An animation of the oldest complete geared mechanism in the world. The gears drive a calendar display on the back of a medieval astrolabe.

The instrument was made by Muhammad b. Abi Bakr in Isfahan in 1221/2 and is in the collection of the Museum of the History of Science, Oxford. For more information see the collections database at www.mhs.ox.ac.uk (MHS inv. 48213).

Further details from the collection database (MHS inv. 48213).