$e ; On Earthquakes—their causes and 
_tarine volcanoes, which show themselves by throwing up 
. - large quantities of water into the air, and are in a state 
action in concert with those at a considerable di A 
continuance of those eruptions frequently produces” felands; 
some of which again disappear suddenly, as though they 
were the apex of a huge crater “falling into its own bowels. 
Of this description was the island of Sabrina, among the 
Azores. In June 1811, it made its appearance where the 
Sea was sixty fathoms deep: and was nine hundred toises in 
diameter. Many of the West India Islands expanencotae 
ee at the same time, at a distance of eight hundred _ 
eagues 
: It may be objected to this theory that rocks do not b eu 
&- = In answer I state, that when rocks are decomposed, th 
metallic bases, calcium, silicium, aluminum, magnesium, a! ‘3 
are highly incandescent, and prove a never failing source. of 2 
- matter for combustion. 5 
If there should We an accumulation of gaseous vapours i ee 
one of those channels, and it should be unable t in. 
consequence of some Peis toa Gecatng volute it. 
forces another opening, “~ causes, -by passing t ——_ a = ee? 
ee channel, an earthqu t ‘onsi erable Pacts 
_ from whence it originated. jSeierothin ng o “thi 
ees when Riobamba was ore The volcano of 
to, which had continued to eject smoke, ceased at once ; 
at that moment the city was destrayed, at the a of 7 
ie thirty-five leagues south. : 
| Earthquakes frequently occur ee any s) 
of connexion with voleanoes. These may be a 
Be 
; of the sea to one of those channels, the water, sicing 
with an ignited mass, is suddenly converted into elas- 
; tic vapour, and expands itself throughout its openings, 
“ causing @ concussion or trembling of the superincumbent 
strata. Dolomieu, in his examination of Calabria, says, ‘‘ La 
fore: ce motrice paroit avoir residé sous la Erlabre elle 
, méme.’? He afterwards informs us that the motion appears 
. ‘ ‘to have advanced progressively along the chain of the A Appe- 
nines, from the south to the north. “Phe action of an cots. 
‘ e was almost instantly communicated from rin ie 
“Gudyaquil, a distance of six hundred leagues. If | 
boldt’s idea, that the Cordilleras form a vast volcanic w valk 
be correct, the pulsation must have been communicated 
iia acraamaeaai 
