WASHINGTON, August 30, 1862.

General S. WILLIAMS,

Assistant Adjutant-General:

I have consumed all the forces Casey has to give. Another regiment goes over the Eastern Branch to-day. I do not immediately assign it to increase garrisons, because there is an immense amount of chopping to do, as necessary for the security of the works as garrisons even. Telegraphic communication on this side has been ordered to Forts Marcy, Alexander, Pennsylvania, Massachusetts, Lincoln, Baker, and Carroll.

There is a station at Arlington which answers pretty well for the chain of works from Corcoran to Craig and Albany.

Before giving directions about the rest of the line I desire to know whether it is considered as under my charge. Colonel Tyler's regiment is not part of my command, nor are the troops which guard that part of the line.

Colonel Congdon, with about 300 or his command, has been sent up the Potomac with instructions to watch carefully the river as far as Edwards Ferry. I am not kept posted as to the situation, but I know the fords above are practicable, and the appearance of the enemy on this side would not be extraordinary. The forts alone cannot prevent his passage and the troops are few and raw, and I would recommend that a division, or at least a brigade, of old troops be posted on this side. I had already made arrangements to meet the need of artillerymen reported by Colonel Webb. Captain Ellis is held responsible for the destruction of the Chain Bridge.

The roads leading into the city are held as well as means admit.

I shall have guards at the two bridges over the Eastern Branch and the draws raised from 9 to 5.

J. G. BARNARD,

Brigadier-General.

CAMP NEAR ALEXANDRIA,

August 30, 1862-3.20 p.m.

Brigadier-General BARNARD, Washington:

Your telegram to General Williams received. Of course everything is under your charge, as usual. Upon arriving here and finding the state of things uncertain in my front, I took all the means in my power to place affairs in a safe condition. At the request of General Halleck I sent some of my staff officers to inspect the works. I have placed Tyler's regiment in garrison near here and ordered the Fourteenth Massachusetts to duty again as heavy artillery. I have merely used my authority as the senior general officer for duty to assist you, having failed to find you.

The whole of Sumner's corps has been ordered to the front by General Halleck. Couch's division will take the same destination as soon as it arrives. I am now sending off my own camp guard and escort, the best I can do. Tyler will of course be under your orders so long as he remains in the works. I have no more troops to give you, and, as I have no command nor any position, I shall not regard it as my duty to take any further steps in regard to the works except that I shall always be glad to confer with you in regard to any point about which you may be in doubt.

I shall try to see General Cox at Upton's Hill to-day or to-morrow.

48 R R-VOL XII, PT III