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 

 tlie routp. 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. 



The most difficult portion of the whole route is, however, that which is now entered upon, 

 viz : from Sun river to the Spokane, a distance of 365 miles, embracing the Rocky mountains 

 proper, and a secondary chain lying west of them, called Occur 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 

 2^ 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 &quot;believed&quot; practicable, with 

 grades of 50 feet per mile. The interval 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 4|- 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 4^ or even 2| 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 Blackfoofc 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. ID order to reach Clark s fork, two routes were examined. The first fol 

 lows the Blackfoot river to its junction with Hell-Grate, 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 &quot;all great difficulties of location 

 upon the route cease.&quot; The earth-excavation and embankment throughout this section 

 (from the east base of the Rocky mountains to the Spokane river, 365 miles) will be large in 



