Page:Mathematical collections and translations, in two tomes - Salusbury (1661).djvu/428

 In my opinion, it cannot be denied, but that your discourse carrieth with it much of probability, arguing, as we say, ex suppositione, namely, granting that the Earth moveth with the two motions assigned it by Copernicus: but if that motion be disproved, all that you have said is vain, and insignificant: and for the disproval of that Hypothesis, it is very manifestly hinted by your Discourse it self. You, with the supposition of the two Terrestrial motions, give a reason of the ebbing and flowing; and then again, arguing circularly, from the ebbing and flowing, draw the reason and confirmation of those very motions; and so proceeding to a more specious Discourse, you say that the Water, as being a fluid body, and not tenaciously annexed to the Earth, is not constrained punctually to obey every of its motions, from which you afterwards infer its ebbing and flowing, Now I, according to your own method, argue the quite contrary, and say; the Air is much more tenuous, and fluid than the Water, and lesse annexed to the Earths superficies, to which the Water, if it be for nothing else, yet by reason of its gravity that presseth down upon the same more than the light Air, adhereth; therefore the Air is much obliged to follow the motions of the Earth: and therefore were it so, that the Earth did move in that manner, we the inhabitants of it, and carried round with like velocity by it, ought perpetually to feel a Winde from the East that beateth upon us with intolerable force. And that so it ought to fall out, quotidian experience assureth us: for if with onely riding post, at the speed of eight or ten miles an hour in the tranquil Air, the incountering of it with our face seemeth to us a Winde that doth not lightly blow upon us, what should we expect from our rapid course of 800. or a thousand miles an hour, against the Air, that is, free from that motion? And yet, notwithstanding we cannot perceive any thing of that nature.

To this objection that hath much of likelihood in it, I reply, that its true, the Air is of greater tenuity and levity; and, by reason of its levity, lesse adherent to the Earth than Water so much more grave and † bulky; but yet the consequence is false that you infer from these qualities; namely, that upon account of that its levity, tenuity, and lesse adherence to the Earth, it should be more exempt than the Water from following the Terrestrial Motions; so as that to us, who absolutely pertake of of them, the said exemption should be sensible and manifest; nay, it happeneth quite contrary; for, if you well remember, the cause of the ebbing and flowing of the Water assigned by us, consisteth in the Waters not following the unevennesse of the motion of its Vessel, but retaining the impetus conceived before,