely the outline but many of the most minute ramifications of sciences which did not yet exist, must be an object of admiration to all succeeding ages.”

It was Sir John Herschel who remarked that “previous to the publication of the ‘Novum Organum’ natural philosophy, in any legitimate and extensive sense of the word, could hardly be said to exist.” In the address presented in 1623 by the University of Oxford to Sir Francis Bacon, he is represented “as a mighty Hercules who had by his own hand greatly advanced those pillars in the learned world which by the rest of the world were supposed immovable.”

Treating of the electric fluid, Bacon has given (“Physiological Remains,” London, 1648) a detailed list of attractive and non-attractive bodies and the results of his very extensive experiments and observations in physical science generally, as well as of the investigations contained in Dr. Gilbert’s work. To the latter, however, many allusions had already been made in Bacon’s “The Advancement of Learning,” published during 1605, two years before he was made Solicitor-General.

The most satisfactory analyzation of Bacon’s researches is to be found in the attractive edition of his complete works published by Spedding, Ellis and Heath, fifteen volumes, Boston, 1863. Therein will be seen the following references to the magnet and magnetic virtue:

Vol. I. p. 435 (note). In Gilbert’s philosophy, the earth’s magnetic action is not distinguished from gravity (De Mundo, II. c. 3). That the magnetic action of the earth or of a magnet is confined to a definite orb, appears from a variety of passages (see “De Magnete,” II. c. 7, and the definitions prefixed to this work). Gilbert distinguished between the “Orb of Virtue” which includes the whole space through which any magnetic action extends, and the “Orb of Coition” which is totum illud spatium per quod minimum magneticum per magnetem movetur. He asserts that the orb of the magnetic virtue extends to the moon and ascribes the moon’s inequalities to the effects it produces (“De Mundo,” II. c. 19).

Vol. VIII. Aphorisms. “If, before the discovery of the magnet, any one had said that a certain instrument had been invented by means of which the quarters and points of the heavens could be taken and distinguished with exactness ... it would have been judged altogether incredible ...” (pp. 141–142). “The ‘Clandestine Instances’—which I also call ‘Instances of the Twilight’ [the attraction or coming together of bodies]—and which are pretty nearly the opposite of ‘Striking Instances....’ The most remarkable ‘Striking Instance’ is the magnet ... a ‘Clandestine Instance’ is a magnet armed with iron; or, rather, the iron is an armed magnet ...” (pp. 224–226). “The polarity of the iron needle when touched with the magnet” (p. 261). “The magnetic or attractive virtue admits of media without distinction, nor is the virtue impeded in any kind of a medium” (p. 269). “There is no medium known by the interposition of which the operation of the magnet, in drawing iron, is entirely prevented” (pp. 285–286). “A piece of a magnet does not draw so much iron as the whole magnet” (p. 301). “As for the help derived from the virtue of a cognate body, it is well seen in an armed magnet, which excites in iron the virtue of detaining iron by similarity of substance; the torpor of the iron being cast off by the virtue of the magnet” (p. 311). “There are four virtues or operations in the magnet ... the first is the attraction of magnet to magnet, or of iron to magnet, or of magnetised iron to iron; the second is its polarity, and at the same time its declination; the third, its power of penetrating through gold, glass, stone, everything; the fourth, its power of communicating its virtue from stone to iron, and from iron to iron, without communication of substance” (p. 313). “But the flight of iron from one pole of the magnet is well observed by Gilbert to be not a flight strictly speaking, but a conformity and meeting in a more convenient situation” (p. 315). “The magnet endues iron with a new disposition of its parts and a conformable motion, but loses nothing of its own virtue” (p. 318).

Vol. IX. In the fifth book of “De Augmentis Scientiarum,” these questions are asked: (1) A magnet attracts a solid piece of iron; will a piece of a magnet dipped in a dissolution of iron attract the iron itself and so get a coating of iron? (2) Again, the magnetic needle turns to the pole; does it, in so doing, follow the same course as the heavenly bodies? (3) And, if one should turn the needle the wrong way, that is, point it to the South and hold it there for a while, and then let it go; would it, in returning to the North, go round by the West rather than by the East? (pp. 75–76).

Vol. X. This contains, at pp. 269–272, the “Inquiry respecting the Magnet,” of which the original paper is to be found in Vol. IV. pp. 121–125. In Dr. Rawley’s list of works composed by Bacon, during the last five years of his life, this “Inquisitio de Magnete,” first published in 1658, stands last but two. At p. 335 this same Vol. X will be found an extract from “De fluxu et reflexu maris” (“The ebb and flow of the sea”) relative to the inquiry as to whether the earth itself is a magnet, as was asserted by Gilbert.

Besides the “Clandestine Instances” or “Instances of the Twilight” alluded to above, mention could have been made more particularly of Bacon’s observations (in s. 3 of the “Nov. Organ.”) under the direct headings of “Instantiæ Citantes ... Supplementi ... Radii ... Magicæ,” as well as of “Motus Magneticus ... Excitationis ... Fugæ,” etc., which are fully explained at ss. 190–200 of Sir John Herschel’s “Discourse on the study of Natural Philosophy.”

They have been analyzed as follows:

Instantiæ Citantes, to which may be reduced the “discovery of a moving magnetic fluid, or an action circular and perpendicular to the electrical current, yet connected with it.”

Instantiæ Supplementi, such as the magnet which attracts iron through many substances that may be interposed. Perhaps, says he, “some medium may be found to deaden this virtue more than any other medium; such an instance of substitution, would be in the way of degree, or approximation”; that is, it would approach toward destroying the magnetic virtue. Iron possesses, perhaps, this quality in a more marked manner than any other substance.

Instantiæ Radii, leading to the suggestion that there may exist some kind of “magnetic virtue which operates by consent, between the globe of the earth and heavenly bodies; or between the globe of the moon and the waters of the sea; or between the starry heavens and the planets, by which they may be drawn to their apogees,” or greatest distances from the earth.

Instantiæ Magicæ, such as the loadstone animating a number of needles without loss of its own magnetism.

Motus Magneticus, such as the attraction of the heavenly bodies, from an idea, perhaps, that it might be due to a species of magnetism.

Motus Excitationis, such as the new property which is given to iron by the magnet without any loss of power by the latter.

Motus Fugæ, such as “the repulsion of electrified pith balls; also of the similar poles of two magnets. In the latter case, all the force of a strong man has proved insufficient to make the two north poles touch each other.”

The last-named work of Sir John Herschel is alluded to, under the heading of “Prerogative Instances” (“Prærogativæ Instantiarum”) by Thomas Fowler, who calls attention to the fact that among the contemporaries of Francis Bacon by whom the Copernican theory was rejected are: Tycho Brahé (who, however—having died in 1601—did not live to become acquainted with the discoveries of Galileo); Vieta, the greatest mathematician of the sixteenth century (who died as early as 1603); Christopher Clavius (who was employed by Gregory XIII to reform the Calendar and was called the Euclid of his age); and possibly, from his silence, the famous mechanician Stevinus (Delambre, “Histoire de l’Astronomie Moderne”).

