BOOK ture of from 52° to 56° F. equal to that of France and LomLXXXIII. bardy. Still, vegetation there, is much less vigorous, and the Seasons. rains. plants of Europe do not grow with the same rapidity as in their native soil. The winters, at an elevation of 8200 feet, are not extremely severe. It must, however, be admitted that, in summer, the sun never heats the rarefied air of these plateaus sufficiently to accelerate the expansion of flowers, and to bring the fruit to perfect maturity. It is this unvarying equability of temperature, this absence of a fervent but ephemeral heat, which impresses a peculiar character on the climate of the high equinoctial regions. Accordingly, the cultivation of many vegetables is less successful on the ridge of the Mexican cordilleras, than on the plains situated to the north of the Tropic, although it often happens that the mean temperature of these latter is lower than that of the plateaus comprised between the 19° and 22° of north latitude. In the equinoctial region of Mexico, and even as far as the Periodical 28° of north latitude, only two seasons are known; namely, that of the rains, which commences in the month of June or July, and ends in September or October; and the dry season, which continues eight months, namely, from October till the end of May. The formation of clouds, and the precipitation of the water dissolved by the air, generally begin on the eastern slope of the Cordillera. These phenomena, accompanied by loud electrical explosions, extend in succession from east to west, in the direction of the trade-winds; so that the rain falls fifteen or twenty days later on the central plateau than at Vera-Cruz. Sometimes, in the months of December and January, rain, mixed with sleet and snow, is seen falling on the mountains, even at an actual elevation of more than 6562 feet. These rains, however, continue only a few days; and, cold as they are, they are looked upon as highly beneficial to the vegetation of wheat, and the growth of pastures. From the parallel of 24° to that of 30° the rain falls less frequently, and continues a shorter time. Fortunately, the snow, of which there is a consider able quantity from the 26° of latitude, compensates for this BOOK scarcity of rain.* LXXXIII. peratures. In France, and in the greater part of Europe, the em- Cause of ployment of land, and agricultural divisions, exclusively the diffedepend on geographical latitude; the configuration of the rent temcountry, the proximity of the ocean, or rather local circumstances, exerting only a feeble influence over the temperature. On the other hand, in the equinoctial regions of America, the climate, the nature of the productions, the aspect, and general features of the country, are almost all of them modified by the elevation of the land above the level of the sea. In latitudes 19° and 22°, sugar, cotton, and especially cocoa and indigo, do not afford an abundant crop at a less elevation than 2000 or 2600 feet. European wheat occupies a zone which, on the slope of the mountains, generally commences at the height of 4585 feet, and finishes at 9752 feet. The banana, that most useful plant, which constitutes the principal nourishment of all the inhabitants of the tropics, almost entirely ceases to bear fruit above the level of 5000 feet. The oak of Mexico grows only between 2500 and 10,078 feet of elevation. The pine descends towards the shores of Vera Cruz, only as low as 6068 feet; but it must also be added, that they do not rise higher, towards the line of perpetual snow, than 13,123 feet.f ture of the The provinces denominated internas, and situated in Temperathe temperate zone, but especially those comprehended interior between the 30° and 38° of latitude, enjoy, with the rest provinces. of North America, a climate essentially different from that which prevails under the same parallels, on the old Continent: it is particularly distinguished by a striking inequality in the temperature of the different seasons. Winters of a German rigour succeed to summers that vie with those of Naples and Sicily. But this difference of temperature is much less marked in those parts of BOOK the new Continent which approach the Pacific Ocean, than LXXXIII. in the more eastern regions. Dryness of the soil. snow. If the plateau of New Spain is singularly cold in winter, the temperature of summer is far higher than could be inferred from the thermometrical observations made by Bouguer and Condamine, in the Andes of Peru. It is to this heat, and to other local causes, that we must attribute the aridity which incommodes these beautiful countries. In fact the interior, particularly an extensive portion of the plateau of Anahuac, is completely stripped of vegetation. The enormous mass of the Mexican Cordillera, and the immense extent of its plains, produce a reflection of the solar rays, which, at an equal height, is not observed in other mountainous countries of a more unequal surface. Independently of this circumstance, the land is so high that its mere elevation, from the consequently diminished atmospheric pressure which is exerted on fluids by the rarified air, must sensibly augment the evaporation that Limits of takes place from the surface of these great plateaus. On the perpetual other