horses in attempting to cross it. The ground is firm, however, at the base of the trees, which are planted very close; many of them are of great size—fifteen or sixteen yards in circumference. They are all of the noble species of cypress mentioned in a former letter, as the cupressus disticha. A raised causeway running from the northeast angle, evidently connected this island garden with the main land.
There exists no reason why this should not have been one of the numerous gardens of Montezuma; but, in all probability, the hands which planted those aged trees belonged to men of an age greatly anterior to that monarch: quien sabe?—who knows? I have seen few remnants of antiquity in the valley of Mexico which interested me more than this solitary grove.
Before we quit the shore of Lake Tezcuco, I may mention a circumstance which has struck me greatly, as I have every reason to credit the source of my information.
I have made you attentive to the gradual change which has been operated on the surface of the valley of Mexico, from the retirement of its waters within narrower bounds. At what time, or under what circumstances, those waters first overflowed the country, it was to be expected that even tradition would be silent, when it is recollected that the people through whose medium the few traditions we possess were transmitted to our knowledge, had only occupied the valley for a few brief generations. But that there was a time, however remote, at which the waters, if they existed at all, occupied a much lower level than even at the present day, at the same time that the continent was in the occupation of people considerably advanced in the rude arts of semi-civilization, would seem to be an incontrovertible fact.
Some time before our visit, a number of workmen were employed on the neighbouring estate of Chapingo, to excavate a canal over that part of the plain, from which the waters have gradually retired during the last three centuries. At four feet below the surface, they reached