References.—The works of Sir Francis Bacon, Lord Chancellor of England, by Basil Montagu, 16 vols., London, 1825–1834, and the review thereof made by Thomas Babington Macaulay (“Essays,” 1855, Vol. II. pp. 142–254 (“Edinburgh Review,” July 1837); Dr. W. Windelbrand, “History of Philosophy,” New York, 1893, translated by Jas. H. Tufts, pp. 380–388; Dr. Friedrich Ueberweg, “History of Philosophy,” translated by Geo. S. Morris, New York, 1885, Vol. II. pp. 33–38; Leopold Von Ranke, “History of England,” Vol. I. pp. 455–459, Vol. III. p. 383; William Whewell, “The Philosophy of the Inductive Sciences,” London 1840, Vol. II. pp. 388–413; “Critical Dictionary of English Literature,” S. Austin Allibone, Philad. 1888, Vol. I. pp. 89–96; “Catalogue Général des livres imprimés de la Bibliot. Nation.,” Paris, 1901, Vol. VI. pp. 236–253; Chas. Wells Moulton, “Library of Literary Criticism,” Vol. I. pp. 638–669; “The Philosophical Works of Francis Bacon,” by John M. Robertson, New York, 1905; “The Grammar of Science,” by Karl Pearson, London, 1900, pp. 506–508; “Encycl. Britann.,” Edinburgh, 1842, seventh edition, Vol. I. as per Index pages 16–17 and at “Dissertation First,” pp. 32–40; “Essai Theorique ... des connaissances humaines,” par G. Tiberghien, Bruxelles, 1844, Vol. II. pp. 409–419; Geo Miller, “History Philosophically Illustrated,” London, 1849, Vol. II. p. 430; “Francis Bacon,” by B. G. Lovejoy, London, 1888; “His Life and Character,” pp. 1–188, and “His Essays and Extracts,” pp. 19–277; “Francis Bacon,” by Kuno Fisher, London, 1857; “Encycl. Brit.” ninth edition, Vol. III. pp. 200–218; Bacon’s “Novum Organum,” by Thomas Fowler, New York, 1881, and Oxford, 1889; “Histoire des Sciences,” par F. L. M. Maupied, Paris, 1847, Vol. II. pp. 252–281, for “Enumeration Méthodique—Eléments—Analyse—des ouvrages de Francis Bacon”; “Library of Useful Knowledge,” for account of Lord Bacon’s “Novum Organum”; “Epitome of Electricity and Galvanism,” Philad., 1809, pp. xvi, 105; Whewell, “History of the Inductive Sciences,” Vol. I. pp. 339, 385, 494, 530; Van Swinden, “Recueil de Mémoires ...” La Haye, 1784, Vol. II. pp. 355, 364, 369–370; and, for an exhaustive biographical account of Francis Bacon, consult the “English Cyclopædia,” Vol. I. pp. 470–476. It is stated by C. R. Weld in his “History,” Vol. I. p. 64, that the establishment of the Royal Society was much accelerated by the writings of Lord Bacon (Buchmeri, “Acad. Nat. curi. Hist.”).

A.D. 1620–1655.—Bergerac (Savinien Cyrano de), a very witty French writer, is the author of a fragment on physics, as well as of a curious philosophical romance, “Histoire comique des états et empires de la lune,” a translation from which latter is here given, as in a measure suggesting the phonograph: “On opening the box, I found a number of metallic springs and a quantity of machinery resembling the interior of our clocks. It was, in truth, to me a book, indeed, a miraculous book, for it had neither leaves nor characters, and to read it, one had no need of eyes, the ears alone answering the purpose. It was only necessary to start the little machine, whence would soon come all the distinct and different sounds common to the human voice.”

Another translation reads as follows: “On opening the box I found inside a concern of metal, something like one of our watches, full of curious little springs and minute machinery. It was really a book, but a wonderful book that has no leaves or letters; a book, for the understanding of which the eyes are of no use—only the ears are necessary. When any one wishes to read, he winds up the machine with its great number of nerves of all kinds, and turns the pointer to the chapter he wishes to hear, when there come out, as if from the mouth of a man or of an instrument of music, the distinct and various sounds which serve the Great Lunarians as the expression of language.”

As has been said by one of his biographers, “amid the extravagance of some of his works, Bergerac nevertheless exhibited a pretty good acquaintance with the philosophy of Descartes.”

References.—Article “Aeronautics” in the “Encycl. Brit.,” 1853, Vol. II. p. 168; Larousse, “Dict.,” Vol. V. p. 730.

A.D. 1621.—Helmont (Jean Baptiste van), famous Belgian scientist, publishes in Paris his “De Magnetica,” etc. (on the magnetic cure of wounds). His theories on magnetism greatly resemble those of Paracelsus, but in his treatment of them he shows himself much superior to the Swiss alchemist, whom Dr. Hœfer says he took as his model. “Magnetism,” Van Helmont observes, “is an unknown property of a heavenly nature, very much resembling the stars, and not at all impeded by any boundaries of space or time.... Every created being possesses his own celestial power and is closely allied with heaven ... the spirit is everywhere diffused; and the spirit is the medium of magnetism ... it is not the spirits of heaven and of hell which are masters over physical nature, but the soul and spirit of man which are concealed in him as the fire is concealed in the flint.”

The above-named work of Van Helmont was “translated, illustrated and ampliated,” in 1650 by Dr. Walter Charleton, physician in ordinary to King Charles I, under the name of “A Ternary of Paradoxes.” From its interesting contents, we make the following extracts:

Page 10. “A loadstone placed upon a small trencher of wood, floating on water, does instantly in one determinate point australize, and in the other septentrionate ... all which various and admirable effects of the loadstone, thou maiest, if thy judgement relish them, finde made good by multiplyed observations, by William Gilbert, not many yeers past, a physician in London, in his book, ‘De Magnete’: of which subject no man ever writ more judiciously or experimentally: and by whose industry the variation of the compasse may be restored....”

Page 12. “There is a book imprinted at Franekera, in the year 1611, by Vldericus Dominicus Balck, of the Lamp of Life. In which you shall finde, out of Paracelsus, the true magneticall cure of most diseases, as of the Dropsie, Gout, Jaundice, etc.”

Page 15. “Doth not the needle of the Mariner’s Compasse, through a firme glasse, closely sealed up with melted soder (in which there can be no pore or crany discovered) steer it self to the Artick pole? ... wherefore the same numericall accident streaming in one continued radius from the loadstone into the aer, passes through the glasse, and perhaps goes as farre as to touch the pole it self....”

Page 38. “Wherefore the loadstone owes its polarity to a natural inhærent faculty, flowing from its owne seminall entity, and not to any forreigne alliciency, or attractive influx transmitted from the north star. But that otherwise the loadstone may, by its own instinct, be elevated towards the Zenith, we have upon ocular demonstration found it true, by a certain instrument invented by Guilielme Guilbert (the glory of which excellent invention Ludovicus Fonseca hath lately endeavoured to ravish) ... which by the spontaneous elevation of the loadstone in a brasse ring suspended by a thread or small wier, shews not only the latitude but also the altitude of the pole, in all places of the earth.”

Page 39. “... the loadstone is endued with a domestick pilot, a directive faculty, which guides it to some determinate place, but is not at all attracted by the pole.”

Page 40. “The loadstone onely by the affriction of Garlick, amits its verticity, and neglects the pole, conserving to it self, in the meane time, its peculiar forme, materiall constitution, and all other dependent proprieties. The reason, because Garlick is the loadstone’s proper Opium, and by it that spirituall sensation in the magnet is consopited and layd asleep.... Verily, that alliciency of the pole must be extreame weake and of inconsiderable energy, which passing through so many and so immense orbes of heaven, and striking through great and firme buildings, and thick walls, cannot yet be of power sufficient to pierce the thin juice of Garlick or the fume of Mercury....”

Page 42. “There is therefore inhærent in the magnet an influentiall virtue, which, being not obliged to the propinquinty or comtiguous admotion of its object, is after the nobler names of coelestiall influences, freely and without interruption or languor transmitted so farre as to the pole it self: since there is a spontaneous eradiation, or emission of atomicall radii from the body of the magnet to the pole.”

Page 74. “That the magnetisme of the loadstone and other inanimate creatures is performed by a certaine naturall sensation, the immediate anthrix of all sympathy, is a truth unquestionable.”

Page 75. “For by one phansy it is directed to iron, and by another to the pole ... the phansy of amber delights to allect strawes, chaffe, and other festucous bodies; by an attraction, we confesse, observe obscure and weake enough, yet sufficiently manifest and strong to attest an Electricity or attractive signature....”

