AND OTHER WATER WAVES 301 



were diagonal standing waves. Coming down, a 

 knobbly surface travelled along with us, one of 

 the knobs of water occasionally bursting. There 

 were no regular roll-waves in this case, but in 

 that of the Territet-Glion conduit I was able from 

 the car, which travelled down at nearly the same 

 speed as the roll-waves, to observe that, in addi- 

 tion to the larger waves with front extending the 

 whole breadth of the stream, there were innumer- 

 able embryo waves, which seemed to be in continual 

 course of production. How embryo waves become 

 united into relatively large roll -waves, regular in 

 form and travelling in orderly procession, can be 

 better explained from the phenomena observed in 

 the conduit of the Griinnbach, at Merlingen, on 

 the Thunersee, Switzerland, during 1904 and 

 1905. 



Observations on the Conduit of the Griinnbach 

 ( M erlingen, Thunersee ) 



The Griinnbach is the torrent flowing through 

 the great gorge of the Justisthal to the Thunersee. 

 The lower portions are first controlled by a series 

 of weirs causing waterfalls, and, finally, for the last 

 1,360 feet, the stream is carried in a straight, paved 

 conduit about 7 feet deep and 15 feet wide, with 

 nearly vertical sides, the form and structure being 



