On the Magnet/II-19

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On the Magnet
by William Gilbert
Book II. Chap. 19.
[ 88 ]
CHAP. XIX.
Union with an armed Loadstone is stronger;
hence greater weights are raised; but the
coition is not stronger[176], but
generally weaker.


Gilbert De Magnete IlloA.jpg
n armed magnet raises a greater weight, as is manifest to all; but a piece of iron moves towards a stone at an equal, or rather greater, distance when it * is bare, without an iron cap. This must be tried with two pieces of iron of the same weight and figure at an equal distance, or with one and the same versorium, the test being made first with an armed, then with an unarmed loadstone, at equal distances.
The page and line references given in these notes are in all cases first to the Latin edition of 1600, and secondly to the English edition of 1900.

176 ^  Page 88, line 2. Page 88, line 3. Coitio verò non fortior.—This heading to chap. xix., taken with the seven lines that follow, and the contrast drawn between unitio and coitio, throw much light on the fundamental sense attached by Gilbert to the term coitio. It is here clearly used in the sense of mutual tendency toward union. Note also the contrasted use in chap. xx. of the verbs cohære and adhære. Adhærence connotes a one-sided force (an impossibility in physics), cohærence a mutual force.