On the Magnet, by William Gilbert

Chap. xxiii.

Magnetick Force causes motion towards unity, and binds firmly together bodies which are united.

M agnetick fragments cohære within their strength well and harmoniously together. Pieces of iron in the presence of a loadstone (even if they are not * touching the loadstone) run together, seek one another anxiously and embrace one another, and when joined are as if they were cemented. Iron * filings or the same reduced to powder inserted in paper tubes, placed upon a stone meridionally or merely brought rather close to it, coalesce into one body, and so many parts suddenly are concreted * and combine; and the whole company of corpuscles thus conspiring together affects another piece of iron and attracts it, as if it constituted one integral rod of iron; and above the stone it is directed toward the North and South. But when they are removed a long * way from the stone, the particles (as if loosed again) are separated and move apart singly. In this way also the foundations of the world are connected and joined and cemented together magnetically. So let Ptolemy of Alexandria, and his followers, and those philosophers of ours, be the less terrified if the earth do move round in a circle, nor threaten its dissolution.

Iron filings, after being heated for a long time, are attracted by a loadstone, yet not so strongly or from so great a distance as when not heated. A loadstone loses some of its virtue by too great a heat; for its humour is set free, whence its peculiar nature is marred. Likewise also, if iron filings are well burnt in a reverberatory furnace and converted into saffron of Mars, they are not attracted by a loadstone; but if they are heated, but not thoroughly burnt, they do stick to a magnet, but less strongly than the filings themselves not acted upon by fire. For the saffron has become totally deformate, but the heated metal acquires a defect from the fire, and the forces in the enfeebled body are less excited by a loadstone; and, the nature of the iron being now ruined, it is not attracted by a loadstone.

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Last updated Friday, March 14, 2014 at 22:17