LETTERS OF TRANSMITTAT. 
OFFICE OF THE CHIEFY OF ENGINEERS, 
Washington, D. C., July 21, 1876. 
Sur: Capt. William Ludlow, Corps of Engineers, Chief Engineer Department of Dakota, has 
subinitted to this office a copy of the report of his reconnaissance from Carroll, Montana Territory, 
on the Upper Missouri, to the Yellowstone National Park, and return, made in the summer of 1875. 
It embraces the reports of reconnaissances by Lieut. R. E. Thompson, Sixth Infantry, and scientific 
reports by Messrs. George Bird Grinnell, Edward 8. Dana, and R. P. Whitfield. 
I have respectfully to recommend that the report be priuted at the Government Printing- 
Office, and that 1,500 copies be furnished on the usual requisition. 
Very respectfully, your obedient servant, 
, A. A, LUMPHREYS, 
Lriy. Gen. and Chief of engineers 
Hon. J. D. CAMERON, ° 
Seeretary of War. 
Approved by the Secretary of War: 
If. T. Crosby, 
Chief Clerk. 
WAR DEPARTMENT, July 21, 1876. 
TIEADQUARTERS DEPARTMENT OF DAKOTA, 
~ OFFICE OF THE CULEF ENGINEER, 
Saint Paul, Minw., March 1, 1876. 
Sir: [have the honor to forward herewith a copy of my report of the reconnaissance of last 
summer from Carroll, Mont., over the Carroll road, to Camp Baker, Mont., thence to Fort. Ellis, 
Mont, including a brief tour through the Yellowstone National Park, and the return journey to 
Carroll. Accompanying my report, for incorporation therewith, are those of Messrs. Grinnell and 
Dana, which will be found both interesting and valuable. 
A map of the reconnaissance is presented, which shows the authorities used, in addition to my 
own field-notes, which were made as complete as possible. Two sketches are added, one of the 
Judith Basin and the other of the Upper Geyser Basin, to be inserted in the proper places in the 
report. : 
A set of astronomical observations at Carroll, Camp Lewis, and Camp Baker, three principal 
points on the Carroll road, are furnished ; also a tabular statement of latitudes, longitudes, distances, 
&e., and a list of distances on the Missouri River, from a survey by the United States Boundary 
Commission. The region included within the limits of the Yellowstone Park is, for its area, the 
most interesting in the world. It is situated at the very heart of the continent, where the hidden 
pulses can, as it were, be seen and felt to beat, and the closely-written geological pages constitute 
a book which, being interpreted, will expose many of the mysterious operations of nature. My 
own interest in this land of wonder is so keen as to lead me again to hope that it will be protected 
from the vandalism from which it has already suffered, and that the suggestion of an accurate 
topographical and geological survey, to complete the work so well inaugurated by Professor Hayden, 
may be made the subject of favorable consideration and recommendation by the Chief of Engineers. 
aspe ient servant 
Very respectfully, your obedient s ; Pees: 
Captain of Engineers. 
The Cu1erF oF Encinrerrs, U.S. A., 
Washington, D. C. 
