se of in constructing ships and in the actual expeditions, as
well as in other operations), were ignorant of magnetick aid, the art of
the mariners' compass: For had it been in use amongst them, without doubt
the Greeks and also Italians and all barbarians would have understood a
thing so necessary and made famous by common use; nor could matters of much
repute, very easily known, and so highly requisite ever have perished in
oblivion; but either the learning would have been handed down to posterity,
or some memorial of it would be extant in writing. Sebastian Cabot was the
first to discover that the magnetick iron varied[18]. Gonzalus Oviedus[19]
is the first to write, as he does in the _Historia_, that in the south of
the Azores it does not vary. Fernelius in his book _De Abditis Rerum
Causis_ says that in the loadstone there is a hidden and abstruse cause,
elsewhere calling it celestial; and he brings forth nothing but the unknown
by means of what is still more unknown. {5} For clumsy, and meagre, and
pointless is his inquiry into hidden causes. The ingenious Fracastorio, a
distinguished philosopher, in seeking the reason for the direction of the
loadstone, feigns Hyperborean magnetick mountains attracting magnetical
things of iron: this view, which has found acceptance in part by others, is
followed by many authors and finds a place not in their writings only, but
in geographical tables, marine charts, and maps of the globe: dreaming, as
they do, of magnetick poles and huge rocks, different from the poles of the
earth. More than two hundred years earlier than Fracastorio there exists a
little work, fairly learned for the time, going under the name of one Peter
Peregrinus[20], which some consider to have originated from the views of
Roger Bacon, the Englishman of Oxford: In which book causes for magnetick
direction are sought from the poles of the heaven and from the heaven
itself. From this Peter Peregrinus, Johannes Taisnier of Hainault[21]
extracted materials for a little book, and published it as new. Cardan
talks much of the rising of the star in the tail of the Greater Bear, and
has attributed to its rising the cause of the variation: supposing that the
variation is always the same, from the rising of the star. But the
difference of the variation according to the change of position, and the
changes which occur in many places, and are even irregular in southern
regions, preclude the influence of one particular star