724. • REPORT — 1897. 



6. South-eastern Alaska GeograTpliy and the Camera, 

 By Otto J. Klotz. 



The First Ascent of Mount Lefroy and Mount Aberdeen, 

 By Professor H. B. Dixox, F.R.S. 



8. Mexico Felix and Mexico Deserta. By O. H. Howarth. 



Tlie physical structure of tlie region comprised in the Mexican Republic, viz.^ 

 that of a high plateau of some 550,000 square miles in area, fringed by a narrow 

 belt of low-lying lands on either coast, has led to its being usually described 

 imder three climatic divisions — the Tierra Caiiente, or Hot Lands, the Tien-a 

 Templada, or Temperate Lands, and the Tierra Fria, or Cold Lands. For practical 

 purposes such a description can hardly be said to afford any strict geographical 

 definition, inasmuch as the climatic conditions of any particular locality are not 

 dependent only on temperature, but also on altitude, rainfall, evaporation, forest 

 growth, proximity of ocean waters, and other modifying causes, all of which 

 operate in varyiog degrees at difiBrent latitudes. Omitting the coast levels, which 

 are essentially tropical in character, though not wholly within the tropical- 

 limits, and the higher mountain ranges of the interior, it is to be observed tliat the 

 general characteristics of that portion of Central America are still subject to much 

 misapprehension in the minds of those unacquainted with Mexico. Regarding- 

 the conditions of human life and prosperity, it occurs to me that the general 

 distinction into ' Mexico Felix ' and ' Mexico Deserta ' is somewhat more to the 

 purpose ; and it will be seen that those conditions haye little to do with mere 

 temperature by itself — still less with actual latitude. 



From a breadth of some 1,200 miles at the United States frontier, on about the 

 30th parallel, the continent narrows gradually throughout its south-easterly trend 

 to one of only 120 miles at the Isthmus of Tehuautepec, widening again at the 

 borders of Guatemala, some 14 degrees further south, before it contracts finally 

 to a 45-mile strip at Panama. From the general altitude of 3,000 to 4,000 

 feet, extending through the south of Arizona, New Mexico, and Texas (U.S.A.), 

 there is a further gradual rise beyond the course of the Rio Grande, and a 

 general level of 5,000 feet and upwards is maintained for 1,200 miles, until, south 

 of the city of Mexico, it declines again by a series of terraces to under 2,000 feet, 

 mounting up once more in the States of Oaxaca, Guerrero, and Chiapas. Yet the 

 mean temperatures and evaporation are considerably higher, and the rainfall lower, 

 in the northern portion of this tract than in the south, which is commonly supposed 

 to belong to the torrid regions of the earth. While the mean temperature during- 

 last year in the city of Mexico was slightly under 60° (Fahr.) that of Monterey, in 

 the State of Nuevo Leon, was over 74° ; whereas at the city of Oaxaca, 300 miles 

 further south than Mexico City, and at 2,000 feet less elevation, it was no more 

 than 67°. The northern States of Chihuahua, Coahuila, and Nuevo Leon preserve 

 largely the characteristics of Nevada and Arizona, comprising vast arid plains of 

 sage-brush, mosquite, and cactus, intersected by treeless mountain ranges, and 

 forming a zone between the regions of winter and summer rains upon which the 

 latter intrude but sparsely and only in occasional seasons. Hence it is that in the 

 southern States of North America the higher rainfall, together with the altitude and 

 approximation of the oceans, has developed a climate both healthier and mor& 

 equable, and a vegetation which in the north is only found in patches or amongst 

 the heights of the coast ranges. 



Perhaps the evidences of this peculiarity which possess the most direct interest 

 for us are those bearing upon the population of these southern regions in remote 

 ages, the study of which is rapidly leading us to assign to them an antiquity at 

 least as preat as any of which tlie world holds any record. 



