x. 
228 Earthquakes in Sicily. 
iransmissive power of the body moved, and te various local 
circumstances favourable, or otherwise, to the propagation of 
motion. After having combated with the obstacles which 
e, roaring under the earth, like the winds of Eolus, to 
| 
find an outlet from the places in "which they were produced, 
they circulate in various canals, until a cold temperature de- 
prives them of the heat which gave them such power, and 
they sink into their former state. Often, however, they 
drive before them the matter which the heat has liquified ; 
and urging it towards the ancient mouths of volcanoes, belch 
it out in flaming rivers in the midst of the terrible phenomena 
hs i they themselves produce.* 
by the passion for observation, | have often de- 
vended into the horrid cavity of the crater, and approached 
near the blazing brink of the new orifices which have vom- 
ited forth streams of fire in my own time; I have seen im- 
mense torrents of aqueous vapour urged from the vast chim- 
ney, whose base is lost in the deep furnaces below; I have 
been bathed in the water, to which the vapour was redu' 
by the low temperature of the atmosphere into which it en- 
tered ; often have 1 seen it fall in fine showers all around me. 
Having penetrated into the recesses of the globe, it is in this 
pee forced out again by the heat to which it is exposed. 
observed the hydrogen gas; one time, burning with 
its peculiar colour; at another, bursting forth with a loud, 
deep explosion ; the sulphuric and muriatic vapours, whiten- 
ing the i immense Clouds of smoke, and filling all the air with 
their suffocating breath ; or, seizing upon the solid substances 
around, ee fixed upon them. Fused substances, forced 
up by the elastic vapours, are disgorged from the same 
ben spread about in torrents of fire, and consolidated by 
the contact of the air. Is it not possible that the seat of 
*In my “Description of Atna,”’ I have proved that the furnaces fo 
this voleano cannot be under the foundation of the mountain, but at va- 
Hortcs distaxies Ti from it. The immense vau pe ich must have 
rm € 
_o 
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so many 
shock, have swallowed up the whole sboutitatihy and the combustible ma- 
als wou. be mall a ci e 
exhausted in 
matter in different situations, from causes established 
usage, flows abinatgel #tna, and i is ejected by it. Seneca acknow: 
Poti ignem in ipso monte non alimentum, sed viam habere— 
+ 
