Images in Some Problems of Surface Waves. 280 
The calculations were made for the same values of &; and as we have taken 
4/ (ga) as the unit of velocity, we get a different set of velocities, but they cover 
much the same range. We notice that the decrease of the ratio a /f from 4 to 4 
has diminished considerably the difference between ( and D, and also the dis- 
placement £. The results have the same general character as we noted in 
the previous case. Q 
In any given case there are two significant quantities involved: one is the 
ratio of the radius to the depth and the other is the ratio of the wave-length 
to the depth. It would require a more elaborate numerical study than has been 
attempted here to enable us to state precisely the degree of accuracy of the 
first approximation for given values of these ratios. 
HarRIsoON anp Sons, Ltd., Printers in Ordinary to His Majesty, St. Martin’s Lane, 
277 
