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IV. Concerning the Load for an Overftoot Wheel, in 
order that it may produce a Maximum . 
The maximum load for an overjhot wheel, is that 
which reduces the circumferences of the wheel to its 
proper velocity 3 and this will be known, by dividing 
the efFedt it ought to produce in a given time by the 
fpace intended to be deferibed by the circumference 
of the wheel in the fame time : the quotient will be 
the refinance overcome at the circumference of the 
wheel ; and is equal to the load required, the fric- 
tion and refiftance of the machinery included. 
V. Concerning the great eft pojftble Velocity of an 
Over {hot Wheel. 
The greateft velocity that the circumference of an. 
over fir ot wheel is capable of, depends jointly upon 
the diameter or height of the wheel, and the velo- 
city of falling bodies 3 for it is plain that the velocity 
of the circumference can never be greater, than to 
deferibe a femi- circumference, while a body let fall 
from the top of the wheel will defeend thro’ its di- 
ameter 3 nor indeed quite fo great, as a body de- 
feending thro’ the fame perpendicular fpace cannot 
perform the fame in fo fmall a time when paffing 
thro’ a femi-circle, as would be done in a perpendi- 
cular line. Thus, if a wheel is i 6 feet i inch high, 
a body will fall thro’ the diameter in one fecond : 
this wheel therefore can never arrive at a velocity 
equal to the making one turn in two feconds 3 but, 
in reality, an over (hot wheel can never come near 
this velocity 3 for when it acquires a certain fpeed,. 
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