BOOK II.. ~chap. 1.~ _that the Planets Move in a Space

~CHAP. 1.~ That the planets move in a space empty of sensible matter p. 161 The system of the world described p. 162 The planets suffer no sensible resistance in their motion p. 166 They are not kept in motion by a fluid p. 168 That all space is not full of matter without vacancies p. 169

~CHAP. 2.~ Concerning the cause that keeps in motion the primary planets p. 171 They are influenced by a centripetal power directed to the sun p. 171 The strength of this power is reciprocally in the duplicate proportion of the distance ibid. The cause of the irregularities in the motions of the planets p. 175 A correction of their motions p. 178 That the frame of the world is not eternal p. 180

~CHAP. 3.~ Of the motion of the moon and the other secondary planets That they are influenced by a centripetal force directed toward their primary, as the primary are influenced by the sun p. 182 That the power usually called gravity extends to the moon p. 189 That the sun acts on the secondary planets p. 190 The variation of the moon p. 193 That the circuit of the moons orbit is increased by the sun in the quarters, and diminished in the conjunction and opposition p. 198 The distance of the moon from the earth in the quarters and in the conjunction and opposition is altered by the sun p. 200 These irregularities in the moon’s motion varied by the change of distance between the earth and sun p. 201 The period of the moon round the earth and her distance varied by the same means ibid. The motion of the nodes and the inclination of the moons orbit p. 202 The motion of the apogeon and change of the eccentricity p. 218 The inequalities of the other secondary planets deducible from these of the moon p. 229

~CHAP. 4.~ Of comets

They are not meteors, nor placed totally without the planetary system p. 230 The sun acts on them in the same manner as on the planets p. 231 Their orbits are near to parabola’s p. 233 The comet that appeared at the end of the year 1680, probably performs its period in 575 years, and another comet in 75 years p. 234 Why the comets move in planes more different from one another than the planets p. 235 The tails of comets p. 238 The use of them p. 243 244 The possible use of the comet it self p. 245 246

~CHAP. 5.~ Of the bodies of the sun and planets

That each of the heavenly bodies is endued with an attractive power, and that the force of the same body on others is proportional to the quantity of matter in the body attracted p. 247 This proved in the earth p. 248 In the sun p. 250 In the rest of the planets p. 251 That the attractive power is of the same nature in the sun and in all the planets, and therefore is the same with gravity p. 252 That the attractive power in each of these bodies is proportional to the quantity of matter in the body attracting ibid. That each particle of which the sun and planets are composed is endued with an attracting power, the strength of which is reciprocally in the duplicate proportion of the distance p. 257

The power of gravity universally belongs to all matter p. 259

The different weight of the same body upon the surface of the sun, the earth, Jupiter and Saturn; the respective densities of these bodies, and the proportion between their diameters p. 261

~CHAP. 6.~ Of the fluid parts of the planets

The manner in which fluids press p. 264 The motion of waves on the surface of water p. 269 The motion of sound through the air p. 270 The velocity of sound p. 282 Concerning the tides p. 283 The figure of the earth p. 296 The effect of this figure upon the power of gravity p. 300 The effect it has upon pendulums p. 302 Bodies descend perpendicularly to the surface of the earth p. 304 The axis of the earth changes its direction twice a year, and twice a month p. 313 The figure of the secondary planets ibid.