52 REPORT OF THE SECRETARY. 



of the one-hundredth meridian, that connection was had with the base- 

 line measured by Captain, now Brig.-Gen. E. O. C. Ord, near Los An- 

 geles, Cal., in 1854. The "base" in question was measured in April and 

 May 1853, by Assistant George Davidson, United States Coast Survey. 



2. The work of the United States Geological and Geographical Survey of 

 the Territories, under the direction of Professor Hay den, during the season of 

 1876. — The United States Geological Survey for the season of 1876 was 

 divided by Dr. Hayden into five parties for field-work. The late date 

 at which the appropriation was made available delayed the commence- 

 ment of the work until late in August, so that only the completion of 

 the atlas of Colorado was attemjited and successfully accomplished. 

 The work of 1876 was therefore a continuation westward of that of the 

 three preceding years, finishing the entire mountainous portion of Col- 

 orado with a belt of Northern New Mexico, 15 miles in width and a 

 breadth of 25 miles, of Eastern Utah, and also a rectangle of Arizona, 15 

 by 25 miles. The areas of exploration are located in the interior, remote 

 from settlements and largely on the reservation for the Ute Indians. Each 

 party was assigned a special area for examination, which was so selected 

 as to connect with each other topographically. The common point of 

 departure was Cheyenne, in Wyoming Territory. 



The main division or party of primary triangulation was under the 

 charge of A. D. Wilson, and accompanied for part of the season by Dr. F. 

 V. Hayden, director of the survey. The object of this party was to com- 

 plete the primary triangulation of Colorado. The field was taken at Trin- 

 idad, the southern terminus of the Denver and Eio Grande Eailroad, and 

 the first station was made on Fisher's Peak, a point near Trindad. 

 Marching thence westward through the Eaton Hills, a station was made 

 on Culebra Peak, one of the highest points of the Sangre de Cristo 

 Eange. Crossing the range, the next point was Blanca Peak, the 

 highest peak in Colorado, one of the Sierra Blanca group of the San- 

 gre de Oristo Eange. Its elevation is 14,464 feet above sea-level. 

 From the Sierra Blanca the party proceeded westward across the San 

 Luis Park and up the Eio Grande to its source, making two stations on 

 the way, one near the Summit district and the other on the Eio Grande 

 Pyramid. From the head of the Eio Grande the Continental divide 

 was crossed, and the next station made on La Plata Peak in the La 

 Plata group of the San Juan Mountains. From this point the party 

 turned northwest, traveling across the broken mesa country west of the 

 Dolores, making three secondary stations to complete the topography 

 omitted in 1875 on account of the hostility of the Indians. After occu- 

 pying the highest point of the Sierra Abajo, one of the isolated moun- 

 tain-groups of the plateau region, they went eastward to Lone Cone, 

 where another station was made. Thence they proceeded northward, via 

 the Uncompahgre agency, crossing the Gunnison and Grand Elvers to 

 the I lateau region at the head of White Eiver, a branch of the Green. 



