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.