Brass; cast, chased, engraved and inlaid with silver and a black compound
H. 4 1/2 in. (11.4 cm), Diam. 5 3/4 in. (14.6 cm)
Edward C. Moore Collection, Bequest of Edward C. Moore, 1891 (91.1.527a,b)
In addition to the seven planets known to them at the time, medieval Arab astronomers believed that an invisible, eighth planet was responsible for the eclipses of the Sun and of the Moon. They probably took the idea from Indian sources, because Hindu mythology includes such a planet. Islamic astronomers termed this pseudo-planet, which sometimes devoured either the Sun or the Moon and provoked an eclipse, al-tinnin ("the Dragon") or al-jawzahr. Two of the medallions on this mortar show Jawzahr, which though described in texts as a dragon monster, is depicted here as a seated figure flanked by snakes with dragon heads.