222 STEUCTUEE AND MODE OF ACTION 



is to be viewed as a single volcanic furnace. The subter- 

 ranean fire breaks forth sometimes through one and some- 

 times through another of these openings, winch it has been 

 customary to regard as separate and distinct volcanos. The 

 progressive march of the subterranean fire has been here 

 directed for three centuries from North to South. Even the 

 earthquakes which occasion such dreadful ravages in this 

 part of the world afford remarkable proofs of the existence 

 of subterranean communications, not only between countries 

 where there are no volcanos (a fact which had long been 

 known), but also between fire- emitting openings situated 

 at great distances asunder. Thus in 1797 the volcano 

 of Pasto, east of the Guaytara Kiver, emitted uninterruptedly 

 for three months a lofty column of smoke, which column 

 disappeared at the instant when, at a distance of 240 

 geographical miles, the great earthquake of Biobamba and 

 the immense eruption of mud caJed " Moya" took place, 

 causing the death of between thirty and forty thousand 

 persons. 



The sudden appearance of the Island of Sabrina near the 

 Azores, on the 30th of January, 1811, was the precursor 

 of the terrible earthquake movements which, much farther 

 to the west, shook almost incessantly, from the month of 

 May 1811 to June 1813, first the West Indian Islands, 

 then the plain of the Ohio and Mississipi, and lastly, the 

 opposite coast of Venezuela or Caraccas. Thirty days after 

 the destruction of the principal city of that province, the 

 long tranquil volcano of the Island of St. Vincent burst 

 forth in an eruption. A remarkable phenomenon accom- 



