Seiches in Some Lakes of Japan. 



2& 



TABLE ]0. 



Tmazu. III. 



m. 



m. 



in. 



31.7 X 5 



29.5 X 8 



17.9 X 7 



31.4 X 2 



29.3 X 7 



17.7 X 7 



31.2 X 2 



28.9 X 3 



17.4X G 



31.0 X 5 



28.8 X 4 



10.0x13 



30.7 X 18 



28.7 X 5 



9.7x27 



30.4x14 



19.1 X 6 



9.5x18 



30.3 X 3 



18.7 X 4 



9.4 X 8 



30.0 X 4 



18.1 X 5 



8.7 X 8 



29.7 X 3 



18.0 X C 



8.1x10 



Plotting these periods on a section paper, we deduce as probable 

 periods of seiches at Imazu, 30.1, 18.1, 9.4 and 8.5 minutes. Of 

 these, the first motion was very conspicuous. Not only did it 

 appear frequently, but it continued sometimes for a long time. 

 Thus early on the morning of the 17th. of August, we had a heavy 

 thunderstorm, which excited this motion very strongly. It appear- 

 ed first Avith a double amplitude of about four centimeters and 

 continued till the noon of the next day, making about forty 

 clear oscillations. (PI. III). This is very good example of a seiche 

 caused by a thunder storm. The presence of the second motion 

 18.1 was rather doubtful, for it appeared only during the third 

 series of observations under conditions very unfavorable for the 

 determination of a period. The last two motions may, in reality, 

 be one motion, they appeared however pretty often with a double 

 amplitude of about one centimeter, and their presence is quite 

 certain. (PI. Ill, Fig. 2). 



