ON THE THEORY OP CAPILLARY ATTRACTION. l^f 



feut, by all means, let us have a view of the mechanism hy 



which the wkok column is supported* 



Mr. La Place, probably from considering the matter in ErrourinMs 



this liffht, save the world his second method ; which appears second 



o ' o ■ ' nietnocl. 



to be as erroneous in falsely explaining the true*, as the 



^rst had been in assigning a wrong cause. 



My own intention, at present, is to show what part of a Object of the 

 capillary tube keeps a fiuid elevated ; and the precise man- ^" ®'^° 

 oer, in which it causes this elevation: or, in other words, 

 to supersede this second method of Mr. La Place, and all 

 similar theories, by one more conformable to truth. 



The remarkable experiment of Abat, which Mr. La Place Experimereief 

 seems to have thought one of the best proofs of his first ' 

 theory, will be very easily explained here on quite different 

 principles. 



We shall also see what is the limit of the height of the 

 fluid in that experiment, which no one I believe has yet 

 shown. 



1 suppose, -with Mr. La Place, and other writers on the '^"'^'^^1°^ ^^ 

 subject, that the attractions of the particles of the fluid for itself and for 

 itself, and of the tube for the fluid, extend only to insensi- t^ie tube differs 

 fole distances ; that they follow the same law of the distances; gity. 

 «nd ov^y differ by their intensity at the same distance. 



Prop. 



Let A B C D E F (fig. 4) be the section, through the Propositi«». 

 axis, of a circular tube, every where of equal diameter, 

 bent into a rectangular form, and standing in a vertical 

 plane. Let the part A B C D, of the tube, be formed of 

 matter, the intensity of attraction of which for the fluid 

 within it is represented by r, while that of the other part 

 C D E F is r'. The excess of the mass of fluid in the leg 

 A B over that in the leg E F is as (2 r — 2 r') x diameter of 

 the tube. 



Let e n m n s he s. slender canal of fluid, extending from Demonsfcra- 

 tlie surface in one leg to that in the other, and parallel to 

 the side of the tube, as well as every where at the sam« 

 distance from it. It is, in the first place, evident that this 



* The balancing force of the tubg. 



«aaaV 



