Torquetum

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 torquetum is thought to have been built by Jabir ibn Aflah (Geber) in the 12th century or 13th century, though the only surviving examples date from the 16th century.