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

FROM FORT BENTON TO WALLAH-WALLAH.
275
connexion through here from Blackfoot river to Clark's fork, promising better than the Jocko
river. This summit I estimated could be easily attained, with a forty-foot grade, from the large
plain where we encamped on Sunday, 25th September. It is not a ridge, but a flat, or almost a
flat, with a sluggish beaver-dammed brook running through it, sometimes almost motionless. It
is very likly that the trail forked here; but although I searched for it for a considerable time,
I could discern no crossing of the stream, and no certain indication that there was a division of
the trail.
The approach to this summit is so easy, that I am encouraged to believe that a railroad line
will be obtained here which shall avoid the difficulties near Hell Gate, and the summit between
St. Mary's and Jocko river.
I regret that I am not able to speak more positively on this matter. The route which I really
followed I considered to be every way practicable, but I think it goes altogether too far north,
and that it leads to Flathead lake, although of this I am not certain.. It may be worthy of
remark that, in crossing over the mountains towards the British trading posts, there was a vast
amount of the finest limestone suitable for building, and lying in large square blocks, and
stratified.
Very respectfully, your obedient servant,
A. W. TINKHAM.
Lieutenant DONELSON,
Corps of Engineers, Olympia, Washington Territory.
EXTRACTS FROM MR. F. W. LANDER'S REPORT OF FEBRUARY 15, 1854, TO GOVERNOR STEVENS,.
GIVING THE RESULTS OF PERSONAL EXAMINATIONS, IN CONNEXION WITH THE RAILROAD SURVEY
OF LIEUTENANT DONELSON FROM FORT BENTON TO WALLAH-WALLAH.
My own examinations extend through Lewis and Clark's Pass, and were abandoned at a point
seven and a half miles west of the summit of the pass.
From the rapid descent from this pass towards the west, I was led to give my attention wholly
to the line extending west from Cadotte's Pass. My examinations upon the line of Cadotte's
Pass commenced at a point sixty miles west of the summit. (Mr. Lander's route was in fact
along the valley of Hell Gate river.)
The ascent to Lewis and Clark's Pass can be made at forty (40) feet per mile. The minimum
curvature adopted in the approach is of fifteen hundred (1,500) feet radius. The tunnel is two
and three-fifths miles in length. Grades should descend from the eastern orifice of the tunnel
towards the west, iii order to reduce inclination.
The grade in descent towards the west is forty (40) feet per mile for about seven and a half
miles; minimum curvature, fifteen hundred (1,500) feet radius; from the point seven and a half
miles west by the present reconnaissance, a steeper inclination must be adopted. I am of the
belief that gradients of fifty (50) feet per mile can be secured.
My own examinations have been upon a line through the valley of the Blackfoot fork [Hell
Gate river] and Bitter Root river, and Clark's fork of the Columbia, passing south of Lake Pend
d'Oreille to the lower extremity of that lake, and thence in a southwesterly direction to the Great
Plain of the Spokane, thence by the northern bank of the Peluse to the northern branch of the
Snake, thence to the Columbia. (Mr. Lander's route left the Blackfoot river some distance
down the trail, crossed the mountain spurs to the south into the valley of Hell Gate river, and
then followed that river down. The railroad practicability, therefore, of which he speaks, is of a
portion of the Hell Gate, and not of the Blackfoot trail. Hence, whenever Mr. Lander speaks of
the Blackfoot trail, he must be understood as really describing the Hell Gate valley; and Hell
Gate will accordingly be substituted in brackets for Blackfoot.)
From the point where my own examinations commence, the general descent of the Blackfoot