104 Messrs. K. Honda, T. Terada, and D. Isitani on the 
and 23 m, 6 in good agreement with the observed values. 
These two modes of oscillation were clearly seen from the 
photographs taken in the way before described. Figs. 8 
and 9 of the annexed cut are the stream-lines traced on the 
FiK. 9. 
ffaXodate 
photographs. It is exceedingly interesting to trace the 
stream-lines in the case of the lateral oscillation. Certain 
of these lines extend from Hakodate to Tomikawa gradually 
diverting towards the middle, while other lines run toward the 
mouth of the bay from the Tomikawa side. Fig. 1 in PL IV. 
is a photograph of the fundamental oscillation of the bay. 
In experimenting with models, it was observed that the 
period of the forcing wave, which corresponded to the maxi- 
mum resonance, was not well defined ; within a certain 
range of the period, which did not much differ from the 
period of free oscillation, the oscillation remained fairly con- 
spicuous. In the actual case such a phenomenon was also 
observed : conspicuous undulations of 45 m '5-57 m, 5 were 
frequently observed, though the period of free oscillation of 
the bay is 47 m '0. 
(ii.) Bay of Aomori. 
The dimensions of the model were as follows : — Length 
1 : 110700, and depth 1 : 731, so that the factor r was 4090. 
This bay had also two modes of oscillation, as in the Bay 
of Hakodate : the fundamental and the lateral oscillation. 
The periods of these oscillations were 4 S, 45 and I s * 60 respec- 
tively ; multiplying by r we get 303 m and 108 m . During 
our observations, the oscillations of periods 295 m and 103 m 
were observed, which agree well with the above values. 
Fig. 2 in PL IV. is a photograph of the lateral oscillation of 
the bay. Here the greater part of the stream-lines extends 
from Aomori to Ominato, while the other part runs from 
Aomori toward the mouth of the bay; the case is just analogous 
to the corresponding oscillation in the Bay of Hakodate. 
