tinued firing about twenty hours, and knocked off the face of the wall around one embrasure of the pan-coupe to the depth of 22 inches. Instead of one 12-pounder rifle gun, suppose we have twenty of large caliber, and instead of two 8-inch columbiads, some 12, 10 or 11 inch guns there is little doubt of our ability to make a breach of any desired magnitude in a week or ten days. If we cut away the masonry between three or four of the lower embrasures to the depth of 3 feet, I believe the scarp opposite and above these cuts will fall over in a body, pressed as i always is by the trust of the communicating arches. If we cut away the 5 or 7 inch pier between any two casemate arches, all the casemate arches on that front of the work will, I think, fall down, for the piers are far from being abutment piers. Should any such accident occur to the right flank-a matter simply of time-I think the work could not much longer hold out. An assault would hardly be necessary.

Vessels drawing about 9 feet can be taken around the south side of Fort Sumter and placed opposite the gorge, 150 from the work, below the range of the barbette guns. The two casemates of each story, at each end of the gorge, are occupied as powder magazines.

Fort Sumter can the more easily of Fort Moultrie is taken first. From the latter place and its vicinity all the barbette guns which bear upon Cummings Point can be enfiladed in reverse. There is a platform 10 feet in width around Fort Sumter, about 5 feet below the lower embrasures. The outer slope of this platform are composed of rough granite, a part of the original artificial island.

Landing from boats on this platform would be very difficult.

OPERATIONS AGAINST CASTLE PINCKNEY.

This small work could not make much resistance after the capture of Moultrie and Sumter, provided we have the two iron-plated vessels considered essential to success in the general attack. These vessels may take a position north of the work at the distance of about 500 yards, where only guns can bear upon them, unless batteries have been built outside of the fort. Castle Pinckney, to vessels approaching Charleston by the main channel a semi-circle 168 in diameter, with eight casemate and ten barbette guns; two other barbette guns look north. The interior crest stands about 25 feet above the foot of the scarp and probably about 35 feet ;low water. The exterior pavement is 4 or 5 below the embrasures, and nearly on the level of the parade. The details may be learned from the drawing.

Castle Pinckney was supplied by the United States with the following armament: For casemates, four 42-pounders, four 24-pounders; for barbette, four 8-inch sea-coast howitzers, ten 24-pounders=22; two more apparently, than can be mounted in the work.

ESTIMATE OF THE MEANS REQUIRED FOR THE GENERAL ATTACK UPON CHARLESTON HARBOR.

Troops, including enough to hold some adjacent islands, 15,000; transports sufficient to carry the troops; fleet as large as the one which captured the works at Port Royal.

Iron-plated vessels required, 2.

Flats or small craft drawing 3 or 4 feet, and capable of carrying 100 men each, proof against musketry and field artillery, armed with boat howitzers, 30.