References.—“Dict. of Nat. Biog.,” Vol. X. pp. 116–119, containing a full list of Charleton’s works; Thomson, “Hist. of the Roy. Soc.,” 1812, p. 3; Munk, “Coll. of Phys.,” 1878, Vol. I. p. 390; “Journal des Savants” for February and March 1850, June 1851; Mme. Blavatsky, “Isis Unveiled,” Vol. I. p. 170; Eloy, “Dict. Hist. de la Médecine,” Vol. II. pp. 478–482; “Dict. Hist. de la Médecine,” par. J. E. Dezeimers, Paris, 1839, Vol. III. pp. 97–104; “Ency. Brit.,” ninth edition, Vol. XI. p. 638; “History and Heroes of the Art of Medicine,” by J. Rutherfurd Russell, London, 1861, pp. 197–204; Larousse, “Dict. Univ.,” Vol. IX. p. 158; Van Swinden, “Recueil,” La Haye, 1784, Vol. II. pp. 351–352, 361–363; Joseph Ennemoser, “The History of Magic,” London, 1854, Vol. II. pp. 242–253.

A.D. 1623.—Hervart—Heroart—Herwart—Hörwarth (Joannes Fridericus), son of Johann Georg Hervart ab Hohenburg, the well-known scientist (1554–1622), who during forty-five years occupied the post of Bavarian Chancellor under three reigning princes—completes his father’s work entitled “Admiranda ethnicæ theologiæ ...” which, Larousse says (“Dictionnaire Universel,” Vol. IX. p. 250), was published at Munich, 1624, and in which he demonstrates that the earlier Egyptian divinities were natural phenomena personified and adored under symbolic names. Michaud, who reiterates this (“Biographie Universelle,” Vol. XIX. p. 364), speaks of the edition which appeared at Munich in 1626, and he also states that, at the end of the latter, will be found “Exacta temporum ... chronologiæ vulgaris errores,” which is the continuation of the “Chronologia Nova,” left unfinished by the Bavarian Chancellor. This is, in fact, so mentioned in the only copy possessed by the British Museum, which was published by J. F. Hervart ab Hohenburg at Ingolstadii, 1623, and of which the title reads: “Admiranda Ethnicæ Theologiæ Mysteria propalata. Ubi lapidem magnetem antiquissimis passim nationibus pro Deo-deocultum: et artem qua navigationes magneticæ per universum orbem instituerentur....”

Libri’s “Catalogue,” 1861, Part I. p. 405, No. 3703, has the following entry: “Admiranda Ethnicæ ... ubi Lapidem Magnetem antiquissimis Nationibus pro Deo cultum commonstratur ...” Ingolstadii, 1623. The work itself endeavours to prove that the loadstone’s properties were well known to the ancients.

The “General Biographical Dictionary” of Alexander Chalmers, London, 1814, Vol. XVII. p. 426, makes following entry: “Herwart (or Hervart) John George, Chancellor of Bavaria at the beginning of the seventeenth century, published some works wherein his learning was more displayed than his judgment, in supporting the most extravagant systems. Two of his works are: ‘Chronologia nova et vera,’ in two parts, 1622 and 1626, and ‘Admiranda Ethnicæ Theologicæ Mysteria propalata, de antiquissima veterum nationum superstitione, qua lapis Magnes pro Deo habitus colebatur,’ Monach, 1626, quarto. It was here asserted that the ancient Egyptians worshipped the magnet,” etc. (see Deveria, under B.C. 321).

References.—Allusions to Hervart, made at p. 546, Vol. XXIV. of Dr. Hœfer’s 1861 “Nouvelle Biographie Générale,” or at p. 546, Vol. XXVIII of the 1858 edition, and also at p. 163, Vol. II of the “Bibliographie Générale de l’Astronomie,” by Houzeau et Lancaster, Bruxelles, 1882. Likewise Chr. G. Jöcher, “Compendiöses Gelehrten Lexicon,” Leipzig, 1787, Vol. II. p. 1969, and “A New General Biogr. Dict.,” London, 1850, Vol. VIII. p. 304.

A.D. 1624.—Gunter (Edmund), professor of astronomy at Gresham College, publishes his work “Of the Sector, Cross-Staff, and other Instruments,” at Chap. V of the second book of which he gives the result of the eight observations he made on the variation of the variation “in various parts of the ground” at Limehouse on the 13th of June, 1622. His observations of the declination, as given by Prof. Gellibrand, are detailed at Chap. I of Walker’s “Ter. and Cos. Mag.,” Cambridge, 1866.

References.—De La Rive, “Electricity,” etc., Vol. I. p. 165; Poggendorff, “Geschichte der Physik,” Leipzig, 1879, p. 275.

A.D. 1625.—Carpenter (Nathaniel), Dean of Ireland, well-known mathematician, publishes at Oxford, “Geography delineated forth in two bookes, containing the sphæricall and topicall parts thereof,” wherein he thus alludes to Dr. Gilbert’s “De Magnete”: “Magneticall proprieties, I find in ancient writers, as little knowne as their causes; and if any matter herein were broached, it was merely conjectural, and depending on no certain demonstration; neither had we any certain or satisfactory knowledge of the thing vntill such time as it pleased God to raise vp one of our countrymen, D. Gilbert, who, to his euerlasting praise, hath trodden out a new path to Philosophie, and on the Loadstone, erected a large Trophie to commend him to posterity. This famous Doctor being as pregnant in witty apprehension as diligent in curious search of naturall causes, after many experiments and long enquiry, found the causes of most magneticall motions and proprieties hid in the magneticall temper and constitution of the Earth, and that the earth it selfe was a meere magneticall body challenging all those proprieties, and more than haue expressed themselves in the Loadstone; which opinion of his was no sooner broached than it was embraced, and wel-commed by many prime wits as well English as Forraine. Insomuch that it hath of late taken large root and gotten much ground of our vulgar Philosophie.”

References.—“Nature,” September 26, 1901; “Dict. of Nat. Biogr.,” Vol. IX. pp. 161–162; Larousse, “Dict.,” Vol. IV. p. 438; Prince’s “Worthies” (1810), pp. 173–175, 603.

A.D. 1625.—Naudé (Gabriel), a celebrated French savant and one of the most learned of his day, also physician to King Louis XIII, and an intimate friend of Gassendi, is the author of “Apologie pour tous,” etc. (“Apology for great men falsely accused of magic”), of which other editions appeared in 1652, 1669 and 1712. The magico-theosophical philosophy, as Madame Blavatsky expresses it, is fully indicated in his work, and he proved to be the warmest defender of the doctrines of occult magnetism, of which he was one of the first propounders.

References.—“Biog. Générale,” Vol. XXXVII. pp. 514–518; P. Hallé, “Gab. Naudé Elogium”; N. Sanson, “Hist. Chr. d’Abbeville,” 1653; Sainte Beuve, “Portraits Littéraires,” 1855; Alf. Franklin, “Hist. de la Biblioth. Mazarine,” 1860.

A.D. 1627.—Hakewill (George), Archdeacon of Surrey, publishes at Oxford, England, the first edition of “An Apologie or Declaration of the Power and Providence of God,” the tenth chapter, fourth section of the third book of which alludes to the use of the “mariner’s compass or sea-card, as also of another excellent invention sayd to be lately found out upon the loadstone.” As the reviewer justly observes: “While perusing his description one can hardly imagine that the writer had not in his mind’s eye one of our modern telegraphic instruments ... and it will be seen that the date at which his work is written was nearly two hundred years prior to the first attempt made to communicate at a distance by means of magnetic needles.”

Hakewill alludes (“Apologie,” 1635, lib. ii. p. 97) to Hipparchus—Abraxis—“who reports that, in his time, the starre commonly called the Polar Starre, which is in the tayle of the lesser Beare, was twelve degrees and two-fifths distant from the Pole of the Æquator. This starre, from age to age, hath insensibly still crept nearer to the pole so that at this present it is not past three degrees distant from the pole of the Æquator. When this starre then shall come to touch the Pole, there being no farther place left for it to go forward (which may well enough come to pass with five or six hundred yeares) it is likely that then there shall be a great change of things, and that this time is the period which God hath prefixed to Nature” (see Morell’s “Elem. ... Phil. and Sc.,” London, 1827, pp. 116–119 et seq.).

