Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 1, Pt. 2

ROUTE FROM FORT BENTON TO WALLAH-WALLAI.
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 railroad. The main party passed fromt 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 connlecting the line with Fort Colville 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.
3e followed an Indian trail, and crossing,the Saptin or Lewi-s'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. From 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 Dearbornwould
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
sixty-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.
From Mfr. Tinkham's report, I would judge that the approach along the route he followed is
f-ar 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 Dearborn 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 remainder 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
for 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 bu-ilding-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 mniles 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
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