Remarks on Mr. Quinby’s Crank Problem. 339 
it to different standards, according to the nature of the effect 
produced by it, set according to the purpose for which the. 
im no other way, for by its effects only do we diseover 
its existence. When therefore the eflects produced by two — 
powers are so dissimilar in their nature as to be incapable of 
being referred to the same standard of measurement, the pow- 
ers producing them evidently cannot be compared. 
A certain power will exert a pressure of ten pounds, 
Aaoshe will drive a body against a given resistance ten 
fee 
pe — savale water one foot at the rate of one gal- 
Jon per min 
he powers a ey to produce these several effects are 
definite, and may be definitely measured by referring them 
respectively to their proper standards. But even after this is 
done, no one can say, thateither of them is equal to, or by 
how ~—— it is greater or less than, another, because they are 
in their nature. The ioe onsists of one attribute 
only, like linear measure. The sa of two, “like super- 
ficial measure. third, of eas like solid measure. To 
say, therefore, that one of them is greater or less than another, 
would be as absurd as to say, that a mile is greater than a 
square foot, or that a square foot is less than a cubic inch. 
A clear apprehension of these distinctions is indispensable 
to a correct -anderstanding of the subject of mechanical pow- 
er ; and it is to be regretted that they are not fully developed 
insisted on in ry treatise 
a far as I have been ia with the joe of mechan- 
ics, I have noticed more errors and disputes arising from 
misapprehensions here, than from all other sources. 
In the few remarks which I have to make, I shall have oc- 
casion to use the term power, and others of similar import, 
chiefly with reference to two sorts of quantities, which I 
distinguish by a difference of phraseology. The first I call 
Power. By this is meant the amount of power 
nae hich is exerted on a 
a nee - ee 5 ak body at any 
int 0 ee 0. 
fe pre oae The second I call Quantity of Power. 
* ee r multiplied by the dis- 
y this is meant the degree fs ro ia 
tance through which it as exerted. Quantity of power, 
