(Κλεουήδης), author of a Greek treatise in two books on the Circular Theory of the Heavenly Bodies (Κυκλικῆς Θεωρίας Μετεώρων Βίβλια δύο).
Of the history of Cleomedes nothing is known, and the date of his work is uncertain. He professes (ad fin.), that it is compiled from various sources, ancient and modern, but particularly from Poseidonius (who was contemporary with Cicero); and, as he mentions no author later than Poseidonius, it is inferred, that he must have lived before, or at least not much after Ptolemy, of whose works he could hardly have been ignorant if they had been long extant. It seems, also, from the eagerness with which he defends the Stoical doctrines against the Epicureans, that the controversy between these two sects was not obsolete when he wrote. On the other hand, Delambre has shewn that he had nothing more than a second-hand knowledge of the works of Hipparchus, which seems to lessen the improbability of his being ignorant of Ptolemy. And Letronne (Journal des Savans, 1821, p. 712) argues, that it is unlikely that Cleomedes should have known anything of refraction before Ptolemy, who says nothing of it in the Almagest (in which it must have appeared if he had been acquainted with it), but introduces the subject for the first time in his Optics. The same writer also endeavours to shew, from the longitude assigned by Cleomedes (p. 59) to the star Aldebaran, that he could not have written earlier than A. D. 186. Riccioli (Almag. Nov. vol. i. pp. xxxii. and 307) supposes, that the Cleomedes who wrote the Circular Theory lived a little after Poseidonius, and that another Cleomedes lived about A. D. 390.
A treatise on Arithametic and another on the Sphere, attributed to a Cleomedes, are said to exist in MS. Vossius (de Nat. Art. p. 180b.) conject tures that Cleomedes wrote the work on Harmonics attributed to Cleonides or Euclid. [EUCLEIDES.][*](GRC 2008-06-9: I moved the section on the life of Cleomedes to the start of the article to conform to the more general pattern in Smith's.)[W.F.D]