Contents xxi 



PAGE 



191. Reception of the Principia 239 



192. Third period of Newton's life, 1687-1727: Parlia- 

 mentary career : improvement of the lunar 

 theory : appointments at the Mint and removal 

 to London : publication of the Optics and of the 

 second and third editions of the Principia, edited 

 by Cotes and Pemberton : death . . . 240 



193. Estimates of Newton's workby Leibniz, by Lagrange, 



and by himself 241 



194. Comparison of his astronomical work with that of 

 his predecessors : " explanation " and " de- 

 scription " : conception of the material universe 

 as made up of bodies attracting one another 

 according to certain laws 242 



195. Newton's scientific method : " Hypotheses nonfingo " 245 



CHAPTER X. 



OBSERVATIONAL ASTRONOMY IN THE EIGHTEENTH 



CENTURY, 196-227 . . . . . . 247-286 



196. Gravitational astronomy : its development due 

 almost entirely to Continental astronomers : use 

 of analysis : English observational astronomy . 247 

 *97~8. Flamsteed : foundation of the Greenwich Ob- 

 servatory: his star catalogue .... 249 

 199. Halley : catalogue of Southern stars . . . 253 



2OO. Halley 's comet . 253 



2O I. Secular acceleration of the moon's mean motion . 254 



202. Transits of Venus 254 



203. Proper motions of the fixed stars . . . 255 

 204-5. Lunar and planetary tables : career at Green- 

 wich : minor work .. 255 



206. Bradley : career 257 



207-11. Discovery and explanation of aberration: the 



constant of aberration 258 



212. Failure to detect parallax ... . 265 



213-5. Discovery of nutation : Machin .... 265 

 216-7. Tables of Jupiter's satellites by Bradley and by 

 Wargentin : determination of longitudes, 



and other work 269 



2l8. His observations : reduction . , . .271 



