CONCLUSION. 29 
this region, rendered it unnecessary to do more than make what may be strictly called a railroad 
exploration. 
The examination of the eastern portion by Capt. Pope, assisted by Lieut. Garrard, of the 
dragoons, was made under the most disadvantageous circumstances, the party having been 
organized at a remote point, where neither instruments, nor assistants specially instructed in 
the scientific branches connected with the survey, could be procured. It was, however, 
creditably performed, and satisfactorily exhibits the topography and general character of the 
country along the line surveyed. , 
CONCLUSION. 
To aid in a comparison of the several routes, reference is made to a table prepared by Capt. 
A. A. Humphreys, and hereto appended. 
With regard to the estimates of cost, although lelieved to be as accurate as can be made 
under present circumstances, they are to be considered as intended not so much to show the 
absolute sums of money which would build the several roads, as to represent the relative 
quantities of materials and labor required for the purpose. If now tested in the actual con- 
struction of any one of the roads, they will doubtless be found to contain many errors; but as 
the same data have been assumed on all the routes, the same amount of error will probably 
be found in each, and the actual expense will thus preserve the same proportion. 
With regard to the equated lengths of the seycral roads, or, in other words, the influence 
of ascents and descents upon the expense of working, it is proper to direct attention to the 
remarks of the engineer, appended to the tables, in which he states that, on all the routes, the 
amount reported will be subject to increase when the minor undulations of the ground shall be 
measured ; and this increase will be greatest on those routes and in those portions where the 
features of the country are less regular—that is, where there are most of such minor undula- 
tions to be measured. The equated distances also affect the cost of working a road only 
under certain circumstances, which may or may not exist on the contemplated route. 
A comparison of the results stated above, and of those exhibited in the tables referred to, 
conclusively shows that the route of the 32d parallel is, of those surveyed, ‘‘the most prac- 
ticable and economical route for a railroad from the Mississippi river to the Pacific ocean.’’ 
This is the shortest route; and not only is its estimated cost less by a third than that of 
any other of the lines, but the character of the work required is such that it could be executed 
in a vastly shorter period. It is obvious that a road on any of these routes, with the exception 
perhaps of the 47th parallel, must be built continuously from the two extremities, and an 
obstacle that arrests its progress at any point defers the commencement of all the work in 
advance. The tunnels and much of the other work on the more northerly routes in the most 
desolate regions are such as could not be commenced until a road was constructed up to those 
points, and would then require a long period for their completion. 
On the southernmost route, on the contrary, the progress of the work will be regulated 
chiefly by the speed with which cross-ties and rails can be delivered and laid, the nature of the 
country being such that throughout the whole line the road-bed can easily be prepared in 
advance of the superstructure. The few difficult points, such as the Pass of the Guadalupe 
and Hueco mountains, and the passes between the Rio Grande and Gila, would delay the work 
but an inconsiderable period. 
This peculiarity of the ground presents another advantage in the fact that temporary tracks 
could be laid upon the natural surface of the earth to almost any extent, to serve for the trans- 
portation ot materials and supplies. ¥ 
The climate on this route is such as to cause less interruption to the work than on any 
other route. 
Not only is this the shortest and least costly route to the Pacific, but it is the shortest 
and cheapest route to San Francisco, the greatest commercial city on our western coast: while 
the aggregate length of railroad lines connecting it at its eastern terminus with the Atlantic 
