SURVEY OF THE COLORADO OF THE WEST. 
that portion of the Green between its junction with the Grand and the 
crossing of the Union Pacific Railroad ever been mapped; but its posi- 
tion at three different points had been determined by Government 
explorers, viz* at the mouth of Henry’s Fork, at the mouth of the Uin- 
tah, and at Gunnison’s Crossing, on the old Spanish trail. 
During the years 1867, 1868, and the first part of 1861), I was engaged 
with a small party of naturalists, volunteers like myself, in the explora- 
tion of the mountains of central and western Colorado about the sources 
of the Grand, White, and Yampa Rivers. After exploring a number of 
canons through which these streams run, i determined to attempt the 
exploration of the great cafious of the Colorado. Boats were built in 
Chicago and transported by the Union Pacific Railroad, which was then 
running construction-trains, to the point where that road crosses Green 
River, and from thence in our boats we descended Green River to the 
Colorado, and the Colorado through the series of great canons to the 
mouth of the Rio Virgen. 
On starting we expected to devote ten months to the work ; but 
meeting with some disasters, by which our store of rations was greatly 
reduced, we were compelled to hasten the work, so that but three months 
were given to it. • 
On this trip astronomic stations about fifty miles apart were made, 
and observations taken for latitude with the sextant, and also for longi- 
tude by the method of lunar distances. The meandering course of the 
river was determined by compass-observations from point to point, with 
the intervening distances estimated, thus connecting the astronomic 
stations. For hypsometric data a series of tri-daily barometric observa- 
tions were recorded, taken at the water’s edge, and using this as an ever- 
falling base-line, altitudes on the walls, and such adjacent mountain- 
peaks as were visited were determined by synchronous observations. 
The results of this hypsometry were used in the construction of the 
geological sections. The course of the river and the topographic features 
of the canons only were mapped. It should be remarked here that- a 
portion of the records of this trip were lost at the time when the 
men, who had them in charge, were killed by Indians. 
Having demonstrated the practicability of descending the river in 
boats, it was determined to make a more thorough survey of the series of 
canons along the Green and Colorado Rivers, and of the more import- 
ant side canons, and also to include as broad a belt of country as it was 
possible from the river, and application was made to Congress for the 
necessary funds to carry on the work. The assistance asked was granted , 
and the work has been in continuous progress from July, 1870, until 
the present time. 
It had been determined that it would not be i>racticable to perform 
the elaborate work projected, depending on such supplies as it was pos- 
sible to take with us on the boats from Green River Station, but that 
