Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/389

Simpl.To tell you true, I do not very well know; perhaps, because I have not so much as learnt the reasons that are by Ptolomy produced, of those effects, I mean of those stations, retrogradations, accessions, recessions of the Planets; lengthenings and shortnings of dayes, changes of seasons, &c. But omitting the consequences that depend on the first suppositions, I find in the suppositions themselves no small difficulties; which suppositions, if once they be overthrown, they draw along with them the ruine of the whole fabrick. Now forasmuch as because the whole module of Copernicus seemeth in my opinion to be built upon infirm foundations, in that it relyeth upon the mobility of the earth, if this should happen to be disproved, there would be no need of farther dispute. And to disprove this, the Axiom of Aristotle is in my judgement most sufficient, That of one simple body, one sole simple motion can be natural: but here in this case, to the Earth,Four several motions assigned to the Earth. a simple body, there are assigned 3. if not 4. motions, and all very different from each other. For besides the right motion, as a grave body towards its centre, which cannot be denied it, there is assigned to it a circular motion in a great circle about the Sun in a year, and a vertiginous conversion about its own centre in twenty four hours. And that in the next place which is more exorbitant, & which happly for that reason you pass over in silence, there is ascribed to it another revolution about its own centre, contrary to the former of twenty four hours, and which finisheth its period in a year. In this my understanding apprehendeth a very great contradiction.

The motion of descent belongs not to the terrestrial Globe, but to its parts.Salv.As to the motion of descent, it hath already been concluded not to belong to the Terrestrial Globe which did never move with any such motion, nor never shall do; but is (if there be such a thing) that propension of its parts to reunite themselves to their whole. As, in the next place, to the Annual motion, and the Diurnal,The annual and diurnal motion are compatible in the Earth. these being both made towards one way, are very compatible, in the same manner just as if we should let a Ball trundle downwards upon a declining superficies, it would in its descent along the same spontaneously revolve in it self. As to the third motion assigned it by Copernicus, namely about it self in a year, onely to keep its Axis inclined and directed towards the same part of the Firmament, I will tell you a thing worthy of great consideration: namely ut tantum abest (although it be made contrary to the other annual) it is so far from having any repugnance or difficulty in it,Every pensil and librated, body carryed round in the circumference of a circle, acquireth of it self a motion in it self contrary to that. that naturally and without any moving cause, it agreeth to any whatsoever suspended and librated body, which if it shall be carried round in the circumference of a circle, immediate of it self, it acquireth a conversion about its own centre, contrary to that which carrieth it about, and of