Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/336

 ebb and flow in its channel after the manner of the Sea. If the attraction of the body S were taken away; the water would acquire no motion of flux and reflux by revolving round the quiecent centre of the globe. The cae is the ame of a globe moving uniformly forwards in a right line, and in the mean time revolving about its centre. (by cor. 5. of the laws of motion) and of a globe uniformly attracted from its rectilinear coure (by cor. 6. of the ame laws.) But let the body S come to act upon it, and by its unequable attraction the water will receive this new motion. For there will be a tronger attraction upon that part of the water that is nearet to the body, and a weaker upon that part which is more remote. And the force LM will attract the water downwards at the quadratures, and depres it as far as the yzygies; and the force KL will attract it upwards in the yzygies, and withhold its decent, and make it rie as far as the quadratures; except only in o far as the motion of flux and reflux may be directed by the channel of the water. and be a little retarded by friction.

If now the annulus becomes hard, and the globe is diminihed, the motion of flux and reflux will ceae; but the ocillating motion of the inclination and the præceion of the nodes will remain. Let the globe have the ame axis with the annulus and perform its revolutions in the ame times, and at its urface touch the annulus within, and adhere to it; then, the globe partaking of the motion of the annulus, this whole compages will ocillate, and the nodes will go backward. For the globe, as we hall hew preently, is perfectly indifferent to the receiving of all impreions. The