Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/155

 been partaker, as part of the ship, at the time that it was upon the Mast; the other is the new motion of descent, which also must needs be an hinderance of that other progressive motion.

As to the impediment of the Air, I do not deny it you; and if the thing falling were a light matter, as a feather, or a lock of wool, the retardation would be very great, but in an heavy stone is very exceeding small. And you your self but even now did say, that the force of the most impetuous wind sufficeth not to stir a great stone from its place; now do but consider what the calmer air is able to do, being encountred by a stone no more swift than the whole ship. Neverthelesse, as I said before, I do allow you this small effect, that may depend upon such an impediment; like as I know, that you will grant to me, that if the air should move with the same velocity that the ship and stone hath, then the impediment would be nothing at all. As to the other of the additional motion downwards; in the first place it is manifest, that these two, I mean the circular, about the centre, and the streight, towards the centre, are not contraries, or destructive to one another, or incompatible. Because that as to the moveable, it hath no repugnance at all to such motions, for you your self have already confest the repugnance to be against the motion which removeth from the centre, and the inclination to be towards the motion which approacheth to the centre. Whence it doth of necessity follow, that the moveable hath neither repugnance, nor propension to the motion which neither approacheth, nor goeth from the centre, nor consequently is there any cause for the diminishing in it the faculty impressed. And forasmuch as the moving cause is not one alone, which it hath attained by the new operation of retardation; but that they are two, distinct from each other, of which, the gravity attends only to the drawing of the moveable towards the centre, and the vertue impress't to the conducting it about the centre, there remaineth no occasion of impediment.

Your argumentation, to give you your due, is very probable; but in reality it is invelloped with certain intricacies, that are not easie to be extricated. You have all along built upon a supposition, which the Peripatetick Schools will not easily grant you, as being directly contrary to Aristotle, and it is to take for known and manifest, That the project separated from the projicient, continueth the motion by vertue impressed on it by the said projicient, which vertue impressed is a thing as much detested in Peripatetick Philosophy, as the passage of any accident from one subject into another. Which doctrine doth hold, as I believe it is well known unto you, that the project is carried by the medium, which in our case happeneth to be the Air. And