Mention of the star in the tail of Ursa Major is made by Gilbert, (“De Magnete”),[41] in connection (1) with Marcilius Ficinus, who, says he, seeks in that constellation the cause of the magnetic direction, as he believes that in the loadstone the potency of Ursa prevails and hence is transferred to the iron; (2) with Cardan, who assigns the cause of variation to its rising, for he thinks variation is always to be relied upon at the rising of the star; (3) with Lucas Gauricus, who holds that the loadstone beneath the tail of Ursa Major is ruled by the planets Saturn and Mars; (4) with Gaudentius Merula, who believes that the loadstone draws iron and makes it point North because it is of a higher order than is the iron in the Bear.

References.—Larousse, “Dict. Univ.,” Vol. IX. p. 26; “Dict. of Nat. Biog.,” Vol. XXIV. pp. 6–8; Walton and Cotton, “Complete Angler,” New York and London, 1847, Part I. p. 118.

A.D. 1628.—Leurechon (Jean), a student belonging to the Order of Jesuits (1591–1670), who became the confessor of Charles IV of Lorraine, publishes, under the name H. Van Etten, “La Récréation Mathématique,” carefully revised editions of which were made by Claude Mydorge and Denis Henrion in 1630, 1638 and 1661. In these, Leurechon alludes to the reported transmission of intelligence by the agency of a magnet or other like stone, saying: “The invention is beautiful, but I do not think there can be found in the world a magnet that has such virtue.”

References.—Georges Maupin, “Opinions touchant la mathématique,” Paris, 1898, pp. 20–24; Larousse, “Dict.,” Vol. X. p. 436; “Sc. Am. Suppl.,” Nos. 56, p. 881, and 384, p. 6125.

The curious title-page of the English version of Leurechon’s work, published by T. Cotes in 1633, merits reproduction: “Mathematicall Recreations, or a Collection of sundrie Problemes, extracted out of the Ancient and Moderne Philosophers, as secrets in nature, and experiments in Arithmeticke, Geometrie, Cosmographie, Horologographie, Astronomie, Navigation, Musicke, Optickes, Chimestrie, Waterworkes, Fireworks, etc., Fit for Schollers, Students, and Gentlemen ... lately compiled in French by Henry Van Hetten. And now delivered in the English tongue.”

Claude Mydorge, as stated in the “Biog. Gén.,” Vol. XXXVII. p. 87, was a French scientist (1585–1647), a very close friend of Descartes, and, according to Baillet, was next to Vieta, the foremost mathematician of his day. The second edition of his “Examen du livre des Récréations Mathématiques (du Père Leurechon),” contains notes of Denis Henrion following the observations of Père Mersenne in “Universæ ...” Paris, 1639 (see Bouillet, “Vie de Descartes,” Vol. I. pp. 36–37, 149–150, and Vol. II. pp. 43, 76, 78, 325).

Denis Henrion was also a French mathematician, who died about 1640. He was the author of many very meritorious papers, notably of a “Traité des Globes et de leurs usages,” 1618, translated from the Latin of Robert Hues, 1593, 1594 (Larousse, “Dict. Univ.,” Vol. IX. p. 192).

A.D. 1629.—Cabæus—Cabeo (Nicolaus), a learned Jesuit of Ferrara, describes (“Philosophia Magnetica”)[42] numerous experiments made by him to ascertain the possibility of two persons communicating intelligence by means of magnetized needles.

Cabæus was the first to observe electrical repulsion, and he thus announces his discovery in the tenth chapter of the above-named work: “Magnetic attractions and repulsions are physical actions which take place through the instrumentality of a certain quality of the intermediate space, said quality extending from the influencing to the influenced body.... Bodies are not moved by sympathy or antipathy, unless it be by means of certain forces which are uniformly diffused. When these forces reach a body that is suitable they produce changes in it, but they do not sensibly affect the intermediate space nor the non-kindred bodies close by it....”

The “Philosophia Magnetica” is the second Latin book published on electricity, Gilbert’s “De Magnete” being the first.

References.—Becquerel, “Résumé,” Chap. III; Stuello, “Bibl. Scrip. S. J.,” Rome, 1676; Francisco de Lanis, “Magist. nat. et artis,” 1684; L. L. de Vallemont, “Description de l’aimant,” 1692, pp. 167, 170; Dechales C. F. Milliet, “Cursus seu Mundus Mathem.,” 1674, 1690.

A.D. 1632.—Sarpi (Pietro)—Fra Paolo Sarpi—Father Paul—Paulus Venetus—Paolo Sarpi Veneto (b. 1552, d. 1623), who was the author of the celebrated history of the Council of Trent (“the rarest piece of history the world ever saw”) is referred to by Gilbert in “De Magnete,” Book I. chap. i. Therein, he says that Baptista Porta, who has made the seventh book of his “Magia Naturalis” a very storehouse and repertory of magnetic wonders, knows little about the movements of the loadstone and never has seen much of them, and that a great deal of what he has learned about its obvious properties, either through Messer Paolo, the Venetian, or through his own studies, is not very accurately noted and observed.

In the introduction to the 1658 edition of his “Natural Magick,” Porta admits that he gained some knowledge of Sarpi, who, says he, is of all men he ever knew the most learned and skilful and the ornament and splendour not only of Venice or of Italy, but of the entire world. Bertelli refers (“Memor. sopra P. Peregrino,” p. 24, note) to P. Garbio’s “Annali di Serviti,” Lucca, 1721, Vol. II. pp. 263, 272, 274, and to Fra Fulgenzio Micanzio’s “Life of Sarpi,” Helmstat—Verona, 1750, in which it is stated that not only Porta but likewise a celebrated ultramontane studied magnetism under him. Garbio asks: “Could this ultramontane be Gilbert of Colchester?”

By Griselini (“Vita de Fra P. Sarpi”—memoria anecdote—Lausanne, 1760), Paolo is said to have written a treatise on the magnet and to have therein recorded many observations, including the earliest mention that magnetic properties are destroyed by fire.

Bertelli—whose afore-named memoir we must confine ourselves to, as it is more satisfactory than are the accounts elsewhere given—makes mention that he has had in his possession, by courtesy of Sig. Giuseppe Valentinelli, the Royal Librarian of the Marciana at Venice, copy of a manuscript (Cod. CXXIX, classe 2, MS. Ital.) containing a brief comparison of Sarpi’s magnetic researches with those of Musschenbroek. This manuscript is again alluded to by Bertelli (Memor., p. 88) wherein it is said that lines 5–38 of the first column, p. 170, are headed “Observations of F.P.S. on the loadstone, collated with P. Musschenbroek’s Researches,” and embrace five paragraphs translated as follows:

1. The author had first tried the action of one magnet on another without entering into the question of calculation, but modern authors have, in view of the observations made, endeavoured to discover a method of computing magnetic forces in any proportion to the distances, and in the same better regulated systems they have discovered the cause to be uncertain (or varying) owing to the contemporaneous action of magnetic repulsion.

2. He was acquainted with the well-known action of the magnet on iron, but he understood—as even at this day some understand—that it was caused by the atmosphere. New experiments have made us seriously doubt this. He did not pay attention to the proportion of the magnetic forces as compared with the distances of iron, to the discovery of which the efforts of present philosophers are directed but in vain. He saw, however, that the facility or difficulty of attraction depends upon the size of the iron (maximum and minimum).

3. He was not ignorant of the direction of the magnet and of iron rubbed with the magnet towards certain quarters of the sky when he mentions the new discovery of the poles in the magnet, and the variation of the magnetized needle, from the Northern or the Southern quarters, but he did not know a greater number than two poles found in the magnet, the variation of the declination, or, I should rather say, the uncertainty of the variation and the different inclinations of the needle at different places on the earth.

