The command is improving daily in target practice, and a company of good sharpshooters can be selected from them. The skirmishing and bayonet exercise (the latter, however, the non-commissioned officers only drill at) are progressing as well as could be expected. They are ready to march when ordered, and prefer it to lyaing in garrison.

Very respectfully, your obedient servant,

EDWIN A. RIGG,

Major, Commanding Post.

P. S. -Lieutenant Nichols, First Cavalry, has arrived here, recalling Doctor Prentiss, substituting Doctor Meacham as judge-advocate. As soon as their horses get the rest they require after hard travel, the doctor will report as per instructions. I am of the opinion that Doctor Prentiss and Lieutenant Nichols, coming as they have on the trail from San Bernardino, but little traveled heretofore, the fact of their coming in four days from San Bernardino is evidence of the route being a good one for mounted men; but the doctor thinks that a party of five or six only could travel together.

E. A. R.

[Inclosure Numbers 2.] FORT YUMA, January 13, 1862.

Major E. A. RIGG,

Commanding Fort Yuma:

SIR: Pursuant to special instructions dated at Fort Yuma, Jauary 10, 1862, I proceeded, accompanied by John Costello, as guide, to Fort Gaston, on the Colorado River, via the Hoffman route. The following is the result of my observations: From Fort Yuma to Hoffman's camp, on lagoon, six miles; good road to an plenty of wood and water at camping place; no sand, and very bushy. Thence the trail is plain, good for about ten miles over a gradually ascending mesa, or table-land. Thence five miles over a rough, broken country, washed out in deep gullies and ravines; a range of black hills on the west and Chimney Peak on the east. Some Gila grass in the ravines; plenty of wood (mesquite and iron-wood), but no water; thence gradually descending alongisde of a ravine for about six miles, toi a tank marked by a pile of stones on the east side of the trail; plenty of water at this time; very little wood, and no grass of any kind. The guide informed me that the water dries up certain seasons of the years. Thence down along the same ravine about one mile. Here the trail goes into the bottom of the ravine. Thence down the bottom of the ravine, over deep sand, for about two miles to small lake, with good water, the hills narrowing in and forming a deep canon, in some places not over twenty feet between bluffs. Thence the trail crosses a rough, steep rock ridge about one mile from the base to the ravine on the other side. Trail over loose stones and steep ground very difficult even for mules to pass. At the foot of the hill on the north side is a tank of living water sufficient for all purposes; very little wood, no grass of any kind. Thence two miles down the ravine, over heavy sand to the Colorado River. Plenty of wood, but no grass. Thence up the river about nine miles to grass. A very fine place for camping for a small train, the grass being limited in quantity, say about two acres of good grass; wood plenty. Nine miles farther up the river is Hoffman's, or Grass Camp. Here is plenty of good grass and wood. thence nine miles, to Fort Gaston, where there is conisdrable Gila and bunch grass. The sit eof the old fort is on a gravelly bluff about thirty feet in height. The trail up the river is generally good. In some places, however, it is washed in gullies and ditches, which