Quadrant (رُبْع), comprising an astrolabe quadrant (ربع المُقَنْطَرَات, Side A), and a sine quadrant (ربع المُجَيَّب, Side B). The quadrant is signed by its maker, Aḥmad ibn Ibrāhīm al-Sharbatlī (أحمد ابن إبراهيم الشربتلي, Side A), and dated 1256/1840-1 (Side B).