SURVEY OF THE COLORADO OF THE WEST. 
7 
Such was the character of the astronomic, topographic, and hypsome- 
tric work done np to this time, methods not absolutely correct, but giv- 
ing valuable approximate results. 
But the wonderful features of the Grand Canon district had yet to be 
mapped, and it was determined to do the work in this region by more 
thorough methods. A general reconnaissance was made for the purpose 
of selecting a site for a base-line, and the valley of the Kanab was chosen. 
Then a point midway between the extremities of the proposed line was 
selected, and an astronomic transit mounted for the purpose of determin- 
ing the meridian direction and fixing the extremities of the line. This 
accomplished, the alignments were made with a theodolite. The lati- 
tude of the northern extremity of the line was determined by an ex- 
tended series of observations with the zenith telescope, and the longitude 
by telegraphic signals with the previously-mentioned astronomic station 
at Salt Lake City. The base-line was measured with wooden rods, lev- 
eled on trestles, and aligned by sighting on small steel pins in either 
extremity. The rods were trussed to prevent sagging and warping, 
thoroughly seasoned, oiled, and varnished, and the extremities were shod 
with small metallic cones, for the purpose of securing accurate contact. 
The rods were measured with a standard steel tape, at a temperature of 
52°. Three rods were used, two always remaining in position as a pro- 
tection against accidental movement. The leveling instrument was a 
plummet, or an inverted T, the base of which was the same length as the 
rods. Every hundred feet of distance was marked ofi‘ by a stake, in the 
top of which was inserted an iron wire sharpened to a point, and this 
point connected with the point at the end of the rod by a plummet, and 
each hundred feet of the distance was re-measured with the steel tape. 
The ground selected for the site of the base-line was very good, being 
nearly level and quite smooth, and we found that the work could be 
done more rapidly than had been anticipated, the only delay being due 
to windy weather. When the wind was blowing briskly it gave a trem- 
bling motion to the rods, which rendered it impossible to make that cor- 
rect alignment and accurate contact between the points which was 
desirable, and for that reason the work was carried on only during still 
weather. The line was found to be 48,099^ feet in length. Then a sys- 
tem of triangles was expanded from the extremities of this line, so as 
to embrace all of the country from the Mar-ka-gunt and Pauns-a-gunt 
Plateaus on the north to salient points a few miles south of the Grand 
Canon, and from the Beaver Dam and Pine Valley Mountains on the 
west to the Navajo Mountain beyond the Colorado on the east, and still 
farther to the northeast, so as to embrace the country from the Sevier 
River on the west to salient points immediately beyond the Colorado on 
the east, and as far north as the southern tributaries of the Dirty Devil 
River. The angles of these triangles were measured with a seven-inch 
theodolite. At the geodetic points mounds were built and flag-staffs 
erected, and in that clear atmosphere it was found that it was practica- 
