LETTER TO LIEUTENANT MULL AN. 
61 
struck the Missouri there is a very excellent prairie road leading westward; hut being unable 
to ford the stream where I struck it, I was compelled to follow down the course of it for eight 
miles to find a ford, and then crossed a high ridge of mountains west of the Missouri, in order 
to cut off the distance to my left. This prairie extends about twenty miles to the west, to the 
dividing ridge, where rises the main fork of the Bitter Root river. This dividing ridge, from 
which flow the waters of the Missouri and the Columbia, I crossed on the second day from the 
Missouri, and it proved the only difficult point of passage in my route from Fort Benton. This 
divide is about four hundred feet high, and about three miles across. I here fell upon the 
headwaters of the main fork of the Bitter Root river, the valley of which I followed down till it 
unites with the Blackfeet fork of the Bitter Root river at Hell Gate. This valley is about a mile 
wide, and well wooded with the pine and cotton-wood tree, and affords a most excellent road 
for the passage of wagons. There is a well-beaten trail along this valley, made by the Flat- 
heads in their course to their hunting-grounds east of the Missouri. I would here mention 
that this same trail leads along the north fork of the Muscle Shell river; thence down the river 
to its mouth. The grade of this valley is scarcely perceptible, and along it you pass along the 
slope of but one mountain, which, with but little trouble, would allow wagons to pass over it. 
After leaving the main fork, I crossed the Blackfeet fork of the Bitter Root, and followed 
along it for six or eight miles, and thence crossed to the St. Mary’s by a most excellent prairie 
road. I found good grass and water for my animals on nearly the whole route, and slept but 
one night without wood, which was between the Missouri and Muscle Shell. I would mention 
particularly the valleys of the Muscle Shell and the main fork of the Bitter Root rivers, as being 
well grassed. I found, in both valleys, the grass green, rich, and luxuriant, and water and 
wood in abundance. This wood I found to be principally the pine, cotton-wood, spruce, cedar, 
and hemlock. I would also mention that game in the greatest abundance is to be found along 
the whole route—buffalo, elk, antelope, and bear. I would also mention that I found the 
weather much more mild west of the Missouri than east of it. For full details as to the char¬ 
acter of the country, for each day’s march, and the streams and rivers passed, I would refer 
you to my journal. 
I have the honor to be, sir, your obedient servant, 
Hon. Isaac I. Stevens, 
Governor of Washington Territory. 
J. MULL AN, 
Lieutenant United States Army. 
No. 2. 
Northern Pacific Railroad Exploration and Survey, 
Fort Oxoen, St. JSlarif s Valley, October 3, 1853. 
Dear Sir: You are placed in charge of the meteorological and supply post established in 
this valley, with Mr. Adams and Mr. Burr, assistants; Sergeant Simpson, in charge of the an¬ 
imals; Corporal Rose, Privates Wolfe Williams and Toohill Isham, of the 7th infantry; and 
Simpson, Farnham, Osborne, Osborne, jr., Mechelbach, and Bell, quartermaster employes, and 
Gates, to be chargeable to the survey. 
The object in establishing this post is twofold: lirst, to ascertain the character of the seasons 
in this valley, and the adjacent ranges of mountains, by numerous and carefully-made meteoro¬ 
logical observations: and, second, to continue the exploration and survey of the country between 
the Rocky and Bitter Root ranges of mountains, extending it to Fort Hall, to connect with the 
survey of Fremont, and northward to the Flathead lake, and even to the upper waters of Clark’s 
fork. As much time as practicable should be given to the examination of entrances to passes. It 
is believed you will be able to work late, and to resume operations at an early period in the spring. 
