‘ROUTE NEAR THE FORTY-SEVENTH AND FORTY-NINTH PARALLELS, 9 
470 miles—forest-growth suitable for ties and lumber not being found at closer intervals on 
the route. These, in connexion with the uninhabited and uncultivable condition of the country 
for 740 miles, form the difficulties of this portion of the route, and will materially increase the 
cost of its construction. 
ait most difficult portion of the whole route is, however, that which is now entered upon, 
: from Sun river to the Spokane, a distance of 365 salen embracing the Rocky mountains 
proper, and a secondary chain lying west of them, called Coeur d’Alene and the Bitter Root 
mountains, 
Through the Rocky mountains seven passes were explored; but the only ones among them, 
upon which the information obtained was sufficiently thorough and complete to enable 
projects to be made, are two (Clark’s and Cadotte’s) lying near each other in latitude 47°, 
and connecting the headwaters of Dearborn river, a tributary of the Missouri, with the Black- 
foot, a head branch of the Columbia. 
The summit ridge of Clark’s Pass has an elevation of 6,323 feet, and requires a tunnel 
21 miles long, at an elevation of 5,300 feet. Its connexion with the main line of survey 
along the valley of the Blackfoot river was not made, though ‘‘believed’’ practicable, with 
grades of 50 feet per mile. The interyal unexamined is 4} miles long. This pass has been 
adopted by Governor Stevens in the railroad estimate, and is probably practicable. 
The approach to the other pass (Cadotte’s) is difficult, owing to the numerous deep ravines 
of the tributaries of a branch of Dearborn river, which the road must cross. The summit 
of the pass has an elevation of 6,044 feet; requires a tunnel 44 miles long, at an elevation of 
5,000 feet, with grades of approach of 60 feet, and of departure of 40 feet, per mile. 
A tunnel 44 or even 24 miles in length, in rock or part rock, at a depth below the summit 
of 1,000 feet, in a severely-cold climate, 800 or 1,000 miles distant from a thickly-inhabited 
district, is a work of vast difficulty; and the necessity of the construction of one of these two 
tunnels, in connexion with the character of the approach, and the difficult nature of the work 
required, continuing westward as far as the crossing of the Spokane river, in all a distance of 
365 miles, is one of the most serious objections to the route. 
From either pass the route seeks the Blackfoot river, with the view of reaching Clark’s 
fork, which opens the only pass through the Bitter Root mountains, the practicability of which 
was determined. Ip order to reach Clark’s fork, two routes were examined. The first fol- 
lows the Blackfoot river to its junction with Hell-Gate, a distance of 93 miles. The valley is 
narrow and wooded, the stream winding, and for twenty miles there is a narrow gorge. 
Numerous’ bridges will be required. The Hell-Gate, a few miles after being joined by the 
Blackfoot, empties into the St. Mary’s, called below this junction the Bitter Root. The con- 
struction of the road along this stream to its junction with Clark’s fork will be a work of . 
great difficulty and expense, requiring short curves, steep gradients, numerous bridges, heavy 
side-cutting, and high embankments, in consequence of the spring freshets, (from twenty to 
thirty feet of vertical rise.) From the nature of the examination, its practicability cannot be 
considered as established. 
The other route, (shorter, and probably less difficult,) having followed the Blackfoot but 
a short distance, crosses to the Jocko, descends this to the Flathead, and descends the latter 
to its junction with the Bitter Root, forming Clark’s fork, bounded closely by high, rocky 
mountains. Having reached Clark’s fork, the route continues along this river as far as Lake 
Pend d’Oreille, between rugged, rocky mountains, which at several points crowd upon the 
river. The valley of this river is heavily timbered, principally with pine, and, with the lake, 
it is subject to freshets fifteen feet in height. Leaving Lake Pend d Oreille at its lower 
extremity, the route crosses to the Spokane without difficulty. At the Spokane river the 
continuous mountain region and the forest terminate, and ‘‘all great difficulties of location 
upon the route cease.’ The earth-excavation and embankment throughout this section 
(from the east base of the Rocky mountains tu the Spokane river, 365 miles) will be large in 
2a 
