218 THE GREEK ASTRONOMY. 



5^ equinoctial hours after noon), the moon was in 

 3 degrees of Pisces, by her distance from the sun 

 (which was 92 degrees, 8 minutes) ; and half an 

 hour after, the sun being set, and the quarter of 

 Gemini on the meridian, Regulus appeared, by the 

 other circle of the astrolabe, 57^ degrees more 

 forwards than the moon in longitude." From these 

 data the longitude of Regulus is calculated. 



From what has been said respecting the obser- 

 vations of the Alexandrian astronomers, it will 

 have been seen that their instrumental observations 

 could not be depended on for any close accuracy. 

 This defect, after the general reception of the Hip- 

 parchian theory, operated very unfavourably on the 

 progress of the science. If they could have traced 

 the moon's place distinctly from day to day, they 

 must soon have discovered all the inequalities 

 which were known to Tycho Brahe ; and if they 

 could have measured her parallax or her diameter 

 with any considerable accuracy, they must have 

 obtained a confutation of the epicycloidal form of 

 her orbit. By the badness of their observations, 

 and the imperfect agreement of these with calcu- 

 lation, they not only were prevented making such 

 steps, but were led to receive the theory with 

 a servile assent and an indistinct apprehension, 

 instead of that rational conviction and intuitive 

 clearness which would have given a progressive 

 impulse to their knowledge. 