hand, the Cordillera is not sufficiently elevated for any considerable number of its peaks to enter within the limit of perpetual snow. This snow, at the period of its minimum, in the month of September, does not descend, under the parallel of Mexico, lower than 14,465 feet; but in January, its boundary is met with as low as 12,159 feet. To the north, from latitude 20°, and, especially, from 22° to 30°, the rains, which continue only during the months of June, July, August, and September, are by no means frequent in the interior of the country. The ascending current, or column of heated air that rises from the plains, prevents the clouds from being precipitated in the form of rain, and thus saturating the dry saline earth, almost denuded of shrubs. There are few springs in the mountains, which, in a great measure, are composed of porous amygdaloid and laminated or shattered porphyries. Instead of collecting in little subterraneous basins, the water filters through the earth, and loses itself in the crevices which have been opened by ancient volcanic eruptions. This water only issues at the base of the Cordillera. On the BOOK coasts, it forms a great number of rivers, the course of LXXXIII. which, however, is very short. efflores The aridity of the central table, and the want of trees, Saline are extremely injurious to the working of the mines; these cences. evils have sensibly increased since the arrival of Europeans in Mexico. Not only have the conquerors destroyed without planting, but by artificially drying up extensive tracts of land, they have occasioned a still more important evil. The muriates of soda and of lime, the nitrate of potass, and other saline substances, cover the surface of the soil. They have spread themselves with a degree of rapidity which the chemist feels it difficult to explain. In consequence of this abundance of salts-these efflorescences so injurious to cultivation-the table land of Mexico resembles, in some places, that of Thibet, or the saline Steppes of central Asia. Happily this parched aridity of soil reigns only on the most elevated plains. A great part of the vast kingdom of New Spain may be classed with the most fertile countries of the earth. The shelving declivity of the Cordillera is exposed to humid winds, and to frequent fogs; and vegetation, promoted by these aqueous vapours, displays an imposing degree of beauty and luxuriance. The truth is, the humidity of the coasts, favouring the putre- Salubrity. faction of a prodigious mass of organic substances, proves the cause of diseases to which Europeans, and others not habituated to the climate, are exposed for, under the burning sky of the tropics, the unhealthiness of the air is almost invariably a sure indication of extraordinary fertility in the soil. Nevertheless, with the exception of some sea-ports, and of some deep and humid valleys, where the natives suffer from intermittent fever, New Spain ought to be considered as a singularly healthy country. A dry and uniform degree of heat is very favourable to longevity. At Vera Cruz, in the midst of the epidemic attacks of the yellow fever, (the black vomit,) the natives, and those strangers who have been already some years habitu BOOK ated to the climate, enjoy the most perfect state of health. LXXXIII. In general, the coasts and arid plains of Equatorial Ame produc tions. rica ought to be looked upon as healthy, notwithstanding the intense heat of the sun, the perpendicular rays of which are reflected from the soil. Vegetable Vegetation varies with the temperature, from the burning shores of the ocean, to the icy summits of the CordilIn the hot leras. In the hot regions, as high as 1200 feet, the regions. fan-leaved palms, the miraguana and pumos palms, the white oreodoxd, the Tournefortia hirsutissima, the Cordia geraschantus, the willow-leaved cephalanthus, the Hyptis bursata, Salpianthus arenarius, globular amaranthus, pinnated calabash tree, or Crescentia cujate, the podopterus, Mexican willow-leaved bignonia, Salvia Mexicana, Perdicium Havanense, Gyrocarpus, Letiocophyllum ambiguum, Gomphia Mexicana, Panicum divaricatum, Bauhinia aculeata, Haematoxylon radiatum, Hymenaea courbaril, foliis retusis, Swietenia Mexicana, and the sumac-leaved Malpighia, predominate in the spontaneous vegetation of this region. On the confines of the temperate and the torrid zone are cultivated the sugar-cane, the cotton, cocoa, and indigo plants; but they never ascend above the elevation of 1800 or 2400 feet. The sugar-cane, however, prospers well in valleys elevated 6000 feet above the level of the sea. The In the tem- banana-tree extends from the shores of the sea, to a height of perate re- 4350 feet. The temperate region, from 1200 to 6600 feet of gion. elevation, presents the Liquidambar styrax, Erythroxylon Mexicanum, Piper longum, Aralia digitata, distaff of Pazcuar, Guardiola Mexicana, Tagetes minuta, Psychotria pauciflora, quamoclit of Cholula, Helxine cissampelos, veronica of Xalapa, Globular Mexican veronica, stachys of Actopan, Mexican sage, soft gatilier, thick-flowered arbutus proteiflowered eryngo, laurel of Cervantes, willow-leaved daphne, Fritillaria barbata, Yucca spinosa, (rhus) Cobaea scandens,* yellow sage, four varieties of Mexican oak, commencing |