Secondary Undulations of Oceanic 2 ides. 
119 
felt on the Pacific coast of Ecuador ; it was accompanied by 
a sea-wave, which traversed the Pacific from America to 
Japan. The wave was recorded by the tide-gauges of 
Hakodate, Ayukawa, Kushimoto, and Hososhima. The 
earthquake of Valparaiso, which was also followed by a 
sea-wave, occurred on July 17 o£ the same year. The wave 
arrived nt Hakodate, Ayukawa, and Kushimato. The above 
two waves also slightly affected the tide-gauges* at 
San Francisco, San Diego, and Honolulu. The periods 
observed in these bays are : — 
Bay. 
Ecuador Wave. 
Valparaiso Wave. 
Ordinary Case. 
Hakodate 
51 n "8— 48 m '3 
24-2—26-0 
7-3-83; 20 
210 ; 132 
204 
47 m '0— 52 m -0 
23-5—26-0 
73; 23 
12-3; 21-4 
45 m -5— 57 m, 5 
21-9—24-5 
6-8—8-9 ; 22 
11-6—13-0; 21-5—237 
17-8—20-3 
San Francisco ... 
San Diego... 
Honolulu 
25-3 
32-2; 43 
26-2 
16-7; 33-5 
248-26-8 
Thus in the bays on our coast the periods of the sea-waves 
are the same as those observed in ordinary cases. The periods 
observed at San Francisco and San Diego are those frequently 
observed in the case of other sea-waves ; they correspond to 
the multinodal oscillations o£ these bays. The periods observed 
at Honolulu are quite constant ; they possibly correspond to 
the fundamental oscillation in the inlet of Honolulu. 
In passing, it is interesting to calculate the velocity of 
propagation of sea-waves through the Pacific. If the path of 
the sea-waves which travel across the Pacific be known, the 
velocity of propagation can be estimated. Now the sea-wave 
which has usually a long wave-length compared with the 
depth of the ocean, must be refracted according to the con- 
dition of the bottom, so that it is very difficult to know the 
actual path by which these waves travelled through the ocean. 
"We therefore conceived several paths between the place where 
the waves originated and the observed station in question, 
and then we measured the lengths, and also the mean depths, 
of each by mechanical integration f . The velocity of propa- 
* The tide-gauge records utilized are those furnished by Dr. Tittmami 
to Prof. Omori. 
j* The chart published by " Deutsche Seewarte " was used. 
