HOW A LODESTONE ATTRACTS IRON
If you wish the stone, according to its natural desire, to attract iron,
proceed as follows: Mark the north end of the iron and towards this end
approach the south pole of the stone, when it will be found to follow
the latter. Or, on the contrary, to the south part of the iron present
the north pole of the stone and the latter will attract it without any
difficulty. Should you, however, do the opposite, namely, if you bring
the north end of the stone towards the north pole of the iron, you will
notice the iron turn round until its south pole unites with the north
end of the lodestone. The same thing will occur when the south end of
the lodestone is brought near the south pole of the iron. Should force
be exerted at either pole, so that when the south pole of the iron is
made touch the south end of the stone, then the virtue in the iron will
be easily altered in such a manner that what was before the south end
will now become the north and conversely. The cause is that the last
impression acts, confounds, or counteracts and alters the force of the
original movement.