, in accordance with magnetick rules, turned round
and changed, excited, repaired, or disturbed. But a loadstone itself, by
being rubbed on another, whether a larger or a more powerful stone, is not
disturbed from its own property and verticity, nor does it turn round
toward the opposite direction in its boat, or to the other pole opposite to
that to which it inclines by its own nature and implanted verticity. For
strength which is innate and has been implanted for a very long time abides
more firmly, nor does it easily yield from its ancient holding; and that
which has grown for a long time is not all of a sudden brought to nothing,
without the destruction of the substance containing it. Nevertheless in a
long interval of time a change * does take place; in one year, that is to
say, or two, or sometimes in a few months; doubtless when a weaker
loadstone remains lying by a stronger one contrary to the order of nature,
namely, with the northern pole of one loadstone adjoined to the northern
pole of another, or the southern to the southern. For so the weaker
strength gradually declines with the lapse of time.

* * * * *

CHAP. XI.

On the Rubbing of a piece of Iron on a Loadstone
in places midway between the poles, and upon
_the aequinoctial of a terrella_.

Select a piece of iron wire of three digits length, not touched by a
loadstone (but it will be better if its acquired verticity be rather weak
or have been damaged in some way); touch it and rub it on the aequator of a
terrella, exactly on the aequinoctial line in the direction of its length,
on the one end, or the ends only, or in all its parts; place the wire
touched in this * way on water in a cork fitted for it; it will swim about
doubtfully on the waves without any acquired verticity, and the verticity
previously implanted will be disturbed. If, however, it float by chance
toward the poles, it will be checked a little by the poles of the earth,
and will at length by the influence of the earth be indued with verticity.

* * * * *

{139} CHAP. XII.

In what way Verticity exists in any Iron that has
_been smelted though not excited by a lodestone_.

[Illustration]

Having thus far[211] demonstrated natural and inborn causes and powers
acquired by means of the stone, we will now examine the causes of magnetick
virtues in smelted iron that has not been excited by a stone. Loadstone and
iron f