58 LETTER TO THE SECRETARY OF WAR, 
route was good, there having been a scarcity only two nights. He fitted out Mr. Tinkham’s 
party for this difficult work to his entire satisfaction, and at the last crossing of Clark’s fork 
he despatched, in conformity with my instructions, Lieutenant Arnold to Fort Colville, with a 
thoroughly organized detached party, with instruments for the determination of the barometric 
profile and the latitude. At Colville I left instructions to Lieutenant Arnold to place his ani- 
mals and most of his men in camp, to ascend the main Columbia in canoes to the 49th parallel, 
and there ascertain the important facts of the geography, and to send word by Indian runners 
to Dr. Suckley to cross by land from the Pend d’Oreille mission to Colville, the navigation 
thence to Colville being dangerous and almost impracticable ; and I left it discretionary with 
Lieutenant Arnold to go to Wallah-Wallah from Colville either by land, along its left bank, 
or in boats, leaving also Dr. Suckley a like discretion in reference to my original instructions. 
For my instructions to Lieutenant Arnold, see paper 9 from Colville, (this paper has been 
mislaid,) paper 10 from Camp Washington; and to Dr. Suckley, see paper 11, also from Camp 
Washington. I will here observe that on the route from St. Mary’s valley I met many Pend 
d’ Oreille Indians, and took measures which I trust secured Dr. Suckley an Indian guide the 
whole distance from Fort Owen to the Pend d’Oreille mission. I also was able to do something 
towards bringing into relations with Lieutenant Mullan all the Indians going to the buffalo 
hunt. They have a common route through the St. Mary’s valley, and pass within a short dis- 
tance of Fort Owen. 
In a letter received from Lieutenant Arnold by the Hudson’s Bay express, and which is given 
in paper 12 in the appendix, (this has been mislaid,) I learned that he reached Colville with 
his party on the 31st of October, and that after making the examinations required of the 
Columbia, in the vicinity of the 49th parallel, he should decide to go to Wallah-Wallah by 
land; and I am assured by that chivalric and American-hearted man, A. McDonald, Esq., the 
factor in charge of the Colville post, that he would render him every assistance in his power, 
With it and the examination already made, we shall have an excellent general knowledge of 
the country from Colville to Wallah-Wallah, and the several crossings of the Columbia, Spo- 
kane, and Snake rivers, and be able to connect the best pass of the Cascades with that of the 
Coeur d’ Alene range. It was in moving from Colville and the Clark river crossing, on the 
morning of the 26th of October, that the only snow on the entire route fell. It was to the 
depth of some three to six inches, and disappeared in a few days. 
Camp Washington was putes up on the 29th, 30th, and 31st of October, and Wallah- 
Wallah was reached by myself on the 2d of November, by Lieutenant Donelson on the 6th, 
and Captain McClellan on the 7th of that month. 
Here I learned that the emigrant wagons had succeeded in crossing to the sound by the Nah- 
chess Pass, and learning from Pu-pu-mux-mux, the Wallah-Wallah chief, that his people were 
now going through it on horseback, and being satisfied, from the known height of the pass, the 
general character of the season as shown in the quantity of snow on the Blue mountains, and 
the inferences to be drawn from the extraordinary mildness of the Puget sound climate, that it 
would be practicable for some twenty days, I assigned Mr. Lander to the duty of carrying over 
it the odometer survey, of observing the general character of that range as regards railroad 
constructions, and of adding to our knowledge of the meteorology of that region. I have not 
a copy of that order with me, but will send it in a future communication. 
To fit out Mr. Lander for that duty, I got horses and grain; but the day after my departure 
Indians came in with information that snow had fallen in the pass, that the last emigrants had 
lost their animals in it, and that even Indians had been compelled to turn back. Mr. Lander 
then determined to follow in the trail of the other parties to the Dalles: 
Although I regret Mr. Lander did not persevere, I do not censure him for his course. Ina 
new country it is very difficult to get the truth from the information given, and it has been 
found to be our most vexatious experience on the whole march. But it would have proved, 
in my judgment, an entirely practicable undertaking, and would have made our information 
