How magnetick pieces of Iron and smaller
_loadstones conform themselves to a terrella & to_
the earth itself, and by them are
_disposed_.
Coition of those bodies which are divided, and do not naturally cohære, if
they are free, occurs through another kind of motion. A terrella sends out
in an orbe its powers in proportion to its vigour and quality. But when
iron or any other magnetick of convenient magnitude comes within its orbe
of virtue, it is allured; but the nearer it comes to the body, the more
quickly it runs up to it. They move towards the magnet, not as * to a
centre, nor towards its centre. For they only do this in the case of the
poles themselves, when namely that which is being allured, and the pole of
the loadstone, and its centre, are in the same straight line. But in the
intervening spaces they tend obliquely, just as is evident in the following
figure, in which it is shown how the influence is extended to the adjoining
magneticks within the orbe; in the case of the poles straight out.
{76} [Illustration]
The nearer the parts are to the æquinoctial, the more obliquely are
magneticals allured; but the parts nearer the poles appeal more directly,
at the poles quite straight. The principle of the turning of all
loadstones, of those which are round and those which are long, is the same,
but in the case of the long ones the experiment is easier. For in whatever
form they are the verticity exists, and there are poles; but on account of
bad and unequal form, they are often hindered by certain evils. If the
stone were long, the vertex is at the ends, not on the sides; it allures
more strongly at the vertex. For the parts bring together stronger forces
to the pole in right lines than oblique. So the stone and the earth conform
their magnetick motions by their nature.
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