Wikipedia: Ptolemy

2. Claudius Ptolemaeus (A.D. c. 85 - c. 165), known in the English language as Ptolemy, was a Greek astronomer who lived in Alexandria in Egypt.

Ptolemy was the author of the astronomical treatise which is now known as the Almagest? (although that was not its original name). In this work he formulated a geocentric model of the solar system which was to remain the generally accepted model in the Western and Arab worlds for more than 1300 years. The Almagest also contains a star catalogue. Its list of 48 constellations is ancestral to the modern system of constellations, but unlike the modern system there were gaps between them.

Ptolemy also wrote several other books. In his Geography he attempted to map the known world, although the results are often very inaccurate due to the absence of reliable data. In his Optics, a work which survives only in a poor Arabic translation, he writes about properties of light, including reflection, refraction and colour. His other works include Planetary Hypothesis, Planisphaerium and Analemma.

This is an unabridged republication of the work originally published by The New York Public Library, N.Y. in 1 9 3 2. At that time it was translated and edited by Edward Luther Stevenson.

Although Ptolemie's "Geography" was well known in Europe for almost 1900 years , 1932 was the first time ever of its translation into English.