F. GEOGRAPHY. 249 



to a satisfactory conclusion for the season. The Scientific 

 Corps of the Survey now consists of the geologist in charge 

 and his staif of three assistants ; several eminent paleontolo- 

 gists, a botanist, a zoologist, a photographer, and an artist ; 

 a geographer and his staif of three topographers, three assist- 

 ant topographers, a meteorologist and draughtsman, and a 

 quartermaster and his assistant. There are also a few young 

 men attached as general assistants. The field of operations, 

 in accordance with the plan presented to Congress for the 

 season of 1873, comprised the Territory of Colorado, and that 

 part of Utah lying east of Green River, bounded on the north 

 by the belt of the 40th parallel survey. The triangulations 

 formed part of the same system carried across the Sierra 

 Nevada. The whole map work of the survey is to be based 

 upon a trigonometrical survey connected with measured 

 bases ; several of the geodetic stations having been deter- 

 mined astronomically by the United States Coast Survey. 

 The area marked out for examination at the commencement 

 of the season was divided into three districts. The detailed 

 survey of each was intrusted to separate parties, embracing 

 an assistant geologist, topographer, and assistant, and one 

 naturalist. The primary triangulation was carried on with 

 an eight-inch theodolite from the loftiest peaks, thus connect- 

 ing the whole area to be examined by a net-work of accurate 

 triangles. During the past season Mr. George W. Dean, as- 

 sistant in charo-e of lonsritude determination of the United 

 States Coast Survey, spent three months in Colorado, direct- 

 ing the work of establishing observations at the principal 

 points along the east base of the Rocky Mountains. 



The first of these-was at Denver; the second at Colorado 

 Springs, at the foot of Pike's Peak ; the third near the Raton 

 Mountains, on the southern boundary of Colorado. Sherman, 

 nine miles north of the northern boundary of Colorado, was 

 located by the United Coast Survey last year. These four 

 Coast Survey observations at Sherman, Denver, Colorado- 

 Springs, and Trinidad, at which the triangulations of the sur- 

 vey connect, are nearly in the same meridian, and from sixty 

 to one hundred and twenty miles apart in latitude. The 

 longitudes were determined telegraphically, and the latitude 

 by the well-known zenith telescope method. Upon this me- 

 ridianal astronomical base, 290 miles long, established by the 



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