120 Messrs. K. Honda, T. Terada, and D. Isitani on the 
gation of the long waves over each path was then calculated 
from the various mean depths. The times of transmission of 
the waves over each path were compared, and the path with 
the minimum time was taken to be the actual one. From 
the path thus found and the actual time of transmission, we 
calculated the mean velocity of propagation of the sea-wave, 
as given in the following tables. The time of the occurrence 
of the earthquake we took as the starting-time of the 
sea- wave. 
Sanriku Wave. 
Station. 
Distance. 
Mean Depth *. 
Igh. 
Time Interval. 
Velocity. 
Honolulu 
6000 km. 
492 km. 
220 m./sec. 
7 h 44 m 
216 m./sec. 
San Francisco . 
7970 
5-51 
234 
10 h 34m 
209 
Ecuad 
or Wave. 
Hakodate 
14330 km. 
4-92 km. 
220 m./sec. 
20 h 16 m 
195 m./sec. 
Ayukawa 
„ 
„ 
>5 
20 h 12 m 
200 
Kushimoto ... 
15280 
4-81 
217 
20 h 44 m 
208 
! Hososhima ... 
15610 
55 
» 
- 
20 h 38 m 
211 
Valparai 
so Wave. 
Hakodate 
17080 km. 
4-66 km. 
214 m./sec. 
23b 48 m 
200 m./sec. 
1 Ayukawa 
,. 
„ 
,, 
23 h 17 m 
204 
1 Kushimoto ... 
17600 
4-58 
212 
23 h 31 m 
208 
Hitherto it has been customary to measure the path of the 
sea-waves as supposedly lying along the great circle of the 
earth ; but the actual distribution of the depth being com- 
plicated, this is not a proper method. 
The value V 'gk of the fourth column in the above tables 
represents the theoretical velocity of long waves. This 
theoretical velocity is always greater than the actual mean 
velocity, but here the difference is not constant, while in one 
case it is very small, in another considerable. This fact has 
* One of us (K.Honda) calculated the mean depths of the ocean by the 
same method ; but having- used '* Berghaus Physikalischer Atlas," the 
values were considerably greater than in the present case. See Proc. 
Tokyo Math.-Phvs. Soc. iii. No. 9 ( 
(1906). 
