Mountain Journeys 63 



MM. Truqui and Craveri, in their ascent in September, 1855, 

 were more fortunate: 



I ought to say (remarks one of them)'" that we experienced almost 

 no difficulty in breathing during the ascent; at least, we thought that if 

 we did feel any oppression, it should be attributed only to the fatigue 

 of a long and difficult climb, (P. 316.) 



In January, 1857, under the guidance of M. Laverriere, Director 

 of the School of Agriculture of Mexico, a scientific ascent of Popo- 

 catapetl was made, and this expedition was part of a series of 

 researches on the natural history of Mexico undertaken with the 

 most praiseworthy ardor by the government of General Comonfort. 



M. Laverriere in his notes and memoranda collected the data 

 which were of physiological interest in this ascent which was so 

 fruitful from the standpoint of physics and geography. I am 

 quoting in full his communication, for which I thank him sincerely: 



Among the tasks which had devolved upon us was the ascent of 

 Popocatepetl, situated southeast of the city of Mexico. I expected to 

 begin our operations by this ascent, because the season at that time 

 seemed to me particularly favorable. 



In fact, all who before us had attempted the ascent of Popocatepetl 

 had failed or had only partially succeeded. Forgetting the latitude and 

 the peculiarities of the climate of Mexico, they had made their attempts 

 at times when such explorations are made in Europe, that is, spring or 

 summer. I thought, on the contrary, that our expedition should be made 

 in winter, a period when the atmosphere in Mexico is perfectly trans- 

 parent and suitable for observations, and when, because of a relatively 

 lower temperature, the snows which cover the upper part of the cone 

 occupy a greater surface on its slopes, which lessens the distance to be 

 traversed in the deep and unstable sands which cover them, while fur- 

 nishing by their hardness a firmer footing for the traveller. 



Consequently our little caravan, composed of Dr. Sonntag, astro- 

 nomical engineer, a major-domo, two students from the School of 

 Agriculture, and three servants, left Mexico (2278 meters) on Saturday, 

 January 17, 1857, in very hot weather; on January 18 passed through 

 Chalco situated on the lake of the same name; on January 19 through 

 Amecameca (2493 meters), and entered the vast pine forests which 

 cover the first foothills of the volcano, reaching the ranch of Tlamacas 

 (3899 meters) on the evening of January 20. 



The ranch of Tlamacas, situated at the foot of the north slope of 

 the volcano, is composed of a few cabins in which the sulphur occa- 

 sionally brought from the interior of the crater is refined. It occupies a 

 clearing near the timberline, and near it are found several varieties of 

 pines, noteworthy for their hardiness, the excellence of their timber, 

 and the abundance of their resin, and capable of being acclimatized in 

 Europe. 



We passed the night in this spot. At six o'clock in the evening the 



