[ ro 9 ] 
In like manner, in feeking the greateft produdt, 
or maximum of effedt ; having found by trials what 
weight gives the greateft produdt, by limply multi- 
plying the weight in the fcale by the number of turns 
of the wheel, find what weight in the fcale, when 
the cord is on the contrary fide of the cylinder, will 
caufe the wheel to make the fame number of turns 
the fame way, without water ; it is evident that this 
weight will be nearly equal to all fridtion and relift- 
ance taken together ; and confequently, that the 
weight in the fcale, with twice * the weight of the 
fcale, added to the back or counter-weight, will be 
equal to the weight that could have been raifed, fup- 
pofmg the machine had been without fridtion or re- 
fiftance ; and which multiplied by the height to 
which it was raifed, the produdt will be the greateft 
effedt of that power. 
The quantity of water expended is found thus : 
The pump made ufe of for replenishing the head 
with water was fo carefully made, that no water 
efcaping back by the leathers, it delivered the fame 
quantity of water at every Stroke, whether worked 
quick or flow ; and as the length of the Stroke was 
limited, confequently the value of one Stroke (or on 
account of more exadtnefs 12 Strokes) was known, by 
the height to which the water was thereby raifed in 
the head j which being of a regular figure was eafily 
meafured. The Sluice, by which the water was drawn 
upon the wheel, was made to Stop at certain heights 
by a peg ; fo that when the peg was in the fame hole. 
* The weight of the fcale makes part of the weight both ways. 
the 
