Mr. Blake's Reply to Mr. Quinbij. 355 



I. That which I have called degree of power ; or power in 

 its most limited sense, without relation to time, space, or ve- 

 locity. 



II. Power, as a magnitude, varying with time only. 



III. Power, as a magnitude, varying with space only. 



IV. Power, as a magnitude, varying with velocity, that is, 

 with space directly, and time inversely. 



The method usually pursued by writers on this subject, is 

 to treat power as an object having but one dimension, and to 

 consider the circumstances of time, place, and velocity, mere- 

 ly as multiples of it. The method I would propose, is, to treat 

 power, as an object having several dimensions ; and to con- 

 sider the circumstances of time, space, and velocity, as con- 

 stituents of it. By their method of considering the subject, 

 authors have often been led into the most circuitous mazes 

 of analytical investigation, in order to discover truths, when 

 the very same truths would flow almost spontaneously, from 

 self evident principles, which will immediately suggest them- 

 selves, in the method of considering the subject, here propos- 

 ed. The doctrine of percussion, as copied by Gregory from 

 Don Juan, is a remarkable instance of this kind. Every use- 

 ful result, which he has there deduced from many pages, may 

 be drawn, with much more clearness, from as many lines. 

 Had this method of considering the subject been pursued, 

 by those who have contributed the theorems which now con- 

 stitute our volumes of mechanical science, those volumes 

 would have contained fewer errors. It is these errors which 

 have given rise to so many complaints, of the difference be- 

 tween the results of theory and practice, and which have 

 brought the science into disrepute. Of these errors, the absurd 

 doctrine ofthe " maximum effects of machines," is a prominent 

 example. This doctrine was justly condemned by Mr. duinby, 

 in a recent number of your Journal ; and though I think he 

 is mistaken, with regard to the error, on which the fallacy of 

 the doctrine is based, he is, in my view, entitled to no small 

 credit, for having perceived and exposed its absurdity. 



