48 ■5- Nakamiitca and K. Honda : 



integrated along the median line, where li is the depth at a point 

 X. Prof. Nagaoka* has shown that this formula can be applied to 

 a lake whose median line is not straight, provided its curvature is 

 not too great, the integration being performed along the curved 

 median line. In order to see how far the values of T calculated 

 from these formulée will agree with the observed value, we made 

 the following calculations. 



(1) A curved line is drawn along the middle line of the lake 

 and its length L is found to be equal to 6570 meters. The total 

 volume and the total surface area of the lake are measured with 

 a planimeter, and the mean depth h,,, is obtained by dividing 

 the total volume by the surface area. 



Ä,„ = 2668^™- 

 T = 13.51.'"- 



(2) The curved median line is divided into G4 equidistant 

 segments, and transverse sections are made at each of these segments 

 and plotted on a section paper. We thus have 63 sections together 

 with two end sections of zero area. The areas S of these sections are 

 determined by a planimeter and are divided by the corresponding 

 breadth h of the free surface and the result is taken as the mean 

 depth /' for these sections. The values of h in meters, of S in square 



meters, and of h in meters, together with those of V h and ^Ji' 

 are given in Table 27. 



* Proc. Tokyo Plijs. Math. Soc, Vol. I. 1902, p. 12(5. 



