Earthquake Waves on the Western Coast of the U. States. 41 
Five successive waves of considerable height are spoken of as 
having occurred at Simoda, while by the gauge we trace eight, 
of which seven are of considerable height. ‘The highest wave 
at Simoda was estimated at thirty feet, at Peel’s Island fifteen 
feet ;—at San Francisco it was 0°65 feet and at San Diego in the 
first series 0°50 feet. 
At San Diego the same three series of waves are distinctly 
shown. The first begins 1h 22™ Jater than at San Francisco, 
correction having been made for the difference of longitude, and 
ends 04 52™ later. The interval is 30™ less than at San F'ran- 
cisco, the oscillations being rather shorter than at the last named 
point. ‘The second begins at Ub §4™ Jater than at San Francisco, 
and ends 34™ later. The third begins about 54™ Jater than at 
San Francisco. The average time of oscillation of the first set 
of waves is 31™, and of the second 29™, being respectively 4m 
and 2™ less than of the corresponding series at San F'rancisco. 
he average height of the first set of waves was ‘I7 feet 
lower than at San I’rancisco, and the second as much higher. 
This fact taken with the difference in the times of oscillation 
leads me to suppose the difference in the two series due to inter- 
ference, which is also suggested by the position of San Diego in 
reference to the islands separating the Santa Barbara sound from 
Ne ocean. 
began near high water and was chiefly upon a falling tide of 7 
feet, while at San Francisco it was upon a rising tide of 4 feet. 
_ The forms of some of the individual waves in the second se- 
hes at San Francisco and San Diego, accord remarkably, as those 
. fe observations at San Diego confirm then, in general, the 
inferences derived from those at San F'rancisco. : 
he register at Astoria throws no new light on the subject. 
The bar at the entrance of the Columbia river would explain 
Why the oscillations were lost or greatly reduced at Astoria, even 
if they arrived off the entrance of the river. The disturbance 
1S marked on the register but in an irregular and confused manner. 
oe apparently preceded by unusual oscillations of the 
Stoowp Seni, Vol, XXI, No. 61—Jan, 1856. 6 
