ESTIMATE OF COST. 25 



The route from the foot of Warner's pass, at San Felipe, to the Gila, 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 Carriso 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 efi'ected, 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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