A.D. 1693.—In the first volume (Letter IV. pp. 25–28) of the “Memoirs for the Ingenious ...” by J. de la Crosse, are given accounts of several “New experiments on the loadstone; of a needle touch’d with it, and plac’d directly over the needle of a compass; of two Mariner’s Needles hang’d freely over one another, at several distances; of a touch’d steel-ring. Reasons of these experiments. The earth magnetical.”
In explanation of all this, M. de la Hire supposes “that the mass of the earth is a great loadstone, which directs the poles of the same name in all the loadstones and touch’d needles, towards the same place of the earth; so that the two hang’d needles do but remove from this natural position by the particular force they have of driving away each other’s poles of the same name; which force, in a certain degree, is not sufficient to overcome the power of the great loadstone of the earth.”
An account of M. P. de la Hire’s “new sort of a magnetical compass” had already appeared in the Phil. Trans. for 1686–1687, Vol. XVI. No. 188, p. 344.
References.—For De la Hire, the following abridgments of the Phil. Trans.: Lowthorp, London, 1722, Vol. II. pp. 620–622; Baddam, London, 1739, Vol. IV. pp. 473–478; Hutton, London, 1809, Vol. III. p. 381; also “The Phil. Hist. and Mem. of the Roy. Acad. at Paris,” by Martyn and Chambers, London, 1742, Vol. II. pp. 273–277; Vol. V. pp. 272–282 and the “Table Alphab. ... Acad. Royale,” by M. Godin, Paris, Vol. II. p. 16 and Vol. X. pp. 164 and 734.
A.D. 1696.—Zahn (F. Joannes), prebendary of the Prémontrés Order at Celle near Wurtzburg and provost of the convent of Niederzell, celebrated for his philosophical and mathematical studies, publishes his highly valued “Specula physico-mathematico-historica-notabilium ac mirabilium sciendorum ...” throughout the three folio volumes of which he treats extensively of the wonders of the entire universe.
In his tabulated list of the origin and properties of all the different known gems and stones (Vol. II. chap. vii. p. 55), he states that the loadstone, first discovered at Magnesia in Lydia (Caria—on the Mæander) is heavy, very well shaped, and of a dark colour verging upon blue. The marvellous properties of gems and stones are detailed at pp. 59–73 of the same volume, the fifth paragraph of Chap. VIII treating of the loadstone’s many virtues and admirable qualities, as exemplified in the writings of Guilielmus Gilbertus, Nicolaus Zucchius, Nicolaus Cabæus, Athanasius Kircherus, Eusebius Nierembergius, Laurentius Forerus, Hieronymus Dandinus, Jacobus Grandamicus, Ludovicus Alcazar, Claudius Franciscus Milliet de Chales, as well as of many others.
References.—Michaud, “Biog. Univ.,” Vol. XLV. p. 340; Dr. John Thomas, “Universal Pron. Dict.,” 1886, p. 2514; Brunet, “Manuel du Libraire,” Vol. V. p. 1519.
A.D. 1700.—Bernoulli (John I), son of Nicolas, the founder of the celebrated family of that name, improves upon Picard’s discovery of the electrical appearance of the barometer, made A.D. 1675, by devising a mercurial phosphorus or mercury shining in vacuo (“Diss. Physica de Mercurio Lucente,” etc., Basel, 1719). This procured the favourable notice of King Frederick I, of Prussia, who rewarded him with a medal. John Bernoulli I (1667–1748) was a member of nearly every learned society of Europe and “one of the first mathematicians of a mathematical age.” His exceedingly valuable memoirs, found in all the scientific transactions of the day, were first collected in their entirety during the year 1742, by Cramer, Professor of Mathematics, and published at Lausanne and Geneva.
“Is it not surprising,” remarks Prof. Robison, in his able article on “Dynamics” (Eighth “Britannica,” Vol. VIII. p. 363), “that, twenty-five years after the publication of Newton’s ‘Principia,’ a mathematician on the Continent should publish a solution in the Memoirs of the French Academy, and boast that he had given the first demonstration of it? Yet, John Bernoulli did this in 1710. Is it not more remarkable that this should be precisely the solution given by Newton, beginning from the same theorem, the 40th I., Prin., following Newton in every step and using the same subsidiary lines? Yet, so it is.” This was five years after he had accepted (1705) the chair of mathematics made vacant by the death of his brother, James I.