112 Mechanick Power. BOOK VI.

neither is there had ſuch a meaſure as we require, to vit,ſome weight to which percuſſion is equal, or a weight whichis moved in the ſame manner as a nail, although it drive it oneinch. a

Mr. Hobbs reduces all percuſſion to the firſt endeavour whichthe weight hath, but knows not whether the firſt endeavourgiven be indiviſible and determinate, and ſo in this explicationhe wraps himſelf in queſtions of continual diviſion.

PRO PO. VI.The meaſure F Percuſſion.

Spot a hammer of 1 pound, and let it be of any figure,it matters not, which being ſtruck with the force of aman, hath the ſame velocity, as if it had deſcended 425 feet,and drove a nail one inch, now tis demanded what weightthis percuſſion is equal to: And tis certain, chat a weight ofone pound falling 425 feet, acquires a force to raiſe i pound425 feet, which I fhew in any Pendulum , wherein the weightaſcends almoſt the ſame as it deſcends. Therefore this per-cuſſion ſeems to be in equilibrio with a weight of one pound, inmoving through 425 feet: But if you ask what weight heingmoved one inch, will be in eguilibrio with a weight of onepound, moved 425 ſeet, multiply 425 by 12, it makes 5 100inches, in 423 feet; I ſay, if a weight of 5 100 pounds be place don the nail, the nail will be forced in one inch; for onepound moved 5 100 inches, is in equilibrio with 5 100 poundsmoved one inch, wherefore the percuſſion of the man ſeemsto be equal to 5; ro pounds, which was to be ſnewn; never-theleſs, there is a doubting in this calculation, becauſe thatthe velocity of the weight aſcending, always decreaſes,Wherefore theſe things cannot be conſtituted, but according tothe doctrine delivered of heavy bodies falling.

P ROP OS.