28ft Z>.'s Secot2d Replij to C. 



Mr. H.'s proposition, ^ihat the VELOCITIES of the moving bodies 

 have no effect on the INTENSITIES of the strokes ?' " Let us here 

 observe that the part of the quotation in Itahcs is what C. has 

 given between double inverted commas, and therefore intendett 

 to be a verbatim, I presume, transcript of one of Mr. Herapath's 

 " pi'opositions." The fact however is, there is no such a thing 

 in words, sense, or import ; and not merely in Mr. H.'s pro- 

 positions, but not even in any part of his printed writings that 

 I can perceive. His first Prop., which seems to be the only 

 one relating to this subject, says: ^^ If two bodies absolutely 

 hard impinge on one another, the DURATION or SMJBTNESS of 

 the stroke is independent of the velocity of contact ^ This is all 

 that he says of this subject in his ^'■propositions ;'' and in a Cor. 

 to the first Prop, he says : " Hence we gather, that in per- 

 fectly hard bodies the intensity of the impulse depends on the 

 violence or momentum of contact, and is independent of the 

 velocity of contact, except inasmuch as it is augmented or di- 

 minished by that ivlociti/." Here, therefore, C. not merely 

 gives to Mr. H. words which he never used, and a "proposi- 

 tion" which he never wrote, but actually a meaning totally 

 different from any thing he ever published ; and this for the 

 mere purpose of creating a groundless opposition between 

 Dr. Hutton, Prof. Playfair, and Mr. Herapath. If C. can 

 edge out of this without a frank avowal of " wilful misrepre- 

 sentation," let him ; I shall be happy to see his manoeuvres. 



So much at home does C. appear in misrepresentations, and 

 so easily and rapidly do they How from him, that, even after 

 he had indulged in the above glaring specimen, which one 

 might have thought would last him through a lew pages at 

 leastj he could not finish the subsequent paragraph in the same 

 page without presenting us with another. As this is however 

 one of C.'s ordinary aberrations from truth, I will leave it 

 without further comment. In the very next page C. in- 

 forms us, " D. says that the velocity of B after the stroke is = 



■J— g-." Turnmg to p. 362, Annals for May, from which C. 



pretends to have extracted diis idea, I find I said : " die 7no- 

 tion it" (that is, *he momentum B) "acquires by the stroke = 



. , g ." In the former case of misrepresentation C. put in 



Mr. H.'s mouth " intensity of the stroke " for " duration of the 

 stroke," that is, violence tor time,- and he has now thought pro- 

 per to mistake for me velocity for momentum ; and this at a 

 time when he is trying to demonstrate a paradox I had pro- 

 posed. Of course his demonstration must be very complete 

 and very unique. 



One 



