Finding the qibla

The lavishly decorated astrolabe depicted here was made in c.1788/89 by the Persian instrument maker Hâjjî ‘Al. Its back plate offered two ways of finding the qibla using the alidade: a trigonometric grid (top right quadrant) and a ‘qibla map’ (top left) based on a scale for the Sun’s noon altitude in the course of a year.

Commentary. Philipp Nothaft (May-June 2019)