5Ü 



s. Xakamura and K. Honda 



(b) Tlie position of the node for the same is situated at 2.9 

 kilometers from the Umijiri end, i. e. 0.558 of the total 

 length of the lake from the southern, Hakonc end. 



Chrystal and Wedderburn have calculated the periods and the 

 positions of the nodes of the Scottish Lochs, Earn and Treig, from 

 bathymétrie data according to the theory and formula given by 

 Chrystal in the paper above cited. They found that Chrystal' s 

 formula agreed with the observations very satisfactorily, but Du 

 Boys' s formula gave values considerably in excess of the observed 

 periods. The following small table gives the periods of the 

 uninodal seiches in minutes as obtained by them. 



TABLE 29. 





Observed 



Chrystal 



Du Boys 



Loch Lain 

 Loch Treig 



14.55 

 9.18 



14.50 

 9.14 



17.82 

 10.20 



There must be some reason for this peculiarity, but we are not able 

 to give a satisfactory explanation. 



In the following, we shall apply Chrystal' s theory to ITakonc 

 lake, so it may not be superfluous here to give here a brief outline 

 of his theory. AVhen the breadth and the form of the transverse 

 section of a lake vary as well as the depth, provided these 

 variations are not too abrupt, he shows that it can be submitted to 

 calculation by introducing two variables, «• and v. a is the product 

 of the area A (6' iu our notation) of the transverse section by the 

 breadth b uf this section at the surface, while v is the area of the 

 surface of the lake between the trace on the surface of the transverse 

 section corresponding tu a, and iuiy other similar line chosen for 



