LETTER TO THE SECRETARY. 



Office of the United States Geological and 



Geographical Survey of the Territories, 



Washington,, D. 0., December 1, 1878. 



Sm : I have the honor to submit the following report of the opera- 

 tions of the Survey under my charge, both in the field and in the office, 

 during the year 1877.* 



On the completion of the work in Colorado in 1876, it was decided 

 that it should continue northward into Idaho and Wyoming Territories. 

 The belt of country along the fortieth parallel, including the Union 

 Pacific Eailroad, having been explored in detail by the Survey of the 

 Fortieth Parallel under Clarence King, it was deemed best to commence 

 at the northern boundary of that work and continue northward and 

 westward. 



The survey was divided into five parties for field, geological, and topo- 

 graphical work, besides several others for special investigation. The 

 following notes present the salient features of the summer's work : 



PRIMARY TRIANGULATION. 



The primary triangulation party in charge of Mr. A. D. Wilson, chief 

 Topographer of the Survey, took the field from Rawlins Springs, Wyo. 

 Near this place a base-line was carefully measured and from this a net- 

 work of triangles was extended to the north and west. After com - 

 pleting the work in the vicinity of Rawlins, the party marched north- 

 ward, making stations on Seminoe and Whiskey Peaks, and thence 

 traveled westward to TeUow Butte, where another station was located. 

 From this point the work was carried to the Wind River Range. Three 

 stations were made on the more prominent points of this range, with 

 much difficulty, owing to the great quantities of snow found in these 

 mountains during the month of June — the time the party was working 

 there. 



Continuing the work northward and westward, stations were made 

 on the Grosventre and Wyoming Ranges and on Caribou Mountain and 

 Mount Putnam near Fort Hall. After refitting at the latter place, the 

 party marched south via Soda Springs to the valley of Bear Lake, where 



*A portion of this introduction was printed in the Preliminary Report of the Field 

 Work of the Survey for 1877 (Ann. Rep. Secretary of the Interior for 1877, pp. 755-787), . 

 and also in the Annual Report of the Smithsonian Institution for 1877. It remains 

 nearly as it was written over one year ago. 



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