85 
ductive of some trouble, there would at all events be very lit- 
tle ill opening the shoal ol the Boca Barra of San Francisco, 
and giving more depth to a canal in the lakes, the bottom of 
which is nothin<j- but mud and shinule. 
These dilUculties once conquered, nothing remains but to 
convey a sufficient quantity of water to an elevated point from 
whence it may be distributed and directed on the one side to 
the Coatzacoalcos, and on the other to the upper lagoon. Both 
objects may be attained by different means. 
FIRST PROJECT. 
This would be to open a trench that would lead the waiers 
of the Ostuta to the valley of theChicapa; and another, whicii 
beginning a little above the " Ultimo liancho, " would direct 
the waters thus collected to the table-land of Tarifa, following 
the brows of the hills to the north of the valley watered by the 
Upper Chicapa and the Monetza. These two proposed trenches 
are shown in the plan of the southern part of the Isthmus. 
The point of distribution of the canal would be placed between 
the Cerro del Convento and the estate of Tarifa, from whence 
it would descend on the one side to the Coatzacoalcos follow- 
ing nearly the natural course of the waters, and on tne other 
would reach the upper higoon, descending along the eastern and 
southern sides of the hills of Masahua by means of proper 
locks. Bj the annexed geological plan it will be seen that 
the proposed canal would have to be cut through a soil formed 
in some parts of an argillaceous rock of excellent quality, and 
in others of marl, clayish sand, and slates. All these rocks 
are easy to excavate, and of sufficient consistency to require 
no revestments. Now and then among the slate, the quartz 
makes its appearance, but we have always found it so broken 
as to cause no difficulty whatever. 
General Orbegozo saw in the ordinary fissures ol the slate 
a considerable obstacle, supposing that through them the wa- 
ters might escape, but it would not be at all difficult to reme- 
dy this inconvenience by stopping such joints as might require 
it both in the bed and sides of the canal with a good hydraulic 
