270 
ROUTE FROM FORT BENTON TO WALLAH-WALLAH. 
instructions from you as to the further continuation of the survey. Mr. Tinkham, who had left 
the main party on the 26th for the purpose of examining a route which led to the Jocko river, did 
not return until after we left the Flathead village, and was then placed by you on duties which 
separated him from the main party. In continuing the survey, Mr. Lander was directed to follow 
the Bitter Root to its junction with Clark’s fork, in order to determine its practicability for a rail¬ 
road. The main party passed from the Bitter Root to the Jocko, and following the latter to its 
mouth, entered the valley of Clark’s fork. Mr. Lander rejoined us at Horse Plain. Hence we 
pursued the line of Clark’s fork to a point twelve miles below Lake Pend d’Oreille. Here 
Lieutenant Arnold left with a select party for the purpose of connecting the line with Fort Col¬ 
ville and with Captain McClellan’s survey, in case he should not have arrived at that point. The 
main party crossing to the Spokane river, thence proceeded to a point twelve miles west, where 
we met yourself and Captain McClellan with his party. 
Here terminated the operations directed in your instructions to me of the 2d of October. But, 
in pursuance of further orders, the party, organized as before, proceeded to Wallah-Wallah. 
We ibllowed an Indian trail, and crossing the Saptin or Lewis’s fork of the Columbia, at the 
mouth of the Peluse, arrived at Wallah-Wallah on the 6th of November. 
The results of the survey, which tend to show the capacity of the country for a railroad, must 
be briefly stated. F’rom Teton river to the foot of the dividing ridge are two summit levels to be 
attained, and on the route we followed a difficult approach to that ridge, along the sides of the 
mountain spur, adjacent to the south fork of the Dearborn. The following are the probable 
gradients on this route: From the Teton to the first summit, twenty-one miles of ascent, at the 
rate of twenty-seven feet per mile. Then to the crossing of the Sun river, thirty-one miles, 
descending at seventeen feet per mile. To the second summit an ascent of twenty miles, at the 
rate of forty-four feet per mile, but this with the supposition that there will be a tunnel of half a 
mile in length at that summit. From here to a point on the south fork of the Dearborn would 
be sixteen miles, with gradients of twenty feet per mile. Then to the foot of the dividing 
ridge, eight miles of heavy and costly work, and with an ascending gradient of not less than 
sixiy-five feet per mile. While this route is thus barely practicable with respect to the gradients, 
it is exceedingly unfavorable in other respects. A portion of the country between Sun river and 
the Dearborn is so very rugged, that it would be advantageous to make a considerable detour to 
cross it, and this detour could not be made after passing the former stream. 
F’rom Mr. Tinkham’s report, I would judge that the approach along the route he followed is 
far preferable to that which has been considered. And if, as I have estimated, the direct approach 
can be made with a gradient of sixty-five feet per mile, the oblique approach will not require one 
steeper than sixty feet. In the matter of construction, it may be said that Teton, Sun, and Dear¬ 
born rivers would furnish sufficient sand and gravel for the road-bed, and would contribute to the 
supply of timber, their banks producing a moderate quantity of good cotton-wood. The re¬ 
mainder of the timber would come from the mountains in the vicinity of the pass, where grow 
yellow and pitch pine—a good quality. The soil between the Teton and Sun rivers is favorable 
fir the purpose of a railroad; that between the Sun and Dearborn containing a large proportion 
of clay, would be somewhat affected by frost. I noticed but one locality of good building-stone, 
and this was a few miles to the east of Beaver creek. In a country where, like this, a variety of 
rock is known to exist, it is reasonable to suppose that extensive deposits of good building-stone 
could be found: one of these being connected with the line by a branch railway, would provide 
for the supply of this material. The point at which I have supposed the main tunnel should 
commence on the eastern side, is one thousand and fifteen feet below the mountain summit. The 
tunnel would be four and three-quarter miles in length, and would issue at a point three and a 
half miles from the western base of the dividing ridge. In this connexion, it should be remarked 
that the western is five hundred and sixty-seven feet higher than the eastern side of the mountain. 
The location of the road east of the mountains was not decided upon with sufficient detail to 
