No. 5, 
TABLE EXHIBITING THE COMPARATIVE LENGTHS, COST, ETC., OF THE 
DIFFERENT ROUTES, WITH EXPLANATORY REMARKS. 
BY CAPTAIN A. A. HUMPHREYS, CORPS TOPOGRAPHICAL ENGINEERS. 
The distances and estimates of cost of the route of the thirty-fifth parallel, given in the 
following table, are not those contained in Captain Whipple’s revised report. The line from 
the Big Sandy river to the Colorado river, adopted hy Captain Whipple, is 54 miles in length. 
It is nearly an air line, has never been passed over, and was not noted during the examination 
in the field as probably affording a practicable route, but was deemed practicable after a study 
in the office of the field notes. For these reasons,'it can only he considered a line which future 
examinations may show to he practicable ; and not one to he adopted, and the cost of a railroad 
along it elaborately estimated. Upon this principle, the reports upon the other routes have 
been revised. The corrected distance along the route examined between these two points is 160 
miles, which is the length used in the following table. The shortest probable railroad route, 
from the Mojave river to the Tah-ee-chay-pah pass, is 73 miles in length. The measured 
distance through the Tah-ee-chay-pah pass is 42 miles. There are parts of the line where the 
reduction of length shown in Captain Whipple’s report may be considered problematical. 
However elaborate the field operations of an exploration of this character may be, tbe extent 
of ground passed over in a day is so great, that even detailed maps like those of Captain Whip¬ 
ple, though prepared with great care, must represent tbe ground less broken than it really is. 
Had, however, tbe location of the railroad line been made in the field, and notes taken, or rough 
computations made upon the spot of tbe excavation, embankments, &c., required, or bad tbe 
portions of tbe line been assimilated at the time to lines of road already built, with which the engi¬ 
neer was personally familiar, the liability to error in the estimate of cost would have been less 
than hy the method followed on the route of the thirty-fifth parallel. The location of th 
railroad line of that route was made on the maps in the office; it follows the actual line of 
survey for less than half the distance, in many places deviating widely from it. and in occasional 
cut-offs (one of which is over 50 miles in length) lying over ground that was not examined. 
Tbe chances of error in tbe estimates of cost by tbis method are greater than by the other, and 
any computations of excavation and embankment are rendered liable to serious inaccuracies. 
Captain Whipple’s estimated cost of the first 706 miles is probably $5,000 per mile too small. 
The estimated cost on the cut-off from the Big Sandy to the Colorado, where there is a descent 
of 3,400 feet in less than 40 miles, if the line be found practicable, will probably be doubled ; 
but until the line has been examined, the route should be estimated along Bill Williams’ fork. 
In the estimate contained in the following table, one-third of the distance to the mouth of that 
