140 On the Measure of 
The converse of this case is stated by Dr. 
Wollaston, as follows: “ It may be of use also 
to consider another application of the same 
energy, and to shew more generally that the 
same quantity of total effect would be the con- 
sequence not only of direct action of bodies 
upon each other, but also of their indirect 
action through the medium of any mechanical 
advantage or disadvantage ; although the time 
of action might by that means be encreased 
or decreased in any desired proportion. For 
instance, if the body supposed to be in motion 
were to act by means of a lever upon a spring 
placed at a certain distance from the centre of 
motion, the retarding force opposed to it 
would be inversely as the distance of the body 
from the centre; and since the space through 
which the body would move to lose its whole 
velocity would be re lly as the retarding 
force, the angular motion of the lever and 
space through which the spring must bend, 
would be the same, at whatever point of the 
lever the body acted.”* Practical men are 
much beholden to Dr. Wollaston. He is, I 
believe, the only author, professedly on the 
theoretical principles of mechanics, who has 
written decidedly in support of Mr. Smeaton’s 
* Philos. Trans. 1806, p. 21. 
