340 REPORT AND ESTIMATE. 
one-tenth feet to the mile; though, without large excavations and embankments and proper 
side-hill location, there will be no necessity of using grades greater than fifty feet to the mile. 
It is probable that a better line can be found by turning to the south seven miles before 
reaching the western end of the prairie, crossing the Big Blackfoot, passing through the 
extensive Kamas prairie on its southern side, and returning to the immediate valley of the 
river, six miles before reaching the end of the cafion. There will be no difficulty from freshets 
in this section. The prairies are not overflowed in high water, except small portions of the 
Belly prairie, and the greatest rise and fall of the Big Blackfoot will be about six feet. 
Before describing further the railroad line, I will briefly state the characteristics of the route 
of 1853 down Clark’s Fork. 
HELL-GATE CROSSING, VIA CLARK’S FORK, TO THE SPOKANE. 
The route is the same with the route of 1855 for seven and a half miles below the Hell-Gate 
crossing, when it follows the northern foot slope of the Hell-Gate Ronde and passes over the 
summit which lays between it and the Flathead river, with a gradient of thirty-five feet per 
mile, or, allowing for errors in the barometer, of forty feet. Having attained this summit, it 
strikes a tributary of the Jocko, and descending along that stream to the valley of the Flathead, 
the gradient being forty feet (assumed at fifty) down the tributary of the Jocko, and down the 
main streams as well as down the Flathead to its junction with the Bitter Root, twenty feet. 
By the barometer the average fall of Clark’s Fork is about eleven feet per mile. The road is 
estimated to descend at gradients of from fifteen to twenty feet per mile. After leaving the 
Jocko the road should follow the hills on the left side of the Flathead, to a point some miles 
above its junction with the Bitter Root. Then crossing, it would follow the right bank of 
Clark’s Fork as far as Big Rock. Here it would cross, and following down the left bank, would 
recross at the Cabinet. Then tunnelling the Cabinet mountain three hundred yards, it would 
continue on the right of the river to Lake Pend d’ Oreille, and on the northern side of that 
lake to its lower extremity. Both along Clark’s Fork and the lake fifteen feet is about the 
difference of high and low water mark, and the road must therefore keep the sides of the hills, 
in some instances requiring high embankments. The tunnel at the Cabinet mountain would be 
through a formation of which fifty per cent. is rock, this being basaltic trap. The transit from 
Clark’s Fork to the Spokane could be made with gradients of not more than twenty-five feet. 
It might be facilitated by making use of the valley of a small stream which empties into Clark’s 
Fork about twelve miles below the lake, and by a valley seen ten miles west of Clark’s Fork, 
which appears to make into Coeur d'Aléne prairie. А bridge half a mile long would be required 
to cross Pack river. Excellent timber and good stone are found along the whole of this dis- 
tance. The crossing of the Spokane will involve heavy work of bridging, excavation, and 
embankments, but beyond, over the Great Plain of the Columbia, there are many practicable 
lines. But to resume. 
HELL-GATE CROSSING TO CROSSING OF BITTER ROOT—DISTANCE 65 MILES. 
Hell-Gate crossing is about three thousand and three hundred and fifty-nine feet above the 
sea. The line for ten miles and a half crosses diagonally the Hell-Gate Ronde. There are 
several small streams and swales in this distance. Excavations and embankments moderate; 
grade 30.5 feet to the mile. Here a stream is crossed, and continuing down on the east side of 
the Bitter Root for sixteen miles through, for nearly the entire distance, a wide, open valley, 
