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unable to proceed with a few simple processes ofmultiplication and division, undoubtedly the greatdiscovery which was now being revealed to him mighthave led to such a result. For he clearly recognizedthe fact that the interpretation of the moon’s motionswas not what was in reality in question, nor even the jexplanation of the movements of all the bodies of the jsolar system ; but that the law he was inquiring intomust be, if once established, the law of the universe |itself. . J
If we consider the position in which matters now |stood, we shall see that in reality the law of gravita- jtion had already been placed on a somewhat firm and jstable basis. Newton had shown that the motions ofthe planets are conformable to the theory that the sunattracts each planet with a force inversely proportional jto the square of the planet’s distance. The motions ofJupiter ’s satellites (the only scheme known to Newton)agreed similarly with this law of attraction. And nowhe had shown that in the case of our own moon, theattraction exerted by the central body round whichthe moon moves, is related to the attraction exertedby this body, the earth, on objects at her surface,according to precisely the same law. Furthermore, itwas known that all bodies are attracted in the sameway by the earth, let their condition or elementaryconstitution be what it may. The inference seemedabundantly clear that the law of attraction,—witheffects proportional to the attracting masses, and in-versely proportional to the distances separating them,