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snows with which it is covered, occasion in the Mexican atmosphere frigorifications by no means to be expected in these regions. If the table-land of New Spain is singularly cold in winter, its temperature is, on the other hand, much higher in summer than what was found by the thermometrical observations of Bouguer and La Condamine in the Andes of Peru. The great mass of the Cordillera of Mexico, and the immense extent of its plains, produce a reverberation of the solar rays, never observed in mountainous countries of greater inequality. This heat, and other local causes, produce the aridity of these fine regions. To the north of 20’, from the 22° to the 30° of latitude, the rains which only fall in the months of June, July, August, and September, are very unfrequent in the interior of the country. We have already observed that the great height of this tableland, and the small barometrical pressure of the rarefied air, accelerate the evaporation. The ascending current or column of warm air which rises from the plains prevents the clouds from precipitating in rain to water a land, dry, saline, and destitute of vegetation. The springs are rare in mountains composed principally of porous amygdaloid, and fendilated (fendillé) porphyry. The filtrated water, in place of collecting in small subterraneous basins, is lost in the crevices which old volcanic revolutions have opened, and only is
sues forth at the bottom of the Cordillera. It forms a great number of rivers on the coast, of which the course is very short on account of the configuration of the country. The aridity of the central plain, the want of trees, occasioned, perhaps, in a good measure by the length of time the great vallies have remained covered with water, obstruct very much the working of the mines. These disadvantages have augmented since the arrival of Europeans in Mexico, who have not only destroyed without planting, but in draining great extents of ground have occasioned another more important evil. Muriate of soda and lime, nitrate of potash, and other saline substances, cover the surface of the soil, and spread with a rapidity very difficult to be explained. Through this abundance of salt, and these efflores. cences, hostile to cultivation, the table-land of Mexico bears a great resemblance in many places to Thibet and the saline steppes of central Asia. In the valley of Tenochtitlan, particularly, the sterility and want of vigorous vegetation have been sensibly augmenting since the Spanish conquest; for this valley was adorned with beautiful verdure when the lake occupied more ground, and the clayey soil was washed by more frequent inundations. Happily, however, this aridity of soil, of which we have been indicating the principal physical causes, is only to be found in the most elevated
plains. A great part of the vast kingdom of New Spain belongs to the most fertile regions of the earth. The declivity of the Cordillera is exposed to humid winds and frequent fogs; and the vegetation nourished with these aqueous vapours exhibits an uncommon beauty and strength. The humidity of the coasts, assisting the putrefaction of a great mass of organic substances, gives rise to maladies, to which Europeans and others not seasoned to the climate are alone exposed; for under the burning sun of the tropics the unhealthiness of the air almost always indicates extraordinary fertility of soil. Thus at Vera Cruz the quantity of rain in a year amounts to 1",62*, while in France it scarcely amounts to 0",80 f. Yet with the exception of a few sea-ports and deep vallies, where the natives suffer from intermittent fevers, New Spain ought to be considered as a country remarkably salubrious. The inhabitants of Mexico are less disturbed by earthquakes and volcanic explosions than the inhabitants of Quito, and the provinces of Guatimala and Cumana. There are only five burning volcanoes in all New Spain, Orizaba, Popocatepetl, and the mountains of Tustla, Jorullo, and Colima. Earthquakes, however, are by no means rare on the coast of the Pacific Ocean, and in the environs of the capital; but they never produce such desolating effects as have been witnessed in the cities of Lima, Riobamba, Guatimala, and Cumana. On the 14th September, 1759, a horrible catastrophe took place: the volcanos of Jorullo burst, and was seen surrounded with an innumerable multitude of small smoking cones. Subterraneous noises, so much the more alarming as they were followed by no phenomenon, were heard at Guanaxuato in the month of January 1784. All these phenomena seem to prove, that the country between the parallels of 18° and 22° contains an active internal fire, which pierces, from time to time, through the crust of the globe, even at great distances from the sea shore. The physical situation of the city of Mexico possesses inestimable advantages, if we consider it in the relation of its communication with the rest of the civilized world. Placed on an isthmus, washed by the South Sea and Atlantic Ocean, Mexico appears destined to possess a powerful influence over the political events which agitate the two continents. A king of Spain resident in the capital of Mexico, might transmit his orders in five weeks to the Peninsula in Europe, and in six weeks to the Philippine islands in Asia. The vast kingdom of New Spain, under a careful cultivation, would alone produce all that commerce collects together from the rest of the globe, sugar, cochineal, cacao, cotton, coffee, wheat, hemp, flax, silk, oils, and wine. It would furnish every metal withWOL. I. Q_
* 63.780 inches. Trans. + 37.496 inches. Trans.
out even the exception of mercury. Superb timber and an abundance of iron and copper would
favour the progress of Mexican navigation; but
the state of the coasts and the want of ports from
tepec, and is consequently very dangerous in winter.
When we examine the eastern coast of New Spain we see that it does not possess the same advantages as the western coast. We have already observed, that, properly speaking, it possesses no port; for Vera Cruz, by which an annual commerce of fifty or sixty millions of piastres is car