Natural History of Volcanos and Earthquakes. 43 
to the force of elastic fluids, brought forward, in support of their 
opinion, the total cessation of earthquakes in the island of Au- 
boa, after the opening of a chasm in the Lelantic fields.* 
The intimate connection of earthquakes with voleanos is not 
less clearly proved by the direction which the former take. With 
the assistance of a simple instrument (the sismograph) invented 
by Cacciatore, and erected at Palermo, it was found in twenty- 
Seven cases that the shock was propagated in a fixed linear di- 
rection, which coincided remarkably with the cardinal points. 
N nineteen cases the shocks were transmitted in a direction from 
east to west, corresponding with the situation of Mount Fina, 
the source of all these subterranean concussions, which lies di- 
rectly to the east of Palermo. In four cases it was from south 
to north; but, for want of corresponding observations, the seat of 
these shocks cannot be determined ; and it certainly does not 
seem to have been the effect of chance, that three shocks, which 
were felt on the 9th February, 30th June, and 2d July 1831, 
traveled from the south-west to the north-east: for it was pre- 
cisely in that direction, at a distance of about 70 Italian miles, 
that the small new volcano suddenly appeared in the sea, prob- 
ably on the 2d J uly. The two latter shocks were also the very 
Same that were felt with greater force at Sciacca, on the southern 
Coast, opposite to the new volcano. 
On the other hand, Boussingault{ asserts that the most mem- 
orable earthquakes in the New World, which ravaged the towns 
of Latacunga, Riobamba, Honda, Caraccas, Laguayra, Mer ’ 
Bar quisimeto, &c., do not coincide with any well established 
Voleanic eruption. 'The oscillation of the surface, owing to an 
eruption, is, as it were, local; whilst an earthquake, which is 
Not subject (at least apparently) to any volcanic eruption, extends 
to incredible distances, in which case it has also been remarked 
that the shocks most commonly follow the direction of chains 
of mountains, 
In favor of the hypothesis, that earthquakes are produced by 
aqueous vaporl| penetrating to great depths, the following circum- 
Siar BEEBE i 0 9 EE 
* Strabo, lib. i, ed. Oxon. 1807, t. i, p. 85- 
' F. Hoffman in Poggend. Ann. t. xxiv, p. 63. 
+ Annal. dé Chim. et de Phys. t. Iviii, p. 83. 
{| A remarkable case which has taken place at the iron-foundery at Sayn, proves, 
that shocks of the earth may be several times repeated by the effect of elastic flu- 
