112 On the Resistance of Fluids. 
particle is as the velocity of the plane, aes of the square of the 
velocity, as we have now shown it to 
Now who does not see that in these sentences, Mr. Blake identi- 
fies his “ force’ of a particle, with the force of a particle as the 
term is understood in the common theory, and if we take as the 
meaning of his ‘‘ force,” what he insists upon, viz. the action at a 
‘point of time, i. e. in no time, is it not obvious that he has commit- 
ted an error? Does not Mr. B. know that the force of a particle 
in the common theory, is the vis motrix, the momentum, in short, 
the whole force of a particle, and has he not expressly said, in his 
last paper, “‘ when Idetermined the force of a particle, I determined 
not its whole action, but only its action at any instant ?”” Any com- 
ment is unnecessary. ‘There is not even the consolation of a dilem- 
ma. Ido not pretend to know whether this will “ amuse’? your 
readers, but coming as it does from a professed reformer of the abuse 
of compounding terms, it is sufficiently amusing. 
But secondly, is it not most clear that Mr. Blake has entirely 
failed in his attack upon the demonstration of the received theory ? 
The only degoment he pretends to bring against it is this. It is “a 
fundamental error,” in that dutntiiatnasler that the force of a particle 
is as the volocity, because [ prove that the force of a particle is as 
the square of the velocity ; which, in the light of his definition is 
just this: it is a fundamental error in that, demonstration that the 
whole force of a particle is as the velocity, because I prove that that 
force of a particle which is not the whole action, but the action in 
no time, is as the square of the velocity. 
e above is, in substance, the argument I should have given in 
et last, could I have thought that Mr. Blake could have overlooked 
€ point so essential to even an appearance of success. Here, there- 
fore, I might close, for my whole object has been to defend the ar- 
guments and conclusions of the common theory, and your readers 
must have perceived it. That theory was attacked by Professor 
Wallace ; 1 showed that his objection to it rested on an unwarranta- 
ble assumption: it was again attacked by Mr. Blake. I have now 
shown that his objection to it rests on an error. With your permis- 
sion, however, Mr. Editor, I will make a few additional remarks. 
And first, if any of your readers suppose that, having regard to Mr. 
Blake’s formal definitions of “ force of resistance,” or “‘ force,” ViZ- 
« irrespective of duration,” * at any indivisible instant.” ought 
to have tood, in spite of the evidently consequent error, that he 
