276 LINE OF THE MARIAS PASS. 



[Hell Gate] valley does not exceed forty (40) feet per mile. The width of the valley is such 

 that, by using curvature of twelve hundred (1,200) feet radius, at a few sudden changes of di 

 rection, the line need not make crossings of the stream; or should larger radii seem preferable, 

 the character of the route may still be preserved, the river crossed at right angles to the current, 

 and a reasonable length of straight line secured between the changes. The cost of all the bridg 

 ing upon the division will be excessive, from the scarcity of the proper material for masonry, the 

 basaltic rock of the section being unfit for such structures. 



Should the line keep the northern bank of the river, an embankment formed of rock and earth 

 by borrowing would avoid many deep ledge cuttings, and could be protected from the danger of 

 sudden freshets by placing the weightier material upon the outer slope. For a portion of the 

 distance through this valley, however, it will be necessary to make several crossings of the 

 stream at high cost. The general grade down the Blackfoot [Hell Gate] fork of forty (40) feet 

 per mile will probably be broken by the severe work, and lead to the location of steeper 

 inclinations. 



The descent of the Bitter Root is very severe. The general grade of the river valley for that 

 distance is not great, but the changes in level are abrupt; the valley extremely narrow and 

 crooked; sharp curvature and steep gradients will be needed under any system of location, and, 

 by the best mode of conquering these difficulties, the line will be extreme in cost and nearly 

 impracticable. 



Many crossings of the stream are made; deep rock-cuttings occur, and all embankments must 

 be thoroughly sustained against the effects of the rapid current and the danger of sudden freshets. 



From the junction of the Bitter Root and Clark s fork to the crossing of Clark s fork, below 

 Lake Pend d Oreille, the line assumes a more favorable character, and although still severe, may 

 be readily adjusted to reasonable rate of curvature and grade. The crossing of the summit 

 section between Lake Pend d Oreille and the valley of the Spokane is very favorable, and can be 

 made upon gradients of forty (40) feet per mile. 



All great difficulties of location upon the route, as delineated upon the sketch, cease at the 

 valley of the Spokane, and choice can be made of several practicable lines to the great valley of 

 the Columbia. 



19. REPORT OF MR. A. w. TINKHAM, ASSISTANT ENGINEER, AS TO THE RAILROAD PRACTICABILITY 



OF THE LINE OF THE MARIAS PASS OF THE NORTHERN LIT.TLE BLACKFOOT TRAIL, AND OF THE 



SOUTHERN NEZ PERCES TRAIL. 







WASHINGTON, D. C., July 19, 1854. 



SIR: On the 7th of October, 1853, in the valley of the St. Mary s river, I received from you 

 instructions to examine Marias Pass, to return to Fort Benton, and again from that post to travel 

 westward, crossing the Rocky mountains by such pass as shall be expedient, and the Bitter Root 

 mountain by the southern Nez Perces trail, to Wallah-Wallah. 



Three days later, having rested my animals, I left the last camping ground made by Lieuten 

 ant Donelson with the main train on Jocko river, and travelling northwardly, followed Jocko 

 river to its mouth, and then journeyed up the valley of Flathead river. Until near Flathead 

 lake, the valley of this river continues wide, grand, and bordered by partially-wooded hills. 

 Most of this land is capable of occupation and settlement. The river is a fine, clear stream, one 

 hundred to one hundred and fifty yards wide, occasionally fordable, swift current, and is esti 

 mated to have a descent of about ten feet per mile. About ten miles before reaching Flathead 

 lake we leave the river and pass out of sight of it, and its issue from the lake could not be ascer 

 tained. The trail wound around the western shore of the lake. Its edge curves sharply and 

 often, winding around the woody and rocky hills rising from the waters. The lake itself is a 

 sheet of water of great beauty, some twenty-five miles long, and six or eight broad ; is adorned 



