The torquetum or turquet is a medieval astronomical instrument designed to take and convert measurements made in three sets of coordinates: Horizon, equatorial, and ecliptic. In a sense, the Torquetum is an analog computer. The first torqueta is thought to have been built by Khajeh Nasir-o-Din Tousi in the 12th century or 13th century, though the only surviving examples date from the 16th century. A torquetum can be seen in the famous portrait The Ambassadors (1533) by Hans Holbein the Younger.… (More on Torquetum)