2 
OBJECT OF THE EXPLORATION. 
specific instructions, I Lad them all printed, except the paper called u General Organization of 
the Expedition,” as it was more economical than to he subjected to clerk hire for so great a 
labor. 
I have the honor to be, very truly, your obedient servant, 
ISAAC I. STEVENS. 
Hon. Jefferson Davis, 
Secretary of War. 
NORTHERN PACIFIC RAILROAD EXPEDITION. 
The special object of the exploration is the determination of a railroad route from the head¬ 
waters of the Mississippi river to Puget sound. In consequence of the meagreness of the in¬ 
formation in reference to the country to be gone over, particularly in the Rocky and Cascade 
mountains, a general topographical survey must be had of these mountains between the 46th 
and 49th parallels, and of most of the intervening country, in order to determine the general 
course of the railroad and furnish the data to guide the civil engineers in determining the 
route. The operations involved are therefore as follows: 
1. A general reconnaissance of the country. —This reconnaissance will embrace the general 
features of the country, as mountain ranges and passes, windings of rivers and streams, their 
dividing ridges, prairies, and everything which shall be necessary in the construction of a 
general map of the country passed over. The result of this examination, done by recon¬ 
noitring corps assigned to the special duty, will be to determine the most advantageous route to 
be pursued for the railroad, and to direct the movements of the party intrusted with locating 
it. It will be an important object in the general reconnaissance to determine, with all possible 
accuracy, the important features of the country, especially those which have a bearing upon the 
location and construction of the proposed railroad. Of this class are the important points of 
the Missouri and Columbia rivers, as the heads of steamboat and boat navigation; the debouches 
of the mountain passes, both of the Cascade and Rocky mountain ranges; and of such import¬ 
ant points the latitude and longitude should be determined, either by the sextant and transit, 
or by the sextant and chronometer, as may be practicable. The observations of important 
objects by compass ranges should be referred either to those points whose geographical positions 
have been determined, or to the base line of the route. 
Parties intrusted with reconnaissances and surveys will make topographical sketches of the 
country on the several routes pursued by them, and will, as far as practicable, be supplied with 
the necessary instruments for working with facility. In the lack of an odometer for measure¬ 
ment, such means must be made use of as are generally resorted to in similar cases, as measure¬ 
ment by the pace of a horse or a man, &c. 
2. The survey and location of the railroad. —This will be along the route resulting from the 
labors of the reconnoitring corps, and will embrace all the facts bearing upon the construction 
of the road; particular regard being had by the reconnoitring corps, and the corps intrusted 
with the location of the road, to the natural facilities for the transportation of iron, supplies, 
&c., which will be required for the road. Objects observed will be referred to the known points 
of the base line of the route, referred to hereafter. The route will be run by compass courses 
day by day, and measured by an odometer, and the results thus obtained, checked by the daily 
determination of latitude and longitude, will form the base line, to which will be referred all 
objects observed in the survey. 
A general profile of the route will be determined by means of barometrical measurements. 
The altitudes of the halting places at night and noon, the tops of ridges and bottoms of valleys, 
and, so far as possible, the altitudes for the construction of a continuous profile, in connexion 