4. Almost all the experiments referred to by Academies, with reference to the action of one piece of iron on another piece of iron, magnetized and not magnetized, and with regard to the changes of forces which arise from the various inflections of iron, have been sufficiently sketched out by F. P. S.

5. The magnetic effects acquired by an old piece of iron continually exposed to the air have also been alluded to. Now, however, natural philosophers have observed that this iron exposed for a length of time in the magnetic meridian points with greater readiness to the above-mentioned quarters. They have, moreover, ascertained that iron when heated and afterwards cooled in water is more sensitive to magnetization: which is directly opposed to the opinion of F. P. S.

Bertelli further remarks that, from information given in the manuscript, it is seen that Sarpi was at that time acquainted with the greater number of the magnetic phenomena referred to by Porta, and developed by Gilbert, viz.:

1. The reciprocal action of magnets;

2. The action of magnets on iron;

3. The manifestation of magnetic activity about the poles (sphere of action or field of force);

4. The Maximum and the Minimum of the attractive force of magnets on iron, according to the size of the latter;

5. The inversion of polarity which may arise in the magnetization of needles—(but not the corresponding poles—the magnetic variation or declination—Petrus Peregrinus, A.D. 1269—yet not the variation of the variation—Henry Gellibrand, A.D. 1635—nor the dip or inclination—Robert Norman, A.D. 1576).

6. The magnetic properties acquired by iron constantly exposed to the air.

After detailing the observations of Giulio Cesare Moderati, Filippo Costa (Costæus) of Mantua, Ulysses Aldrovandi, Francesco Acoromboni, Luigi Matteini, Father Garzoni and Father Cabæus concerning the magnetized ironwork of the belfry of the church of St. Augustine at Arimini (the parochial church of St. John the Baptist, which at that time, 1586, belonged to the monks of St. Augustine) and relative to the iron rail in the belfry of the tower of St. Laurence at Rome, Bertelli says: “From all that precedes, we gather at all events, that the fact of the spontaneous magnetization of iron was well known in Italy before Sarpi, Porta and Gilbert. This, Gilbert, and still better Cabæus, explained as the influence of terrestrial magnetism. However, with regard to the observations of the needle’s deviation made by Father Garzoni at Rome, we can, without having attributed it, as does Cabæus, to the magnetization of pieces of iron concealed in its wall, explain it, as is done in the new and important experiments of the illustrious professor Silvestro Gherardi, who attributes it to the magnetic polarity of the Mattoni [bricks] in the structure itself.”

It is said by Humboldt (“Cosmos,” 1849, Vol. II. p. 718, note) that this observation, the first of the kind, was made on the tower of the church of the Augustines at Mantua (Mantova) and that Grimaldi and Gassendi were acquainted with similar instances (instancing the cross of the church of St. Jean, at Aix, in Provence), in geographical latitudes where the inclination of the magnetic needle is very considerable. Some writers give Gassendi’s observation as occurring during 1632 (see Rohaulti, “Physica,” 1718, Par. III. cap. 8, p. 399; or, Rohault’s “System of Nat. Phil.,” 1728, p. 176).

“As the iron cross of an hundred weight upon the Church of St. John in Ariminum, or that load-stoned iron of Cæsar Moderatus, set down by Aldrovandus” (Sir Thomas Browne, “Pseudodoxia Epidemica,” 1658, p. 66).

Consult “Lettera dell’Eccel. Cavallara.,” Mantova, 1586, for a detailed account of this discovery, made January 6, of the last-named year. The iron rod supported a brick ornament in the form of an acorn, and stood on a pyramid at the summit of the belfry of the church of St. Augustine (Cabæus, “Philos. Magn.,” p. 62; “Ulysses Aldrovandi, Patr. Bonon ... Barthol. Ambros ...” Lib. i, cap. 6, p. 134).

For the account given by Aldrovandi of the Arimini observation and for references to Browne’s “Pseudodoxia Epidemica,” as well as to Boyle’s “Experiments,” see p. 53 of the valuable “Notes on the ‘De Magnete’ of Dr. William Gilbert,” by Silvanus P. Thompson, attached to the English translation of the original 1600 edition, which was so attractively produced by the Gilbert Club during the year 1900. Dr. Thompson further gives, at the page following (54), additional references to examples of iron acquiring strong permanent magnetism from the earth.

References.—Biography of Sarpi in the “Encycl. Brit.,” ninth edition, Vol. XXI. pp. 311–313; F. Micanzio, “Vita de F. P. Sarpi,” Verona, 1750; Rev. Alex. Robertson, “Fra Paolo Sarpi—the greatest of the Venetians,” 1894; Hallam, “Intro. to Lit.,” 1839, Vol. II. p. 464; U. Aldrovandi, “Musæum Metallicum,” 1648, p. 134; Tiraboschi, “Storia della Lettera,” Modena, 1794, Vol. VI. part ii. p. 506; Sarpi’s Complete Works, first published at Helmstat, 1750; Fabroni, “Vitæ Italorum,” Pisa, 1798; Giovini, “Vita,” Brussels, 1836; “Engl. Cycl.,” Biography, Vol. IV. pp. 695–697; Larousse, “Dict. Univ.” Vol. XIV. pp. 230–231; “History of the reign of Charles the Fifth,” by Wm. Robertson and Wm. H. Prescott, Philadelphia, 1883, Vol. III. p. 68; “Dict. Hist. de la Médecine,” N. F. J. Eloy, Mons, 1778, Vol. IV. pp. 180–181; “The Atlantic Monthly,” New York, January and February, 1904, wherein the author, Andrew D. White, ranks Sarpi with Machiavelli and Galileo; Libri, “Hist. des Sc. Mathém.” Paris, 1838, Vol. IV. p. 214, note.

A.D. 1632.—Gassendi (Pierre), an eminent French savant, professor at the Royal College of France, “ranked by Barrow among the most eminent mathematicians of the age, and mentioned with Galileo, Gilbert and Descartes,” discovers that a part of the iron cross of the Church of St. Jean at Aix possesses all the properties of a loadstone after being struck by lightning and lying in one position a certain length of time. Gilbert mentions, “De Magnete,” 1600, Book III. chap. xii.) that the fact of magnetism being imparted to an iron bar by the earth was first ascertained by examining the rod upon the tower of the church of St. Augustine at Arimini (Sir Thomas Browne, “Pseud. Epidemica,” London, 1650, p. 48; U. Aldrovandi, “Musæum Metallicum,” Milan, 1648, p. 134).

In the “Vie de Pierre Gassendi,” par le Père Bougerel de l’Oratoire, Paris, 1737, p. 14, it is related that during the month of September 1621, while promenading about three leagues’ distance from Aix in a village named Peynier, he observed a light in the heavens to which he gave the name of aurora borealis, as much on account of its location as by reason of its resemblance to the light which precedes the rising of the sun.

From the “History of the Royal Society,” by C. R. Weld, 1848, Vol. II. p. 430, is taken the following, communicated by Humboldt:

“The movement of the magnetic lines, the first recognition of which is usually ascribed to Gassendi, was not even yet conjectured by William Gilbert; but, at an early period, Acosta, ‘from the information of Portuguese navigators,’ assumed four lines of no declination upon the surface of the globe.... In the remarkable map of America appended to the Roman edition of the Geography of Ptolemy in 1508, we find, to the north of Gruentland (Greenland), a part of Asia represented and the magnetic pole marked as an insular mountain. Martin Cortez, in the ‘Breve Compendio de la Sphera’ (1545), and Livio Sanuto, in the ‘Geographia di Tolomeo’ (1588), place it more to the south. Sanuto entertained a prejudice, which, strange to say, has existed in later times, that a man who should be so fortunate as to reach the magnetic pole (Il calamitico) would then experience alcun miracoloso stupendo effecto” (“Cosmos,” translated under the superintendence of Col. Sabine, Vol. II. p. 280). In a footnote to the Otté translation of Humboldt, 1859, Vol. V. p. 58, it is stated that calamitico was the name given to the instruments in consequence of the first needles for the compass having been made in the shape of a frog.

