1848, at Guadalupe, between the United States and Mexico, to have embraced an area of one million six hundred and fifty thousand square miles, including Texas. By the treaty just mentioned we acquired an undisputed title to Texas, and a territorial cession of New Mexico and Upper California.

If we, therefore, deduct from the preceding estimate of one million six hundred and fifty thousand square miles, the sum of eight hundred and fifty-one thousand five hundred and ninety-eight square miles, we shall have, as the best approximate calculation, that we can now make, seven hundred and ninety-eight thousand four hundred and two square miles, for the total superficial extent of the Republic of Mexico, as at present bounded since the ratification of our recent international treaty. By that negotiation it consequently appears that we have obtained one half the former territory of Mexico and twenty-six thousand five hundred and ninety-eight square miles besides.

The geological structure or physiognomy of Mexico is peculiar. The great Cordillera of the Andes, which traverses the whole of South America, from its southernmost limit, is exceedingly depressed at the Isthmus of Panama, where its gentle swells serve merely to form a barrier between the union of the Pacific and Atlantic. But, as soon as this massive chain enters the broader portion of North America, it divides into two gigantic arms, to the east and west along the shores of the Gulf and of the Pacific, which support between them a continuous lofty platform, or series of table lands, crossed, broken, and intersected by innumerable and abrupt sierras, some of which rise to the height of seventeen thousand feet above the level of the sea. This geological structure prevails throughout the whole of Mexico, as now bounded; for, at the Rio Grande, the southern limit of Texas, the land sinks to comparative levels, and affords channels for the numerous and important streams with which, Louisiana, Florida and Texas are abundantly irrigated. Whilst this is the case on the northern and eastern confines of Mexico, the western portion is still traversed by the main body of the gigantic Cordillera, which, penetrating California with its icy peaks of the Sierra Nevada, passes onward to the north until its rocky walls are lost, beyond Oregon, in the wilderness that bounds the Frozen Sea.[5]

The reader who pictures to himself such a country will easily understand that all temperatures are gained in Mexico on the same parallel of latitude,—or that eternal heat and eternal frost are encountered in crossing the country in a straight line from Vera Cruz to the Pacific coast. It is a country hanging on the two slopes of a mountain, one of which descends to the Gulf and the other to the Western Ocean; and the traveller, in penetrating it, even by the road usually traversed by public conveyances, must attain a height of ten thousand six hundred and sixty feet, before he begins to descend into the valley of Mexico, which is, still, seven thousand five hundred and forty-eight feet above the level of the sea! Thus it is, that throughout the table lands, the geographical position, as far as latitude is concerned, is entirely neutralized by the extreme rarefaction of the atmosphere obtained by ascending through loftier regions. Humboldt graphically declares that climates succeed each other in strata or layers, as we pass from Vera Cruz to the capital, or from the capital, descend to Acapulco or San Blas on the west coast,—beholding in our varied journey, the whole scale of vegetable life. The wild abundance of vegetation on the shore of the Gulf,—its beautiful palms whose stems are wreathed by a myriad of impenetrable parasites which grow with such rank luxuriance in the hot and humid air of the tropics,—are exchanged, as we begin to rise from the level of the sea, for hardier forest trees. At Jalapa the air is milder, though the vapors from the Gulf which concentrate and condense at about this height on the sides of the mountains, sustain the perpetual freshness of the verdure. Further on, the oak and the orange give place to the fir and pine. Here the rarefied air becomes pure, thin and perfectly transparent; but as it necessarily lacks moisture, which condenses below this region, the vegetation is neither so luxuriant nor so constantly vigorous. Great plains or basins, spread out in silent and melancholy vistas before the traveller,—many of them, cold, bleak and lonely moors, whose dreary levels sadden the heart of the spectator. The sun which comes down through the cloudless medium of an atmosphere unscreened by the usual curtain of vapor, parches and crisps the thirsty soil, whilst the winds that sweep uninterruptedly over the unbroken expanse, fill the air, during the dry season, with sand and dust. These high barren plains occupy a large portion of the centre of the country between Zacatecas, Durango and Saltillo; and such is in fact the character of large portions of the whole of Mexico, except when the comparatively level nature of the soil permits the small rivulets that filter from the Cordillera through the narrow vallies, to form themselves into rivers which may be used for irrigation. Wherever this is the case nature at once recovers her vigor under the influence of heat and moisture.

These physical features, and consequent diversities of temperature, have caused the division of Mexico, as it rises from the two Oceans, into three regions, or superficial strata, which are called, the tierras calientes, or hot lands; the tierras templadas, or temperate lands; and the tierras frias or cold lands. The tierra caliente covers chiefly that portion of the territory which lies on the borders of the Atlantic and Pacific; yet it is not confined exclusively to the coast, inasmuch as all those parts of Mexico in which there is heat and moisture enough to produce the fruits and maladies of the tropics, are classed under this head. The tierra fria comprises the mountainous districts rising above the level of the capital up to the limit of constant snow; while the tierra templada embraces those milder middle regions not comprehended in the two other sections. Classing them by elevation in feet, we may suppose that the tierras calientes extend to between 3,000 and 4,000 feet above the level of the sea; the tierras templadas to between 4 and 8,000 feet; and that the tierras frias embrace all the remaining portions up to the region of eternal ice.

Political Divisions and Boundaries of Mexico.

It is, perhaps, more of historical or antiquarian interest, than of actual present