Oregon cavalry on the completion of the sixth company. It is now deemed important that the regiment should be completed, and I have directed Brigadier-General Alvord to call out sis more companies and organize the regiment in accordance with General Orders, Numbers 126, current series. Inclosed herewith is a slip from a paper published at Lewiston, Wash. Ter., relative to the navigation of Snake River, and the probability that steamers will be able to ascend as far as Boise or Salmon Falls.

Hoping that my action in completing the Oregon regiment may be approved, and that the establishment of a post at Fort Boise may be authorized, I have the honor to be, your most obedient servant,

G. WRIGHT,

Brigadier-General, U. S. Army, Commanding.

[Inclosure.] NAVIGATION OF SNAKE RIVER. -STEAMERS TO THE BOISE MINES.

Our readers will remember that in our issue of October 24 we alluded to the navigation of Snake River, and furnished the outlines of the explorers who were sent up to Boise to examine the reiver. Through the kindness of Captain Ankeney we are able to give a much mor eextended account of the trip. The party consisted of three reliabel men, Charles Clifford, Washington Murray, and Joseph Denver, and started from Lewiston under the auspices of Captain A. P. Ankeney, on the 20th of September. They followed the meandering of Snake to the mouth of the Grande Ronde, and found the distance to be twenty-seven miles, due south. It is an open river, with no obstructions. From Grande Rnde they proceed to interesect the old emigrant road, and reached it at or near its crossing of Powder River; a short distance farther on diverged toward Snake River, and followed it up to the Boise. For several miles the river runs through deep canons or mountain gorges, and has the appearance of being very deep, and shows by the banks that during certain season s of theyearit rises to the height of sixty feet. The party met several Indians, but none that were unfriendly. A great similarity exists in the whole country between Fort Boise and Lewiston, as does between Lewiston and where Snake empties into the Columbia. Sometimes bold, rocky sides, then beautiful rolling table-lands, interspersed with trees and prairie lands. The party passed through some of the most beautiful farming land in the world; deep, rich, dark loam, well watered and well timbered, with gold in all the ravines and gulches for the minner, and soil to provide him with the necessaries of life.

After their arrival at Fort Boise they proceeded to construct a boat, or more property a raft, to navigate the river with. In a few days they were rested and prepared, having taken the precaution to lash their provisiions on to the raft, bid adieu to Fort Boise, and came dashing, foaming, down the wild, tortuous Snake. The first canonof note was twelve miles in lenght, and here the banks gave indication of the water rising sixty or seventy feet. After this came an open space of eight miles, in which you could observe for a long distance the glorious open country. The weather was delightfull, and scenery inviting. The next canon or gorge was fourteen miles in lenght, and penetrated the two ridges of the Blue Mountains. The course seemed to be north, showing that Snake River runs north and south. After passing this cannon there came an open space, and alternately changing, but with no perceptible difference. About sixty miles brought them down to the mouth of Salmon, making, as they reckoin, inside of 100 miles from Fort Boise to Salmon.