though it does not so eagerly snatch and
suddenly pluck at it as would a fairly strong loadstone; this you may know
thus: A small piece of cork, the size of a hazel-nut, rounded, is traversed
by an iron wire up to the middle of the wire: when set swimming on still
water apply to one end of it, close (yet so as not to touch), the end of
another iron wire; and wire draws wire, and one follows the other when
slowly drawn back, and this goes on up to the proper boundaries. Let A be
the cork with the iron wire, B one end of it raised a little above the
surface of the water, C the end of the second wire, showing the way in
which B is drawn by C. You may prove it in another way in a larger body.
Let a long bright iron rod (such as is made for hangings and window
curtains) be hung in balance by a slender silken cord: to one end of this
as it rests in the air bring a small oblong mass of polished iron, with its
proper {30} end at the distance of half a digit. The balanced iron turns
itself to the mass; do you with the same quickness draw back the mass in
your hand in a circular path about the point of equilibrium of the
suspension; the end of the balanced iron follows after it, and turns in an
orbit.

[Illustration]

* * * * *

CHAP. XII.

*

A long piece of Iron, even though not excited by a
_loadstone, settles itself toward North and South._

Every good and perfect piece of iron, if drawn out in length, points North
and South, just as the loadstone or iron rubbed with a magnetical body
does; a thing that our famous philosophers have little understood, who have
sweated in vain to set forth the magnetick virtues and the causes of the
friendship of iron for the stone. You may experiment with either large or
small iron works, and either in air or in water. A straight piece of iron
six feet long of the thickness of your finger is suspended (in the way
described in the foregoing chapter) in exact aequipoise by a strong and
slender silken cord. But the cord should be cross-woven of several silk
filaments, not twisted simply in one way; and it should be in a small
chamber with all doors and windows closed, that the wind may not enter, nor
the air of the room be in any way disturbed; for which reason it is not
expedient that the trial should be made on windy days, or while a storm is
brewing. For thus it freely follows its bent, and slowly moves until at
length, as it rests, it points with its en