lude to any extended voyages away from
land. This appears to have been known to the Chinese from quite
ancient times, and utilised on their junks as early as the eleventh
century. The Arabs, who voyaged to Ceylon and Java, appear to have
learnt its use from the Chinese, and it is probably from them that
the mariners of Barcelona first introduced its use into Europe.
The first mention of it is given in a treatise on Natural History
by Alexander Neckam, foster-brother of Richard, Coeur de Lion.
Another reference, in a satirical poem of the troubadour, Guyot
of Provence (1190), states that mariners can steer to the north
star without seeing it, by following the direction of a needle
floating in a straw in a basin of water, after it had been touched
by a magnet. But little use, however, seems to have been made of
this, for Brunetto Latini, Dante's tutor, when on a visit to Roger
Bacon in 1258, states that the friar had shown him the magnet and
its properties, but adds that, however useful the discovery, "no
master mariner would dare to use it, lest he should be thought to
be a magician." Indeed, in the form in which it was first used
it would be of little practical utility, and it was not till the
method was found of balancing it on a pivot and fixing it on a
card, as at present used, that it became a necessary part of a
sailor's outfit. This practical improvement is attributed to one
Flavio Gioja, of Amalfi, in the beginning of the fourteenth century.

[Illustration: THE MEDITERRANEAN COAST IN THE PORTULANI.]

When once the mariner's compass had come into general use, and
its indications observed by master mariners in their voyages, a
much more practical method was at hand for determining the relative
positions of the different lands. Hitherto geographers (_i.e._,
mainly the Greeks and Arabs) had had to depend for fixing relative
positions on the vague statements in the itineraries of merchants and
soldiers; but now, with the aid of the compass, it was not difficult
to determine the relative position of one point to another, while
all the windings of a road could be fixed down on paper without
much difficulty. Consequently, while the learned monks were content
with the mixture of myth and fable which we have seen to have formed
the basis of their maps of the world, the seamen of the Mediterranean
were gradually building up charts of that sea and the neighbouring
lands which varied but little from the true position. A cha