40 Earthquake Waves on ihe Western Coast of the U. States. 
The average time of oscillation of one of the first set of waves 
was 35™, one of the second 31™, and one of the third about the 
same. ‘The average height of the first set of waves was *45 of 
a foot on a tide which fell two feet; of the second -19 of a foot 
on a tide which rose three feet; of the third somewhat less than 
‘10 of a foot, on a tide which fell some seven feet. The phe- 
nomena occurred on a day when the diurnal inequality of the 
tide was very considerable. The greatest fall of the tide during 
the occurrence of the first set of waves was -70 feet, and the cor- 
responding rise *60 feet. In the second the corresponding quanti 
ties were ‘30 feet, and in the third ‘20 feet. ‘These waves wou 
not oe attracted general attention 
The a general analogy in the sequence of tte waves of 
the rlitee is: which seems to mark them as belonging to a re- 
currence of the same series of phenomena. In the diagram No. 
3 A (see plate), the heights of the successive waves of the first 
set at San Francisco are shown by the dots joined by full lines, 
and of the second by those joined by the fine dotted line. The . 
full faint lines show the heights of the first series at San Diego 
and the broken faint lines the heights of the second. The heights 
in hundredths of a foot are marked at the side of the diagram, and — 
those of the gaye = waves are placed at regular intervals, the 
waves being n red from 0 to 7 at the top of the diagram. 
The height is pees mean of | the fall from a crest to a hollow and 
of the succeeding rise from the same hollow to the next crest. 
The times of oscillation from one crest to the next succeeding, 
are placed on the same diagram, the times being written at the 
right hand, and the wave being designated at the lower part of 
the iagram No. 3, B. ‘The full line represents the times of the 
first series at San Franciso and the broken line the times of the 
second. The full and broken faint lines represent the times of 
the first and second series at San Die 
The intervals between the times of occurrence of the crests 
of the successive waves in the first and second series diminish 
from 5 10™ to 45 48m by irregular differences. 
The effect of the rising or falling tide upon which these waves 
occur is of course greater in disturbing . heights than the times. 
The series itself looks like the result of several impulses, not 
of a single one, the heights rapidly i sie apo el to the third wave, 
then diminishing, as if the impulse had cedsed, then renewed, 
then ceasing, leaving the oscillation to extingtish itself. 
If we hada good | scientific report of the facts as they occurred 
at Simoda, the subject would lose the conjectural character which 
must otherwise belong to it. Although we have no account of 
the place where the earthquake had its origin, the violence of its 
effects in Japan and the diminished effects at Peel’s Island, show 
that Japan was certainly not far from the seat of action. = =—=— 
* 
