B.--MAGNETISM.

Pole of magnet pointing toward the north. N

The opposite pole. S

Force of a pole, quantity of magnetism. _m_

Distance of the poles of a magnet. _l_

Magnetic moment. M = _m.l_

Intensity of magnetization. J

Intensity of the horizontal component of terrestrial

magnetism. H

Scientific American Supplement, No. 595, May 28, 1887 · 第 21 / 39 题