AND OTHER WATER WAVES 345 



speed of each individual cone increasing as it fell, 

 the pointed shape sometimes becoming more pro- 

 nounced, until at last the forces making for 

 disintegration dissipated the structure in spray. 



This appearance is closely paralleled in the case 

 of the snow avalanches seen from Grindelwald 

 when they leap the edge of precipices on the Eiger 

 or the Mettenberg. There is the same appearance 

 of cones amidst the white clouds of snow, the cones 

 increasing in speed, with sharpening points, and 

 finally bursting in 'dust. The drawing out to finer 

 lines as the cone descends is easily understood 

 if we remember the acceleration of gravity, and 

 the air-resistance at the edges, and the greater 

 retardation of the finer particles. In water it is 

 the same. When jets are thrown upwards, as from 

 the " Horse-Shoe " at Niagara, the sharpening of 

 a cone proceeds still more quickly. 



On visiting the Tschingelbach in June, 1905, 

 I saw the water -cones in very fine development, 

 and they were even united into roughly transverse 

 bands. Between these the veil of misty spray was 

 thin and semi-transparent. I then perceived that 

 there was a local cause for their unusually fine 

 development in the last big leap of the fall, for 

 the water above slides over a steep face of rock, 

 where it goes into fairly well defined roll -waves. 



