), 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.]1
A Greek treatise in two books on the Circular Theory of the Heavenly Bodies (Κυκλικῆς Θεωρίας Μετεώρων Βίβλια δύο）
This work is rather an exposition of the system of the universe than of the geometrical principles of astronomy. Indeed, Cleomedes betrays considerable ignorance of geometry (see his account, p. 28, of the position of the ecliptic), and seems not to pretend to accuracy in numerical details.
The first book treats of the universe in general, of the zones, of the motions of the stars and planets, of day and night, and of the magnitude and figure of the earth. Under the last head, Cleomedes maintains the spherical shape of the earth against the Epicureans, and gives the only detailed account extant of the methods by which Eratosthenes and Poseidonius attempted to measure an arc of the meridian.
The second book contains a dissertation on the magnitudes of the sun and moon, in which the absurd opinions of the Epicureans are again ridiculed; and on the illumination of the moon, its phases and eclipses.
The most interesting points are, the opinion, that the moon's revolution about its axis is performed in the same time as its synodical
revolution about the earth; an allusion to something like almanacs, in which predicted eclipses were registered; and the suggestion of atmospherical refraction as a possible explanation of the fact (which Cleomedes however professes not to believe), that the sun and moon are sometimes seen above the horizon at once during a lunar eclipse. (He illustrates this by the experiment in which a ring, just out of sight at the bottom of an empty vessel, is made visible by pouring in water.)
The Κυκλικὴ Θεωρία
was first printed in Latin by Geo. Valla, Ven. 1498, fol.
In Greek by Conrad Neobarius, Paris, 1539
; in Gr. and Lat. with a commentary, by Rob. Balfour, Burdigal. 1605, 4to. The two latest editions are by Janus Bake, with Balfour's commentary, &c., Lugd. Bat. 1820, 8vo., and C. C. T. Schmidt, Lips. 1832, 8vo. (a reprint of Bake's text, with select notes).
Delambre, Hist. de l'Astron. Ancienne
, vol. i. chap. 12; Weidler, Hist. Astron.
p. 152; Voss. de Nat. Art.
p. 117a.; Fabric. Bibl. Graec.
iv. p. 41.