Majus_, Bacon, our first English worker in the exact sciences, allows
the world-summit not to be exactly 90 degrees from the east, although so
placed by mathematicians. Yet there is no contradiction, he urges,
because the men of theory are "speaking of the habitable world known to
them, according to the true understanding of latitude and longitude,"
and this "true understanding" is "not as great as has been realised in
travel by Pliny and others." "The longitude of the habitable world is
more than half of the whole circuit." This, reproduced in the _Imago
Mundi_ of Cardinal Peter Ailly (1410), fell into the hands of Columbus
and helped to fix his doctrines of the shape of the world ("in the form
of a pear") of the terrestrial paradise, and of the earth's
circumference,--so enormously contracted as practically to abolish the
Pacific.[11]

[Footnote 11: In Columbus' letters to Queen Isabella in 1498, we catch,
as it were, the last echo of the Arabic _mélange_ of Moses and Greek
geography, along with the results of Roger Bacon's corrections of
Ptolemy. "The Old Hemisphere," he writes "which has for its centre the
isle of Arim, is spherical, but the other (new) Hemisphere has the form
of the lower half of a pear. Just one hundred leagues west of the Azores
the earth rises at the Equator and the temperature grows keener. The
summit is over against the mouth of the Orinoco."]

To return to the Arabs: We have seen how they not merely followed Greek
theories, which their own experience as conquerors in the Further East
went to discredit, but, in the great outlines of geography, added to
earlier errors, put prejudice in the place of knowledge, and handed on
to Christendom a half-fanciful map of the world. It only remains for us
to illustrate their leading fault, of a too vivid fancy, with a few
details on minor points.