HOW TO DISTINGUISH THE POLES OF A LODESTONE
I wish to inform you that this stone bears in itself the likeness of the
heavens, as I will now clearly demonstrate. There are in the heavens two
points more important than all others, because on them, as on pivots,
the celestial sphere revolves: these points are called, one the arctic
or north pole, the other the antarctic or south pole. Similarly you must
fully realize that in this stone there are two points styled
respectively the north pole and the south pole. If you are very careful,
you can discover these two points in a general way. One method for doing
so is the following: With an instrument with which crystals and other
stones are rounded let a lodestone be made into a globe and then
polished. A needle or an elongated piece of iron is then placed on top
of the lodestone and a line is drawn in the direction of the needle or
iron, thus dividing the stone into two equal parts. The needle is next
placed on another part of the stone and a second median line drawn. If
desired, this operation may be performed on many different parts, and
undoubtedly all these lines will meet in two points just as all meridian
or azimuth circles meet in the two opposite poles of the globe. One of
these is the north pole, the other the south pole. Proof of this will be
found in a subsequent chapter of this tract.
A second method for determining these important points is this: Note the
place on the above-mentioned spherical lodestone where the point of the
needle clings most frequently and most strongly; for this will be one of
the poles as discovered by the previous method. In order to determine
this point exactly, break off a small piece of the needle or iron so as
to obtain a fragment about the length of two fingernails; then put it on
the spot which was found to be the pole by the former operation. If the
fragment stands perpendicular to the stone, then that is,
unquestionably, the pole sought; if not, then move the iron fragment
about until it becomes so; mark this point carefully; on the opposite
end another point may be found in a similar manner. If all this has been
done rightly, and if the stone is homogeneous throughout and a choice
specimen, these two points will be diametrically opposite, like the
poles of a sphere.