A treatise of artificial magnets ; in which is shewn an easy and expeditious method of making them, superior to the best natural ones, and also, a way of improving the natural ones, and of changing or converting their poles : Directions are likewise given for making the mariner's needles. In the best form, and for touching them most advantageously, &c / by J. Michell.

  • John Michell
Date:
1750
Catalogue details

Licence: Public Domain Mark

Credit: A treatise of artificial magnets ; in which is shewn an easy and expeditious method of making them, superior to the best natural ones, and also, a way of improving the natural ones, and of changing or converting their poles : Directions are likewise given for making the mariner's needles. In the best form, and for touching them most advantageously, &c / by J. Michell. Source: Wellcome Collection.

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    Fifthly, The Poles of Magnets are not at their Extremities, but at a little diflance from thence; that is. Magnets are not fo Magne- tical at the Ends, as in the Middle; and in fpring-temper’d and foft Steel Magnets, the Poles are generally fomewhat farther from the Extremities than in hard ones. * Sixthly, The Attra&lon and Repulfion of Magnets decreafe, as the Squares of the di- fiances from the refpedive Poles increafe. This property, from fome experiments I have made myfelf, and from thofe I have feen c 2 of equality, the greater the diflance of the two Magnets is, with which the experiments are made ; and vice verfa : And fo great is the effed of Magnets on each other, that, when the repellent Poles of a large Magnet and a fmall one are brought into contact, the fmall one fhall fome- times have its Repellency changed into Attradion. * There have been fome, who have imagined, that the decreafe of the Magnetic Attradion and Repulfion is inverfely as the Cubes of the diflances ; others, as the Squares ; and others, that it follows no certain ratio at all, but that it is much quicker at greater diflances, than at fmall ones, and that it is different in different Stones : amongft thefe lafl is Dr. Brook Taylor, and P. Alufcben- broek, who feem to have been pretty accurate in their ex¬ periments. [See Pbilofoph. Tranf. N© 368 and 390. or Vol. VI. Part II. Page 253 and 255. EcuneAs Abridgement.] The conclufions of thefe Gentlemen were drawn from their experiments.