﻿Motion of a Sphere in a Viscous Fluid. 537 



of Va/v is 23. In this figure it will be seen that point of 

 zero velocity has approached nearer to the sphere and also 

 moved still further back, the stream-lines around it being 

 nearly elliptical ; the increase of velocity behind the sphere 

 is very marked, the velocity of the fluid being nearly the same 

 as that of the sphere for a considerable distance behind it. 



In the case shown in tig. 7 the velocity has been increased 

 to 13 cm. per sec, the corresponding value of Ya/v being 

 125. The point of zero velocity has come almost into line 



Fi<r. 7. 



Sphere in water, Ya/v = 125 (Experimental). 



with the top of the sphere. The velocity in front of the 

 sphere is very similar to that in the ir rotational solution 

 (see Lamb, p. 137), and behind the sphere is seen a " wake" 

 of nearly constant velocity as shown by the parallel stream- 

 lines. 



Fijr. 8. 



Sphere in water, Va/v=720 (Experimental). 



Fig. 8, Photo E (PI. IX.), represents a velocity of 7*5 cm. 

 per sec, the corresponding value of Va/v being 720. In this 

 •case the wake is considerably shortened and the whole motion 



