A YOUNG NATURALIST. 6 1 



" Popocatepetl, Istaccihuatl," said I'Encuerado gravely, point- 

 ing out the mountains. 



The two mountains, mentioned by the Indian, were towering 

 up behind us, — a sight that alone repaid for our difficult ascent ; 

 we could admire in turn the three loftiest volcanoes in Mexico. 



" Where is Popocatepetl % " asked Lucien. 



" There ; that enormous cone which rises to our right," I 

 answered, pointing in that direction. 



" Is it the smallest of the three 1 " 



"No, on the contrary, it does not measure less than 18,000 

 feet in height. Dias Ordas, one of the captains of Fernando 

 Cortez, made its first ascent. Its name signifies ' smoking 

 mountain.' " 



" Yes ; and I know that Istaccihuatl means ' white woman ; 

 but I do not know the height of it.'' 



" It is 15,700 feet above the level of the sea." 



" How can mountains like these be measured ?" asked Lucien. 



" In the first place, by geometrical calculations, and then, by 

 the aid of a barometer, when an ascent has been made; the 

 column of mercury in the instrument falls in proportion as the 

 barometer is carried up the mountain, because the air which 

 presses upon the mercury reservoir becomes less and less dense." 



I quite forgot the lapse of time while contemplating the glorious 

 panorama spread beneath. Just around us, the ground was rocky 

 and volcanic, and covered with mosses of various colours ; rather 

 lower down, the ground was hidden by the fallen leaves of giant 

 trees ; beyond was a succession of smaller crests, frequently quite 

 barren, sometimes covered with sun-scorched verdure. On the 

 horizon, which was hidden by a transparent mist, the two vol- 

 canoes of the plateau stood out in bold relief against the blue 

 sky, facing the other colossus, which seemed to protect us with its 

 shadow. The peaks of these mountains, clad with their per- 

 petual snow, can be seen by sailors forty leagues at sea. 



I was really sorry to give the signal for departure. We again 

 met with the pine-needles, and though our ascent was difficult and 

 slow, our descent was proportionably rapid. Thus we fell forwards 

 instead of faUing backwards. Gringalet, who seemed amused at 



