und magnet and terrella, and in a narrow one they agree
more and are better united, and a united stronger force excels and is
preeminent. A much weaker office, however, does a plane or oblong stone
perform, when the length is extended according to the leading of the
parallels, and the pole stops neither on the apex nor in the circle and
orbe, but is spread over the flat. Wherefore also it invites a friend
wretchedly, and feebly retains him, so that it is esteemed as one of an
abject and contemptible class, according to its less apt and less suitable
figure.

* * * * *

{83} CHAP. XV.

*

The Magnetick Virtue which is conceived in Iron is
more apparent in an iron rod than in a piece of iron that
_is round, square, or of other figure_.

Duly was it said before that the longer magnet attracts the greater weight
of iron[167]; so also in a longish piece of iron which has been touched the
magnetick force conceived is stronger when the poles exist at the ends. For
the magnetick forces which are driven from the whole in every part into the
poles are not scattered but united in the narrow ends. In square and other
angular figures the influence is dissipated, and does not proceed in
straight lines or in convenient arcs. Suppose also an iron globe have the
shape of the earth, yet for the same reasons it drags magnetick substances
less; wherefore a small iron sphere, when excited, draws another piece of
iron more sluggishly than an excited rod of equal weight.

* * * * *

CHAP. XVI.

Showing that Movements take place by the Magnetical
Vigour though solid bodies lie between; and on
_the interposition of iron plates_.

Float a piece of iron wire on the surface of water by transfixing it
through a suitable cork; or set a versatory piece of iron on a pin or in a
seaman's compass (a magnet being brought near or moved about underneath),
it is put into a state of motion; neither the water, nor the vessel, nor
the compass-box offering resistance in any way. Thick boards do not
obstruct[168], nor earthen vessels nor marble vases, nor the metals
themselves; nothing is so solid as to carry away or impede the forces
excepting an iron plate. Everything which is interposed (even though it is
very dense) does not carry away its influence or obstruct its path, or
indeed in any way hinder, diminish, or retard it. But all the force is not
suppressed by an iron plate, but i