272 Natural History of Volcanos and Earthquakes. 
consisting of two peaks, which they probably would have done, 
if the Monte Somma had stood, as at present, distinct from the 
cone of Vesuvius.* It is also remarked that the distance men- 
tioned in ancient writers, as intervening between the foot of 
Vesuvius and the towns of Pompeii and Stabiae, appears to 
have been greater than exists at present, unless we measure it 
from the foot of Monte Somma, so that this affords an additional 
probability, that the latter mountain was then viewed as a part 
of the former, and that no separation between them had at that 
time occurred. We may also be sure from the semicircular fig- 
ure which the southern escarpment of the Monte Somma pre- 
sents towards Vesuvius, that it constituted a portion of the walls 
of the original crater ; and Visconti, it is said, has proved by ac- 
tual measurements, that the centre of the circle, of which it isa 
segment, coincides as nearly as possible with that of the present 
crater. ‘There seems, therefore, little room to doubt, that the old 
mouth of the voleano occupied the spot now known by the name 
of the Attrio del Cavallo, but that it was greatly more extensive 
than this hollow, as it comprehended likewise the space now 
covered by the cone, which was thrown up afterwards in con- 
sequence of the renewal of the volcanic action that had been 
suspended during so many ages. This view likewise tends, as 
it seems, to reconcile the accounts which ancient writers have 
given of the structure of the mountain, antecedently to the pe 
riod before mentioned.t 
_ As for the mode of action of the vapors, it is indifferent whether 
they have to contend with loose and unconnected, or with melt- 
ing masses, only that the former are propelled into the air like 
cannon balls,{ and falling into a parabolic curve, accumulate and 
Ne a ee 
_* Daubeny, a Description of Active and Extinct Volcanos, «&c. p- 144, - Be 
also Von Buch in Poggendorff’s Ann. t. xxxvii, p. 173. . 
1 See the Historical Notices given by Daubeny, loco cit. p. 145, and following: 
¢ V. Humb. (Reise, v. i, p. 226) calculates from the time the stones thrown . 
during the lateral eruption of the Peak of Teneriffe, on the 9th June 1798, arg 
in falling (which according to Cologan was from twelve to fifteen seconds, ree 
oning from the moment they reached their greatest height,) that they yes 
. ; ; $ mai 
tions made by other observers, give still greater heights. 
of such projections was observed at Cotopari by La Condamine (Voy 
teur.) He saw propelled laterally, a block of about 1000 square feet, 
of nearly 14 geographical miles, 
age 4 J Equa 
to a distance 
