Bibliographical history of electricity & magnetism : chronologically arranged / Researches into the domain of the early sciences, especially from the period of the revival of scholasticism, with biographical and other accounts of the most distinguished natural philosophers throughout the middle ages, comp. by Paul Fleury Mottelay ; with introduction by the late Prof. Silvanus P. Thompson and foreword by Sir R.T. Glazebrook.

  • Mottelay, Paul Fleury, 1841-
Date:
1922
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Licence: Public Domain Mark

Credit: Bibliographical history of electricity & magnetism : chronologically arranged / Researches into the domain of the early sciences, especially from the period of the revival of scholasticism, with biographical and other accounts of the most distinguished natural philosophers throughout the middle ages, comp. by Paul Fleury Mottelay ; with introduction by the late Prof. Silvanus P. Thompson and foreword by Sir R.T. Glazebrook. Source: Wellcome Collection.

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    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, “ Diet. 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 Academicae,” 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 (Stradae, “ Prol. Acad.,” Oxoniae, 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.,” I75°» Vol. I. p. 354; Abbe Moigno’s Traite de Tel. Elec./’ p. 58;