56 
ENGINEERING REPORTS. 
Tangents, Curvature, c&c, over Middle Division. 
Total length of tangent lines, . 
" curved " 
Length of line, . 
47 miles. 
21.7 " 
68.7 " 
Degrees of curvature right, 1734°.23' 
" " left, 1656°.25' 
Total degrees of curvature,. 3390°.48' 
Total ascent, from Jaltepec to Pacific plains, 1 346 feet. 
" descent, " " 1221 " 
Elevation of summit to be overcome above Pacific 
plains, 593 " 
Equated distance for mean of total ascent and descent, 48.6 miles. 
Equated distance for curvature, 2.2 " 
Total length of line equated for grades and curvature, 119.5 miles. 
This shows the length of a straight and level road, which, 
with a given engine and train of cars, would require the same 
amount of power in passing over it, as the same given engine 
and train would consume in passing over all the grades and 
curves on the line as actually surveyed. 
It should be borne in mind, that these calculations are made 
only on the most difficult part of the line, between the Jaltepec 
River and the base of the mountains on the Pacific plains. On 
the portion of the route from Mina-titlan to the Jaltepec, and 
from the base of the mountains to Yentosa, there are no engi- 
neering difficulties to be met with. 
As the maximum grade approaching the summit, on either 
slope of the dividing ridge, will be sixty feet to the mile, the 
same weight of maximum train would have to be made up from 
each terminus. 
Comparative Table of Grades, Curvatures, and Tunnelling. 
Name of Road. 
Baltimore and Ohio, 
Baltimore and Susquehanna, 
Connecticut River, 
Boston and Worcester, 
Western 
New York and Erie,. 
Tehuantepec, 
Maximum 
Grade 
per mile. 
Minimum 
radius 
of Curvature. 
Feet. 
116 
880 
90 
32 
882 
40 
600 
84 
882 j 
60 
800 
60 
1000 
Length of Tunnels. 
2 miles. 
A tunnel 4 miles long is now 
being built through Hoosac 
Mountain. 
$ mile. 
