Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/127

 from this to the other yet bigger of Saturn, whose period is of thirty years, it is necessary, I say, that you passe to another Sphere incomparably greater still than that, and make this to accomplish an entire revolution in twenty four hours. And this yet is the least disorder that can follow. For if any one should passe from the Sphere of Saturn to the Starry Orb, and make it so much bigger than that of Saturn, as proportion would require, in respect of its very slow motion, of many thousands of years, then it must needs be a Salt much more absurd, to skip from this to another bigger, and to make it convertible in twenty four hours. But the motion of the Earth being granted, the order of the periods will be exactly observed, and from the very slow Sphere of Saturn, we come to the fixed Stars, which are wholly immoveable, and so avoid a fourth difficulty, which we must of necessity admit, if the Starry Sphere be supposed moveable, and that is the immense disparity between the motions of those stars themselves; of which some would come to move most swiftly in most vast circles, others most slowly in circles very small, according as those or these should be found nearer, or more remote from the Poles; which still is accompanied with an inconvenience, as well because we see those, of whose motion there is no question to be made, to move all in very immense circles; as also, because it seems to be an act done with no good consideration, to constitute bodies, that are designed to move circularly, at immense distances from the centre, and afterwards to make them move in very small circles. And not onely the magnitudes of the circles, and consequently the velocity of the motions of these Stars, shall be most different from the circles and motions of those others, but (which shall be the fifth inconvenience) the self-same Stars shall successively vary its circles and velocities: For that those, which two thousand years since were in the Equinoctial, and consequently did with their motion describe very vast circles, being in our dayes many degrees distant from thence, must of necessity become more slow of motion, and be reduced to move in lesser circles, and it is not altogether impossible but that a time may come, in which some of them which in aforetime had continually moved, shall be reduced by uniting with the Pole, to a state of rest, and then after some time of cessation, shall return to their motion again; whereas the other Stars, touching whose motion none stand in doubt, do all describe, as hath been said, the great circle of their Orb, and in that maintain themselves without any variation. The absurdity is farther enlarged (which let be the sixth inconvenience) to him that more seriously examineth the thing, in that no thought can comprehend what ought to be the solidity of that immense Sphere, whose depth so stedfastly