96 THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



lakes. Nevertheless, there have been certain periods when nature has triumphed over 

 human endeavor and the waters have returned to the level which they would naturally 

 occupy if man had never interfered. A comparison of the chief epochs of this sort seems 

 to afford some ground for the beUef that the climate of Mexico has passed through fluctu- 

 ations like those of Asia, on the one hand, and of more northern regions in America, such 

 as California and New Mexico, on the other hand. 



The great authority on early Mexico is Humboldt, whose "Essai Politique sur la 

 Royaume de la Nouvelle-Espagne " was published in 1811 as the third part of the "Voyage 

 de Humboldt et Bonpland." Later and less authoritative writers, such as Prescott and 

 Romero, follow him closely, adding little that is new. Humboldt specifically states his 

 belief that the climate of Mexico in his day was more arid than it was at the time of the 

 founding of the capital about 1325 a. d. He attributes the change in part to undefined 

 meteorological causes whereby evaporation has exceeded precipitation, and in part to the 

 reckless destruction of forests by the Spaniards. He is sure that the level of Lake Tezouco 

 has fallen, tlu'ough natural causes as well as through the works of man, and cites this fact 

 as the chief evidence of a change of climate. 



According to tradition, the Aztec founders of Mexico, like most of the world's great 

 races, came from the north. After a century of adventurous wanderings, enlivened by 

 the vicissitudes of war, conquest, and slavery, they appear to have reached the shores of 

 Lake Tezcuco about 1.325 a. d. Hoping for peace and safety, they located themselves on 

 some small islets several miles from the shore. There they laid the foundations of the 

 present proud City of Mexico by sinldng piles into the marshy shallows and erecting upon 

 them light huts of reeds and rushes above the reach of the water. During the succeeding 

 century, according to Humboldt, the city grew and prospered and its rule spread over 

 the neighboring regions. It was still an island city with houses on piles, with canals 

 instead of streets in many cases, and with canoes in place of beasts of burden. Sometimes 

 it suffered when the lake rose more than usual. The first well-authenticated event of this 

 kind is recorded by Torquemada,* a monk who lived in Mexico from the middle of the 

 sixteenth century well into the seventeenth. It happened in the early years of the reign 

 of Montezuma, who became king in 1436 a. d. In this year the water "submerged the whole 

 city and the inhabitants travelled in canoes and barques, without knowing how to remedy 

 matters nor how to defend themselves from so great an inundation. " The next year was 

 also phenomenal, and Torquemada enlarges on the abundant crops and great prosperity, 

 which, he says, are affirmed by all historians. At about this time the fii'st known dike was 

 built in the year 1446 a. d. If it were not for Torquemada's direct statement as to the 

 great rain and abundant crops we might suppose that the dike happened to be built then 

 merely because of an advance in the art of engineering; or because the increasing number 

 of buildings in the city caused the land to settle, as it has done in recent years, when the 

 erection of the new National Theater, for instance, has caused a local subsidence of 4 or 

 5 feet which is evident to the most casual observer by reason of the warping of the pavements 

 of the streets. It seems probable, however, that the Ijuilding of the dike was due more to 

 chmate than to any other cause, for the water did not remain at a high level thereafter, but 

 near the end of the fifteenth century, fell so low that the city suffered much distress because 

 canoes laden with suppUes of food could not come in as formerly from the surrounding 

 country. When Cortez came to Mexico in 1519 the water had again risen and the capital 

 was still a western Venice. He describes it as located on an island two leagues from the 

 mainland. In order to besiege it effectively he was obliged to build brigantines, and in these 

 he was able to sail completely around the city, except for a small distance on the southwest 



* Fray Juan de Torquemada: Los Veinte i vn Libros Rituales y Monarcliia Indiana, etc., etc. Edition of 1723. (Tlie 

 original edition is 1613.) Book ii, Chap, xxxvii, p. 157. For tliese references to variations in Mexican lakes, I 

 am indebted to the researches of Mr. Adolph Bandelicr. 



