330 



GREEK SCIENCE. 



rences, which, as we have observed, could not long remain unnoticed 

 even in the most infant state of society. 



Egyptians. We may judge of the state of Egyptian astronomy from the circum- 

 stance of Thales having first taught them how to find the heights of 

 the pyramids from the length of their shadows. It is true that they 

 had some idea of the length of the year, and had, in a certain measure, 

 approximated towards a determination of the obliquity of the ecliptic, 

 or of the path of the sun, which they stated to be 24. The Chaldeans 

 appear to have made some rude observations on eclipses, but still little 

 scientific knowledge can be attributed to this people ; who, after ob- 

 serving these phenomena, were contented to explain them by teaching 

 that the two great luminaries of the heavens were only on fire on one 

 side, and that eclipses were occasioned by the accidental turning of 

 their- dark sides towards us. And again, that these bodies were 

 carried round the heavens in chariots, close on all sides except one, in 

 which there was a round hole, and that a total or partial eclipse was 

 occasioned by the complete or partial shutting of this aperture. Si- 

 milar absurd and extravagant notions will be found amongst all the 

 early pretenders to the study of astronomy ; but we cannot concede to 

 such knowledge and pretences the term science ; they had, in fact, no 

 science, they had amassed together a number of rude observations, and 

 had been thus enabled to determine certain periods, and to predict 

 some few phenomena; but we have no proof, nor even any reason 

 whatever to imagine, from any facts that have been handed down to 

 us, that these predictions rested upon any other basis than that of 

 simply observing the repeated returns of these appearances within 

 certain periods. 



If to the knowledge above indicated, we add an arbitrary collection 

 of certain clusters or groups of stars into constellations ; the division 

 of the zodiac into twelve signs, corresponding to the twelve months of 

 the year ; into twenty-seven or twenty-eight hours, answering to the 

 daily motion of the moon ; an obscure idea of the revolution of the 

 earth upon its axis, which was afterwards lost; a knowledge of five 

 planets; and some contradictory notions respecting the nature and 

 motion of comets, we shall have a pretty correct picture of the state 

 of astronomy as it was received amongst the Greeks; from whom it 

 first derived its scientific character. It is, therefore, only from this 

 period that we shall commence our historical sketch. 



Thales is generally considered as the founder of astronomy amongst 

 the Greeks. This philosopher, who must have flourished about 600 

 years before the commencement of the Christian era, is said to have 

 taught that the stars were fire, or that they shone by means of their 

 own light ; the moon received her light from the sun, and that she 

 became invisible in her conjunctions, in consequence of being hidden 

 or absorbed in the solar rays, which it must be acknowledged is but 

 an obscure way of saying that she then turned towards us her unen- 

 lightened hemisphere. He taught farther that the earth is spherical, 



Astronomy 

 as it was 

 received by 

 the early 

 Greeks. 



Thales. 

 B. c. 600. 



