156 Proceedings of Royal Society of Edinburgh. [sess. 
along the length of the vessel, passing through each other, and, 
after being reflected from the ends, crossing again. The position 
of crossing changes from side to side of the central transverse line, 
hut always approaches nearer to this as a limiting position. When 
this condition is reached no further change takes place, and a 
single standing wave with a fixed period (as observations showed) 
oscillates in the trough with a ventral segment in the middle. 
This is obviously the binodal seiche. 
Sometimes this state of matters comes about without a great 
diminution of amplitude, but generally the movement dies down 
considerably before this condition is reached. 
( Issued separately June 11 , 1906 .) 
