90 Explorations and Surveys for the Pacific Railroad. 



ridges divide it, is about 4,100 feet; the mean elevation of the 

 summits of the passes through the ridges is 4,700 feet, the high- 

 est, through the Chiricahui range, being 5,180 feet. Except 

 through the passes, the surface is so smooth as to require but 

 little preparation to receive the superstructure of a railroad; 

 and even in the two most difficult of the passes, the natural 

 slope of the ground may be used for a railroad until the con- 

 struction of the road reduces the cost of materials and supplies 

 to the lowest rates. In one of these two passes (the Chiricahui) 

 the steepest natural slope is 194 feet per mile for 2 J miles. In 

 the second pass the steepest natural slope is 240 feet per mile for 

 three-fourths of a mile. Both these grades are within the power 

 of a thirty-ton engine, carrying 200 passengers and baggage. 



In one case deep cutting in rock, or a tunnel near the surface, 

 at the summit, with heavy side cutting and high embankments 

 for short distances ; and, in the other, a short cut of 60 feet, 

 probably through rock, are proposed by Lieut. Parke, to attain 

 grades of 46 feet and 90 feet per mile, or less by increasing 

 distance. 



The great difficulty experienced in crossing this district is in 

 the long distances over which no water is found at certain sea- 

 sons. The survey by Lieut. Parke was made during the dryest 

 season of the year, and, irrespective of the springs found at in- 

 termediate points, the whole distance between the two rivers, 

 Rio Grande and Gila, may be divided into five spaces, varying 

 from 80 to 53 miles in length, at the termination of which, large 

 permanent supplies of water are found at the most unfavorable 

 season of the year. 



These spaces and points are — 



From the Rio Grande to the Rio Mimbres, 75 miles. 



From the Rio Mimbres to the stream of the Valle de Sauz, 72 " 

 From the Valle de Sauz to the San Pedro, 80 " 



From the San Pedro to the Tuczon, 53 " 



From Tuczon to the Gila, 19 " 



From the point now attained, the nearest port in our territory 

 is San Diego, but the passes of the intervening Coast range are 

 very difficult, if not impracticable, and the route is forced north- 

 ward to the San Gorgonio Pass, which is much the most favora- 

 ble of the passes in the Coast range explored by Lieut. William- 

 son for this route. It is an open valley, from two to five miles 

 wide, the surface smooth and unbroken, affording, in its form 

 and inclination, every facility to the building of a railroad. The 

 entrance of this pass is 133 miles from the mouth of the Gila, 

 in a straight line over the Colorado desert, a smooth and nearly 

 horizontal plain, requiring but little preparation for the super- 

 structure of a railroad. Thirty -five miles of this is a gravel 

 plain ; the remainder is alluvial soil, which only needs irrigation 



