_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. BOOK III. ~CHAP. 1.~ _Concerning the cause of colours inherent in the light_ _The sun’s light is composed of rays of different colours_ p. 318 _The refraction of light_ p. 319 320 _Bodies appear of different colour by day-light, because some reflect one kind of light more copiously than the rest, and other bodies other kinds of light_ p. 329 _The effect of mixing rays of different colours_ p. 334 ~CHAP. 2.~ _Of the properties of bodies whereon their colours depend._