TOPOGRAPHY OF THE MEXICAN VALLEY.
This is the map given in Wilson’s New Conquest of Mexico, p. 390, in which he makes the present topography represent that of Cortés’ time, in opposition to the usual view that at the period of the Conquest the waters of the lake covered the parts here represented as marsh. The waters of Tezcuco are at present seven or eight feet (Prescott says four feet) below the level of the city, and Wilson contends that they did not in Cortés’ time much exceed in extent their present limits; and it is one of his arguments against Cortés’ representations of deep water about the causeways that such a level of the lake would have put the town of Tezcuco six or seven feet under water. Wilson gives his views on this point at length in his New Conquest, pp. 452-460. The map will be seen also to show the line of General Scott’s approach to the city in 1847. (Cf. Prof. Henry Coppée on the “Coincidences of the Conquests of Mexico, 1520-1847,” in the Journal of the Military Service Institution, March, 1884.) The modern city of Mexico lies remote by several miles from the banks of the lake which represents to-day the water commonly held to have surrounded the town in the days of the Conquest. The question of the shrinking of the lagunes is examined in Orozco y Berra’s Mémoire pour la carte hydrographique de la Vallée de Mexico, and by Jourdanet in his Influence de la pression de l’air sur la vie de l’homme, p. 486. A colored map prepared for this latter book was also introduced by Jourdanet in his edition of Sahagun (1880), where (p. xxviii) he again examines the question. From that map the one here presented was taken, and the marsh surrounding “Lac de Texcoco” marks the supposed limits of the lake in Montezuma’s time. Jourdanet’s map is called, “Carte hydrographique de la Vallée de Mexico d’après les travaux de la Commission de la Vallée en 1862, avec addition des anciennes limites du Lac de Texcoco.”
Humboldt in his Essai politique sur la Nouvelle Espagne, while studying this problem of the original bounds of the water, gives a map defining them as traced in 1804-1807; and this is reproduced in John Black’s translation of Humboldt’s Personal Essay on the Kingdom of New Spain, third edition, London, 1822. Humboldt gives accounts of earlier attempts to map the valley with something like accuracy, as was the case with the Lopez map of 1785. Siguenza’s map of the sixteenth century, though false, has successively supplied, through the publication of it which Alzate made in 1786, the geographical data of many more modern maps. Cf. the map in Cumplido’s edition of Prescott’s Mexico (1846), vol. iii., and the enumeration of maps of the valley given in Orozco y Berra’s Cartografia Mexicana, pp. 315-316.
A map of Mexico and the lake also appeared in Le petit atlas maritime (Paris, 1764); and this is given in fac-simile in the Proceedings of the American Philosophical Society, xxi. 616, in connection with a translation of the Codex Ramirez by Henry Phillips, Jr.
There is reason to believe that the decrease in the waters had begun to be perceptible in the time of Cortés; and Humboldt traces the present subsidence to the destruction of neighboring forests. Bernal Diaz makes record of the changes observable within his recollection, and he wrote his account fifty years after the Conquest.
The geographers of the eighteenth century often made the waters of the valley flow into the Pacific. The map in the 1704 edition of Solis shows this; so do the maps of Bower and other English cartographers, as well as the map from Herrera on a later page (p. 392).
The inundations to which the city has been subjected (the most serious of which was in 1629), and the works planned for its protection from such devastations are the subject of a rare book by Cepeda and Carillo, Relacion universal del sitio en que esta fundada la ciudad de México (Mexico, 1637). Copies are found complete and incomplete. Cf. Carter-Brown, ii. 441; Leclerc, no. 1,095, complete, 400 francs, and no. 1,096, incomplete, 200 francs; Quaritch, incomplete, £10.
In this, however, he failed, and returned to Tezcuco. Then followed some successful fighting on the line of communication with the coast, which enabled Cortés to bring up safely some important munitions, besides two hundred soldiers, who had lately reached Villa Rica from the islands whither he had sent for help the previous autumn.
