A whole tribe of commentators on place-names, on the climates and
constellations, and on geographical instruments was at work in this last
age of the Spanish Caliphate, and their results are brought together by
Abou Hamid of Granada and by Edrisi.

[Footnote 14: The school of Persian mathematicians who produced the maps
of Alestakliry-Ibn-Hankal, the book of latitudes and longitudes,
ascribed by Abulfeda to Alfaraby the Turk, was the immediate descendant
of Albyrouny.]

Born at Ceuta in 1099, this great geographer travelled through Spain,
France, the Western Mediterranean, and North Africa before settling at
the Norman Court of Palermo. Roger, the most civilised prince in
Christendom, the final product of the great race of Robert Guiscard and
William the Conqueror, valued Edrisi at his proper worth, refused to
part with him, and employed men in every part of the world to collect
materials for his study. Thus the Moor gained, not only for the Moslem
world but for Southern Europe as well, an approximate knowledge even of
Norway, Sweden, Finland, and the coasts of the White Sea. His work,
dedicated to Roger and called after him, _Al-Rojary_, was rewarded with
a peerage, and it was as a Sicilian Count that he finished his Celestial
Sphere and Terrestrial Disc of silver, on which "was inscribed all the
circuit of the known world and all the rivers thereof."

Each of his great Arabic predecessors, along with Eratosthenes, Ptolemy,
and Strabo, was welded into his system--the result of fifteen years of
abstract study, following some thirty of practical activity in
travel.[15]

[Footnote 15: The world he divided by climates in the Greek manner,