Mineralogy and Geology. 279 
boring volcano, and forms a semi-circle. e awe-inspiring sound was 
Some ten minutes later by one more severe. I saw the roof and walls 
of my little habitation trembling without at first perceiving the cause. 
quietly. He was a native of the country, and therefore accustomed 
en the region a nar 
the fact. But though these slight shocks are constantly occurring, es- 
b 
pected about once i ntury to overwhelm the city in total destruc- 
d 
Conducting off the vapors and liquid matter from the vast fires beneath, 
or, to quote Humboldt, as a safety-valve against destructive earth- 
quakes, 
_ the shocks continued throughout Good-Friday, with pretty regular 
intervals, about as often as two or three per hour, and having all the 
same direction, west-southwest to east-northeast. In this direction, ata 
distance of a short league from the city, and at an elevation of about 
feet above it, is the great crater of Guscatlan. This crater seems 
amore ancient formation than that of San Salvador, and is 
partly filled up bya lake. Here the shocks seem to originate, and not 
cu 
lering fell from ceilings, and many tiles were thrown from the roofs. 
lance to earthquakes, they would probably have come down in mas- 
Ses. These houses are all low, very broad, and of only one story, the 
walls of loam-mud possessing considerable elasticity, and covered with 
flexible cane—no better construction being possible to meet the case. 
