Savasorda

Savasorda is the Latin name of Abraham bar Hiyya, a Jewish scholar of the twelfth-century Latin world. The Encyclopaedia of Islam has no article on him. He appears in the article on mensuration, misaha, and in the article on astrological decrees, and in a bibliographic title in the article on al-Battani. ^{1 3 4} The articles read give no birth or death date and no biography, and the museum gives none.

The article on misaha, the Arabic practical geometry of measuring areas and solids, calls him the Jew Abraham Savasorda, who may be reckoned among the western Arabs. It names his book as the only one in the genre that gives logically worked-out proofs in any number, whereas almost all other misaha works quote rules without scientific geometrical proofs, since practical men wanted values easy to calculate rather than great mathematical accuracy. ¹ Among the formulae quoted, the article gives his rule for the area of an oval, an ellipse, as one quarter of the sum of two measures, a and b, multiplied by pi. ¹

The article adds that Leonardo of Pisa's Practica geometrica, which remained a standard work for three centuries, depended closely on Savasorda, and that Savasorda most probably owed much to Abu Bakr, whose Liber mensurationis shows striking similarities to Savasorda's Liber embadorum. ² See Fibonacci, the same Leonardo of Pisa. The article's bibliography lists M. Curtze's 1902 study of the Liber embadorum of Abraham bar Chijja Savasorda in the translation of Plato of Tivoli. ² See Plato of Tivoli.

The article on astrological decrees says Abu Ali al-Khayyat's book on nativities was translated into Latin as De iudiciis nativitatum by Plato of Tivoli and Abraham b. Hiyya, known as Savasorda, and was edited by Joachim Heller in 1546 and 1549 and dedicated to Melanchthon. ³ The article on al-Khayyat itself names only Plato of Tivoli, at Barcelona in 1136, and John of Seville in 1153 as the two translators, so the articles differ on who is credited. ⁵

The same article says that the book on choosing propitious times by Ahmad al-Imrani, known to Europeans as Haly Imrani, was translated by Plato of Tivoli together with Abraham b. Hiyya, and also by John of Seville under another title. ⁶

A bibliography entry in the article on al-Battani names an Abraham bar Hiyya as the Jew of Barcelona and cites a study of his work, La obra Forma de la tierra, with the byname ha-Bargeloni. ⁴ The OCR text of that entry is damaged, and the museum reads it only as showing that the encyclopaedia's bibliography places him in Barcelona.

The articles read give no birth or death, do not say where or when he wrote the Liber embadorum, and say nothing of his own works beyond that book. On the Abu Bakr behind the Liber mensurationis the article's bibliography says only that the author is presumably Abu Bakr, who died in 447/1055, citing Suter. ²