Moving Force. 165 
kind; and is, of all our resources, that which 
it most behoyes us to economize.”’* 
Now, I apprehend, it is obvious, from the 
whole of Mr. Smeaton’s reasoning on this 
subject, that he was perfectly aware, that, in 
most cases of moving force, if the pressure, the 
time, and the manner of its acting be given, the 
effects may be found. He observed, however, 
(as in the two first cases) that the effects were 
not always in proportion to the pressure and 
the time of its acting, But he found, that if 
the pressure and the space through which it 
acts (or when variable, the fluent of the 
pressure into the space) be given, the effects 
may always be determined, without reference 
to the manner, or the time, in which they may 
be produced; and finding the total amount of 
the effects to be, in all cases in proportion to 
the product of ‘the pressure multiplied by the 
_ space through which it acts, whatever may be 
the time or the manner of its acting, he con- 
_ siders that product to be the principle capable 
of the most general application, and conse- 
quently adopts it as the proper measure of 
mechanical force. 
_ With regard to the proper economy of time, 
I have always understood that Mr. Smeaton 
was fully sensible of its value, and most ex- 
emplary in his punctual attention to it, in all 
* Edinburgh Review, vol. 12. p. 128. 
