CHARLESTON, December 13, 1862.

Major HARRIS,

Chief Engineer, Dept. South Carolina and Georgia:

SIR: The question asked me are:

First. When was boom commenced?

It was commenced about 5th May.

As I do not know what the object of the inquiry it is difficult to conjuncture what additional facts may be useful; but I must state that neither the nor the amount of labor will serve as an index of what might have been the rate of progress in construction.

It was a constant subject of mortification and remonstrance that either labor or material were wanting; consequently little effective work was done before September. By way of illustration, in the month of May no timber was received; in June 455 logs were received, a large portion of which were unfit for use; in July 463 logs; in August 594 logs; in September 3,622 logs received, and there was no excess; logs; in September 3,622 logs were received, and there was no excess; that is, they were consumed nearly as fast as received.

Second. How much of it is a present in useful condition?

Two thousand two hundred and fifty yards of boom are in dock ready for use. Of that which has been laid it is supposed that one in the may want repairs.

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

If the means are furnished the work requiring most time is the construction of chains. It is safe to say 16 feet of this may be made per diem at each forge engaged. Seven thousand feet of chain will lay 1,000 yards of boom in the manner proposed; that is, with a pair of anchors every 90 feet. This amount could be made in forty-four days by the forges. I think it can be made in less time, but time certainly would be lost in organizing work, &c.

Fourth. What proportion of raw material have you on hand necessary to carry out your plans (and finished material)?

We have about 150 logs, about 28 tons cast iron, and 16,000 feet round iron for making chains.

With respect to finished material, we have on hand 1,122 feet good chain, suitable for morning; an uncertain amount of inferior chain that would serve to connect the lines of boom. We hope to recover about 4,500 feet.

If a thousand yards of boom are to be laid it will require 66 anchors; 1,500 yards will require 99 anchors, allowing one up and one down stream.

We have in the channel from 25 to 30 anchors, but there will probably be some loss in recovering them.

I beg to call attention to the fact that the light-boat windlass is inadequate to the work required. Before it be carried on again it will be necessary to provide something more powerful. We have suffered from this deficiency since the beginning of the work. To continue in the same way will only bring discredit on our operations, which is not merited. Also I have a white employed as watchman over the yard, and docks since the withdrawal of all the negroes. He cannot be held responsible for losses. It is my wish to transfer all material, &c., to the engineer department as soon as possible.

Respectfully, your obedient servant,

JOHN R. CHEVES.