1877-3 
Prof. Hayden's Explorations. 
245 
and quality of almost all the water, which is scanty through- 
out, and can map with considerable accuracy the topo- 
graphical forms and all the water-courses. The area is 
almost entirely devoid of topographical “ points,” and the 
topographer is obliged to depend to a considerable degree on 
those far to the north and south for the triangulation. The 
country has heretofore been almost entirely unexplored, and 
was described by the nearest settlers as a broken canon 
country, extremely dry. It was marked on the maps as a 
high, undulating plateau, with fresh-water lakes and timber. 
The party saw no lakes of more than 400 yards in diameter, 
and only two or three of these. The country is nearly all 
inhabitable, both winter and summer, and considerable por- 
tions of it valuable ; and though three-quarters of it is 
within the Ute Indian reservation, the advantage of a more 
accurate knowledge of its character can readily be seen. 
While working in the low broken country of south-western 
Colorado last year, Mr. Chittenden made use of a light por- 
table plane-table, and found it of great value. It appeared 
at that time that its value was greatest in that class of 
country, and that in a low rolling district, with few prominent 
points, or in a high mountain country, it would probably be 
of little or no use. Altitudes were determined by the mer- 
curial barometer, with a base at the White River Indian 
Agency, and checked by a continuous system of vertical 
angles. The altitude of the agency has been determined by 
a series of barometric observations extending over two years 
and a half, and referred to railroad levels, and can proloably 
be depended on to within a few feet. The altitude of the 
agency being about 6500 feet, and the altitudes in the district 
ranging from 5000 to 8000 feet, makes its location the best 
possible in height for a barometric survey of the region. 
It is the intention of the Survey, during the coming year, 
to publish some tabulated results of the barometric work in 
Colorado, showing the system, and its accuracy and relia- 
bility. This may be of use in future work, since the topo- 
graphy of the whole west must greatly depend on barometric 
determinations of altitude, and Colorado has furnished almost 
every possible phase of western topography. 
The longest dimension of the work lying east and west, 
and the White and Grand Rivers running in approximately 
parallel courses, the district stretched from the White River 
up over the divide between the Grand and White, and em- 
braced the heads of the lateral drainage of the former river. 
The general topography is a gentle rise from the White 
River toward the south, and a sudden breaking off when 
