K = * _By the nature of motion_, the apparent motion is the same if the Planets revolve about the Sun: this is _simpler_. L = * _By the nature of motion_, the apparent motion of the Sun is the same if the Earth revolve round the Sun: this is _simpler_. M = * Copernicus. The Earth and Planets revolve about the Sun as a center in Orbits nearly circular. The Earth revolves about its axis inclined to the Ecliptic in a constant position, and the Moon revolves about the Earth. The _Heliocentric Theory_ governs subsequent speculations. N = Retaining Moon's Eccentric and Epicycle; By additional observations, the Moon's motion has other inequalities. O = Retaining but referring to the Sun as center the Planets' Epicycles and Eccentrics and the annual Orbit; P = Retaining obs^ns. Earth's Aphelion revolves. Q = Tycho. Moon's _Variation_; _Unequal Motion of Node_; _Change of Inclination_. R = By calc^ns. of the periodic times and distances. S = By additional observations and calculations. T = Planets' Aphelia revolve. Jupiter and Saturn's motions have an inequality dep^g. on their mutual positions. U = THE WEIGHT of bodies dimin^s in going towards the Equator. V = THE SATELLITES of Jupiter and Saturn revolve according to Kepler's Laws. W = Horrox. Halley. The Moon moves in an _Ellipse_ with variable _axis_ and _eccentricity_. X = Kepler. Distances cubed are as times squared. Y = Kepler. Areas as described by Planets are as times. Z = Kepler. Curves described by Planets are as ellipses. a1 = Newton. Earth is oblate. b1 = * By Mechanics. c1 = * Newton. Moon is attracted by the Earth. Fall of heavy bodies. d1 = * Newton. Moon's inequalities produced by attraction of Sun. e1 = * Newton. Wren. Hooke. Sun's force on different Planets is invers. as square of distance. f1 = * Newton. Planets are attracted by the Sun. g1 = * Newton. Sun attracts Planets invers. as square of distance. h1 = * Newton. These inequalities are produced by mutual attraction of the Planets. i1 = Precession of Equinoxes is produced by attraction of Moon and Sun on oblate Earth. j1 = Tides are produced by attraction of Moon and Sun on Sea. Explanation imperfect. k1 = Diminution of gravity and oblateness of Earth arise from attractions of parts. l1 = * Newton. Jupiter and Saturn attract their Satellites inversely as the square of the distance, and the Sun attracts Planets and Satellites alike. m1 = Newton. Earth attracts Moon invers. as square of distance. n1 = Newton. Sun attracts Moon. o1 = Newton. Sun attracts Planets inversely as the square of the distance. p1 = Newton. Planets attract each other. q1 = * Newton. Moon and Sun attract parts of the Earth. r1 = * Newton. Moon and Sun attract the Ocean. s1 = * Newton. Parts of the Earth attract each other. t1 = Newton. All parts of the Earth, Sun, Moon. and Planets attract _each other_ with Forces inversely as the square of the distance. u1 = Newton. THE THEORY OF UNIVERSAL GRAVITATION. (All bodies