172 
EARTH QUAKES. 
on the progress of knowledge in Europe. The germ of a 
great number of physical truths is found in the works of the 
sixteenth century; and that germ would have fructified, 
had it not been crushed by fanaticism and superstition. We 
learned, at Paste), that the column of black and thick smoke, 
which, in 1797, issued for several months from the volcano 
near that shore, disappeared at the very hour, when, sixty 
leagues to the south, the towns of Riobamba, Hambato, and 
Tacunga were destroyod by an enormous shock. In the 
interior of a burning crater, near those hillocks formed by 
ejections of scoriae and ashes, the motion of the ground 
is felt several seconds before each partial eruption takes 
place. We observed this phenomenon at Vesuvius in 1805, 
while the mountain threw out incandescent scoriae ; we 
were witnesses of it in 1802, on the brink of the immense 
crater of Pichincha, from which, nevertheless, at that time, 
clouds of sulphureous acid vapours only issued. 
Everything in earthquakes seems to indicate the action of 
elastic fluids seeking an outlet to diffuse themselves in 
the atmosphere. Often, on the coasts of the Pacific, the 
action is almost instantaneously communicated from Chile to 
the gulf of Guayaquil, a distance of six hundred leagues ; 
and, what is very remarkable, the shocks appear to be the 
stronger in proportion as the country is distant from burn- 
ing volcanoes. The granitic mountains of Calabria, covered 
with very recent breccias, the calcareous chain of the Apen- 
nines, the country of Pignerol, the coasts of Portugal and 
Greece, those of Peru and Terra Pinna, afford striking 
proofs of this fact. The globe, it may be said, is agitated 
with the greater force, in proportion as the surface has a 
smaller number of funnels communicating with the caverns 
ot the interior. At Naples and at Messina, at the foot of 
Cotopaxi and of Tunguragua, earthquakes are dreaded only 
when vapours and flames do not issue from the craters. In 
the kingdom of Quito, the great catastrophe of Riobamba 
led several well-informed persons to think that that country 
would be less frequently disturbed, if the subterranean fire 
should break the porphyritic dome of Chimborazo; and if 
that colossal mountain should become a burning volcano. 
At all times analogous facts have led to the same hypotheses, 
l’he Greeks, who, like ourselves, attributed the oscillations 
