1. Sun's Force on Different Planets. 399 2. Force in Different Points of an Orbit. 400 3. Moon's Gravity to the Earth. 402 4. Mutual Attraction of all the Celestial Bodies. 406 5. " " " Particles of Matter. 411 Reflections on the Discovery. 414 Character of Newton. 416 CHAPTER III.--SEQUEL TO THE EPOCH OF NEWTON.--RECEPTION OF THE NEWTONIAN THEORY. _Sect._ 1. General Remarks. 420 _Sect._ 2. Reception of the Newtonian Theory in England. 421 _Sect._ 3. " " " " Abroad. 429 CHAPTER IV.--SEQUEL TO THE EPOCH OF NEWTON, CONTINUED. VERIFICATION AND COMPLETION OF THE NEWTONIAN THEORY. _Sect._ 1. Division of the Subject. 433 _Sect._ 2. Application of the Newtonian Theory to the Moon. 434 _Sect._ 3. " " " " Planets, Satellites, and Earth. 438 _Sect._ 4. Application of the Newtonian Theory to Secular Inequalities. 444 _Sect._ 5. " " " " to the new Planets.446 _Sect._ 6. " " " " to Comets. 449 _Sect._ 7. " " " " to the Figure of the Earth. 452 _Sect._ 8. Confirmation of the Newtonian Theory by Experiments on Attraction. 456 _Sect._ 9. Application of the Newtonian Theory to the Tides. 457 CHAPTER V.--DISCOVERIES ADDED TO THE NEWTONIAN THEORY. _Sect._ 1. Tables of Astronomical Refraction. 462 _Sect._ 2. Discovery of the Velocity of Light.--Römer. 463 {20} _Sect._ 3. Discovery of Aberration.--Bradley. 464 _Sect._ 4. Discovery of Nutation. 465 _Sect._ 5. Discovery of the Laws of Double Stars.--The Two Herschels. 467 CHAPTER VI.--THE INSTRUMENTS AND AIDS OF ASTRONOMY DURING THE NEWTONIAN PERIOD. _Sect._ 1. Instruments. 470 _Sect._ 2. Observatories. 476 _Sect._ 3. Scientific Societies. 478 _Sect._ 4. Patrons of Astronomy. 479 _Sect._ 5. Astronomical Expeditions. 480 _Sect._ 6. Present State of Astronomy. 481 _ADDITIONS TO THE THIRD EDITION._ INTRODUCTION 489 BOOK I.--THE GREEK SCHOOL PHILOSOPHY. THE GREEK SCHOOLS. The Platonic Doctrine of Ideas. 491