142 



Lord Rayleigh. 



[June 15, 



Experiment showed that the effect depends a good deal upon the 

 exact manner of collision. In almost all cases twenty cells of a 

 De la Rue battery sufficed to produce amalgamation, with subsequent 

 replacement of the original streams by a single one in a direction 

 bisecting the angle between the original directions. With a less 

 battery power the result may be irregular, some of the drops 

 coalescing and others rebounding. When the collisions are very 

 direct, even four cells will sometimes cause a marked transformation. 



The complete solution of the problem of the direct collision of 

 equal spheres of liquid, though probably within the powers of existing 

 mathematical analysis, is not necessary for our purpose ; but it may 

 give precision to our ideas to consider for a moment the case of a 

 row of equal spheres, or cylinders, with centres disposed upon a 

 straight line, and so squeezed together that the distances between the 

 centres must be less than the original diameters. By the symmetry, 

 the common surfaces are planes, and the force between contiguous 

 masses is found by multiplying the area of the common surface by 

 the internal capillary pressure. When the amount of squeezing is 

 small, the internal capillary pressure 'is approximately unaltered, and 

 the force developed is simply proportional to the area of contact. In 

 the case of the cylinder the problem admits of very simple solution, 

 even when the squeezing is not small ; for, as is easily seen, the free 

 surfaces are necessarily semicircular, and thus the condition of un- 

 altered volume is readily expressed. It will of course be noticed that 

 as regards lateral displacements the equilibrium is unstable. 



Collision of Streams before Resolution. 



§ 5. The collision of unresolved streams was considered in my 

 former paper. It appeared that the electromotive force of a single 

 Grove cell, acting across the common surface, was sufficient to deter- 



