Moving Force. 133 
ave considering the sources of extended exer- 
tion or of accumulated energy, whether we 
compare the accumulated forces themselves by 
their gradual or by their sudden effects, the 
idea of mechanic force in practice is always 
the same, and is proportional to the space 
through which any moving force is exerted or 
overcome, or to the square of the velocity of a 
body in which such force is accumulated.” 
This conclusion coincides nearly with Mr. 
Smeaton’s, but still it remains to be explained 
how two given quantities of foree may, con- 
sistently, be considered as equal to each other 
for philosophical purposes, but unequal for all 
practical purposes. 
The Edinburgh reviewers of Dr. Wollaston’s 
lecture, adopt a different doctrine. In refer- 
ence to the first passage quoted above, they 
say, “ Now, with the judgment here given as 
to the respective utility of the two measures of 
the force of moving bodies, we cannot entirely 
agree ; though we differ from Dr. Wollaston 
with considerable diffidence; and the more, 
that his opmion is supported by one of the 
greatest authorities in practical mechanics of 
which this or any other country can boast— 
the late Mr. Smeaton.”* And after some 
_ | * Edinb. Review, vol. 12, p. 122, . 
