When the first two brigantines were launched on the Lake of Tezcuco by the Spaniards, Cortes took Montezuma with him to sail upon the lake, soon leaving the Aztec canoes far behind. They went to a Peñón or rocky hill where Montezuma preserved game for his own hunting, and not even the highest nobility were allowed to hunt there on pain of death. The Spaniards had a regular battue there; killing deer, hares, and rabbits till they were tired. This Peñón may have been the Peñón de los Baños which we are just passing, but was more probably a similar hill a little further off, of larger extent, now fortified and known as El Peñón, the Hill. Both were in those days complete islands at some distance from the shore. Now that we are out of the canal, our Indians begin to pole us along, thrusting their long poles to the bottom of the shallow lake, and walking on two narrow planks which extend along the sides of the canoe from the prow to the middle point. Four walk on each plank, each man throwing up his pole as he gets to the end, and running back up the middle to begin again at the prow. The dexterity with which they swing the poles about, and keep them out of each other’s way, is wonderful; and, as seen from our end of the canoe, looks like a kind of exaggerated quarter-staff playing, only nobody is ever hit. The great peculiarity of the lake of Tezcuco is that it is a salt lake, containing much salt and carbonate of soda. The water is quite brackish and undrinkable. How it has come to be so is plain enough. The streams from the surrounding mountains bring down salt and soda in solution, derived from the decomposed porphyry; and as the water of the lake is not drained off into the sea, but evaporates, the solid constituents are left to accumulate in the lake. In England, I think, we have no example of this; but the Dead Sea, the Caspian, the Great Salt Lake of Utah, and even the Mediterranean, have various salts accumulated in solution in the same way. It seems to me, that, by taking into account the proportion of soluble material contained in the water that flows down from the mountains, the probable quantity of water that flows down in the year, and the proportion of salt in the lake itself, some vague guess might be made as to the time this state of things has been lasting. I have no data, unfortunately, even for such a rough calculation as this, or I should like to try it.