FORT SUMTER, November 14, 1863.

COLONEL: Although I expressed myself to you last night as fully prepared to execute cheerfully and plans proposed under the new project of defense, I take this opportunity to record one or two difficulties which have suggested themselves to my mind as connected with its execution. The advantages of the change are, if I remember rightly, two-the ease of the garrison, and the promise of a more complete capture of the attacking force.

The first is no doubt attainable, but, if the result be adverse, will have ben a fatal concession to the troops. The second is, I must believe, very problematical, judging from the safety with which the boats, large and small, have for nights past landed on the west front of the fort and the known expertness of the enemy's boat-crews.

Again, the advantage of meeting the attack on the parapet does not seem to me a thing to be thrown away. Under the circumstances, I respectfully give it as my opinion that there is no impracticability in a combination of the old and new plans of defense, and that both be tried if perfect success be desired. There would be but little more difficulty in changing from a parapet to a bomb-proof defense in the first than in the last plan. Notice must be given in both of the enemy's approach and of the withdrawal of our men into the bomb-proofs; and the enemy is either case will surely calculate on the contingency of having to attack in the bomb-proofs, and even perhaps under the fire which they know as well as we it would then be practicable for us to open upon the fort from the harbor batteries.

I remain, very respectfully, your obedient servant,

JNO. JOHNSON,

Captain of Engineers.

Colonel D. B. HARRIS,

Chief Engineer.

FORT SUMTER, November 20, 1863-10 p. m.

MAJOR: I have the honor to report the firing last night was as follows:

Rifled shots, 97, of which 25 missed. The working force was engaged upon filling passages to east magazine and casemate, preparing two casemates over hospital for loop-holed musketry defense and repairing top of central bomb-proof.

The working force of 130, under Oversee McNeill, was relieved by fresh force of 119 under Overseer Mikell. The transfer occupied about an hour, and was effected without any casualty.

At 3 a. m. musketry firing from the parapets creating an alarm, the force was withdrawn. Three or four boats from the enemy had been discovered on the sea front, and when fired on were seen to return the fire. The James Island and Sullivan's Island batteries opened in our support, also the gunboat off Fort Johnson. The alarm subsided in an hour.

During the night two slight casualties. The enemy's light was shown during the alarm, but their fire was suspended a half hour. The firing to-day was heavy, and as follows:

Rifles, 18, of which 8 missed; mortars, 379, of which 146 missed; total, 397, of which 154 missed.

About 10.30 a. m. a mortar shell, descending at entrance to east end of center bomb-proof, cut through, without much smashing, the