respect the magnetick
pole: but experience teaches that there is no such definite pole or fixed
terminus on the earth to account for the variation. For the arcs of *
variation are changed variously and erratically, not only on different
meridians but on the same meridian; and when, according to this opinion of
the moderns, the deviation should be more and more toward the east, then
suddenly, with a small change of locality, the deviation is from the north
toward the west as in the northern regions near Nova Zembla. Moreover, in
the southern regions, and at sea at a great distance from the aequator
towards the antarctick pole, there are frequent and great variations, and
not only in the northern regions, from the magnetick mountains. But the
cogitations of others are still more vain and trifling, such as that of
Cortes about a moving influence beyond all the heavens; that of {153}
Marsilius Ficinus about a star in the Bear; that of Peter Peregrinus about
the pole of the world; that of Cardan, who derives it from the rising of a
star in the tail of the Bear[218]; of Bessardus, the Frenchman, from the
pole of the Zodiack; that of Livio Sanuto from some magnetick meridian;
that of Franciscus Maurolycus from a magnetical island; that of Scaliger
from the heavens and mountains; that of Robert Norman, the Englishman, from
a point respective. Leaving therefore these opinions, which are at variance
with common experience or by no means proved, let us seek the true cause of
the variation. The great magnet or terrestrial globe directs iron (as I
have said) toward the north and south; and excited iron quickly settles
itself toward those termini. Since, however, the globe of the earth is
defective and uneven on its surface and marred by its diverse composition,
and since it has parts very high and convex (to the height of some miles),
and those uniform neither in composition nor body, but opposite and
dissimilar: it comes to pass that the whole of that force of the earth
diverts magnetical bodies in its periphery toward the stronger and more
prominent connected magnetick parts. Hence on the outermost surface of the
earth magnetical bodies are slightly perverted from the true meridian.
Moreover, since the surface of the globe is divided into high lands and
deep seas, into great continental lands, into ocean and vastest seas, and
since the force of all magnetical motions is derived from the constant and
magnetick terrestrial nature whic