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lines of direction from the center of motion. -—From 
either of thefe cafes, we may deduce an obvious reafon 
why the weight A, fhould have the fame power to 
turn the wheel, from whatever point it hangs in the 
line M A ; the truth of which, I am perfuaded, can- 
not be proved independent of thofe cafes, and there- 
fore think it ought not to be ufed as a poftulatum in 
demonftrating the general property of the lever. 
Mr.Maclaurin,in his View of Newton’s Philofophy, 
after giving us the methods which Archimedes and 
Newton have ufed for proving the fundamental pro- 
perty of the lever, propofes one of his own, which, 
he fays, appears to be the moft natural one for this 
purpofe. However as to his method I fhall only ob- 
ferve, that from equal bodies fuftaining each other at 
equal diftances from the fulcrum, he (hews us how 
to infer that a body of one pound (for inftance) will 
fuftain another of two pounds at half its diftancefrcm 
the fulcrum, and. from thence that it will fuftain one 
of three pounds at a third of its diftance from the 
fulcrum : and thus he goes on deducing, by a kind 
of induction, what the proportion is in general be- 
tween two bodies that fuftain each other on the arms 
of a lever. But this argument (which I do not think 
by any means fatisfaCtory) he obferves cannot be 
applied when the arms of the lever are incom- 
menfurable. 
Thefe are the methods of demonftrating the fun- 
damental property of the lever, which are moft worth 
taking notice of; and, fince they feem liable to ob- 
jections, and the other methods I have met with are 
ftill more exceptionable, I fhall propofe a new proof 
of this property of the lever, which appears to me 
a very 
