Two Early Arabic Sources On The Magnetic Compass

In this paper two previously unpublished texts on the magnetic compass from the medieval Islamic world will be discussed, the first by the Yemeni Sultan al-Ashraf (ca. 1290) and the second by the Cairene astronomer Ibn Simô¢un (ca. 1300). These two treatises constitute the earliest known evidence attesting the use of the magnetic compass for the determination of the qibla, the sacred direction of Islam. A brief introduction glimpses at the history of the magnetic compass in Europe and China and mentions previously known early Arabic sources on the instrument and its use. This is followed by some remarks on the authors and the manuscripts, the Arabic texts with English translations, and comments on problems encountered while working on the texts. 1. Survey of the history of the magnetic compass The Yemeni astronomer-prince al-Ashraf (ca. 1290) and (apparently) also a Cairene astronomer called Ibn Simô¢un (ca. 1300)1 both wrote treatises on the magnetic compass. These two previously unpublished texts will be presented in this paper, prefaced by a brief survey of the knowledge on and use of the magnetic compass in the European and Islamic Middle Ages in order to put these new sources in the context of previous knowledge on the subject. Although the magnet and its attractive property were known in Antiquity, there is no mention of its directive potential in the sources.2 In the late nine