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as you pleafe, joined to a very final! Elevation : To this 
End you need only fet backwarder the Lever’s Point 
of Reft, along the Perpendicular marked in Fig. 2. 
TAB. IV. Now this is precifely what the Spur does, 
which we have added to our Ambe 5 the Holes it is 
pierced with, as well as the Mortife of the Foot, are 
placed in different Degrees, as the Points 1, 2, 3 /and 
thefe Holes, as has been faid, are the Places of the 
Pin which forms the Lever’s Hinge or Point of Reft. 
The Gradation of thofe Holes therefore enables 
you to augment at Will the Extenfion , whilft the 
Elevation diminishes in the fame Proportion 5 but if 
you have a mind the Elevation fhould diminifti more 
or lefs than in the forefaid Proportion, for Inftance, 
you want to make a great Extenfion, and a very fmali 
Elevation, there is nothing eafier for it than our Ma- 
chine. \ou need only pufh the Spur 1, 3, which is 
moveable, as you know, towards the End of the Lever 
to L, and flop it there : Then the End of the Lever 
A, E, being very fhort, it has but little room to play ; 
on the contrary, if you will have a great Elevation, 
you need only bring back the faid Spur to M, or r! 
or ftill farther ; the farther you remove from the End 
of the Lever, the more it will have room to play, and 
the more conliderable will be its Elevation. ? It is 
true, the Pcfwer of the Lever will decreafe in the 
fame Proportion j but this Power is fo great, that 
Loffes like this ought to be reckoned for nothing. 
You have it therefore in your Power with this fort 
of Ambe to make, as Occafion requires, fuch Exten- 
iions and Counter-cxtenftons as you pleafe $ and you 
may likewife vary all the Degrees of the Elevation, 
which (hall be neceffary to give to the Bone that is 
fff to 
