shores and empties them whilst it moves from a certain
definite point in the sky back to the same point in a daily revolution.
This motion of the waters is incited and the seas rise and fall no less
when the moon is below the horizon and in the lowest part of the heavens,
than if it had been raised at a height above the horizon. So the whole mass
of the earth interposed[171] does not resist the action of the moon, when
it is below the earth; but the seas bordering on our shores, in certain
positions of the sky when it is below the horizon, are kept in motion, and
likewise stirred by its power (though they are not struck by its rays nor
illuminated by its light), rise, come up with great force, and recede. But
about the reason of the tides anon[172]; here let it suffice to have merely
touched the threshold of the question. In like manner nothing on the earth
can be hidden from the magnetick disposition of the earth or of the stone,
and all magnetical bodies are reduced to order by the dominant form of the
earth, and loadstone and iron show sympathy with a loadstone though solid
bodies be interposed.

* * * * *

CHAP. XVII.

On the Iron Cap of a Loadstone, with which
it is armed at the pole (for the sake of the
_virtue) and on the efficacy of the same._

Conceive a small round plate, concave in shape, of the breadth of a digit
to be applied to the convex polar surface of a loadstone and skilfully
attached; or a piece of iron shaped like an acorn, rising from the base
into an obtuse cone, hollowed out a little and fitted to the surface of the
stone, to be tied to the loadstone. Let the iron be the best steel,
smoothed, shining, and even. A loadstone with such an appliance, which
before only bore four ounces of iron, will now raise twelve. But the
greatest force of a combining or rather united nature is seen {87} when two
loadstones, armed with iron caps, are so joined by their concurrent
(commonly called contrary) ends, that they mutually * attract and raise one
another. In this way a weight of twenty ounces is raised, when either stone
unarmed would only allure four ounces of iron. Iron unites to an armed
loadstone more firmly than to a loadstone; and on that account raises
greater weights, because the pieces of iron stick more pertinaciously to
one that is armed. For by the near presence of the magnet they are cemented
together, and since the armature[173] conceives a magnetick vigour