force in the lower apſis is to the force in the upper apſis in a greater than a duplicate ratio of the diſtances. For the forces LM in the quadratures added to the forces of the body T compoſe forces in a leſs ratio, and the forces KL in the ſyzygies ſubducted from the forces of the body T leave the forces in a greater ratio. Therefore the ratio of the whole increaſe and decreaſe in the paſſage between the apſides, is leaſt at the quadratures and greateſt at the ſyzygies; and therefore in the paſſage of the apſides from the quadratures to the ſyzygies it is continually augmented, and increaſes the eccentricity of the ellipſis; and in the paſſage from the ſyzygies to the quadratures it is perpetually decreaſing, and diminiſhes the eccentricity.
Cor. 10. That we may give an account of the errors as to latitude, let us ſuppoſe the plane of the orbit EST to remain immovable; and from the cauſe of the errors above explained it is manifeſt, that of the two force NM, ML, which are the only and entire cauſe of them, the force ML acting always in the plane of the orbit PAB never diſturbs the motions as to latitude; and that the force NM, when the nodes are in the ſyzigies, acting alſo in the ſame plane of the orbit, does not at that time affect thoſe motions. But when the nodes are in the quadratures, it diſturbs them very much, and attracting the body P perpetually out of the plane of its orbit, it diminiſhes the inclination of the plane in the paſſage of the body from the quadratures to the ſyzygies, and again increaſes the ſame in the paſſage from the ſyzygies to the quadratures. Hence it comes to paſs that when the body is in the ſyzygies the inclination is
