Seiches in Some Lakes of Jaijan. 



57 



reference. Then according to Clirystal to study the oscillation of 

 the lake, it may be looked upon as a lake with a straight median line, 

 uniform breadth, and rectangular cross section, its longitudinal 

 section being the curve with v and <^ as abscissa and ordinate of any 

 point of it respectively. This curve is called the normal curve of the 

 lake. Thus v is the distance measured along the median line of the 

 reduced lake, and (^ is the depth at the point v. 



We have calculated the normal curve of Hakoné lake, and 

 found that it is not very simple in form, having one shallow and two 





 r 



, 











'-.*«'*' 



„ 



' 



» It 



K * 



* 



m 









1 h- 

















Pig. 12. 



maximum depths. Table 30 gives the values of <y and v for the 

 normal curve corresponding to the 63 sections before mentioned. 

 The former is calculated from the data given in Table 27 by 

 multiplying h and S together, and the latter is obtained by means 

 of a planimeter. The unit of length is a centimeter. Fig. 12. 

 shows this normal curve ; the shallow in the middle being caused 

 by the great constriction, though at that point it is very deep in 

 the actual lake. As this curve is too complex, we may take as the 

 first approximation for the normal curve four inclined straight lines 

 as shoAvn in Fig. 13. As this is not treated in Chrystal's paper, we 



