COMPARISON OF EOUTES — COST OF CONSTRUCTION. 37 



Pedro route must be worked and improved before wagons enter upon it. This can, however, 

 be done in a short time, there being but few points on the San Pedro requiring working, other 

 than removing the underbrush and thickets. 



On the Gila, there will be about twelve miles, where it will be necessary to grade down the 

 banks of the river, and remove some rocks in its bed at the crossings, and to cut oif the points 

 of some out-jutting rocky spurs. The cost will, however, not exceed ten thousand dollars. 



Section 2. RECAPITULATION AND COMPARISON OF ROUTES. 



Length of central section, from Fronteras, on the Rio Grande, to the Pimas villages, (Mari- 

 copa wells :) 



By survey of 1854, via Tucson, 406 miles. 

 By survey of 1855, via San Pedro, 375 miles. 



Do. Do. via Aravaypa, 345.25 miles. 



Sum of ascents and descents, via Tucson, app. 11,000 feet. 

 Do. do. via San Pedro, app. 8,764 feet. 



Do. do. via Aravaypa, 7,560 feet. 



Number of summits on these routes : Tucson, 10. 

 Do. do. do. San Pedro, 7. 



Do. do. do. Aravaypa, 6. 



Greatest elevation above sea level : Tucson, 5,183 feet. 



do. San Pedro, 4,881 feet, 



do. Aravaypa, 4,601 feet. 



Tucson, 93 feet per mile. 

 San Pedro, 100 feet per mile. 

 Aravaypa, 60.3 feet per mile. 

 It thus appears that by the lines of 1855 we have improved upon the line of 1854 in all the 

 above points — length, number of summits, elevation, and grade. Beside these, another most 

 important improvement is made in regard to the supply of water. The San Pedro is twenty- 

 nine and three-fourth miles longer than the Aravaypa route, but has the advantage of passing 

 through a well watered, cultivable valley of about sixty miles, affording fine sites for stations and 

 settlements. But in locating a line of road of such length as is required to connect the waters 

 of the Mississippi with the Pacific, a saving of distance is one of the chief aims. We will, there- 

 fore, adopt the Aravaypa route — giving the entire length of the section, from the crossing of the 

 Rio Grande to the Pimas villages, three hundred and forty-five and one-fourth miles. 



Section 3. COST OF CONSTRUCTION. 



In estimating the cost of constructing the proposed railroad, it is not practicable, without 

 the aid of detailed and minute instrumental surveys of a line of location, to arrive at any- 

 thing positive and definite with regard to the amount of excavation, embankment, and 

 rock cutting required ; and as such surveys were not made, I will attempt an approxima- 

 tion only to the cost, by comparing the character of the country to be traversed and obstacles 

 to be overcome with those already encountered and overcome on roads now in operation. 

 Of the two items of cost, labor and material, the former may safely be put down at rates not 

 exceeding those paid on the Atlantic board and in the Mississippi basin ; the provisions can be 

 furnished from the termini, and points adjacent to the line. The material will be necessarily 

 much increased in value, owing to the great distances from sources of supply ; but by adopting 



