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.”