In Gilbert’s “De Magnete,” allusion is made to Martinus Cortez, Book I. chap. i., also Book III. chap. i. and Book IV. chap. i.,[43] and to Livio Sanuto in Book I. chap. i., also in Book IV. chaps. i. and ix. In these several passages, Gilbert tells us that Martinus Cortez holds the loadstone’s seat of attraction to be beyond the poles, and he states the views of other writers in this respect, citing more particularly T. de Bessard (author of “Le Dialogue de la Longitude”), Jacobus Servertius (who wrote “De Orbis Catoptrici”), as well as Robert Norman, Franciscus Maurolycus, Marsilio Ficino, Cardan, Scaliger, Costa and Petrus Peregrinus (M. J. Klaproth, “Lettre à M. le Baron de Humboldt,” Paris, 1834, pp. 16–17, 37).

References.—Enfield, “Hist. Phil.,” Vol. III. p. 430; “Le Cosmos” for May and June 1859, containing a very interesting series entitled, “Les Armées Météores”; Lardner, Vol. II. p. 113; Humboldt, “Cosmos,” 1859–1860, Vol. II. p. 335, and Vol. V. pp. 146–153; Julius Cæsar at A.D. 1590; Houzeau et Lancaster, Vol. II. p. 146; “Mém. de l’Acad. Royale des Sciences,” Vol. X. p. 737; “Phil. Hist. and Memoirs of the Royal Acad. of Sc.,” Vol. II. p. 281; “Geschichte der Mathematik,” Vol. IV. p. 474.

A.D. 1632.—Galileo (Galileo Galilei), Italian philosopher and mathematician, publishes his celebrated “Dialogo sopra i due massimi sistemi del mondo tolemaico e copernicano,” 4to, Fiorenza, from p. 88 of which is extracted the following passage:

Sagredus: “You remind me of a man who offered to sell me a secret for permitting one to speak, through the attraction of a certain magnet needle, to someone distant two or three thousand miles, and I said to him that I would be willing to purchase it, but that I would like to witness a trial of it, and that it would please me to test it, I being in one room and he being in another. He told me that, at such a short distance, the action could not be witnessed to advantage; so I sent him away and said that I could not just then go to Egypt or Muscovy to see his experiment, but if he would go there himself I would stay and attend to the rest in Venice.”

This Sagredus (Iohannes Franciscus), or Sagredo (Giovanni Francisco), besides being “a great magneticall man,” was a noble Venetian, even a doge, and had represented his country as ambassador at several courts. We read in Mr. Conrad W. Cooke’s very able article on William Gilbert of Colchester, originally printed in London “Engineering,” that this same Sagredus was the intimate friend of Galileo, and that, together with the powerful Sarpi, he used the whole might of his name and influence to protect the great philosopher and mathematician from the attacks of the clerical party. Pietro Sarpi, otherwise known as Father Paul, was, as already shown, a most illustrious Venetian scholar, who attained great proficiency in the medical and physiological sciences as well as in mathematics and in natural philosophy. Sagredus made several meritorious researches in magnetism, and, while on a voyage to Aleppo, ascertained the declination of the magnetic needle at that place. As a tribute to the scientific attainments of Sagredus, Galileo gave his name to one of the characters in his “Systema Cosmicum,” and many references to the work by William Gilbert are put into the mouth of Sagredus.

In further illustration of Galileo’s appreciation of Gilbert, the following is quoted from the great astronomer’s own writing: “I extremely admire and envy the author of ‘De Magnete.’ I think him worthy of the greatest praise for the many new and true observations which he has made, to the disgrace of so many vain and fabling authors, who write not from their own knowledge only, but repeat everything they hear from the foolish and vulgar, without attempting to satisfy themselves of the same by experience; perhaps that they may not diminish the size of their books” (Drinkwater’s “Life of Galileo”).

Galileo had also published, in 1630, the first edition of his “I discorsi e demonstrazioni ...” which Lagrange considers to be Galileo’s most substantial title to scientific glory.

References.—Galileo’s Biography in “Engl. Cycl.,” Vol. III. pp. 13–17; Miller, “Hist. Phil. Illust.,” London, 1849, Vol. III. p. 203, note; Nelli, “Vita,” 1793; Libri, “Hist. des Sc. Math.,” Paris, 1838, Vol. IV. pp. 157–294, 473–484; Houzeau et Lancaster, “Bibliog. Générale,” Vol. I. part i. pp. 655–657 for an analyzation of the works of Galileo, also Vol. II. pp. 137–145, 1576–1578; Wm. Whewell, “Phil. of the Ind. Sc.,” London, 1840, Vol. II. pp. 379–383; Guillaume Libri, “Histoire des Sc. Math.,” Halle, 1865, Vol. IV. pp. 157–302, and the notes; “Journal des Savants” for September and October 1840, for March and April 1841, for July to November 1858, for September 1868 and for October 1877; “Geschichte der Mathem.,” Vol. IV. pp. 4, 173, etc.; Larousse, “Dict.,” Vol. VIII. p. 954; “La Grande Encycl.,” Vol. XVIII. pp. 383–385; “Biog. Gén.,” Vol. XI. pp. 252–267; Fabroni (A.), “Vitæ Italorum,” 1778–1805, also “Elogi d’Illustri Italiani,” 1786–1789; likewise the very numerous entries concerning Galileo’s history, his Opponents, Supporters and School, which appear at pp. 331–357, Part I. of Libri’s “Catalogue,” published in 1861. Consult also “Galileo,” by Ed. S. Holden, in the “Popular Sc. Monthly” for January, February, May and June 1905; “Bibliot. Brit.,” Vol. XVI. N.S., 1821, pp. 3–21, 79–100, for an account of the life of Galileo by M. G. B. Clément de Nelli; “Journal des Sçavans,” Vol. LXX. for 1721, p. 350 in his “Saggiotore”; “Imperial Dictionary of Universal Biography,” published by Wm. McKenzie, London, pp. 536–539, giving an account of Galileo’s other discoveries.

A.D. 1635.—Delambre (J. B. J.) (1749–1822), professor of astronomy at the Royal College of France, refers (Vol. II. p. 545 of his “Histoire de l’Astronomie Ancienne,” 1817) to the mention made in “Procli Diadochi Paraphrasis Ptolem.,” lib. iv. “de siderum effectionibus,” 1635, p. 20, of the notion long current, especially along the shores of the Mediterranean, “that if a magnetic rod be rubbed with an onion, or brought into contact with the emanations of the plant, the directive force will be diminished, while a compass thus treated would mislead the steersman.”

References.—Humboldt, “Cosmos,” 1859, Vol. V. p. 156, also the entry at A.D. 1653. See likewise Whewell, “Hist. of the Ind. Sc.,” Vol. I. pp. 442, 443, 447, and the biography in the Supplement of the “English Cyclopædia,” pp. 539–541; “Journal des Savants,” for April 1828.

A.D. 1635.—Gellibrand (Henry), prominent English mathematician, professor of geometry and the successor of Edmund Gunter (A.D. 1624), in the chair of astronomy at Gresham College, publishes his discovery of the secular variation of the declination. The credit of this discovery has been by many given to John Mair. The diurnal and horary variation was found by Graham in 1722, and the annual variation was discovered by Cassini, 1782–1791.

Gellibrand’s discovery is published in a small quarto pamphlet entitled “A discourse mathematical on the variation of the magneticall needle—together with the admirable diminution lately discovered,” and is the result of his study of the observations made by Burrough and Gunter as well as of observations made by himself, all showing that the north-east of the needle was gradually moving to the westward.

