ROUTE NEAR THE FORTY-SEVENTH AND FORTY-NINTH PARALLELS. 
43 
the east,) two passes in the Rocky mountains, in latitude 46° 30', were explored. They are 
sometimes called the Northern and Southern Little Blackfoot Passes, hut named in Governor 
Stevens’s map as the Hell-Gate Passes. They connect between the waters of the Little Black- 
toot and Prickly-Pear creeks. 
South of these, in latitude 45° 45', another pass was examined, called the Hell-Gate Pass. 
It connects the south fork of Hell-Gate with a branch of Wisdom river. And still further 
south, in latitude 45° 3S', another pass, called the Big Hole Mountain or St. Mary’s Pass, was 
explored, connecting the waters of St. Mary’s river with a fork of Wisdom river. These last 
four passes are all reported as probably practicable; hut as the southern Little Blackfoot, Hell- 
Gate, and St. Mary’s Passes received no instrumental examination, as the last-named is out of 
direction, and the two former involve a considerable detour from the route of the Missouri, are 
approached with difficulty, and will only become important should a good route or routes be 
found through the Black Hills to the Mississippi, it is unnecessary to note them further. The 
profiles of the northern Little Blackfoot with its approaches from the Missouri, of the valleys of 
the Little Blackfoot and of part of the Hell-Gate river, were determined by Mr. Tinkham, his 
instruments consisting of a barometer and pocket-compass. 
The approach by this route is over a broken region of country, and a better approach, it is 
thought, will be found north of the Missouri, nearer the base of the mountains, along the line 
examined by Lieutenant Mullan. The elevation of the summit is 6,250 feet; a tunnel of two 
miles will be required. The eastern approach is estimated practicable with grades of fifty or 
sixty feet per mile, and the western descent with a grade of thirty feet to the mile. A thorough 
examination of this route is recommended in connexion with the other passes in this vicinity. 
It is unnecessary, therefore, to consider it further, since the data are still too imperfect to 
enable us to form certain conclusions. 
Three passes through the Bitter Root mountains were explored; a fourth was subsequently 
examined, but has not yet been reported upon; a fifth pass, the northern Nez Perces, it was 
not considered necessary to examine. 
The passes reported upon are that of Clark’s fork, which has been adopted as being the 
least difficult; the Cceur d’Alene Pass, by the Coeur d’Alene Mission, and the southern Nez 
Perces trail. Beginning at the south, the southern Nez Perces trail, leading from the head of 
St. Mary’s river to the head of a tributary of the Snake river, (the southern fork of the Columbia) 
was examined by Mr. Tinkham, in the latter part of November and first half of December; 
his instruments were a barometer and pocket-compass until the former was cached. From the 
great height of the summit, 8,000 feet, and the great depth of snow so early in the season, 
it is not necessary to consider this pass. It is probably impracticable. 
The northern Nez Perces trail is reported to be of the same character. 
The Coeur d’Alene Pass, leading from the Bitter Root near its junction with the Flathead 
to the Spokane river, if found to be practicable, would give a route to Wallah-Wallah seventy 
miles shorter than that by Clark’s fork; but as no instruments for measuring vertical or hori¬ 
zontal distances were carried with the party that examined this route, its practicability cannot 
be considered established, but merely such information gained as serves to show that it is 
probably practicable, and that an instrumental profile should be taken. 
The pass of Clark’s fork formed by the passage of the river through the Bitter Root mount¬ 
ains, along which the main party travelled, is practicable. 
It will be noticed that the passes of Lewis and Clark, and Cadotte, give the most direct route 
from the line east of the Rocky mountains to this pass. 
We will now return to the line of the main party at Hell-Gate, the termination of the Black¬ 
foot valley. From this point two lines were examined to Clark’s fork. One follows the valley 
of the Bitter Root to Clark’s fork ; the other crosses a dividing ridge to the valley of Jocko 
river, keeping along this stream to its junction with the Flathead, which it then follows to 
Clark’s fork. 
