CHARLESTON, S. C., December 17, 1862.

Brigadier General THOMAS JORDAN,

Chief of Staff and Assistant Adjutant-General:

GENERAL: In reply to the indorsement of the general commanding on the report of Dr. Cheves concerning the boom, asking the following questions, we have the honor to state:

1st. When was this boom commenced?

It was commenced about the 5th May last but from want of material and labor it was not fairly under construction till about 1st September.

2nd. How much of it is at present in a useful condition?

There are 2,250 yards of it in dock in good condition; 1,500 yards of it laid in boom, one-tenth of which may need repairs; 1,122 feet anchor chains in store; 4,500 feet anchor chains in boom, which may be recovered; raw material and hand, considered ready for use 16,000 feet; iron for making chains will make 5,500 feet. About twenty-eight tons cast iron will make 11 anchors. Twenty-five to thirty anchors laid, 15 of which can be recovered; 150 logs. The distance to be laid, 1,500 yards; double chain 3,000 yards. Sufficient boom to lay it 3,750 yards, constructed; 100 anchors required for laying 1,500 yards double chain; 26 anchors on hand; 21,000 feet chain required for laying 1,500 yards; 6,622 feet on hand; 4,500 feet can perhaps be recovered, making 11, 122 feet.

3rd. When would it be completed if carried on on the present plan?

Dr. Cheves thinks that if material can be procured as needed, in a month and a half ten forges can supply anchor chains; the boom might be railed in two months from the time of beginning to lay.

4th. Can anything, in your opinion, justify the hope of its being completed with success and in time?

The boom is star on enough to resist the tide. The breaking we believe not to have been from any direct strain, but by entangling for want of anchorage to hold it in position. The boom can be retained in position by sufficient anchorage, which can only be determined by experiment. We can state nothing positive in regard to the time of completion as we have no certain information that material can be procured when needed.

5th. What is its present cost and what be its final cost if completed on the present plan?

The cost of the boom to December 15 about $185,000, amounts paid; accounts for the 16,000 fee iron and other not yet presented; estimate inclosed. If completed in two months, according to third answer, it will cost $93,000, inclusive of $5,000, estimated cost of recovering what is now laid.

The boom could be beached at considerable expense and time; the only object being to prevent the floats becoming water-logged; but, as Dr. Cheves reports, perhaps one-tent of it may need repair, it would be necessary to bring it to the city, where it could be done.

The boom, modified to the plan of attaching the floats by swivel single chain, will cost to change and lay it across the harbor about $48,000, including the estimate of cost of removing the present one $5,000. This boom would not have the strength of the double one, but would leave their remainder (1,875 yards) to be used for a second line, or at other