Mention has already been made of the fact that the variation of the variation was at this period attracting the attention it deserved, and it is worth while giving here an account of the discovery in the author’s own words:

“Thus, hitherto, according to the Tenents of all our Magnetical Philosophers, we have supposed the variations of all particular places to continue one and the same. So that when a Seaman shall happly return to a place where formerly he found the same variation, he may hence conclude he is in the same former longitude. For it is the assertion of Mr. Dr. Gilbert’s Variatio unicuiusq; loci constans est, that is to say, the same place doth always retaine the same variation. Neither hath this assertion, for ought I ever heard, been questioned by any man. But most diligent magneticall observations have plainely offered violence to the same, and proved the contrary, namely, that the variation is accompanied with a variation.”

A.D. 1637.—Bond (Henry), Professor of Mathematics in London, and who appears in one of his treatises as “a famous teacher of the art of navigation,” is the author of the “Seaman’s Kalendar ... with a discovery of the ... secret of longitude ...” of which other editions appeared during 1640 and 1696.

This was followed by many papers on the variation (the most important of which are to be found in Phil. Trans. for 1668, 1672, 1673) and, during 1678 by “The Longitude not found, or an answer to a treatise written by H. B. ...” This treatise was in a sixty-five page pamphlet which had been issued by Mr. Bond’s father during 1676, under caption: “The Longitude Found; or a treatise shewing an easie and speedy way, as well by Night as by Day, to find the Longitude, having but the Latitude of the Place and the Inclination of the Magneticall Inclinatorie Needle ...” wherein he explains his discovery of the progress of the deviation of the compass and foretells the variations for London, 1663 to 1716. This treatise led to the controversy with Peter Blackborrow (Beckborrow), the title to whose published work reads: “The Longitude not found: or an answer to a treatise written by H. Bond, senior, shewing a way to find the longitude by the magnetical inclinatory needle: wherein is proved that the longitude is not nor cannot be found by the magnetic inclinatory needle.”

As Humboldt remarks, the resulting controversy, together with Acosta’s view that there were four lines of no variation which divided the earth’s surface, may, as already stated, have had some influence on the theory advanced, in 1683, by Edmund Halley, of four magnetic poles or points of convergence (“Cosmos,” 1859–1860, Vol. I. p. 193, note; Vol. II. pp. 280–281, note; Vol. V. p. 58; also Humboldt’s “Examen Critique de l’Histoire de la Géographie,” Vol. III. p. 60. See likewise the Phil. Trans. for October 19, 1668, p. 790, and for 1673, Vol. VIII. p. 6065, also following abridgments: Hutton, Vol. II. p. 78, and Lowthorp Vol. II. p. 610).

References.—Walker, “Magnetism,” Chap. I; John Pell, “Letter of Remarks on Gellibrand’s Math. Disc.,” 1635; “Annales de Chimie et de Physique,” Mars 1902, Vol. XXV. pp. 289–307; Humboldt, “Cosmos,” 1859, Vol. V. pp. 61, 116; Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. II. p. 219; G. Hellmann, “Neudrucke von Schriften,” No. 9; Baddam’s abridgments of the Phil. Trans., 1739, Vol. IV. p. 102.

A.D. 1641.—Wilkins (John), Bishop of Chester in the reign of Charles II, publishes the first edition of “Mercury, or the secret and swift messenger, showing how a man, with privacy and speed, may communicate his thoughts to a friend at any distance.”[44]

In the above, he thus alludes to the possibility of making a contrivance similar to our modern phonograph: “There is another experiment ... mentioned by Walchius, who thinks it possible so to contrive a trunk or hollow pipe that it shall preserve the voice entirely for certain hours or days, so that a man may send his words to a friend instead of his writing. There being always a certain space of intermission, for the passage of the voice, betwixt its going into these cavities and its coming out; he conceives that if both ends were seasonably stopped, while the sound was in the midst, it would continue there till it had some vent. Huic tubo verba nostra insusurremus, et cum probe munitur tabellario committamus, etc. When the friend to whom it is sent shall receive and open it, the words shall come out distinctly, and in the same order wherein they were spoken. From such a contrivance as this [saith the same author] did Albertus Magnus make his Image, and Friar Bacon his Brazen Head, to utter certain words.”

In the eighteenth chapter, he makes suggestions for “a language that may consist of only tunes and musical notes, without any articulate sound.”

He had previously described a novel mode of telegraphing by the use of only three torches (or lights), to designate the twenty-four letters of the alphabet. These letters were, according to the plan of Joachimus Fortius, to be placed in three classes of eight each. One torch indicated Class I, two torches Class II, three torches Class III, and the number of the letter was shown by the number of times a torch was elevated.

Bishop Wilkins also described a method of telegraphing by means of two lights attached to long poles, which, he says, “for its quickness and speed is much to be preferred before any of the rest.” To interpret messages at long distances, he suggested the use of the then newly invented telescope; which he called “Galileus his perspective.”

References.—The third edition of above-named work, Chap. XVII. pp. 71, 72, also the fifth edition of Wilkin’s “Mathematical Magick,” London, 1707, Chap. XIII. pp. 147–150, “concerning several attempts of contriving a perpetual motion by magnetical virtues.” Likewise Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. I. pp. 332, 395; Mendoza, “Tratado de Navegacion,” Vol. II. p. 72; Alex. Chalmers, “Gen. Biog. Dict.,” London, 1811, Vol. XXXII. pp. 74–82.

A.D. 1641.—Kircher (Athanasius), a German writer on physical and mathematical science (1601–1680), member of the Order of Jesuits, possessed of immense erudition and believing in the magnetism of all things, speaks in his “Magnes sive de arte magnetica” (Book II. pt. iv. chap. v.), of the recently advanced idea of being able to correspond at short distances by employing two spherical vessels bearing the letters of the alphabet, each of the letters having suspended from it a magnetized figure attached to a vertical wire.

He likewise alludes to Gellibrand’s discovery, A.D. 1635, of which he was informed by John Greaves, the eminent English mathematician, and he communicates a letter received from the learned French philosopher, le Père Marin Mersenne, containing a distinct account of the same.

His definition of universal magnetism, according to Madame Blavatsky, is very original, for he contradicted Gilbert’s theory that the earth was a great magnet. He asserted that, although every particle of matter and even the intangible “powers” were magnetic, they did not themselves constitute a magnet. There is but one Magnet in the universe, and from it proceeds the magnetization of everything existing. This magnet is, of course, what the Kabalists term the central Spiritual Sun, or God.... He demonstrates the difference between mineral magnetism and zoömagnetism, or animal magnetism, and says that the sun is the most magnetic of all bodies.... It imparts the binding power to all things falling under its direct rays (“Isis Unveiled,” pp. 208–210).

Another Jesuit, Jacobo Grandamico (1588–1672), published in 1645, “Nova demonstratio immobilitatis terræ petita ex virtute magnetica,” wherein he shares fully the views of Niccolas Cabæus, Athanasius Kircher, Vincentus Leotaudus and others of the same Order relative to the earth’s magnetism (Larousse, “Dict.,” Vol. VIII. p. 1445).

References.—“Journal des Sçavans” pour 1665 et 1666, pp. 519–525, 571–578; “Nouveau Larousse,” par Claude Augé, Paris, Vol. V. p. 485; “Salmonsen ... konversationsleksikon,” 1900, p. 480; Van Swinden, “Recueil,” 1784, Vol. II. pp. 352, 361, 394, and the different works named in Ronalds’s “Catalogue,” pp. 266–267; ninth ed. “Encycl. Brit.,” Vol. XIV. pp. 93–94.

