B42 J.W. Powell's Survey of the Rocky Mountain Region. 
Art. L.— Geographical and Geological Survey of the Rocky 
_ Mountain Region under the direction of Professor J. W. Powell. 
_ Account of work performed during the year 1877. 
AxsouT the middle of last May, the surveying corps again 
took the field. This year the rendezvous camp was at Mount 
Pleasant, a little town in Utah about 125 miles south of Salt 
Lake City. Three parties were organized under the direction of 
Professor A. H. Thompson, one to extend the triangulation and 
two for topographic purposes, the latter being under charge of 
Mr. W. Graves and Mr. J. H. Renshawe respectively, and 
the former under the immediate direction of Professor Thomp- 
son, assisted by Mr. O. D. Wheeler. 
The area designated for the season’s work lies between 38° 
and 40° 30’ north latitude, and between 109° 30’ and 112° west 
longitude, Greenwich, and is embraced in atlas sheets 86 and 75. 
angulation.—The triangulation party left Mount Pleasant 
in June. The work of this year being a continuation of the 
expansion from the Gunnison Base Line measured in 1874, it 
was desirable to first visit some of the geodetic points established 
in previous years but the unprecedented amount of snow yet 
remaining in the high plateaus and mountains rendered this im- 
practicable, and the first part of the season was spent in establish- - 
ing stations on the T’a-va-puts Plateau west of the Green River. 
In midsummer the party was able to visit the high plateaus and 
connect the work of past years with that of this season. ter 
the triangulation was extended to the east joining the work of 
the United States Geological and Geographical Survey of the 
Territories under charge of Dr. F. V. Hayden and to the north 
to join the work of the United States Geological Exploration 
of the 40th Parallel, Clarence King, United States Geologist in 
charge. The whole area of the season’s work embraces some- 
thing more than 13,000 square miles. The instrument used was 
the theodolite hereafter described. The points sighted to on 
‘the geodetic stations were either artificial monuments or well 
defined natural points, and all stations were marked by stone 
cairns, 
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