essential to Matter, &c. 37

is the only tendency planted in matter; or,

to

had a hundred times more pores than solid matter, thefirst should gravitate an hundred times more than the last,as having an hundred times more solid matter ; andy et from the impulse of this medium, it should gravi-tate an hundred times less at least, as having an hundredtimes less surface : for the medium could only act on asurface of an inch square.

There is no way of avoiding this consequence, butby saying arbitrarily that there is an hundred times moresurface in the square inch of the perfectly solid body; orthat the medium impinges on an hundred times moresolid particles in this square inch of surface, than in allthe solid inch of the rarer body: but even that is con-tradictory ; for by supposition, there is but an hundredtimes as much matter in the whole solid inch of the per-fectly solid body; and surely it is not all lodged in oneof the surfaces, or in any of them.

There is another hypothesis that must be maintainedby those who assert this elastick fluid as the cause of gra-vity, which is itself very improbable, viz. that the per-fectly solid parts of all bodies whatsoever, are of equalbigness: for in similar particles, the solidity is in a tri-plicate ratio of the homologous sides, and the surfaceonly in a duplicate ratio of these. So that if similar so-lid particles are of a different bigness, the matter beingin a triplicate, and the action of a fluid only in a dupli-cate ratio of the sides, the same quantity of matter willnot have the fame gravity. If two particles have theirsides as 2 and 3, their gravities will be as 4 and g, andyet tsieir quantities of matter are as 8 and 27.

D 3

Dr.