&ook IV. of Natural Philosophy . 219

V imagining all the Particles of Matter closely■!°in’d, no Body will deny.

That the Resistance of such a Body in any Fluid^°es not depend upon the Bigness of the Parts ofFluid, and is the same, whether the Parts of( he Fluid be equal, or any how unequal, is evi-

If every thing be full of Matter, this Body can?hly move thro’ a Fluid of the fame Density as(stelf, for it must run against all the Matter whichls in those Places thro’ which it pastes ; and in( hem the Matter is without Interstices, as it is injHe Body ; therefore it will lose half its Velocitybefore it has run thro’ the Length of twice itsdiameter.

Now let us suppose the.Body to be increas’d,Quantity of Matter remaining the fame, andl he Body continuing homogeneous; that is, let*here be Pores in the Body, thro’ which the mostkbtile Particles of Matter may pass very freely,a *id let these Pores be equally dispersed all overl he Body ; if the Body thus chang’d be mov'd,the very subtile Fluid, ot which we speak, willrun against the whole Surface, but only those^arts of the Surface which are between the Pores;

^hich Parts being taken together, because weoppose the Body homogeneous, are equal to the'Vface °f the Body in the first Supposition, whenconceiv’d it to be without Pores; for the Bo-being increas’d, the Surface has not been chan-Ited, but only dilated by the Interposition of*Ws; so that in both Cases the Body will un-^rgo the fame Resistance from the Impulse uponSurface, and the Resistance on the dilated®°dy is greater, from the Fluid running againstinternal Parts of the Body ; wherefore this«ody will sooner lose half its Motion in the se-c °nd than in'the first Case, that is, before it has

run