4 GENEEAL DESCRIPTION OF THE COUNTRY. 



openiDg between the Chiricahiu range and Mount Graham. Uniting in the Valle del Sauz, the 

 country in advance was reconnoitred with reference to obtaining water, under the Peloncillo 

 (Sugar Loaf) ridge immediately to the east of us. Keceiving a favorable account, we moved 

 next morning to this point, determining at the same time the barometric altitude of the gap 

 south of camj). 



From the Peloncillo camp we continued eastward, following the trail of the Boundary Com- 

 mission, crossing aplaya turning the north end of the Pyramid ridge^ crossing a second playa 

 and ascending the foot slopes of the extreme southern spurs of the Burro mountains, and 

 reached the southern emigrant road, (Cooke's.) We then entered the arroyo, or caiion, leading 

 from the Ojo de Inez, and ascending it a mile or two to Las Peilasquitas, encamped at some 

 water holes or natural cisterns in the bed rock of the lateral canons ; proceeded thence to the 

 Ojo de la Vaca, Eio Mimbres, and Cooke's spring, making at the same time lateral examinations 

 to obtain barometric readings at stations on lower ground to the south, and of course more favor- 

 able than that passed over by the wagon road. Thence to the Kio Grande, at Fort Fillmore, 

 we followed the usual wagon road, diverging, however, near the edge of the mesa, and descend- 

 ing to the river bottom by a smooth and easy slope, and avoiding the rough canon heretofore 

 encountered north of El Picacho, the examinations of 1854 being most satisfactory, and also 

 impossible to be improved upon. 



The observations taken during this examination and survey embraced not only those necessary 

 to determine the practicability of constructing a railroad through the country traversed, but 

 also, so far as means and time would permit, those required to make a topographical sketch of 

 the country along and adjacent to the proposed line. These embraced, therefore, astronomical 

 and barometrical observations, in connexion with odometer and prismatic compass surveys in 

 the valley and i^lain districts, and also compass and chain and level surveys in the mountain 

 passes. 



Section 1. EXTENT OF SAN FRANCISCO AND LOS ANGELES DIVISION. 



Exploration for railroad purposes in a country whose detailed topography is so little known 

 as is that of the great west, involves the necessity in nearly every instance of primary recon- 

 noissance to develope the topographical features of the district, that the parent mountain 

 chains and radiating spurs with the interlocking rivers and tributaries may be accurately 

 mapped, and thus afford definite data with regard to the gaps and depressions in the several 

 watersheds or divides, and their lines of easiest ascent and descent. This necessity we found 

 to be particularly the case in the California division of our work, where we had reason to exjiect 

 greater accuracy in existing maps, the country along and adjacent to our line of examination 

 being for a long period occupied, but by a population who knew, as a general thing, little of 

 their own country beyond their ranches and lines of communication to the neighboring towns. 

 Our operations were, therefore, confined in the first place in collecting materials for an accurate 

 mapping of the country, and then to determine the question of practicable location of a railroad 

 through its various valleys and mountain passes from San Francisco to Los Angeles. The 

 explorations and surveys, together with the various side explorations, extend throughout the 

 diagonal of tlie area bounded by the parallels 34° and 37° 30' and the meridian 119°, 123°, 

 and have resulted in the location of a practicable route from San Francisco to Los Angeles, 

 lying wholly to the west of the watershed of the CoastrRange, and following in the main what 

 is known as the coast road. 



