§ 35. The division of the surface of the earth into zones 37 § 36. _Eratosthenes_: his measurement of the earth: and of the obliquity of the ecliptic 39 § 37. =Hipparchus=: his life and chief contributions to astronomy. _Apollonius’s_ representation of the celestial motions by means of circles. General account of the theory of eccentrics and epicycles 40 §§ 38-9. Hipparchus’s representation of the motion of the sun, by means of an _eccentric_: _apogee_, _perigee_, _line of apses_, _eccentricity_: _equation of the centre_: the _epicycle_ and the _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 connecting 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_ 51 § 43. Eclipses of the sun and moon: _conjunction_ and _opposition_: _partial_, _total_, and _annular_ eclipses: _parallax_ 56 § 44. Delambre’s estimate of Hipparchus 61 § 45. The slow progress of astronomy after the time of Hipparchus: _Pliny’s_ proof that the earth is round: new measurements of the earth by _Posidonius_ 61 § 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_ and _Hypatia_ 73 § 54. Summary and estimate of Greek astronomy 74 CHAPTER III. THE MIDDLE AGES (FROM ABOUT 600 A.D. TO ABOUT 1500 A.D.), §§ 55-69 76-91 § 55. The slow development of astronomy during this period 76