80 
ENGINEEKING EEPOETS. 
to render a survey through it advisable before the final location 
is made. 
The amount of water-way, for which masonry and bridging 
have been calculated, over the most difficult part of the route 
which we have surveyed between the Jaltepec River and the 
Pacific plains, allowing for the heaviest freshets, amounts to 
3804 feet in 69 miles. This includes all the spans of the cul- 
verts and bridges. Now, in considering the immense range of 
mountains which bound the apparent plains on the east of the 
Coatzacoalcos, around the summits of which collect and dis- 
charge all the great body of clouds passing over that part of 
the Isthmus, and the amount of water-way for which a rail- 
road running nearly parallel with their base must necessarily 
be provided, I am led to the conclusion that the drainage on 
the east of the Coatzacoalcos must be as great, if not greater 
in proportion to the distance, than that on the west, from the 
Jaltepec to the Pacific plains; and, as the distance along the 
base of these mountains is some 7 0 miles, the aggregate amount 
of water-way would be in proportion much greater than on the 
other side of the river. Still, there may be other and sufficient 
reasons, such as the presence of coal, iron, silver, &c, in the 
mountains, which would fully justify building the road on the 
eastern margin.* 
By crossing the Coatzacoalcos at A,f and running down the 
east side of the river, we avoid the heavy drainage opposite to 
the line AB on the west ; and by recrossing again on this same 
line, we avoid the heavy drainage on the east side, and below 
the crossing, and run upon a similar character of profile. 
A line should also be run down from a point near Lake Otia- 
pa to the base of Mount Pelon, at La Barrilla, where the coast 
line seems to indicate that a good and capacious harbor may be 
eventually constructed. In the final location, the shortening of 
the line some twenty miles, and the advantage of saving river 
navigation, may be considerations of sufficient magnitude to 
justify a thorough survey of this line, and its terminus, g 
— _ j . 
* It is said that in the district of Acayucam (west of the Coatzacoalcos) there are 
several coal-beds, which are continuations of those in the adjoining province of 
Oaxaca. f See map number 1. 
