S: aN CAPILLARY ACTION. 



tural bodies, fluids in their situation, upon the simple, although perhaps 

 inadequate supposition of a congeries of irjcompressible par-* 

 tides in contact with each other, actuated by a cohesive 

 force, which extends, without diminution of its intensity, to 

 a certain small distance from each particle. 



In the series of single particles A B (Fig. 8) the particle 

 A, being attracted by all the particles between A and C, 

 the limit of the cohesive force, presses on the next particle 

 D with the whole of this force, which may be represented 

 by the line A E : but the pressure occasioned by the cohe- 

 sion of the particle D is only proportional to the line D F, 

 which is to A E as D C to A C, because the mutual ac- 

 tion of D and A takes from the whole cohesive force a part 

 ■which is equivalent to the action of the particle next beyond 

 C: hence D presses on G with a force represented by the 

 sum of A E and D F ; and in the same manner it may be 

 shown, that the whole mutual pressure of the particles at or 

 beyond C is expressed by the area of the triangle A E C ; 

 and in general, that it may every where be represented by 

 the ordinates of the parabolic curve A H, or of the mixtili- 

 near figure A II I. The same may be inferred from consi- 

 dering the whole force resisting the division of the series 

 between any two of its particles. 



Magnitude of Suppose now that a single particle A (Fig. Q) is placed 

 beyond the limit B C of an attractive body ; it is required 

 to determine the magnitude of the whole force with which 

 it is attracted. The force of the particles situate upon the 

 arc B D, when reduced to the direction A D, is represented 

 by the line D E, since the number of particles in any small 

 portion B F is as much greater than in E G, as A H is less 

 than A B; and in the same manner the force of the particles 

 in the line or narrow ring I K is represented by the line I L; 

 hence the attraction of the whole segment B D H will be 

 represented by the area D H E, I L being always equal to 

 H K, and the curve H E being a hyperbola, which, when 

 A comes into contact with H, becomes a right line. But 

 when B C is considered as representing the surface of a so- 

 lid, the measure of the attraction is the hyperbolic conoici, 

 QT the coue described by the revolution of the line H E on 

 H D as an axis ; and hence the attraction of the solid on a 



parti c<* 



the force of at 

 traction. 



