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leaving the eastern part of the kingdom it runs to the north-west, towards the cities of San Miguel el Grande and Guanaxuato. To the north of this last city, considered as the Potosi of Mexico, the Sierra Madre becomes of an extraordinary breadth. It divides immediately into three branches, of which the most eastern runs in the direction of Charcas and the Real de Catorce, and loses itself in the new kingdom of Leon. The western branch occupies a part of the intendancy of Guadalasara. After passing Bolaños it sinks rapidly, and stretches by Culiacan and Arispe, in the intendancy of Sonora, to the banks of the Rio Gila. However, it acquires again a considerable degree of height under the 30° of latitude in Tarahumara, near the gulf of California, where it forms the mountains de la Primeria alta, celebrated for the gold washed down from them. The third branch of the Sierra Madre, which may be considered as the central chain of the Merican Andes, occupies the whole extent of the intendancy of Zacatecas. We may follow it through Durango and the Parral in New Biscay, to the Sierra de los Mimbres (situated to the west of the Rio grande del Norte). From thence it traverses New Mexico, and joins the crane mountains (Montagnes de la Grue; and the Sierra Verde. This mountainous country, si: tuated under the 40° of latitude, was examined in 1777 by Fathers Escalante and Font. The Rio Gila rises here, of which the sources are near
those of the Rio del Norte. It is the crest of this central branch of the Sierra Madre which divides the waters between the Pacific and Atlantic Ocean. It was a continuation of this branch which Fidler and the intrepid Mackenzie examined under the 50° and 55° of north latitude.
We have thus sketched a view of the Cordilleras of New Spain. We have remarked that the coasts alone of this vast kingdom possess a warm climate adapted for the productions of the West Indies. The intendancy of Vera Cruz, with the exception of the plain which extends from Perote to the Pic d'Orizaba, Yucatan, the coast of Oaxaca, the maritime provinces of New Santander and Texas, the new kingdom of Leon, the province of Cohahuila, the uncultivated country called Bolson de Mapimi, the coast of California, the western part of Sonora, Cinaloa, and New Gallicia, the southern regions of the intendancies of Valladolid, Mexico, and La Puebla, are low grounds intersected with very inconsiderable bills. The mean temperature of these plains, of those at least situated within the tropics, and whose elevation above the level of the sea does not exceed 300* metres, is from 25° to 26°t of the centigrade thermometer; that is to say, from 8° to 90 greater than the mean heat of Naples.
* 984 feet. Trans. + 77° of Fahrenheit's.
From 14° to 16° of Fahrenheit, Trans.
: These fertile regions, which the natives call
Tierras calientes, produce in abundance sugar, indigo, cotton, and bananas. But when Europeans, not seasoned to the climate, remain in these countries for any time, particularly in populous cities, they become the abode of the yellow fever, known by the name of black vomiting, or vomito prieto. The port of Acapulco, and the vallies of Papagayo and Peregrino, are among the hottest and unhealthy places of the earth. On the castern coast of New Spain, the great heats are occasionally interrupted by strata of cold air, brought by the winds from Hudson's Bay towards the parallels of the Havannah and Vera Cruz. These impetuous winds blow from October to March; they are announced by the extraordinary manner in which they disturb the regular recurrence of the small atmospherical tides*, or horary variations of the barometer ; and they frequently cool the air to such a degree, that at Havannah the centigrade thermometer descends to 00 t, and at Vera Cruz to 16° 1; a prodigious fall for countries in the torrid zone.
On the declivity of the Cordillera, at the elevation of 12 or 1500 S metres, there reigns perpetu
* I have explained this phenomenon in the first volume of my Travels (Physique generale), p. 92, 94.
+ 32° of Fahrenheit. Trans. $60° of Fahrenheit. Trans. ş From 3936 to 4920 feet. Trans.
ally a soft spring temperature, which never varies more than four or five degrees (seven or nine of Fahrenheit). The extremes of heat and cold are there equally unknown. The natives give to this region the name of Tierras templadas, in which the mean heat of the whole year is from 20° to 210*. Such is the fine climate of Xalappa, Tasco, and Chilpansingo, three cities celebrated for their great salubrity, and the abundance of fruit trees which grow in their neighbourhood. Unfor. tunately, this mean height of 1300 metrest is the height to which the clouds ascend above the plains adjoining to the sea ; from which circumstance these temperate regions, situated on the declivity (for example, the environs of the city of Xalappa), are frequently enveloped in thick fogs.
It remains for us to speak of the third zone, known by the denomination of Tierras frias. It comprehends the plains elevated more than 22001 metres above the level of the ocean, of which the mean temperature is under 17o9. In the capital of Mexico, the centigrade thermometer has been known to fall several degrees below the freezing point; but this is a very rare phenomenon ; and the winters are usually as mild there as at Naples. In the coldest season, the mean heat of the day is
* From 68° to 70° of Fahrenheit. Trans.
from 13° to 140*. In summer the thermometer never rises in the shade above 21°f. The mean temperature of the whole table-land of Mexico is in general 17° | which is equal to the temperature of Rome. Yet this same table-land, according to the classification of the natives, belongs, as we have already stated, to the Tierras frias ; from which we may see that the expressions, hot or cold, have no absolute value. At Guayaquil, under a burning sky, the people of colour complain of excessive cold, when the centigrade thermometer suddenly sinks to 24°S, while it remains
the rest of the day at 30°ll. . But the plains more elevated than the valley of Mexico, for example, those whose absolute height exceeds 2500 metres , possess, within the tropics, a rude and disagreeable climate, even to an inhabitant of the north. Such are the plains of Toluca, and the heights of Guchilaque, where, during a great part of the day, the air never heats to more than 6° or go **, and the olive tree bears no fruit, though it is cultivated successfully a few hundred metres lower in the valley of Mexico,
All these regions called cold enjoy a mean temperature of from 11° to 13ott, equal to that of