IV. GREEK ASTRONOMY: SECOND PERIOD, B.C. 400 to A.D. 150 1. Plato: the World-Soul 79 2. Eudoxus: the Spheres 88 3. Calippus: the Spheres of Eudoxus improved 93 4. Aristotle: the Philosophy of the Spheres; the three kinds of motion; Earth immoveable at the centre of the Universe; the elements; the celestial movers, and the First Mover 95 5. Aristarchus: Earth turning on her axis, and revolving round the sun 107 6. The School of Alexandria: instruments and methods; Earth’s diameter measured; the theory of Moveable Eccentrics 112 7. Hipparchus: “the Father of Astronomy;” his star catalogue; his inventions and discoveries; the precession of the equinoxes 122 8. Ptolemy: the Almagest; the system of Epicycles and Eccentrics; distance and size of the moon discovered; the stars; astrology; geography, the seven climates 134 V. RETROSPECT: Greek Cosmogonies; Greek calendar 159 VI. ASTRONOMY UNDER IMPERIAL AND CHRISTIAN ROME. B.C. 46 to A.D. 1000. Amateur Astronomers; the Julian Calendar; passion for Astrology; the Fathers; the ecclesiastical Calendar; the Schools; the Monasteries 167 VII. ARAB ASTRONOMY. A.D. 750 to 1250. Schools of Baghdad, Egypt, Spain. Improvements in Mathematics and Instruments; Ptolemy’s values more correctly determined; supposed discoveries of planetary distances and trepidation; a ninth sphere added to Ptolemy’s eight 181 VIII. THE RETURN OF GREEK ASTRONOMY TO EUROPE. A.D. 1000 to 1300. The Universities; Arab influence; Greek books; new European books; the course in Astrology in Bologna; Aristotle and the Church 199 PART II. THE ASTRONOMY OF DANTE. I. POPULAR ASTRONOMY IN ITALY IN DANTE’S TIME. The astronomy of Dante contrasted with Homer and Milton. General feeling for astronomy in his day; some famous astrologers: astronomy considered an ennobling study; Ptolemy’s system final. Knowledge of average educated man. 209