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, whi