by William Gilbert

“ The iron not only receives the necessary strength from the loadstone, if it be a good loadstone, but also imparts its acquired strength to another piece of iron, and the second to a third (always in strict accordance with magnetick laws) . In all these demonstrations of ours it should always be borne in mind that the poles of a stone, as well as those of iron, whether touched or untouched, are always in fact and by nature opposite to the pole toward which they point and are so designated by us, as we have laid down above. ”

“ But the reason must be sought, why a piece of iron when touched by a loadstone acquires a disposition to motion toward the opposite pole of the earth, and not toward that pole of the earth to which that pole of that loadstone turned by which it was excited. It has been pointed out that iron and loadstone are of one primary nature; when the iron is joined to the loadstone, they become, as it were, one body, and not only is the end of the iron changed, but the remaining parts also are affected along with it. A, the north pole of a loadstone, is placed against the cusp of a piece of iron ”