2 ON CAPILLARY ACTION* 



. itiatically conclusive, so fat as it relates to the pliysical foun- 

 dation of the general law of an equal tension of the surface 

 of any given liquid. 



In the first place it appears, that Mr. Laplace's conclu- 

 sion respecting the attraction, which he supposes to be Ex- 

 erted by a liquid, terminated by a plane surface, on any 

 imaginary column within it, may be confuted on every sup- 

 position that can be formed, respecting the nature of the 

 Force that forces concerned. For the force which tends to draw every 



tends to draw guch column downwards into the liquid, can only be derived, 



a column of _ , _. _ , . , , . . _ 



fluid down- irom the actions ot the neighbourmg columns, and must 



ward, tends to therefore tend in an equal deoree to elevate them : so that 

 draw the ntigh- , n ^ i t - ^ i n 



bouring co- ^"^ parts ot each column which are nearest to the surface 



lumns upward, are urged downwards, and the remoter parts upwards, by 

 equal forces ; and the result is merely a general attraction 

 of the whole'stratum for the stratum next below, which of 

 Counteracted course must be completely counteracted by the (repulsive 

 sive force. force, whatever its nature may be. Thus the portion A (PI. I, 

 Fig. 1) is urged downwards by the attractions of the por- 

 tions B and C, while D is urged upwards by those of E 

 and F ; and in the same manner D is urged downwards by 

 G and II, while I is urged upwards by B and C. And 

 thus, by continually adding to the substance any number of 

 successive strata, we shall still find, that the general effect 



Thus equih- ^f ^^^ whole body on the column A I will retain it in equi- 

 biium main- ,., , , i xi i i t • i 



"tained to any bbnum, whatever may be the depth. It is true, that ac- 



depth. cording to Mr. Laplace's own principles, the attraction of 



Laplace's prin- any limited number of strata, on a column passing through 



Jteabfe "o^so-^ them, must disappear, the force of the lower surface, which 



lids, or solids he supposes to be directed upwards, -counteracting that of 



an uids. the upper in a contrary direction; but this consideration, 



although it may lead to a correct result with respect to the 



actions of fluids only, is not applicable to those of solids, 



or to the mutual actions of solids and fluids. 



Hisdctermifta- In the second place, Mr. Laplace's determination of the 



tion of the at- attractive powers of a wedt^e of any kind, as proportional to 



traction of a. '^ -iiit^xti 



wedge leads to its chord, must necessarily lead, as Ur. Young has already 



erroneous piin- observed, to a proposition respecting the equilibrium of the 



surface of a fluid with a so.lid, which Mr. Laplace will 



not justify, and which he has silently abandoned ; that is, 



that 



