ENGINEER DEPARTMENT, Washington, March 23, 1861.

Captain J. G. FOSTER,

Corps of Engineers, Charleston, S. C.:

CAPTAIN: I have to acknowledge the receipt of your favors of the 17th, 18th, and 19th instants. For these and the previously received diurnal reports, the results of your vigilant observations and evidences of your devotion to your duties and loyalty to the Government, be pleased to accept the thanks of this Department.

Very respectfully, your obedient servant,

JOS. G. TOTTEN,

Brevet Brigadier-General, and Colonel of Engineers.

Numbers 81.] FORT SUMTER, S. C., March 23, 1861.

(Received A. G. O., March 27.)

Colonel L. THOMAS,

Adjutant-General U. S. Army:

COLONEL: I have the honor to report that we see them at work at the large battery near Fort Johnson, behind which they appear to be constructing something with heavy timbers, and at battery Numbers 1, on Morris Island, which they are extending. At the last firing from this battery both shot and shell were thrown. They are also at work on a new battery, not far from the Moultrie House, on Sullivan's Island. This makes, as far as we can judge, four batteries between the fort and the east end of the island. As we are very deficient in ammunition, I have directed the quartermaster to turn over to the Ordnance Department a quantity of flannel shirts, from which I shall have cartridge bags made.

Our sick-list is the same as when last mentioned. They practice daily, firing shot and shell in the direction of the junction of the Swash and Main Channels. Their practice is pretty good. They are firing now from heavy mortars in rear of the iron-plated battery on Cummings Point. I have no ammunition to spare, and, therefore, do not show them our proficiency in artillery practice.

I am, colonel, very respectfully, your obedient servant,

ROBERT ANDERSON,

Major, First Artillery, Commanding.

Numbers 82.] FORT SUMTER, S. C., March 24, 1861.

Colonel L. THOMAS,

Adjutant-General U. S. Army:

COLONEL: I have the honor to report that I do not see them working anywhere this (Sunday) morning, except at the large battery at Fort Johnson. I omitted mentioning that buoy Numbers 3 has been put down again, but, I think, not exactly in the place it formerly occupied. Everything was quiet and still last night. Our sick-report has only four to-day.

I am, colonel, very respectfully, your obedient servant,

ROBERT ANDERSON,

Major, First Artillery, Commanding.