CAPILLARY ACTION. 



589 



for a solid of given form is probably difficult, but it is easy to see that at 

 some distance on either side of the body, where the liquid is sensibly at rest, 

 the crest of the wave will approximate to an asymptote inclined to the path 



ntj 



of the body at an angle whose sine is -^., where w is the velocity of the 

 wave and V is that of the body. 



The crests of the different kinds of waves will therefore appear to diverge 

 as they get further from the body, and the waves themselves will be less and 

 less perceptible. But those whose wave-length is near to that of the wave of 

 minimum velocity will diverge less than any of the others, so that the most 

 marked feature at a distance from the body will be the two long lines of 

 ripples of minimum velocity. If the angle between these is 2,0, the velocity 

 of the body is wsecO, where iv for water is about 23 centimetres per second. 



TABLES OF SURFACE-TENSION. 



In the following tables the units of length, mass, and time are the centi- 

 metre, the gramme, and the second, and the unit of force is that which if 

 it acted on one gramme for one second would communicate to it a velocity of 

 one centimetre per second : 



Table of Surface-Tension at 20 C. (Quincke). 



Olive oil and alcohol, 12-2. 



Olive oil and aqueous alcohol (sp. g. '9231, tension of free surface 25-5), 6-8, angle 87 48'. 



