Muslim astronomers and engineers invented a variety of dials for timekeeping and for determining the times of the five daily prayers. In this thorough and technical study, Professor Attila Bir analyses the principle and use of Ottoman sundials. Beginning with the definition of the the day, the hour and the prayer times, he analyses the mathematical formulas of the main two varieties of suncials used by Ottoman astronomers, the horizontal and vertical sundials.
Principle and Use of Ottoman Sundials
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Figure 1. The Tabula Rogeriana, drawn by al-Idrisi for Roger II of Sicily in 1154, one of the most advanced ancient world maps. Modern consolidation, created from the 70 double-page spreads of the original atlas. (Source)
Figure 1: Muslim expansion by the end of Umayyad rule in 750. (Source).
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