solid walnut, inscribed in red and black ink under a yellowish varnish; brass socket for the plumb-line; the lead weight for the plumb-line is housed in the instrument
16.8 x 12.8 x 3cm; radius of quadrant 12.5cm
One side of the instrument carries a Prophatius astrolabe-quadrant for latitude 41°, with an unequal hour diagram (horary quadrant) above. The other side is a sine-cosine quadrant with arcs of sine and versed sine. There are brief instructions in Turkish and Arabic on the sides and edges. The maker’s name and the date appear on each side, with slight variations in some details of the signature. The nisbah of the maker, al-Uﬁ, indicates that he was from Of, a small town on the Black Sea.
F. Maddison & E. Savage-Smith, Science, Tools & Magic, The Nasser D. Khalili Collection of Islamic Art, volume XII, Part One, London 1997, cat.156, pp.266–8.