4 MEXICAN RESOURCES. 



Thus the coast, for quite its entire length, is hot, and much of it extremely un- 

 healthy. The low-lying region appertaining to it is well designated the tierra cali- 

 ente, or " hot country," in which the humid atmosphere perpetually nourishes a 

 vegetation peculiarly tropical. The mean annual temperature of this climatic zone 

 ranges from 75° to 82° (Fahr.), the extremes being from about 55° to 105°. Its 

 influence is felt to an approximate altitude of about 3,000 feet above the sea. It 

 may be safely visited, as a rule, between the months of December and April, when 

 the heated coast is subject to violent gales called northers — los nortes, which cool 

 the air, and dissipate the germs of disease. At an altitude above sea-level of about 

 3,000 feet, we enter the tierra templada, the " temperate country," where the average 

 mean annual temperature is about 70°, and the extremes 50° to 86°. Extremes in 

 temperature are almost unknown in this zone, a delightful coolness prevailing in the 

 shade, while the vegetable forms, though not entirely characteristic, blending as 

 they do those of both the lower and upper regions, are of most astonishing variety. 



The prevailing climate of the tierra templada is warm and moist, the precipitation 

 from the clouds from the Gulf (on the eastern coast) being great, and the rainfall 

 greater than either in the higher, or the lower zone. The classification is an arbi- 

 trary one, and it is difficult to say just at what elevation each zone overlaps and 

 merges into the other ; but it may be roughly stated that the tierra caliente extends 

 upward from the coast to a vertical height of 3,000 feet, the templada from 3,000 to 

 7,000 or 8,000, — the verge of the table-land, — while above that altitude is the 

 tierra fria, or "cold region," with a vegetation varying from the corn and barley, 

 and maguey of the lower levels to the cryptogamia of the mountain-tops. The 

 mean annual temperature of the tierra fria, which includes the greater portion of 

 the vast plateau, is about 60°, the extremes reaching from 75° to the freezing-point. 

 Travel on the table-land may be equally agreeable, summer or winter, excepting 

 that it is liable to frequent detentions during the rainy season. 



The Mexicans divide the year into two periods : el estio, or the dry season, and la 

 estacio7t de las aguas, or the rainy season. The latter comprises the months of June, 

 July, August, and September, while the dry season extends over the greater portion 

 of the rest of the year. "The curving shores of Mexico along the Gulf and interior 

 highlands gather and hem in an immense body of vapor, which is carried on by the 

 trade-winds, and condensed against the cold and lofty inland mountain-peaks which 

 rise above the limit of perpetual congelation. This occurs during the dry season, 

 whilst the sun is at the south! But when its power increases, as it advances north- 

 ward, and until it has long turned back again on its southern course, these vapors are 

 dissolved by the hot intertropical air, and descend almost daily in fertilizing showers." 



Electric storms and water-spouts rarely occur, except in certain well-determined 

 localities, as at various points on the coast. Earthquakes are infrequent, and sel- 

 dom destructive, being rather temblores, or tremblings, than terremotos, or shakings. 



The duration of the day, in winter, including morning and evening twilight, is 

 12 hours 35' to 13 hours 40'; in spring, 14 hours 36' to 15 hours 38'; in summer, 

 15 hours 54' to 16 hours 44'; and in autumn, 13 hours 52' to 14 hours 46'. 



ZONES OF VEGETATION. 



Although the indigenous plants of Mexico are by no means few in number, it now 

 possesses, undoubtedly, through its Old World acquisitions, the richest economic 



