i 4 o Sir I S A A C N E W T O N’s Book II.

new opinion, a double mome?itum may produce a quadrupleeffect, if the velocity is double. But surely the author whogave this answer did not attend to the objection ; for what wehave proved, is not that a double momentum produces a quad-ruple effect, but that a double force, according to their ownnotion and computation, produces a quadruple force, accord-ing to the fame notion and computation. And indeed thesum of the answers they have made to the absurdities whichhave been deduced from their favourite opinion amounts tothis, viz. that they are no absurdities because their new opi-nion obliges them to admit them.

25. The resolution of powers, or pressures, is a necessaryconsequence of their composition. As motion is lost in thecomposition, so it is necessarily gained in the resolution ofmotion ; and as this is allowed of motions, and of the powersthat generate motion, there can be no good reason given whyit ought not to be allowed of the effects of those powers, or ofthe force of bodies. The same reasons that argue for an in-crease in the one case, prove, with the same evidence, that anincrease of the other ought likewise to be allowed. Let thebody c {Fig. 17.) moving in the direction d c, the diagonal ofthe parallelogram cldk, strike the equal body a obliquely, soas to impell it in the direction ca the continuation of'cK, andat the same time the equal body b, in the direction c b the con-tinuation of cl ; the body a will proceed in the right line ca,and the body b will proceed in the direction c b the continuationof cl, and c having communicated all its force to them willstop. It will not appear strange that the motions and forcesof a and b exceed the motion or force of c, if we consider thatc communicates the whole motion or force ck to a, and thewhole motion or force cl to b, that the resistance or inertia ofa reacting upon c, not in the direction of its motion c d, but

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