Kashf al-qināʻ fī waḍʻ al-arbāʻ min al-jihat al-sitt fī ʻilm al-falak

According to the colophon (fol. 12a), the author wrote the work in 830 H [1426] based on the lectures of Nūr al-Dīn al-Naqqāsh ibn ʻAbd al-Qādir. This manuscript in 12 folios is a mid-18th-century copy of Kašf al-Qinā' fī rasm al-arbā' (The removal of the veil in the description of the quadrants), a treatise devoted to the description of the astronomical instrument known as the quadrant. The treatise originally was compiled by Muḥammad ibn Muḥammad Ibn al-Aṭṭar in the first half of the 15th century on the basis of the teachings of his predecessors, al-Mājidī and Nūr al-Dīn al-Naqāš. The treatise is a precious source for understanding the degree of refinement reached by astronomical instrument making during the Mamluk period. Quadrants (rub', plural arbā', literally "quarter") were already in use in ancient Greece. They subsequently were introduced in the Islamic world, where the first descriptions of them date from around the beginning of the ninth century. Astronomers relied on quadrants to measure the meridian altitudes of the sun and the stars, by which they were able to determine values for the latitude, the obliquity of the ecliptic, and the stellar coordinates for a place of observation. Ibn al-Aṭṭar's treatise opens with a lengthy introduction. It then describes the different kinds of quadrants in two main sections, which are divided into nine and ten chapters respectively. Titles of sections and chapters, together with other relevant words in the text, are rubricated in this fine copy of the work. World Digital Library.