Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/160

 velocity, no imaginable diversity could be found either in this, or any other experiment whatsoever, as I am anon to tell you. Now if in this case there appeareth no difference at all, what can be pretended to be seen in the stone falling from the top of the Tower, where the motion in gyration is not adventitious, and accidental, but natural and eternal; and where the air exactly followeth the motion of the Tower, and the Tower that of the Terrestrial Globe? have you any thing else to say, Simplicius, upon this particular?

No more but this, that I see not the mobility of the Earth as yet proved.

Nor have I any intention at this time, but onely to shew, that nothing can be concluded from the experiments alledged by our adversaries for convincing Arguments: as I think I shall prove the others to be.

I beseech you, Salviatus, before you proceed any farther, to permit me to start certain questions, which have been rouling in my fancy all the while that you with so much patience and equanimity, was minutely explaining to Simplicius the experiment of the Ship.

We are here met with a purpose to dispute, and it's fit that every one should move the difficulties that he mets withall; for this is the way to come to the knowledg of the truth. Therefore speak freely.

If it be true, that the impetus wherewith the ship moves, doth remain indelibly impress'd in the stone, after it is let fall from the Mast; and if it be farther true, that this motion brings no impediment or retardment to the motion directly downwards, natural to the stone: it's necessary, that there do an effect ensue of a very wonderful nature. Let a Ship be supposed to stand still, and let the time of the falling of a stone from the Masts Round-top to the ground, be two beats of the pulse; let the Ship afterwards be under sail, and let the same stone depart from the same place, and it, according to what hath been premised, shall still take up the time of two pulses in its fall, in which time the ship will have run, suppose, twenty yards; so that the true motion of the stone will be a transverse line, considerably longer than the first straight and perpendicular line, which is the length of the * Mast, and yet nevertheless the * stone will have past it in the same time. Let it be farther supposed, that the Ships motion is much more accelerated, so that the stone in falling shall be to pass a transverse line much longer than the other; and in sum, increasing the Ships velocity as much as you will, the falling stone shall describe its transverse lines still longer and longer, and yet shall pass them all in those self same two pulses. And in this fashion, if a Canon were