ROCKY MOUNTAIN PASSES. 101 



in whose judgment and experience I place great confidence. The route will be long, in conse 

 quence of the curves of the river, and will involve curves of the minimum radius, numerous bridge 

 crossings, considerable side-cutting, and high embankments on the prairie portions in consequence 

 of the spring freshets. The rock in side-cuttings can be easily quarried. The greater portion 

 of this route has been personally examined by me, and I am satisfied of its practicability, though 

 at great expense. 



The divide of the Jocko, though five hundred and sixty feet above Hell Gate, is entirely 

 practicable. To overcome the summit the approach may require a grade of fifty feet, and the 

 descent a grade of sixty feet ; both, however, for short distances, with heavy embankments and 

 probably a lofty bridge. Farther down the valley is open and easy, and the grades do not 

 exceed twenty feet. There are no short curvatures. Lieut. Donelson is of opinion that these 

 grades may be reduced to forty-five and forty feet. 



The distance to Horse Plain from Hell Gate by the two routes is 136 miles by the Jocko, 

 and 143 miles by the Bitter Root, giving seven miles in favor of the former route. It is probable 

 that the greater amount of curvature on the Bitter Root would be at least as serious a difficulty 

 a^ the greater grades of the Jocko. The cost of the Jocko will probably be some half a million 

 of dollars less than that of the Bitter Root. 



Tt is probable that a better connexion than either of these could be made by leaving the 

 Blackfoot trail some distance before entering the defile, passing over a low divide, and pursuing 

 the valley of one or two streams which flow into Clark s fork. One of these streams is probably 

 a tributary of the Jocko river. Enough is known of the country through an exploration made 

 by Mr. Tinkham, under the direction of Lieutenant Donelson, to make it probable that the 

 grades will not exceed forty feet, and that the curves and expensive embankments, and sustaining 

 walls of the defile ending in Hell Gate, and of the Bitter Root valley, and the high grades of the 

 Jocko route, will thus be avoided. The route is indicated by dotted lines on the sketch, and 

 should be carefully examined in subsequent surveys. By referring to Mr. Tinkham s route, as 

 shown on the map and explained in his report, it will be seen that he observed ah 1 but a few 

 miles of both routes, and that the connexion is almost certain. 



I will observe, however, that the examinations of this mountain range, whilst they have been 

 exceedingly satisfactory, and have established the practicability of a railroad route through them, 

 are by no means complete. 



It is not doubted there are other passes in this portion of the Rocky mountain range even better 

 than those explored; they are indicated by the general depression of the mountain range, with the 

 greater frequency of the streams stretching out to meet each other from the opposite slopes of the 

 mountains; and I consider it important that, in future operations, a whole season should be 

 directed to their thorough examination, and that instrumental surveys should be made of the 

 pass found to be the most practicable. 



In the construction of the road through the Rocky mountains, there will be a scarcity of wood 

 and water in the approach from Milk river, which can be remedied by bringing water in aque 

 ducts from Grizzly Bear lake, and wood from the Rocky mountains, which furnish an inexhaust 

 ible supply. 



