GENERAL REPORT. 
HEADQUARTERS DEPARTMENT OF DAkoTA, 
OFFICE OF CHIEF ENGINEER, 
Saint Paul, Minn., February 1, 1876. 
Sir: [have the honor to submit herewith my report of the reconnaissance from Carroll, Mont., 
to Camp Baker, thence to Fort Ellis and the Yellowstone National Park, made during the months 
of July, August, and September, 1875, in accordance with the instructions given in Special Orders 
No. 110, dated Headquarters Department of Dakota, Saint Paul, Minn., June 14, 1875. 
My report includes those of Mr. George Bird Grinnell on the paleontology and zodlogy and of 
Mr. Edward 8. Dana on the geology of the region traversed. These reports will be found highly 
interesting and valuable. Drawings of fossils collected by Mr. Grinnell form a portion of his report. 
Lieut. R. E. Thompson’s report of the trip to the Judith Basin, and of the return from Carroll to 
Ellis, are also submitted; Lieutenant Thompson’s topographical work having been incorporated in 
the general map. 
A map of the route pursued is presented on a scale of six miles to the inch, and a tabular 
statement is appended to the report, giving the astronomically-determined positions of important 
points, tables of distance, instrumental observations, &c. 
The determinations of Forts Shaw and Ellis are those of Lieut. F. V. Greene, Corps of Engi- 
neers, who was at those posts last summer on duty connected with the United States Boundary 
Commission. His labors obviated the necessity for my going to Fort Shaw (which would have 
consumed some valuable time), and also saved me additional delay at Fort Ellis, at which place, 
out of six days I spent there, rain fell continuously for five. 
The position of Fort Benton and the map of the Missouri River below that post are from the 
survey of the same officer, under direction of Capt. William J. Twining, Corps of Engineers, chief 
astronomer of the Boundary Commission, who with his party descended the river from Benton to 
Bismarck in Mackinac boats, at the close of the season’s operations in 1874, carefully mapping it, 
and establishing almost daily astronomical stations. The river distances determined by this survey 
show an enormous reduction from the crude and exaggerated estimates given in existing tables, 
and which have heretofore been accepted as fair approximations. Above Benton, the river is from 
the various published authorities collated, and as far as possible reconciled. 
The topography adjoining the route is from the field-notes of the reconnaissance. 
Sketches of the Judith and Upper Geyser Basins are given in the body of the report, also from 
field-notes. 
The general topography of the Yellowstone Park is mainly taken from the published maps of 
Dr. Hayden and Captain Jones; using, however, my own latitudes wherever good observations were 
taken. This, however, was Dut seldom, since showers fell every day but one that we were in the 
park, and the nights were almost invariably cloudy. 
Inasmuch as no one who has seen this interesting region can fail to be deeply solicitous for its 
care and preservation, I am impelled to express a hope for favorable consideration from the depart- 
ment commander of the remarks and suggestions in relation thereto. 
2W 
