270 KOUTE FROM FORT BENTON TO WALL AH- WALL AH. 



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 followed 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. 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 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 

 six.ty-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 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 

 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 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 



