t is in some measure diverted aside. For
when the vigour passes into the middle of an iron plate within the orbe of
the magnetick virtue or placed just {84} opposite the pole of the stone,
that virtue is scattered in very large measure towards its extremities; so
that the edges of a small round * plate of suitable size allure iron wires
on every side. This is also apparent in the case of a long iron wand,
which, when it has been touched by a magnet in the middle, has a like
verticity at either end. *

[Illustration]

B is a loadstone, C D a long rod magnetized in the middle A; E being the
Boreal pole; C is an Austral end or pole; in like manner also the end D is
another Austral pole. But observe here the exactness with which a versorium
touched by a pole, when a round plate is interposed, turns towards the same
pole in the same * way as before the interposition, only weaker; the plate
not standing in the way, because the vigour is diverted through the edges
of the small plate, and passes out of its straight course, but yet the
plate retains in the middle the same verticity, when it is in the
neighbourhood of that pole, and close to it; wherefore the versorium tends
towards the plate, having been touched by the same pole. If a loadstone is
rather weak, a versorium hardly turns when a plate is put in between; for
the vigour of the rather weak loadstone, being diffused through the
extremities, passes less through the * middle. But if the plate has been
touched in this way by a pole in the middle and has been removed from the
stone outside its orbe of virtue, then you will see the point of the same
versorium tend in the contrary direction and desert the centre of the small
plate, which formerly it desired; for outside the orbe of virtue it has an
opposite verticity, in the vicinity the same; for in the vicinity it is, as
it were, a part of the loadstone, and has the same pole.

[Illustration]

A is an iron plate near the pole, B a versorium which tends with its point
towards the centre of the small plate, which has been touched by the pole
of the loadstone C. But if the same small plate be {85} placed outside the
orbe of magnetick virtue, the point will not turn towards its centre, but
the cross E of the same versorium does. But an iron globe interposed (if it
is not too large) attracts the * point of the iron on the other side of the
stone. For the verticity of that side is the same as that of the adjoining
pole of the