Seiches in Some Lakes of Japan. 35 



§ 7. Toy a Lake. 



Töya lake is situated at 42° 36' N., and 140° 53' E., in the 

 island of Hokkaido, and is the deepest lake in Japan, the 

 maximum depth reaching 190 meters (Plate XVI). It is a crater 

 ■ lake of nearly circular form with a diameter of about 10.5 kilo- 

 metres, and has some small conical islands in it which are very 

 beautiful. The largest, which is just in the centre of the lake, 

 is covered with pine trees. 



During the summer vacation of 1905, one of us set up a 

 limnimeter of the " H " type at Mukötöya on the northern shore 

 ■of the lake, and took a series of curves for 22 hours. At the com- 

 mencement of the observations, the wind was blowing toAvard the 

 station, and when it gradually subsided, the level fell by a few 

 ■centimetres, showing that the wind heaped up the water toward 

 the shore ; and at the same time a simple oscillation with a period of 



T=9.29 minutes 

 .made its appearance (Fig. 25J. Toward the end of the observation, 

 when the recording cylinder was driven at a slower speed, we 

 .had a very beautiful series of beat phenomena (Fig. 25h). 



Aug. IS, 1905. 



Aug. 18-10, 100.5. 



2^/1 



6* 2A 



Fig. 2 5 b. 



ih 



ßh 



