Ascent to the Summit of the Popocatepetl. 227 
The crater is an immense abyss, nearly round, bulging considera- 
bly to the north, and with some sinuosities to the south. It may be 
a league in circumference, and eight hundred or a thousand feet in 
perpendicular depth. Its edge is not horizontal ; it declines towards 
the east with sufficient steepness to create a difference of one hun- 
dred and fifty feet in the height of the two opposite points. Not- 
withstanding this, the diameter of the center is so great, and the 
height at which it is so immense, that, from whatever part of the 
plain you look at the volcano, that part of the edge which presents 
itself to your view always appears to be the highest. 
The walls of the abyss are perpendicular. Three large horizon- 
tal strata are perfectly visible, perpendicularly striped at almost 
equal distances by black and greyish lines. ‘The bottom is a funnel 
formed by the detached parts which have from time to time fallen 
down, and which now do so daily. On the inside of the edge, down 
to fifteen or twenty feet, are layers, black, red, and whitish, very 
thin, supporting blocks of volcanic rock, which, however, fall occa- 
sionly into the crater. ‘The bottom and the inclined plane of the. 
funnel are covered with an immense quantity of blocks of pure sul- 
phur. From the middle of this abyss, masses of white vapor as- 
cend with great force, but disperse when about half way up the cra- 
ter. Some also escape from openings in the slope of the funnel, and 
others from seven principal fissures, between the layers which form 
the very edge of the crater ; but these do not rise to above fifteen or 
twenty feet. 
The openings in the bottom are round, and surrounded by a circle 
of pure sulphur. There is no doubt that these vapors, which es- 
cape with so much force, must carry with them large quantities of 
sulphur in a state of sublimation, which are deposited on the stones 
and around the vent-holes. So much sulphurous acid gas escapes, 
that it was offensive to us on the summit. ‘The exterior of the edge 
of the crater is free from snow ; but within, on the side whereon the 
sun does not shine, there is a quantity of stagonites of ice down to the 
beginning of the third stratum. The highest summit of the volcano 
is a small platform of about twenty feet diameter, with some of that 
purple sand which is so abundant at the base of the cone. 
You will easily feel how imposing such a sight must be. Such 
masses of lava, of porphyry, of red and black scoria, those whirlwinds 
of vapor, those stagonites, the sulphur, the snow; in short, this 
strange confusion of ice and fire which we met with at eighteen thou- 
