subject, therefore, to the third law of Kepler. The compression of their primary and their reciprocal attraction retains their orbits in the plane of the planet's equator. introduced by integration into series of perturbations 299, 312 Areas, variation of, a test of disturbing forces sum of, zero on two of the co-ordinate planes and a maximum on 86 Circular motion Page 7 77, 92 87,90 92,96 251 223, 231 motion of the same, as if the masses of the planets were united in it of a planet and its satellites distance of primitive impulse from Coefficients of the series expressing the disturbing action of the planets |