JS6 . O^ CAPtLLARY ACTIONi 



ss 



I affirmed therefore before, and I affirm with the snme 

 boldness^* again, tliat, by employinj!^ reasonings totally 



opposite in cases exactly similar, Mr. La Place and Mr. 



Haiiy did virtually coutrudict in one passage what they had 



said in another. 



It is asserted by the Monthly Reviewer, in the course of 



his pleasant observations, that, " If they had been guided 



** by conceptions as vague and uncertain as those of their 



** examiner, they would to this time have been wandering 



" in errour." 

 His faults I will show briefly, that, if they had proceeded according 



true, from a |^ those conceptions, they would have obtained the sayne 



compensation i i i • 



of errours. results, thougri in a manner somewhat different ; consist- 

 ently, and without arriving at truth by a compensation of 

 errours. Instead of making the mass with a plane surface 

 urge the column downwards, with a force K, tliis letter 

 would have represented its action upwards, which add- 

 ed to the action of the concave meniscus, in the same 

 direction, would have given the whole force, with which 



H 



the column is urged upwards, n K H — —*• So that, 



o 



from this method, there wohld have arisen ultimately, by 



the principle of a canal, the equation 



^ ^ 2 VR ^ RV "^ ^ ^ 2\b ^ b'J 



which, by transposition, is the same as the one now given 

 by La Place, (in p. 19 of his work) and must necessarily 

 lead to the same results. 



To conclude — If Mr. La Place had found his fundamen- 

 tal equation in the manner I have pointed out; and, instead 

 of making the whole column support itself, had truly 

 shown how it was held up by the tube: there would not, I 

 think, have been any thing to object to his theory f. 

 I am. Sir, 



Your most obedient servant, 



Papcastle, Dec. Sth, 1810. THO. KNIGHT. 



* Mr. La Place makes it to be urged doivntvards by a force =K — 



^ . where 1 use his notation, 

 P 

 + 3ut thm it would hsive been a different theory. 



XI, 



