The shelling of our camps by the enemy caused me to give the order to Fort Strong always to reply shot for shot to the enemy's batteries. On the night of the 8th to the 9th instant, while a quite lively fire was being exchanged between Fort Strong, and Sullivan's Island, a blockade-runner undertook to run in. Either struck by our shells, or from fear of them not daring to keep in the channel, she ran aground, as was discovered by daylight the next morning. She was an iron steam propeller,of about 200 tons burden. She was aground immediately outside of Fort Moultrie and was entirely knocked to pieces and sunk by our fire.

All the reconnoitering parties sent up to and around Sumter report a very heavy swell in the channel, even during a calm night. This, and the want of professional men,has caused great delay in regard to the placing and explosion of the mines. I have not wished to try anything on a large scale before the men were accustomed to work on a small scale, and in these latter attempts they have failed thus far, simply from want of experience and of care. I am progressing slowly in this matter, but an confident of final success. The greatest effect will doubtless be obtained if we are able to explode those mines at the same time that our artillery fire on the fort is the heaviest.

Orders have been given by me to buoy out the channels of the harbor between Sumter, Jonson, Simkins, Paine's Dock, Forts Strong and Putnam. These orders have been partly executed. One-third of the plank walk from the left batteries over the marsh to Paine's Dock is finished.

The old batteries at the front are at present in tolerable repair. The new battery, I hope, will be finished this week. One of the magazines is nearly finished at present; one of the platforms is ready, one will be finished to-day, and one gun will be mounted to-night. The so-called Swamp Angel Battery was finished and the 30-pounder Parrott mounted there on the 13th instant. The firing from this gun seems to be quite effective, as reported by the pickets on Paine's Dock. The fire from our front batteries against Sumter has necessarily been slow and at long intervals, from want of ammunition and guns.

I have borrowed 450 barrels of powder and 1,000 30-pounder shells from the navy, in order not to be obliged entirely to suspend my fire. I have thus managed to keep the forth in about the state it was a fortnight ago,and it is my intention not to do more for the present and until a sufficient number of guns and supply of ammunition has been brought to the front batteries to admit of a constant fire for about one week. I have made my intentions in this respect the subject of a confidential communication to the major-general commanding.

On the 6th instant, a party of 100 infantry and a section of the Rocket Battery, under command of Captain Zeh, of the Seventy-fourth Pennsylvania Volunteers, was landed at Legareville and proceeded in a westerly direction as far as the bridge across Aberpoolie Creek. The object of the movement was,in case any of our escaped Union officers were on John's Island, back of Legareville, to give them the opportunity to come in. The party proceeded as far as the bridge, driving in the enemy's cavalry pickets before them. No casualties occurred and the party returned at evening.

On the night of the 6th to the 7th, a party of 30 cavalry, 60 infantry, and a section of the Rocket Battery, under command of Captain