292 D.s Second Rcplij to C. 



of a proposition, which to C. appears " too self-evident to rc- 

 (juire further ilhistration " than a mere enunciation. 



C. perhaps will tell us he has distmctly said that " this ef- 

 fect," that is the yielding " to the stroke," " lessening " and 

 " increasing " of motion " in hard bodies, is produced instan- 

 taneously." Two sentences after the prepositional sentence I 

 have quoted, he has indeed used the worcl "instantaneously;" 

 but if he means by this word any thing beyond a very short 

 space of time, he directly contradicts himself both in word and 

 sense. What, for instance, can be understood by saying, that 

 *' B. yields to the stroke, and this it must do by lessetmig A.'s 

 motion and increasing its own, tcfitil it shall have acquired," &c. 

 except that the stroke requires in its communication the lapse 

 of time, though that time may indeed be very short ? But, 

 however short that time may be, it affects not the refutation 

 I have given ; since, by the authority of Newton and other 

 philosophers in their investigationof the laws of refraction and 

 reflection of light, &c. any portion whatever of time in which 

 an effect is, as C. here supposes, continuously produced, may be 

 mentally divided into as many parts as we please ; each of 

 which has its corresponding motion or velocity. This is all 

 I contend for, and all that is necessary to prove the absurdity 

 of C.'s views. I should not indeed have touched on this " in- 

 stantaneously," had it not been to prevent C. from taking re- 

 fuge behind a word whose existence here, it would rather be 

 a compliment to C. to say, appears more the result of accident 

 than design. 



The calculations into which C. has entered, page 210, are, 

 to say the best of them, mere childish amusements. A fine 

 proof truly it must be of his views to give calculations of the 

 collision of bodies; which, with sensible magnitudes, have no 

 existence but in the imagination, and which consequently can- 

 not be found to form experiments with : — he might as well have 

 attempted to show the quadration of the circle by computing 

 the longitude. 



On the principle whose absurdity I have just exhibited de- 

 pends C.'s refutation of most of my theorems, and the solution 

 of a paradox I had proposed in the old theory. Elegant and 

 conclusive of course we must expect his refutation and solution 

 to be, from such a beginning ; especially when we take into ac- 

 count, from the specimens I have given, C.'s tactics and skill 

 at misrepresenting and confounding. 



To narrow the subject of controversy on collision as much as 

 possible, I will, with C.'s permission, pass over the rest of his 

 observations on collision, and confine myself to the one point in 

 question ; namely, the effect of one perfectly hard ball striking 



in 



