A flat or planispheric Astrolabe
Origin: Tunis
Dating: 1184 Hijri / 1770 A.D.
Materials: Copper

This portable instrument was produced in Tunis by Ahmad Ibn Ibrahim Al Harrar. It comprises a suspension device composed of a handle, a ring, and especially a disc-shaped, 18-cm-diameter body. The edge of the body is divided into degrees.

Two mobile elements are used for measurement: the spider on the face and the alidade on the back. The latter is a flat ruler turning around the centre. The astrolabe remained the main navigation instrument until the end of the XVIII century.

It is also an instrument for astronomical measurements as it is used to measure the stars’ height over the horizon or the angular distance between them.