جام گیتی نما

Jām-e gītī-namā is a late instrument for determining qibla introduced in a treatise by Muḥammad Riḍā Yazdī (fl. Yazd, ca. 1867) entitled On Finding Qibla and Some Other Instruments. The author wrote it to investigate some earlier scientific instruments found at that time including a qibla-indicator. Although he did not describe the instrument in detail, his method of expressing its function leads us to consider it as a Mecca-centered world-map for finding the direction and distance to Mecca. As he found it impossible to determine the direction to Mecca through projecting, he devised jām-e gītī-namā to use its numerical results regardless of its spherical representation. This paper examines Muḥammad Riḍā’s approach on devising a new instrument for determining qibla inspired by an old one, in order to shed more light on qibla-indicators, more especially, Mecca-centered world-maps.