Chapter 49

The two Valleys.--The Lake with a leaky Bottom.--The Water could not have been higher.--Nor could the Lagunas or Ponds have been much deeper.--The Brigantines only flat-bottomed Boats.--The Causeway Canals fix the size of the Brigantines.--The Street Canals.--Stagnant Water unfit for Canals.--The probable Dimensions of the City Canals.--Difficulties of disproving a Fiction.--A Dike or Levee.--The Canal of Huehuetoca.--The Map of Cortez.--Wise Provision of Providence.--The Fiction about the numerous Cities in and about the Lake.

It may be well here to repeat that, strictly speaking, there are two valleys of Mexico--the upper northern valley, and the valley of the city of Mexico; the first extends in an oval form to the north of the hills of Tepeyaca, some sixty miles, and communicates with the plains of Otumba and Apam. In this valley are the two ponds, or _lagunas_, of Zumpango and San Cristobal, the highest waters of Mexico; and in it also is the half of the Tezcuco, which is the lowest laguna of the valleys. It is a country of fine farming lands, and was probably inhabited long before the time of the arrival of the Aztecs in the lower valley, as I infer from its proximity to the extensive ruins of Teotihuican, that have come down from a remote and highly-civilized antiquity.

THE ANCIENT LAKES.

The valley of the city of Mexico, which lies to the south of these hills, is also of an oval shape, but is not more than twenty miles in extent. The surface-water with which it is saturated is in part fresh, and in other parts _tequisquite_; that is, where the waters have a current, they are fresh; but where they remain from year to year discharging their volume only by evaporation, then they become infused with the saline properties of the soil,[31] and all about them is marked with barrenness. If the process of evaporation was less intense than it is,[32] all vegetation would die from the extreme humidity of the soil; as the gardener's phrase is, it would rot. Even in the city of Mexico itself, a couple of feet of digging in its alluvial foundation brings you to the water-level in the dry season, and seventy or eighty yards of boring does not carry you beyond the perceptible influence of _tequisquite_.[33] The effects of this law of evaporation puzzled the Aztecs, who were, of course, ignorant of all philosophical principles, and could only account for the disappearance of the immense mass of water that fell in the valley in the wet season, upon the hypothesis that the Tezcuco had a leaky bottom, or that there was a hole in the lake--an idea that thousands in Mexico credit to the present day. This was the origin of that absurd story which Cortez repeats in his letters, that this lake communicated with the sea, and had its daily tides.

There could not have been a much greater volume of water in this marshy valley in the time of Cortez than at present, if the whole accumulations of each year were to be carried off by evaporation alone from so small a surface as is here presented for the sun to act upon. But as the volume of water is the turning-point in the history or fable of the conquest, I must adduce the proofs and arguments that are at hand to establish this statement. The level of the water could not have been higher, it is clear, for in that case neither Mexico, Mexicalzingo, or Iztapalapan could have been inhabited.

Cortez's account of deep waters has often been made plausible by adding the hypothesis that the accumulating mud of centuries has filled up the lakes, so that they now are only shallow ponds. But this by no means removes the difficulty, for then, as now, the waters of the southern laguna flowed into Tezcuco, conveying with them the infinitesimal infusion of _tequisquite_ that had instilled itself into the Chalco. Had the volume of Chalco and Xochimulco been increased several feet, then the slight Indian barriers and the long grass would no longer have been able to retard the progress of the water till evaporation had diminished its quantity, but, precipitating itself in a mass into the Tezcuco, it would have overwhelmed the town of Tezcuco and all other villages upon the shores, and established an equilibrium of surface in the two ponds.

All the lagunas, canals, and ditches that have been described are navigated by small scows that draw but a few inches of water, which are the medium of an extensive internal commerce. Through the lagunas and canal of Chalco come from Cuatla all the supplies of the products of the hot country for the city and surrounding region. This commerce exceeds the whole foreign trade of the republic.[34] This kind of boat was probably introduced by Cortez, and in this convenient form his thirteen brigantines were probably made; for, had his brigantines been of a larger draught of water, they could not have navigated canals intended only for Indian canoes. One of these vessels, when supplied with a sail, a cannon, and a movable keel or side-board, would be a formidable auxiliary in an assault upon the city at the present day. And if one such scow was placed in the ditch on each side of the southern causeway, as Cortez alleges, it would enable an assailing enemy to present just so much more front as the additional width of two boats would give him.

THE CAUSEWAYS AND CANALS.

Writers have expressed their surprise at the existence of two navigable canals to each causeway, one on either side, as an immense expenditure of unnecessary labor. The explanation of this is found in the fact that in the construction of a pathway (for Cortez says that it was only 30 feet in width) through wet and marshy ground, a broad ditch is ordinarily made on either side to obtain earth for the embankment, and to keep the water-level permanently below the top of the pathway. So it is, and so it must always have been at Mexico, in order to keep these foot-paths in traveling condition. In the dry season, which is the winter, these broad ditches are covered with floating islands of green "scum;" but in the rainy season, which is the summer, they may be navigated by the shallow Mexican scows. A pathway of earth thirty feet in width could not endure the winds and waves of a navigable lake, or the wear and "swash" of a canal twelve feet deep on either side; and the fact that Cortez navigated the ditches in the rainy season establishes the insignificant size of his famous brigantines.

