[I3°] 
raifed that height, in order to be in a condition of 
producing the fame effed a fecond time. 
The ratio’s between the powers fo eftimated, and 
the cfjcdts at the maximum deduced from the feveral 
fetts of experiments, are exhibited at one view in 
column 9. of Table II.; and from hence it appears, 
thatthofe ratio’s differ from that of 10 to 7,6 to that 
of io : 532, that is, nearly from 4 : 3 to 4 : 2. In 
thofe experiments where the heads of water and 
quantities expended are lead:, the proportion is near- 
ly as 4 : 3 ; but where the heads and quantities are. 
greateff, it approaches nearer to that of 4 : 1 ; and 
by a medium of the whole, the ratio is that of 3 : 2 
nearly. We have feen before, in our obfervations 
upon the effeds of underfhot wheels, that the gene- 
ral ratio of the power to the effed, when greateff, 
was 3:1; the efedl therefore of overfpot wheels , under 
the fame circumflances of quantity and Jail , is at a 
medium double to that of the underfoot : and, as a 
confequence thereof, that nonelafic bodies, when act- 
ing by their impulje or collifion , communicate only a 
part of their original power ; the other part being 
fpent in changing their figure in confequence of the 
ftroke. 
The powers of water computed from the height 
of the wheel only, compared with the effeds, as in 
column 1 o. appear to obferve a more conffant ratio : 
for if w r e take the medium of each clafs, which is 
let down in column 1 1, we fhall find the extremes 
to differ no more than from the ratio of 10 : 8,1 to 
that of 1 o : 8,5 ; and as the fecond term of the ratio 
gradually increafes from 8, 1 to 8,53 by an incrcafe 
of head from 3 inches to 1 1, the excefs of 8,7 above 
8,i> 
