68 EEPORT OF THE SECRETARY. 



square miles, comprising the region lying between the parallels of 35° 

 and 37°, and the meridians of 109° and 111°, and with an additional 

 rectangle on the southeast, comprised between the parallels of 35° and 

 36° and the meridians of 107° and 109°. A small portion of the latter 

 had been surveyed during the previous year. While this region was, 

 as stated before, in the highest degree favorable to the rapid prosecu- 

 tion of topographic work, it was decidedly unfavorable for triangulatiou, 

 requiring almost everywhere the use of artificial signals and much cut- 

 ting away of timber. The area covered includes much that has been 

 hitherto a terra incognita, partly on account of its aridity and barren 

 condition, and partly on account of the difficulty of traversing it. So 

 little has been known of it that within the area surveyed by Mr. H. M. 

 Wilson (in charge of one of the topographic parties) a small mountain 

 range has been indicated as occupying two places on the same map. 

 Mr. Wilson is also the first white man to ascend Navajo Mountain, a 

 dome-shaped mass that rises 4,000 feet above the general level of the 

 country, between the San Juan and the Colorado Rivers, near the mouth 

 of the former. At the close of the field season, Professor Thompson 

 determined by astronomic methods the geographic position of Fort 

 Wingate. 



The field work of the California division was, as during the previous 

 year, intrusted to the charge of Mr. Gilbert Thompson. The division 

 was organized and took the field early in July. It consisted of two 

 parties, one under the immediate supervision of Mr. Thompson and the 

 other under Mr. Mark B. Kerr. The season proved to be exceptionally 

 unfavorable. Not only was the work seriously interfered with by storms, 

 but during nearly the whole season smoke and haze obstructed the view. 

 In spite of these difficulties the topographers surveyed an area estimated 

 at between 4,000 and 5,000 square miles, lying in the northern part of 

 the State, about Mount Shasta, and extending westward therefrom into 

 the Coast Range. 



The work of preparing a detailed map of Yellowstone Park upon a 

 scale of 1 mile to an inch was intrusted to Mr. J. H. Renshawe. Out- 

 fitting his party at Bozeman, Mont., he reached the Park and com- 

 menced work on the 7th of August, prosecuting work as late as the 

 season would admit. Early in October, however, severe snow-storms 

 caused a cessation of field operations, and he was obliged to withdraw 

 to lower altitudes. The area covered by his party during the season 

 was about 1,500 square miles, lying in the northwestern corner of the 

 Park, and embracing the southern eod of the Gallatin Range, and a 

 •considerable area of plateau country, extending hence southward down 

 to the Geyser basins. Upon the return of the party to Bozeman, in 

 October, a remeasurement with compensated bars was made of the base 

 line at that place laid out and surveyed by the "Geographical Surveys 

 West of the One Hundredth Meridian" in 1877.- 



During the year 1874 the Geological Survey of the Territories, under 

 Dr. F. V. Hayden, made a somewhat detailed topographic map of 



