INDEX. 



385 



Stars, old ones, not true that they are 



not subject to change, 176. 

 Star, what is meant by the opinion 

 that it is the denser part of its own 

 sphere, 181. 



Stars, question respecting the sub 

 stance of, 182. 



Stars, whether kept alive by sustenta- 

 tion, 187 ; whether increased or 

 lessened, generated, extinguished, 

 188 ; whether, during long lapses of 

 ages, stars are produced and decom 

 posed, 185. 



Stars, should be enquired whether 

 give light of themselves, or whether 

 received from the sun, 185. 

 Stars, whether that be the true number 

 of them which is visible, 190 ; what 

 are the real dimensions of each star, 

 190; what data there are for deter 

 mining them, 190. 



Stars, true distances of, for determin 

 ing, if possible, if not comparative 

 should be ascertained, 191. 

 Statement, legitimate mode of, 223. 

 Sound and light, the agreements and 

 disagreements of the phenomena of, 

 231,235, 240,241, 242,243, 244. 

 Sound, reasons for enquiring into the 



theory of, 225. 



Sound, of its generation and the first 

 percussion, 226; whether its form 

 is any local and perceptible motion 

 of the air, 226; three experiments 

 wherein sound is generated contra- 

 rily to the perceptible motion of the 

 air, 227 ; is generated by percus 

 sions, 227 ; air required for its gene 

 ration, 228 ; whether flame would 

 suffice instead of air, 228 ; lasting 

 of, and its perishing, 229 ; confusion 

 and perturbations of sounds, 230 ; 

 compared with light, why many 

 visibles seen at once do not confound 

 one another, and many sounds heard 

 at once do, 231. 



Sound, of the variety of bodies yield 

 ing it, instruments producing it, 

 species of sounds, 237 ; circum 

 stances regulating the pitch in va 

 rious sonorous bodies, 238 ; multi 

 plication, majoration, diminution, 

 and fraction of, 238. 

 Sound, time in which its generation, 

 extinction, and transmission, are 

 effected, 243 ; less quickly trans 

 mitted than light, 244 ; of its affi 

 nity with the motion of the air in 

 which it is carried, 244. 

 Sound, aids and impediments of, stay 

 VOL. xv. 



of, 232 ; diversity of mediums of, 

 232. 



Sound and hearing, history and first 

 inquisition of, 225. 



Sound, communion of the air percussed 

 with the ambient air and bodies, 246. 



Sound, penetration of 232 ; whether 

 heard under water, 232 ; whether it 

 can be generated except there be air 

 between the percussing and per 

 cussed body, 233 ; carriage, direc 

 tion, and spreading of the area it 

 fills, 234 ; compared with light, the 

 former may be conveyed in curved 

 lines, 235. 



Summary of the opinions which this 

 theory affirms and denies, 4. 



Sun, Venus, Mercury, and the Moon, 

 their relative situations doubted by 

 the ancients, 170. 



Sun, phenomena in the year 790, 

 and after the death of Julius Caesar, 

 177. 



System, fourth question, the cohesion 

 of, or substance connecting it : three 

 modes of viewing this, 166. 



System, whether there be different 

 centres around the, theories of Tycho 

 and Galileo, 171. 



System may exist consistently with 

 opinions that the earth revolves and 

 that planets are solid, 163. 



TACITUS, his works breathe more 

 living observation of manners than 

 those of Aristotle and Plato, 102. 



Telesius, the philosophy of, exhibited 

 in the fable of Cupid, 44. 



Time, its operation in promoting dis 

 covery and invention, 36. 



Time, masculine birth of, 223. 



Thales, discussion of his theory that 

 water is the prime element, 52. 



Theory of the motions of the heavenly 

 bodies, 5. 



Theories and common notions to Le 

 done away with, opinions, 41. 



Theories, universal, the invention of, by 

 persons ignorant of particulars, 100. 



Theories of Astronomers, the object of 

 the, 159. 



VACUUM, whether it exists at all, 



theory of, 167. 

 Venus and Mercury, a question which 



is higher than the other, 170. 

 Venus, change of its colour in the 



reign of Ogyges, and in 1578, 177. 

 Viol and lute, use of the perforations 



made in them, 246. 

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