Contents xiii 



PAGE 



35. The division of the surface of the earth into 



zones 37 



36. Eratosthenes : his measurement of the earth : 



and of the_flbHguit^ of the^ecliptic . . 39 



37. Hipparehui : his life and chief contributions to 

 astronomy. Apollonius's representation of 

 the celestial motions by means of circles. 

 General account of the theory pf eccenfracs 

 anil-epicycles 40 



3^-9- Hipparchus's representation of the motion of 

 the sun, by means of an ecgpi*ic-J3Jiag&, 

 perigee, line of apses, eccentricity : equation of 

 thelXn1r7r\^Q^ptcycir^^^& deferent . 41 



40. Theory of the moon : lunation or synodic month 



and sidereal month : motion of the moon's 

 nodes and apses : draconitic month and 

 anomalistic month .... .47 



41. Observations of planets : eclipse method of con- 



necting the distances of the sun and moon : 

 estimate of their distances .... 49 



42. His star catalogue. Discovery of the precession 

 of the equinoxes : the tropical year and the 

 sidereal year 5 1 



43. Eclipses of the sun and moon : conjunction 

 and opposition: partial, total, and annular 

 eclipses : parallax $6 



44. Delambre's estimate of Hipparchus 6l 



45. The slow progress of astronomy after the time of Hip- 

 parchus : Pliny's proof that the earth is round : 

 new measurements of the earth by Posidonius . 6 1 



46. Ptolemy. The Almagest and the Optics : theory of 



refraction 62 



47. Account of the Almagest'. Ptolemy's postulates: 



arguments against the motion of the earth . 63 



48. The theory of the moon : evection and prosneusis 65 



49. The astrolabe. Parallax, and distances of the 



sun and moon 67 



50. The star catalogue : precession . ... 68 



51. Theory of the planets : the equant ... 69 



52. Estimate of Ptolemy 73 



53. The decay of ancient astronomy : Theon ai.d Hypatia 73 



54. Summary and estimate of Greek astronomy . . 74 



