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ON THE FACTS AND THEORY OF EARTHQUAKE PHENOMENA. 125 
times upon her side, once in less than 4 feet of water.” Commodore M. C. Perry, 
U.S. Navy, states,—‘‘ That the whole eastern coast of Japan seems to have suffered 
from this calamity. Yedo itself was injured, and the fine city of Osaka entirely 
destroyed. At 3 p.m. a fresh west wind was blowing at Simoda. The agitation 
of the water and the movement of the vessel had become very slow; barom. 29°°87, 
therm. 10°°5 Reaum. (=55°°63 Fahr.).”’ 
From other sources quoted by Prof. Bache, it appears that on the same day 
(23rd Dec.), at Peel’s Island, one of the Bonin Islands, there was also (the hour 
not stated) a sudden wave rise of 15 feet above high water, followed by a recession 
which left the reefs entirely bare. The tide continued to rise and fall at intervals of 
fifteen minutes, gradually lessening until the evening. Again on the evening of the 
25th of December (as to which time there is no account of a second earthquake), 
the water rose in like manner 12 feet. 
The United States Coast Survey, so ably superintended by Prof Bache, possesses 
stations of observation furnished with self-registering tide-gauges, at San Diego, 
San Francisco and Astoria, on the Pacific Coast; and Prof. Bache presented to the 
Association the curves traced by those instruments, in which the comparative 
heights and times, and the mean heights and times at San Francisco and San Diego, 
are given; also the tidal curves for both, with the abnormal oscillations superimposed; 
and lastly, three diagrams, in which the tidal level being reduced to a horizontal line, 
the abnormal waves alone are shown, for Astoria, San Francisco and San Diego. 
I can only refer to the original for the full results deducible from these valuable 
observations, and repeat here in brief some of their facts :— 
«©The San Francisco curve presents three sets of waves of short interval: the first 
begins at 4h. 12m. and ends at 8h. 52m., the interval being 4h. 40m.; the second begins 
at 9h. 35m. and ends at 13h. 45m., the interval being 4h. 10m. ; the beginning of the 
third is about 133h., and its end not distinctly traceable. Thecrest of the first large 
wave of the three sets occurred at the respective times of 4h. 42m., 9h. 54m., and 
14h. 17m., giving intervals of 5h. 12m., and 5h. 23m.” 
««The average tirne of oscillation of one of the first set of waves was 35m., one of 
the second 31m., and one of the third about the same. The average height of the 
first set of waves was 0°45 foot on a tide which fell 2 feet; of the second 0°19 foot 
on a tide which rose 3 feet; and of the third 0°19 foot on a tide which fell about 
7 feet; the phenomena occurring on a day when the diurnal inequality was very 
considerable. ‘The greatest fall of the tide during the occurrence of the first set of 
waves was 0°70, and the corresponding rise 0°60 foot. In the second set the corre- 
sponding quantities were 0°30 and 0°20 foot ; in the third these waves would not have 
attracted general attraction.’’ There is a general analogy in the sequence of the 
waves of the three sets, which seem to mark them as belonging to a recurrence of 
the same series of phenomena. The series itself looks like the result of several 
impulses, not of a single one, the heights rapidly increasing to the third wave, then 
diminishing as if the impulse had ceased, then renewed and then ceased, leaving the 
oscillation to extinguish itself. If we had a corresponding account of the facts as 
they occurred at Simoda, the subject would lose the conjectural or rather the in- 
complete character that belongs to it. Although there is no account of the place of 
origin of the earthquake, yet its violence on the Japanese coasts and its diminished 
effects at Peel’s Island, as well as the times of arrival of the waves at the Japanese 
and Pacific American coasts, prove that it must have been beneath the sea, and not 
far distant from Japan. ‘‘ Five distinct waves in succession rolled in at Simoda; 
eight are shown by the San Francisco gauge, of which seven were of considerable 
height.”” It seems not improbable, although this does not appear to have occurred 
to Prof. Bache, that three of the San Francisco waves may have been reflected waves 
only. The highest wave at Simoda was estimated at 30 feet, at Peel’s Island 15 feet, 
at San Francisco 0°65 foot, and at San Diego 0°50 foot. 
At San Diego, the gauge shows distinctly the same three series of waves. The 
first begins at 1h. 22m. later than at San Francisco, correcting for difference of 
longitude, and ends 52m. later. The interval is 30m. less than at San Francisco, 
the oscillations being rather shorter than at the latter point. The second begins at 
54m. later than at San Francisco and ends 34m. later. The third begins 
about 54m. later than at San Francisco, The average time of oscillation of the 