As the level of the surface of the land and the surface of the water at Mexicalzingo, at Mexico, and at the village Tezcuco, does not materially vary now from what it was in the time of Cortez, if we can take for data the foundations of the church built by the Conquistadors at these several places, we shall have to look to another quarter for a supply of water for the city canals, which were sufficiently capacious for canoe navigation. This supply we readily obtain by allowing the waters of the canals Tacubaya and Chalco to pass through the streets of the city in ditches sufficiently large for canoes, instead of passing along the south and east fronts outside. By this hypothesis we obtain a current, a prerequisite to the very idea of a canal, particularly in the streets of a city.

The _savans_ of Europe have shown their profound ignorance of the first principles of canal navigation in taking it for granted that the canals of Mexico were filled with stagnant water, that had "set back" from the stagnant pond of Tezcuco; and that the level of the pond must at all times have been so high as to fill the canals, thus keeping the city in constant danger from any sudden rise in the laguna. But, aside from the rules of canal construction, there is an important sanitary question involved. The present ditches in the middle of the streets, though they have a perceptible current, and a slight infusion of _tequisquite_, are an intolerable nuisance, and have a deleterious effect upon the public health. How much more so must they have been when, from the uncleanly habits of the Indians, they were the common receptacle of all kinds of filth, and were constantly stirred up to their very bottoms by the setting-poles of the navigators? The system of canalling is a system of slack-water navigation, but abhors stagnant water.

We come next to the question of the dimensions of these street canals. We know that they were intended only for the navigation of Indian canoes; that two of them, which intersected the causeway of the night retreat, Cortez crossed with his army, all of them climbing down into the canal, wading across, and then climbing up on the other side while loaded with their armor, and fighting all the time against a superior force of the Aztecs; and that Alvarado actually leaped across one of the openings, shows conclusively that the canals could not have more than equaled in breadth the present canal of Chalco. On the hypothesis that Cortez used scows that drew no more water than the scows that at present navigate the canals, his story becomes credible, so far, at least, as the possibility of making the circuit of the city in large boats in a season of rains.

TRUTH AGAINST FICTION.

It is an ungracious task to sift truth from fables. One man is displeased at seeing held up as a fiction a narrative which he has been accustomed to read with pleasure, and to take for truth, because it was elegantly written; and he requires an accumulation of proofs and arguments before he will abandon a belief which he has adopted without evidence. Another man, who deals only in matters of fact, is easily convinced, and is annoyed at an accumulation of proofs and arguments where one is sufficient. The superstitious man can not, of course, be convinced, for his belief does not rest upon evidence; and he is indignant that an attempt should be made to detract from the glory obtained by the Virgin Mary and the Church in this victory over the infidels. Had I attempted to prove that the feather which is now preserved with so much care in the Church of _San Juan de Lateran_ at Rome did not fall from the wing of the angel Gabriel when he came to announce to Mary her conception, and that the whole history of that feather was a fable, notwithstanding it has received the attestations of so many of the Holy Fathers, I should be cursed for my impiety no more than I shall be for raising the question of the authenticity of the histories of the Conquest. With all these difficulties before me, I will venture to add one or two more reasons that have induced me to doubt the existence of those famous brigantines, which required a depth of twelve feet of water.

In support of the hypothesis that the street ditches, called canals, were independent of the Tezcuco for their supply, we have still the remains of an old Indian dike, which extended from near Iztapalapan, along the east part of the city, to Guadalupe or Tepeyaca, which must have been intended to shut off the Tezcuco when the water was high, and when it receded they probably opened a weir at the northern extremity, through which the waters of the city that had been discharged upon the flats of San Lazaro found an outlet.

The waters of the valley are now distributed in the best possible manner to favor evaporation; and yet so completely is this power taxed, that when, in 1629, a water-spout, bursting over the small river Guautitlan, had forced the waters of Zumpango over its barriers into the San Cristobal, and that again into the Tezcuco, the city was inundated to the depth of about three feet. Evaporation was unable to remove or materially lessen this new volume of water in a period of five years. This fully demonstrates that the average annual fall of water is equal to the full capacity of evaporation. The valley of Mexico is a very small one over which to dispose of the mass of water that the mountain-torrents in summer and the tropical rains pour into it, and with the small margin of six and a half feet for rising and falling, the city must have been in constant jeopardy. Still the floods have been much less frequent than would have been supposed, fully demonstrating the great uniformity in the fall of water in the Mexican season of rain. When a water-spout occurred in the Chalco in 1446, in the time of the Aztec kings, there was a flood, which probably ran off into the Tezcuco. Under the Spaniards the following floods are enumerated: the first in 1553; the second in 1580; the third in 1604; the fourth in 1607; the fifth in 1629.

