ABSTRACT
The Libro de las laminas de los siete planetas contains the Alfonsine Castilian translation of two books on the construction of equatoria by the Andalusian astronomers Abu-1-Qasim al-Samh and Abu Ishaq Ibrahim Yahya al-Naqqash. These two treatises have recently been the object of a thorough study by Merce Comes, who has also produced reliable editions of the Arabic text of Ibn al-Zarqalluh’s treatise on the use of the instrument and of the fourteenth-century Italian translations of the Alfonsine texts. One item in Ibn al-Zarqalluh’s book on the construction of the equatorium that has attracted a certain amount of attention from modern scholarship is its description of the method used to draw Mercury’s deferent which, in this instrument, is a non-circular curve.
