Causes concerned with Sounds. Causes concerned with Seeds, Plants and Fruits. Causes concerned with Animals, three books. Miscellaneous Causes. Concerning the Magnet. These works have not been arranged. The mathematical works are these : VII. On a Difference in an Angle, or On Contact with the Circle or the Sphere. On Geometry. Geometrica. Numbers. VIII. On Irrational Lines and Solids, two books. Extensions (Projections). The Great Year, or Astronomy, Calendar. Contention of the Water-clock <and the Heaven>. IX. Description of the Heaven. Geography. Description of the Pole. Description of Rays of Light. These are the mathematical works. The literary and musical works are these : X. On Rhythms and Harmony. On Poetry. On Beauty of Verses. On Euphonious and Cacophonous Letters. a Diels compares Ptolemy, Geogr. vii. 7 v-n-oypa^ tov £KTreTdcr/j.a.Tos. vTroypacpi} 5' £<rrcu /ecu rrjs Toiavrrjs eKweTacrews apixb'govad re Kal Ke<pa\auu8r)s. 77 TOiavTt] rf/s Kpucbffijs a<paipas £iwre8u Karaypacpr) kt\. The title 'EKireTda/uLara may therefore mean " Projection of an armillary sphere on a plane." 45Q