Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/62

18 thoe forces ought to be impres'd, that the motions of the globes might be mot augmented. that is, we might dicover their hindermot faces, or thoe which, in the circular motion, do follow. But the faces which follow being known, and conequently, the oppoite ones that precede, we hould likewie know the determination of their motions. And thus we might find both the quantity and the determination of this circular motion, ev'n in an immene vacuum, where there was nothing external or enible with which the globes could be compar'd. But now if in that pace ome remote bodies were plac'd that kept always a given poition one to another, as the Fixt Stars do in our regions; we cou'd not indeed determine from the relative tranlation of the globes among thoe bodies, whether the motion did belong to the globes or to the bodies. But if we oberv'd the cord, and found that its tenion was that very tenion which the motions of the globes requir'd, we might conclude the motion to be in the globes. and the bodies to be at ret; and then, latly, from the tranlation of the globes among the bodies, we hould find the determination of their motions. But how we are to collect the true motions from their caues, effects, and apparent differences; and vice versa, how from the motions, either true or apparent, we may come to the knowledge of their caues and effects, hall be explain'd more at large in the following Tract. For to this end it was that I compos'd it. Rh