AND OTHER WATER WAVES 311 



transmission of a wave with an amplitude from 

 trough to crest of 6.5 inches. I think the dis- 

 crepancy, however, is to be explained not so much 

 by this circumstance as by an error introduced by 

 the determination of the velocity of the current. 

 I made a note at the time that the floating objects 

 which I was observing were several times caught 

 and pushed along by the foaming front of the 

 waves . Thus their speed was probably greater than 

 the average velocity of the current, making the 

 wave-velocity come out too low. 



On some occasions the failure of the stream 

 just before the arrival of the crest was distinctly 

 noticeable a fact in itself, and apart from the 

 measurements, indicating that the waves differ more 

 in appearance than in essence from ordinary waves. 

 The waves had not completed their growth when 

 they reached the outflow; but if the length of 

 the conduit could be much increased, we should 

 doubtless see the last part of the course traversed 

 by a series of waves of uniform height, length, and 

 speed, as occurred after a short run in the 

 shallower, but smoother, conduit of the Territet- 

 Glion Funicular Railway. 



The following table shows the number of wave- 

 crests passing per minute at different distances from; 

 the entrance of the channel, taken on several days, 



16 



