Seiches in Some Lakes of Japan. 27 



liinnograni. Thus in spite of the apparent calmness of the weather, 

 the hmnogram betrays the presence of some disturbance in the 

 lake. It is very interesting to note in such cases that some twenty 

 or thirty minutes after the first appearance of the indentation, the 

 weather begins to change. The wind blows with increasing, 

 intensity agitating the water into high waves. Soon a shower, 

 sometimes a thunderstorm, arrives and passes over or in front of 

 us. The indentation in the limnogram is therefore a forerunner of 

 the coming meteorological disturbance. The cause of such agitation 

 of the water may be sought for in the rapid barometric pulsation 



Hikone, Lake Biwa, Sept. 25, 1901. 



lOh 13'' Uh 1^^- 



Fig. 9. 



at the center of the atmospheric disturbance, which agitates the 

 lake into very irregular motion, and the latter is propagated to us 

 long before the shower itself arrives at the limnimeter. It may 

 happen of course that the shower goes another way and does not 

 come to us at all. Then we have only indentations in the 

 limnogram telling us that a shower passed somewhere over the 

 lake. Fig. 9 shows an example of such indentations. A study of 

 the distribution of barometric pressure and its variations, and 

 particularly a study of the effect of the " Luftwogen " conducted 

 with suitable microbarographs, Avill throw much light upon this 

 phenomena. 



