An Undated Astrolabic Quadrant from 18th or 19th Century Istanbul, signed by Hilmi, and three Silk Purses Embroidered with Metal Thread, Turkey, 18th-19th Century

some minor surface rubbing and knocks, generally in good condition, as viewed
"In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective, qualified opinion. Prospective buyers should also refer to any Important Notices regarding this sale, which are printed in the Sale Catalogue.
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inscriptions
Signed in red as: 'Hilmi drew it'

In the late period of Islamic astronomy, especially in Ottoman Turkey, the astrolabic quadrant came to replace the astrolabe. Hundreds of such instruments survive. The front bears one-half of a set of astrolabic markings for a specific latitude, the rete being replaced by a thread and movable bead. Its advantage was that it was easier to make, its disadvantage - if only for travellers - was that it served only one latitude and was more useful for timekeeping by day rather than by night. Within these markings is a small universal horary quadrant. On the back is a sine quadrant (with markings resembling modern graph paper) for performing all manner of trigonometric calculations.

This piece is signed by Hilmi (rasamahu Hilmi) in red at the centre of the markings of the universal horary quadrant. The principal astrolabic markings are for latitude 41° ('ard m-a), which serves Istanbul. Additional markings in red relate to the time of the 'asr prayer and the time for fasting in Ramadan (imsak). The trigonometric markings on the back include a quadrant for finding the solar declination, two semicircles for facilitating operations with sines and cosines, and a chord for determining the altitude of the sun at the beginning of the 'asr prayer. The instructions along the edge also relate to the calculation of the time for fasting in Ramadan (tamkin). The elegant plumb-bob may be original.

Bibliography: Article "Rub'" in Enc. Islam, 2nd edn.; King, In Synchrony with the Heavens, X-6.