barrier for the protection of this great city in locating the chain of mountains called the San Bruno across a great portion of the peninsula between the Bay of San Francisco and the Pacific Ocean. Commencing at Point San Bruno and extending to the San Pedro road, where the San Jose road intersects it is a continuous chain of impassable mountains with the exception of a narrow roadway lately cut out of the rock side, which is called San Bruno turnpike.

This road is susceptible of being defeated by sharp-shooters and a few field pieces until they reach Visitation Point a distance of about two miles. On this point batteries should be erected to guard against the enemy's occupying the Guadalupe Valley. On the other extremity of these mountains, as has already been mentioned the two main avenues or roads, the San Pedro and San Jose, connect and passing around the spurs of the mountains on the west reach the city through the extensive valley called the Rancho Rincon de las Salinas. It would become very important to establish batteries at and near the junction of those roads. Good positions for that purpose have been observed on the spurs of the mountains near the Abbey House, where the road passes. Ocean, it will be necessary to establish batteries near the Laguna de la Merced to prevent the position from being turned by an approach on the seashore.

The next important point to be protected by batteries will be on the west end of the Black Hill near what is called Shear's Five Mile House. From the Abbey House to Shear's two roads are constructed, the one diverging from the other until they converge again and unto at a point called Alemany's. From what has just been said of the Black Hills it becomes evident that the city must be defended at these important points by a series of batteries so placed as to command the two main avenues leading to it and at the same time overlooking the three principal and extensive valleys extending from the bay to the Pacific Coast, within the chain of the San Bruno Mountains. In the general plan of defenses for Fort Point and the Presidio there are two heights in the rear of the fort which it is proposed to occupy by permanent redoubts; the absence of sufficient appropriations has thus far prevented their construction, but it is probable that some means will be appropriated this session of Congress for an early commencement upon them. These redoubts are intended to prevent an approach on Fort Point by troops landing in the vicinity of Point L consequence very much needed in the defense of that position. It is believed, general, that the system of defense herein proposed to guard against an enemy's approach on the city of San Francisco will prove the most effective and that the advantages that can be taken of the positions indicated will be conducive of the greatest results with the smallest means of both men and materials.

With great respect, I am general, your most obedient servant,

R. E. DE RUSSY,

Lieutenant-Colonel of Engineers

HEADQUARTERS DISTRICT OF SOUTHERN CALIFORNIA,
Los Angeles, Cal., February 13, 1862.

Lieutenant Colonel E. E. EYRE,

First Cavalry California Volunteers, Commanding Camp Carleton:

SIR: Inform me how many days' subsistence you have on hand; how many you sent with Mr. Allen's train, and the number of days' forage