354 Mr. Blake's Reply to Mr. Quinby. 



tion of one and the same board ; so the three examples for 

 the mensuration of power, may all be drawn from one and 

 the same operation of power. For example ; suppose that 

 we have ascertained with regard to a steam engine, which is 

 in operation, that the pressure on the piston is five hundred 

 pounds. We may now tell what degree of resistance, if di- 

 rectly applied, will be overcome. Suppose we next ascertain 

 the area of the piston, and that five hundred cubic feet of 

 the steam have been expended in giving it motion ; we may 

 then tell, what determinate quantity of mechanical effect it 

 might have produced, if properly applied. Suppose that we 

 next ascertain, that the steam in the boiler is maintained at 

 a uniform density, when it is drawn off at the rate of fifty cu- 

 bic feet per second ; we may then tell the magnitude of the 

 effect, in relation to time. These three examples, drawn 

 from the steam engine, correspond exactly with the three ex- 

 amples before given ; except that in these, the effect is to be 

 determined from the power, while in those before given, the 

 power was to be determined from the effect. 



No other distinctions are here insisted upon, in the mensu- 

 ration of power, than such as we always make, in the men- 

 suration of other objects. In the mensuration of other things, 

 we have different names for the different sorts of quantities 

 that are obtained, expressing respectively, the nature of the 

 quantity ; as, length, area, contents, specific gravity, &c. and 

 the distinctions are made, as a matter of course, and without 

 reflection. But in measuring power, we have no appropriate 

 names to designate the different natures of its dimensions, 

 and hence it is, that they are so often confounded. We 

 readily perceive, into what confusion and embarrassment we 

 should be immediately thrown, by discontinuing the use of 

 the terms, length, area, contents, &c. and substituting for them 

 the general term, measure. From an equal amount of the 

 same kind of embarrassment and confusion, with regard to 

 the mensuration of mechanical power, should we be imme- 

 diately relieved, by the introduction of appropriate terms, to 

 distinguish, without circumlocution, the different natures of 

 its dimensions. Whoever shall introduce these terms, so that 

 they shall come into general use, will, in my view, have con- 

 tributed in no small degree, to the advancement of this 

 branch of science. 



The quantities, which most require to be distinguished by 

 appropriate names, appear to me to be these, viz. 



