Seiches in Some Lakes of Japan. 



75 



minutes, which was frequently observed at Funatsu, we can not say 

 definitely what it is. Since liowever 



-*- 2 — 2 15 



and since it is nearly equal to T3, it is very probable that it is tlie 

 result of the interference of the two motions T, and T^. Wlien a 

 motion T, coexists with another T^ Avith nearly half the period, then 

 at the moment when their phase relations are such that their high 

 Avaters coincide, we get a resultant motion like a in the accompany- 

 ing figure; while, on the contrary, when their low waters coincide, 



Ä, 



Fin-. 19. 



I 



J 



Fiiï. 19. 



the resultant motion is like h; and lastly in the intermediate stage, 

 we have apparently a simple wave with a period |-2V The effect 

 of the interference of two such oscillations as 2\ and T3 is therefore 

 that the resultant motion changes gradually from the state a to the 

 state h by passing through an intermediate stage of an apparently 

 simple wave with a period ^'A and then returns back to the 

 initial state. Such a gradual transition is seen in the beginning of 

 the curve of Funatsu in Fig. 17. We are forced to say that the 

 motion T.^ does not in reality exist. 



