Seiches in Some Lakes of Japan. .21 



gradually, and the sky became clear toward evening. As the 

 limnogram at Irnazu reproduced in PI. III. Fig. 2., shows, the 

 level began to rise gradually at 14 h. 30 m. and fell suddenly at 

 14 h. 52 m., and made many oscillations with a period of 9 

 minutes, the curve being much indented by shorter irregular 

 oscillations. The 30-minute seiche appeared also at 17 h. 50 m. 

 but it was not well developed. On the whole, this storm caused 

 no significant motion of the water at Imazu. At Chömeiji, the 

 instrument was set up at 16 h. 50 m. so that the motion of the 

 water just at the time of the thunderstorm was not recorded. From 

 the curve, which is reproduced in PI. IV, we see that here as in 

 imazu two motions of 30 m. and 9 m. periods were also excited. 



That wind is a cause of the seiche was supposed by many 

 jDeople, though contradicted by some. In Clmzenji lake, it was 

 clearly seen that wind is one of the chief exciting causes of the 

 seiche there. We had such a case also in lake Biwa. The 

 limnogram reproduced in PI. V. Fig. 2, was Obtained at Hikoné 

 on lake Biwa, Sept. 20-21, 1901. On the evening of the 20 th., 

 we had a strong wind accompanied by a light rain on the northern 

 part of the lake, and it caused at Hikoné an anomalous seiche with 

 an amplitude about 9 times larger than that usually appearing 

 there, (PI. V. Fig. 1). It is worthy of notice that the period of 

 the motion does not change much in either curve. 