After the flood of 1607, the tunnel of Huehuetoca was undertaken, and constructed in eleven months, for the purpose of letting out of the valley the waters of the River Guautitlan, so as to prevent it from falling into Tezcuco or flooding the city. For those times it was a great work, but we should say now that it was poorly engineered and badly managed, and not worthy the notice it has received in books on Mexico. Since that time, the great inundation of 1629 occurred while the mouth of the tunnel was closed. After that time, the Spaniards, instead of building inside of the tunnel an elliptical tube, actually, by a hundred years of misapplied labor, turned the tunnel into an open cut.

THE MAP OF CORTEZ.

Cortez furnished a map to illustrate his description. This map has the same defect as his narrative; that is, it was untrue at the time he made it. In order to bring Tezcuco about the city, he places the village of that name due east of Mexico, although he well knew that it was nearly north, as the two towns are distinctly in sight, although at a distance of about six leagues. Now, if we carry the village of Tezcuco and the shore of the lake with it to its correct position, we shall have the Laguna of Tezcuco in about its present form and size. The apology for his defeat at Iztapalapan, by the breaking open of the dike and letting in the salt water, is, of course, inadequate, as the dike could not have supported a head of water sufficient to drown his men, nor could so great a head of salt water be obtained at that point.

In this survey of the ponds of Mexico, I have drawn upon the experience which has been acquired in the process of evaporation at the extensive salt manufactories of Syracuse and the surrounding villages in Western New York, and also the experience of our engineers Upon the Erie Canal, and the engineers upon the dikes or levees at Sacramento, where the nature of the soil resembles that of Mexico. And I may now conclude this long survey of the canals and lagunas of Mexico, by saying that it is a wise provision of Providence that all bodies of water that have no outlet are found to contain a considerable infusion of salt, otherwise their accumulations of decaying matter would be such that mankind could not live in their vicinity. This valley is an illustration of that truth. Tezcuco, surrounded by barrenness, is not deleterious to life, while the fresh-water lagunas, though continually changing their volume, render Mexico unhealthy in summer by the gases which they exhale from decaying vegetation.

ANCIENT POPULATION OF THE VALLEY.

I have pretty thoroughly described this small valley, and have also stated how large a portion of it is flooded with surface-water, and how large a portion of this water is infused with salt. In the vicinity of Tacubaya the land is remarkably fertile, and there is good tillable land as the mountains are approached, especially about Chalco on the southeast; but under Indian cultivation, the whole of this valley could have produced sustenance for only an extremely limited population, if the product of the floating gardens and the ducks caught upon the pond should be added. It is totally inadequate to feed the population of Mexico under the vice-kings, 400,000, or its present population of say 300,000; nor could the valley itself be made to sustain one third of this. This valley, it must be recollected, is inclosed on all sides except the north by mountains that exceed 10,000 feet in height, while the commissariat capacity of barbaric tribes is not such as to provide extensive supplies from a distance. Under such circumstances, we should look for an extremely limited population. Yet the most surprising part of the story of the conquest is the enormous population assigned to the numerous large cities which they allege the valley contained. Diaz says, "A series of large towns stretched themselves along the banks of the lake, out of which [the lake] still larger ones rose magnificently above the water." Cortez says that Iztapalapan contained "10,000 families," which would give the town 50,000 inhabitants; "Amaqueruca, 20,000 inhabitants;" "Mexicalzingo, 3000 families," or 15,000 inhabitants; "Ayciaca more than 6000 families;" "Huchilohuchico, 5000 or 6000." The population of Chalco he does not give, nor the population of the very numerous villages whose names he mentions. At the present day there are a few mud huts in nearly every locality named, but not enough in any one instance to merit the name of a village. And this, I am inclined to believe, was the real condition of things in the time of Cortez. The city of Mexico alone would have exhausted the limited resources of the valley. Old Thomas Gage was as much puzzled two hundred years ago to account for this astonishing disappearance of the numerous Indian cities of this valley as we are, and also for the supposed filling up of the lakes, never appearing to suspect that the story of Cortez was a fiction.

[31] There has been much speculation in regard to the origin of the saline properties of this water; but the Artesian borings going on while I was in Mexico, I think, sufficiently demonstrate that the earthy bottom of the valley, for hundreds of feet, contains an infusion of carbonate and muriate of soda.

[32] The atmosphere of Mexico is so intensely dry, that the hygrometer of Deluc frequently descends to 15 deg..--HUMBOLDT'S _Essai Politique_, vol. ii. p. 110.

[33] When the Artesian well, in process of construction near my residence, had reached a depth of seventy yards, the water that came up was slightly impregnated with this salt.

[34] _Comercio de Mexico_, 1852.