Fragment of a box with a combination lock, cast and hammered brass, inlaid with silver and copper

This combination lock is the work of the astrolabe-maker Muhammad ibn Hamid al-Asturlabi al-Isfahani in 597 H. At around the same time, the mechanical genius al-Jazari described a similar lock in his Book of Ingenious Mechanical Devices. The combination lock must thus be common property, a scientific invention whose origins can be traced back to the Mediterranean cultures of Antiquity.

The four double dials, each of which can be set in 16 positions, allows for 4,294,967,296 combinations. When the right combination is entered, it releases the inner metal plate, which is attached both to an external handle and to the locking mechanism itself.