Ptolemy dan Al Khawarizm

The mathematician and geographer al-Khwarizmi entered the service of al-Mamun in the Dar al Hikma or House of Wisdom of the Great Library of Baghdad as a very young man. His most important work, titled Kitab Surat-al-Ard or the ‘Book of the appearance of the Earth', was finished in 833 AD.

Al-Khwarizmi studied, revised and completed Ptolemy's work just as the latter had done with that of Marinus of Tyre. The three works basically consist of a list of coordinates of cities and other geographical features following a general introduction.

One of the corrections which al-Khwarizmi made in Ptolemy's work is the reduction of the latitude of the Mediterranean from 62º to 52º when, in actual fact, it should be only 42º. The Arab opts for the same zero meridian as Ptolemy, that of the Canaries. The amount of inhabited land extends over 180º.

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