A.D. 1644.—Digby (Sir Kenelme), the very famous Englishman to whom allusion has already been made under the B.C. 600–580 entry, publishes, in Paris, “Two Treatises, in the one of which the Nature of Bodies: in the other, the nature of Man’s Soule is looked into: in Way of Discovery of the Immortality of Reasonable Soules.”[45] In a chapter of this work, entitled “Of the lodestone’s generation and its particular motions,” appears the following interesting reference to Gilbert’s work and reputation: “But to come to experimentall proofes and obseruations vpon the loadstone by which it will appeare that these causes are well esteemed and applyed, we must be beholding to that admirable searcher of the nature of the loadstone, Doctor Gilbert: by means of whom and of Doctor Haruey, our nation may claim euen in this latter age as deserued a crowne for solide Philosophicall learning as for many ages together it hath done formerly for acute and subtile Speculations in Diuinity. But before I fall to particulars, I thinke it worth warning my Reader, how this great man arriued to discouer so much of Magneticall Philosophy; that he, likewise, if he be desirous to search into nature, may, by imitation, advance his thoughts and knowledge that way. In short, then, all the knowledge he gott of this subject was by forming a little loadstone into the shape of the earth. By which meanes he compassed a wonderful designe, which was to make the whole globe of the earth maniable; for he found the properties of the whole earth in that little body; which he therefore called a Terrella, or little earth; and which he could manage and trye experiences vpon att his will. And, in like manner, any man that hath an ayme to aduance much in naturall sciences, must endeauour to draw the matter he inquireth of, into some such modell, or some kinde of manageable methode; which he may turne and winde as he pleaseth. And then lett him be sure, if he hath a competent vnderstanding, that he will not misse of his marke.”

References.—“The Private Memoirs of Sir Kenelme Digby, Gentleman of the Bedchamber of King Charles I,” London, 1827; “Dict. of Nat. Biog.,” Vol. XV. pp. 60–66; “New Gen. Biog. Dict.,” London, 1850, Vol. XI. p. 390; “Gen. Biog. Dict.” of Alex. Chalmers, London, 1811, pp. 70–78; “Emerson’s Works,” London, 1873, Vol. II. p. 35; “The Library” for April 1902, has, at pp. 131–132, the arms of the Digbys.

A.D. 1644.—Descartes (René), a prominent French philosopher and mathematician, publishes his “Principia Philosophiæ,” divided into four parts; the first giving an exposition of the principles of all human knowledge, the second treating of the principles of natural things, and the third and fourth parts developing his theory of vortices. His main idea was that a rush of subtle matter passes very rapidly through the earth from the equator towards each pole, being opposed by magnetic substances throughout its passage and that the sun is the centre of a vortex of an ethereal fluid, whose whirling motion produces the revolution of planets about the sun, or around the fixed stars. Moreover, as Noad states it, “the vortex moves with the greatest facility in a particular direction, one of its ends being always turned toward the north.”

One of the most prominent fellow-students of Descartes was Marin Mersenne, who joined the religious Order of “Minimes,” and who, after publishing in 1634 and 1639 “Les Mécaniques de Galilée” and “Nouvelles Découvertes de Galilée,” brought out, during the years 1644 and 1647, his well-known “Cogitata physico-mathematica,” which, Montucla says, contains un océan d’observations de toutes espèces ... and embraces a very interesting treatise on navigation besides many letters from leading scientists of that period not elsewhere to be found.

References.—“La grande Encyclopédie,” Vol. XXIII. pp. 730–731; Larousse, “Dict.,” Vol. XI. p. 94; “Biographie Générale,” Vol. XXXV. pp. 118–123; “The English Cyclopædia,” Vol. IV. p. 206; Alex. Chalmers, “Gen. Biog. Dict.,” London, 1811, Vol. XXII. pp. 81–83; “Biographie Universelle,” Vol. X. pp. 465–473; Whewell, “Hist. of the Ind. Sc.,” Vol. I. pp. 323, 328, 338, 339, 343, 354, 387, 423, 429, 430; Vol. II. p. 220; likewise pp. 320 and 390 of Vol. I. relative to Le Père Marin Mersenne and pp. 391 and 423 concerning the “Traité de Physique” of James Rohault; Playfair’s Fourth Dissertation in the eighth edition of the “Encycl. Britann.”; “Essai théorique ... des connaissances humaines,” par G. Tiberghien, Bruxelles, 1844, Vol. I. pp. 472–495; Dr. W. Windelband, “History of Philosophy,” New York, 1893, pp. 380–381, 391–396; Dr. F. Ueberweg, “History of Philosophy,” New York, 1885, Vol. II. pp. 41–55; Alfred Weber, “History of Philosophy,” translated by Frank Thilly, New York, 1896, pp. 305–323; Ruard Andala, “Descartes in reality the overturner of Spinosism and the architect of experimental Philosophy”; Erasmus Bartholinus, “De Cometis,” Copenhagen, 1664–1665 (“Biog. Univ.”; Weidler, p. 508) Mahaffy, 1880; Houzeau et Lancaster, “Bibl. Gen.,” Vol. II. for Descartes, p. 119, and for Mersenne, p. 204; “Journal des Savants” for Feb. 1826, p. 103, for Feb. 1827, p. 110, also for Aug.-Oct. 1850, Dec. 1860, Jan.-Feb. 1861, Oct.-Nov. 1869, Feb., April and July 1870, Mar.-April 1880, Aug. 1884, April 1898, Feb. 1899.

A.D. 1646.—Browne (Sir Thomas), an eminent English physician and writer, publishes the well-known treatise “Pseudodoxia Epidemica, or Inquiries into Vulgar and Common Errors,” which ran through six editions in twenty-seven years, and upon which his fame is principally established.

With regard to the possibility of such a magnetic telegraph as Strada speaks of he says (Book II. chap. iii.): “The conceit is excellent and, if the effect would follow, somewhat divine; whereby we might communicate like spirits, and confer on earth with Menippus in the moon. And this is pretended from the sympathy of two needles, touched with the same loadstone, and placed in the centre of two abecedary circles or rings, with letters described round about them, one friend keeping one and another keeping the other, and agreeing upon the hour when they will communicate, at what distance of place soever, when one needle shall be removed unto another letter, the other, by wonderful sympathy, will move unto the same.”

As the result of experiment, he found that “though the needles were separated but half a span, when one was moved the other would stand like the pillars of Hercules, and if the earth stand still, have surely no motion at all.... By electrical bodies,” he says, “I understand not such as are metallical, mentioned by Pliny and the ancients; for their electrum was a mixture made of gold, with the addition of a fifth part of silver; a substance now as unknown as true aurichalcum, or Corinthian brass, and set down among things lost by Pancirollus. Nor by electric bodies do I imagine such only as take up shavings, straws and light bodies, amongst which the ancients placed only jet and amber, but such as, conveniently placed unto their objects, attract all bodies palpable whatsoever. I say conveniently placed, that is, in regard of the object, that it be not too ponderous or any way affixed; in regard of the agent, that it be not foul or sullied, but wiped, rubbed and excitated; in regard of both, that they be conveniently distant, and no impediment interposed. I say, all bodies palpable, thereby excluding fire, which indeed it will not attract, nor yet draw through it, for fire consumes its effluxions by which it should attract.”

The different chapters of this second book treat of the loadstone, of bodies magnetical and electrical, of magnetical rocks and attractive mountains, and also make allusion to the cross on the church of St. John in Ariminium, to the reported magnetical suspension of Mahomet’s tomb, etc. etc.

At pp. 64, 81 and 87 of Chap. II he says: “Neither is it onely true, what Gilbertus first observed, that irons refrigerated North and South acquire a directive faculty; but if they be cooled upright and perpendicularly, they will also obtain the same.... Now this kind of practice, Libavius, Gilbertus and lately Swickardus, condemn, as vain and altogether unuseful; because a loadstone in powder hath no attractive power; for, in that form, it omits the polarity and loseth those parts which are the rule of attraction.... Glasse attracts but weakely though cleere, some slick stones and thick glasses attract indifferently; Arsenic not at all; Saltes generally but weakely, as Sal Gemma, Allum and also Talke, nor very discoverably by any frication; but, if gently warmed at the fire and wiped with a dry cloth, they will better develop their Electricities.”

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.