§§ 76-9. The =De Revolutionibus=. _The first book_: the postulates: the principle of _relative motion_, with applications to the apparent annual motion of the sun, and to the daily motion of the celestial sphere 100 § 80. The two motions of the earth: answers to objections 105 § 81. The motion of the planets 106 § 82. The seasons 108 § 83. End of first book. _The second book_: decrease in the obliquity of the ecliptic: the star catalogue 110 § 84. _The third book_: precession 110 § 85. _The third book_: the annual motion of the earth: _aphelion_ and _perihelion_. _The fourth book_: theory of the moon: distances of the sun and moon: eclipses 111 §§ 86-7. The _fifth_ and _sixth_ books: theory of the planets: _synodic_ and _sidereal periods_ 112 § 88. Explanation of the stationary points 118 §§ 89-90. Detailed theory of the planets: defects of the theory 121 § 91. Coppernicus’s use of epicycles 122 § 92. A difficulty in his system 123 CHAPTER V. THE RECEPTION OF THE COPPERNICAN THEORY AND THE PROGRESS OF OBSERVATION (FROM ABOUT 1543 A.D. TO ABOUT 1601 A.D.), §§ 93-112 125-144 §§ 93-4. The first reception of the _De Revolutionibus_: _Reinhold_: the _Prussian Tables_ 125 § 95. Coppernicanism in England: _Field_, _Recorde_, _Digges_ 127 § 96. Difficulties in the Coppernican system: the need for progress in dynamics and for fresh observations 127 §§ 97-8. The Cassel Observatory: the Landgrave _William IV._, _Rothmann_, and _Bürgi_: the star catalogue: Bürgi’s invention of the pendulum clock 128 § 99. =Tycho Brahe=: his early life 130 § 100. The new star of 1572: travels in Germany 131 §§ 101-2. His establishment in Hveen: Uraniborg and Stjerneborg: life and work in Hveen 132 § 103. The comet of 1577, and others 135 § 104. Books on the new star and on the comet of 1577 136 § 105. Tycho’s system of the world: quarrel with _Reymers Bär_ 136 § 106. Last years at Hveen: breach with the King 138