written in the thirteenth century, speaks of its use in the Syrian
sea. The first Crusaders were probably instrumental in bringing it
to France, at all events Jacobus de Vitry (1204-15) and Vincent de
Beauvais (1250) mention its use, De Beauvais calling the poles of
the needle by the Arab words aphron and zohran.

Ere long the needle was mounted on a pivot and provided with a
moving card showing the principal directions. The variation of the
needle from the true north and south was certainly known in China
during the twelfth, and in Europe during the thirteenth century.
Columbus also found that the variation changed its value as he
sailed towards America on his memorable voyage of 1492. Moreover,
in 1576, Norman, a compass maker in London, showed that the north-
seeking end of the needle dipped below the horizontal.

In these early days it was supposed that lodestone in the pole-
star, that is to say, the "lodestar" of the poets or in mountains
of the far north, attracted the trembling needle; but in the year
1600, Dr. Gilbert, the founder of electric science, demonstrated
beyond a doubt that the whole earth was a great magnet. A magnet,
as is well known, has, like an electric battery, always two poles
or centres of attraction, which are situated near its extremities.
Sometimes, indeed, when the magnet is imperfect, there are
"consequent poles" of weaker force between them. One of the poles
is called the "north," and the other the "south," because if the
magnet were freely pivotted like a compass needle, the former
would turn to the north and the latter to the south.

Either pole will attract iron, but soft or annealed iron does not
retain the magnetism nearly so well as steel. Hence a boy's test