POPOCATEPETL. 

Popocatepetl, the smoking mountain, its name being derived from. 
the Aztec words fopoca, smoking, and ¢efe¢/, mountain, is a volcano. 
taking rank by its altitude among the highest mountains of North. 
America, 
While its altitude is so great that it has often been regarded the 
highest peak on the continent, the most recent determinations assign. 
to it the fourth place. Mt. Logan, situated in Lat. 60° 34’ N., and 
Long. 140° 24' W., according to recent determinations by the United 
States Coast and Geodetic Survey, is the highest, having an altitude 
of 19,539 feet; Mt. St. Elias comes next, with an altitude, according to 
the same Survey, of 18,024 feet; Orizaba in Mexico, third, with a. 
height according to Ferrer, of 17,879 feet, while the fourth is Popo- 
catepetl with a height, by Sonntag’s measurement, of 17,784 feet. 
Seen from the west, or side upon which Ameca is located, Popo- 
catepetl presents the appearance of a symmetrical, rounded, snow- 
capped cone rising about 5,000 feet above the ridge of the Sierra on 
which it stands, The average slope of this cone is about 30 degrees, 
though it appears much steeper to the eye.* Seen from the south, or 
valley of Puebla, the volcano presents a more imposing aspect (See 
Frontispiece) for here its massive cone rises uninterruptedly for 13,000: 
feet out of a valley luxuriant with semi-tropical foliage. Its lower 
slopes are clothed with groves of deciduous trees and firs, and above 
these is a zone of conifers, chiefly pines. The remainder of the cone 
is black and naked except for a mantle of snow of varying length, 
which sometimes disappears altogether from the eastern and southern. 
slopes. | } 
This disappearance of the snow is undoubtedly due to the warm 
airs which rise from the valleys of Puebla and Cuautla and not to. 
the cause suggested by Heilprint—that of the vapors which flow out 
from the lip of the crater. These are too limited in quantity to have 
any appreciable heating effect. 
The summit of the cone is truncated obliquely by the crater, 
whose walls are highest on the west and lowest on the east,{ so that 
*The author, Science, New Series, Vol. IV, No. 87, p. 271. 
+The Geographical Journal, Jan. 1897, p. 100. 
{See p. 94. 
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