544 COSMOS. 



from west to east in the parallel of Rhodes (in the diaphragm 

 of Dicsearchus).* 



An animated desire to arrive at a generalisation of views, 

 the consequence of the intellectual movement of the age, 

 gave rise to the first Greek measurement of degrees between 

 Syene and Alexandria, and this experiment may be regarded 

 as an attempt on the part of Eratosthenes to arrive at an approx- 

 imative determination of the circumference of the earth. In 

 this case, it is not the result at which he arrived from the 

 imperfect premises afforded by the Bematists which excites 

 our interest, but rather the attempt to rise from the narrow 

 limits of one circumscribed land to a knowledge of the mag- 

 nitude of the whole earth. 



A similar tendency towards generalisation may be traced in 

 the splendid progress made in the scientific knowledge of the 

 heavens in the epoch of the Ptolemies. I allude here to the 

 determination of the places of the fixed stars by the earliest 

 Alexandrian astronomers, Arystillus and Timochares ; to Aris- 

 tarchus of Samos, the cotemporary of Cleanthes, who, con- 

 versant with ancient Pythagorean views, ventured upon an 

 investigation of the construction of the universe, and who was 

 the first to recognise the immeasurable distance of the region 

 of fixed stars from our small planetary system ; nay, he even 

 conjectured the twofold motion of the earth round its axis and 

 round the sun; to Seleucus of Erythrsea (or of Babylon), f who 



* Strabo, lib. xi. p. 519; Agathem, in Hudson, Geogr. grcec. min. 9 

 vol. ii. p. 4. On the accuracy of the grand orographic views of 

 Eratosthenes, see my Asie centrale, t. i. pp. 104-150, 198, 208-227, 

 413-415; t. ii. pp. 367 and 414-435; &n.d.Examen critique de VHist. de 

 la Geogr., t. i. pp. 152-154. I have purposely called the measurement 

 of a degree made by Eratosthenes, as the first Hellenic one, since a very 

 ancient Chaldean determination of the magnitude of a degree in camels' 

 paces is not improbable. See Chasles, Recherches sur I' Astronomic 

 indienne et clialdeenne, in the Comptes rendus de I'Acad. des Sciences, 

 t. xxiii. 1846, p. 851. 



t The latter appellation appears to me the more correct, since Strabo, 

 lib. xvi. p. 739, quotes, " Seleucus of Seleucia, among several very 

 honourable men, as a Chaldean, skilled in the study of the heavenly 

 bodies." Seleucia, on the Tigris, a nourishing commercial city, is 

 probably the one meant. It is indeed singular, that Strabo also speaks of 

 a Seleucus, an exact observer of the tides, and terms him, too, 

 a Babylonian (lib. i. p. 6), and subsequently (lib. iii. p. 174), perhaps 

 from carelessness, an Erythraean. (Compare Stobaeus, Eel. phys., p. 440.) 



