ESTIMATE OF COST. 
25 
The route from the foot of Warner’s pass, at San Felipe, to the G-ila, as above described, is 
believed to present facilities for construction greatly superior to that followed by the present 
wagon road. It is evident that some considerable amount of bridging or filling will be incurred 
at two or three points in this location, in order to pass the arroyos cut out of the hard clay of 
the desert by the rains of the wet season, but the cost cannot much exceed the outlay for a 
similar purpose on the more southern line. It is also true, that for the first five or six miles 
after leaving San Felipe the cost of construction must be considerably beyond the average, but 
for the rest of the route no obstacle presents itself throughout the entire distance to the Colorado 
river. By this line some twelve miles of distance are saved, and the grades are more favorable 
as well as more nearly conformable to the natural surface. An important consideration is the 
fact that this line will be built wholly within the territory of the United States, though very 
near and for some distance parallel to the boundary line of Mexico, while the proposed line 
adjacent to the wagon road will pass into Mexico 50 miles before reaching the Colorado river, 
and continue on foreign soil for about that distance before returning to our own territory. 
Explorations recently made show that a more direct route to the desert from Warner’s house 
exists over a collateral summit about five miles northeast of the pass. Its altitude is, however, 
over 100 feet greater, though it is approached by a longer line than the other, being about nine 
miles distant from the rancho. It descends on the other side nearly directly to the mouth of the 
canon of San Felipe, joining the line surveyed at that point. This line is more favorable in 
regard to curvature and distance, though its grades must be steeper than the other. If its 
gradients were practicable it would probably cost less to build than any similar portion of the 
entire route. 
The foregoing embraces most of the facts derived from the survey, the results of which, from 
the fact that the examination of the ground was as minute and thorough as was possible to make 
it with the instruments provided and the time allowed for the work, must be regarded as nearly 
accurate as are similar field operations for railroad purposes. The instruments used were a 
twelve-inch Y levelling instrument, a “railroad transit,” with vertical circle, and one of 
Young’s transits, to the use of the latter of which I am indebted to the kindness of Lieutenant 
Derby, of the Topographical corps. They were in excellent adjustment, and their work was 
repeatedly verified by the usual tests. Every distance was measured with a standard chain, and 
stations were established and marked at an average distance of 300 feet, and on rough ground 
at every 50 and 100 feet. 
The distances across the desert are obtained from the measurements of the United States land 
survey, whose operations have now covered that part of the country and extended to the Colorado 
river. The heights between Carr iso creek and the Colorado are deduced from the reports of 
Lieutenant Williamson and Major Emory. 
THE ESTIMATE OF COST. 
Although it is a matter of considerable difficulty to give a reliable estimate of the expense of 
the undertaking before the final location of the line is effected, yet, as a report of this nature 
can hardly be considered complete without this feature, an approximate calculation of the cost 
will be attempted. The expense of the material for the superstructure and equipment of the 
road when graded can be readily given, but that of the graduation, bridging, and masonry must 
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