F. GEOGRAPHY. 263 



making appropriations. Six parties were, however, organ- 

 ized and placed in the field for the full season, and a seventh 

 for a part of the season, until the near approach of winter 

 necessitated the termination of the field-work about Decem- 

 ber 1st. The work of the year was, as in 1875, divided into 

 two sections, designated as the California and Colorado sec- 

 tions, the work being limited to areas in California, Nevada, 

 Colorado, and New Mexico. In the special branches of 

 Natural History the number of scientific observers was un- 

 avoidably reduced from the limited appropriations of money 

 which were available. 



The year marks a gratifying improvement in the grade of 

 the geodetic and topographic work, one of the features being 

 the collection of materials for a detailed topographical map 

 of Lake Tahoe and the surrounding Sierra Nevada region on 

 a scale of one inch to a mile; and of the section embracing 

 the famous Comstock lode and its surroundings upon a scale 

 of one inch to 500 feet. This implies no departure from the 

 original plan of confining the general topography in the more 

 sparsely settled regions to the amount necessary for the con- 

 struction of a map on a scale of one inch to eight miles, or 

 1 _ 



The astronomical stations occupied in 1873 by parties of 

 this survey on the divide between Virginia City and Gold 

 Hill, Nevada, were connected this season with the extrem- 

 ities of a base-line, more than four miles long, measured in 

 the valley of the Carson River. Triangles developed from 

 this base form the basis of the system of triangles extended 

 over the entire area. 



Main astronomical stations, with the adjacent measured 

 bases, had been determined along the east face of the Rocky 

 Mountains from Hughes, Colorado, on the north, to Las 

 Vegas and Santa Fe, New Mexico, on the south, and the 

 scheme of triangulation already begun was farther carried 

 out. 



A noteworthy feature of the past season's work is the 

 greater attention paid to the determination of the boundaries 

 of areas of marked natural resources, such as those valuable 

 for agriculture, with or without irrigation, for grazing, for 

 timber, and for mines, as contrasted with the arid or abso- 

 lutely sterile parts. The outgrowth of this system will be 



