y. What makes the Tezcuco bridge more
curious is that it is set askew, which must have made its construction
more difficult.

The brigantines which the Spaniards made, and transported over the
mountains in such a wonderful manner, fully answered their purpose, for
without them Mexico could hardly have been taken. After the Conquest
they were kept for years, for the good service they had done; but
vessels of such size do not seem to have been used upon the lake since
then; and I believe the only sailing craft at present is Mr. Bowring's
boat, which the Indians look at askance, and decidedly decline to
imitate. It is true that, somewhere near the city, there is moored a
little steamer, looking quite civilized at a distance. It never goes
anywhere, however; and I have a sort of impression of having heard that
when it was first made they got up the steam once, but the conduct of
the machinery under these circumstances was so extraordinary and
frantic that no one has ventured to repeat the experiment.

Before we left Tezcuco, we went in a boat to explore Mr. Bowring's
salt-works, which are rather like the salines of the South of France.
Patches of the lake are walled off, and the water allowed to evaporate,
which it does very rapidly under a hot sun, and with only three-fourths
of the pressure of air upon it that we have at the sea-level. The
lake-water thus concentrated is run into smaller tanks. It contains
carbonate and sesquicarbonate of soda, and common salt. The addition of
lime converts the sesquicarbonate of soda into simple carbonate, and
this is separated from the salt by taking advantage of their different
points of crystallization. The salt is partly consumed, and partly used
in the extraction of silver from the ore, and the soda is bought by the
soap-makers.

Humboldt's remarks on the small consumption of salt in Mexico are
curious. The average amount used with food is only a small fraction of
the European average. While the Tlascalans were at war with the Aztecs,
they had to do without salt for many years, as it was not produced in
their district. Humboldt thinks that the chile which the Indians
consume in such quantities acts as a substitute. It is to be remembered
that the soil is impregnated with both salt and natron in many of these
upland districts, and the inhabitants may have eaten earth containing
these ingredients, as they do for the same purpose in several places in
the Old World.

We disembarked