160 On the Measure of 
the plane to be still greater than the weight of 
a column of twice the height due to the rela- 
tive velocity of the water and the wheel. 
The most important conclusions drawn by 
Mr. Smeaton from his experiments are (as I 
have already noticed) not in his maxims ; but 
they are to be found, I apprehend, in the two 
following observations, which I shall quote in 
his own words : . 
1. “It is somewhat remarkable,” he says, 
“that though the velocity of the wheel in 
relation to the water turns out greater than + 
of the velocity of the water, yet the impulse of 
the water, in the case of a maximum, is more 
than double of what is assigned by the 
-theory.* . hae eas 
2. “ We have seen before, in our observa- 
tions upon the effects of undershot wheels, that 
the general ratio of the power to the effect, 
when greatest, was 3:1; the effect, therefore, 
of overshot wheels, under the same circwn- 
stances of quantity and fall, is at a medium 
double that of undershot: and as a conse- 
“quence thereof, that non-elastic bodies, when 
acting by their impulse or collision, communi- 
cate only a part of their original power ; the 
other part being spent in changing their figure 
in consequence of the stroke.” t 
= Philos. Trans. 1759, p. 113. + Ibid, 1759, p. 130. 
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