When then the highest jerked up from the ground, falleth down once more, why may it not casually hit upon the declivity of some stone fixed within the floor, and that hath an inclination that method in the direction of which it moveth, and acquiring by that slip a brand new whirle over and above that conferred by the lash, why may it not redouble its movement, and make it swifter than it was at its first lighting upon the ground? Salv.This may essentially follow, if it have been concluded that the Terrestrial Globe moveth circularly; a thing, which I pretend not to be finished, however have onely hitherto attempted, as I shall nonetheless, to look at the power of these causes, which have been alledged by Philosophers to prove the immobility of the Earth, of which this first taken from things falling perpendicularly, hath begat the doubts, that have been mentioned; which I know not of what force they may have seemed to Simplicius; and subsequently before I passe to the examination of the remaining arguments, it could be handy that he produce what he hath to reply to the contrary. But because in throwing the ball, it issueth out of the hand with some roling conferred by the fingers, when ever the hand is below the ball, as it is mostly held; whereupon the ball in its lighting on the ground neer to the mark, between the motion of the projicient and that of the roling, would run a great way from the same: To make the ball stay, they hold it artificially, with their hand uppermost, and it undermost, which in its supply hath a opposite twirl or roling conferred upon it by the fingers, by means whereof in its coming to the ground neer the mark it stays there, or runs very very little forwards.
Tower, or to speak more properly, from the circumference of the circle described by the top of the Tower, via the Earths conversion; however that such recessions be lesser and lesser in infinitum; by how much the moveable finds it self to be lesse and lesse faraway from the primary time period where it rested. And from therefore ariseth the decision of that slight, which the extra skilful Tennis Players use to their benefit; that is, to gull their adversary by reducing (for therefore is their Phrase) the Ball; which is, to return it with a side Rachet, in such a fashion, that it doth thereby acquire a movement by it self opposite to the projected movement, and so by that means, at its coming to the ground, the rebound, which if the ball did not turn in that manner, can be in the direction of the adversary, giving him the same old time to tosse it again again, doth fail, and the ball runs tripping along the bottom, or rebounds lesse than standard, and breaketh the time of the return. But to return to our principal problem which gave occasion for beginning these others; I say it is possible that a person carried very swiftly, could let a ball drop out of his hand, that being come to the Earth, shall not onely comply with his motion, but additionally out-go it, shifting with a better velocity.
Salv.But stay slightly Sagredus, for I’m to acquaint you also with three Observations of mine, that its potential is not going to displease you.A moveable falling from the highest of the Tower, moveth in the circumference of a circle. A B, the circle B I, representing to me the Terrestrial Globe, and prolonging the semidiameter A B to C, I have described the peak of the Tower B C; the which being carried about by the Earth along the circumference B I, describeth with its prime the arch C D: Dividing, in the next place, the line C A within the center at E; upon the centre E, at the gap E C, I describe the semicircle C I A: In which, I now affirm, that it is vitally probable that a stone falling from the top of the Tower C, doth transfer, with a motion mixt of the circular, which is in frequent, and of its peculiar right movement. Sagr.I’m content to excuse you from this narration for the current, provided that this may be one of the Propositions reserved to be examined amongst the rest in another explicit assembly, for that the knowledg thereof is by me very much desired; and in the mean time allow us to return to the road described by the grave physique in its fall from the highest of the Tower to its base.
If subsequently in the circumference C D, sure equal elements C F, F G, G H, H L, be marked, and from the points F, G, H, L, right traces be drawn in the direction of the centre A, the parts of them intercepted between the 2 circumferences C D and B I, shall characterize unto us the identical Tower C B, transported by the Terrestrial Globe in the direction of D I; wherein lines the points the place they arrive to be intersected by the arch of the semicircle C I, are the places by which on occasion the falling stone doth passe; which factors go frequently with larger and higher proportion receding from the top of the Tower. Sagr.I like this motion very well; and since we’re at this liberty, let me take go away, earlier than we passe any farther to ask of you Salviatus, whether or not you probably did ever consider what that line could also be that is described by the grave moveable naturally falling down from the highest of a Tower; and if in case you have reflected on it, be pleased to tell me what you suppose thereof. Sagr.And it would generally wholly retard and stop it, in case the revolution of the highest were very swift.