596 Mr. Hopkins's Remarks on Prof. Forbes's Reply. 



troversy ever provoked. More especially is it unreasonable 

 when considered with immediate reference to the two primary 

 conclusions above-mentioned of the Professor's mechanical 

 reasoning; for after having satisfied himself of his having made 

 one oversight, the single paragraph following fig. 2 of my 

 Third Letter, could not fail to convince him that he had also 

 made a second. Having admitted the one, he must necessa- 

 rily admit the other. 



The Professor, in the commencement of liis reply, makes a 

 formal disclaimer against all deductions from hypotheses re- 

 specting the constitution of matter and forces acting on its 

 integrant parts. But on what are the forces we are here con- 

 cerned with to act if not on the integrant parts of the mass ? 

 and what are these hypotheses against which the Professor 

 lifts his voice of warning? It was his duty, I think, to have 

 informed your readers. As he has not done so, I will state 

 them. It has been assumed, then, that matter may be com- 

 pressed or extended, and that the greater the extension or 

 compression, the greater cceteris paribus will be the compress- 

 ing or extending force. Such are the properties on which 

 it would seem nothing but " tottering fabrics " can be raised. 

 Does Prof. Forbes intend to intimate that his own me- 

 chanical reasoning does not involve the same hypotheses, or 

 that the internal forces called into action, according to his 

 views, do not act on the integrant molecules of the mass? It 

 must be a remarkable case of mechanical action if they do 

 not. Or does he mean to assert that my investigations in- 

 volve, more than his own, vague and uncertain hypotheses 

 respecting the nature and laws of molecular attractions? If 

 he does, why did he not point out where such hypotheses 

 enter? and if he does not, how will he justify his classing my 

 mechanical investigations on this subject with that large class 

 of researches which do professedly involve doubtful supposi- 

 tions respecting the ultimate constitution of matter? It may 

 be that the Professor has written under the unconscious in- 

 fluence of controversy, or possibly with the want of that 

 entire familiarity with the mathematical investigations of me- 

 chanical problems, which can only be acquired by an almost 

 incessant application to the subject, scarcely consistent perhaps 

 with his devotion to those experimental researches by which 

 he has made such valuable contributions to science. Be that 

 as it may, I consider that lie has endeavoured to get rid of 

 investigations which he has not ventured to approach in de- 

 tail, by a general representation respecting the basis on which 

 they rest, unsupported by the slightest evidence ; and there- 

 fore it is that I speak strongly on this point. When men 



