On the Magnet, by William Gilbert

Chap. vii.

A determined Verticity and a disponent Faculty are what arrange magneticks, not a force, attracting or pulling them together, nor merely strongish coition or unition.

figure

I n the neighbourhood of the æquinoctial A there is no coition of the ends of a piece of iron with the terrella; at the poles there is the strongest. The greater the distance from the æquinoctial, the stronger is the coition with the stone itself, and with any part of it, not with its pole alone. Yet pieces of iron are not raised up on account of some peculiar attracting force or a stronger combined force, but on account of that common directing or conforming and rotating force; nor indeed is a spike in the part about B, even one that is very small and of no * weight206, raised up to the perpendicular by the strongest terrella, but cleaves to it obliquely. Also just as a terrella attracts magnetick bodies variously with dissimilar forces, so also an iron snout placed on the stone obtains a different potency in proportion to the latitude, * just as a snout at L by its firmer connection resists a greater weight more stoutly than one at M, and at M than at N. But neither does the snout raise the spike to the perpendicular except at the poles, as is shown in the figure. A snout at L may hold and lift from the earth two ounces of iron in one piece; yet it is not strong enough to raise an iron wire of two grains weight to the perpendicular, which would happen if the verticity arose on account of a * stronger attraction, or rather coition or unition.

206 Page 132, line 9. Page 132, line 10. minimus & nullius ponderis.— The editions of 1628 and 1633 both wrongly read est for &.

http://ebooks.adelaide.edu.au/g/gilbert/william/on-the-magnet/book3.7.html

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