Numbers 27. Report of Captain John Norris, Second Provisional Pennsylvania Heavy Artillery, of the defense of Washington.

FORT DE RUSSY, D. C., July 16, 1864.

GENERAL: I have the honor to report the number of shots fired at the enemy from Fort De Russy on Monday afternoon and Tuesday, the 11th and 12th instant, and their effect, as near as practicable, from Numbers 4 gun (100-pounder Parrott).

We fired 18 case-shot, 10 shells, and 4 solid shot. Twenty-two of these were fired on Monday evening and Tuesday morning on column of the enemy moving down the Brookeville turnpike toward Fort Stevens, and at trains parked in the fields adjoining the turnpike, at a distance, as near as I could estimate, of from 4,200 to 4,500 yards. Elevation and length of fuse were given for these distances. Having the use of a powerful glass, I considered the shots effective, at least in causing the enemy to move their trains and troops from time to time, and yesterday, as I made a close inspection of that point, found the enemy had been there in force. Two shells had exploded and struck the outbuildings of Mr. John Wilson, just to the right of the turnpike, about half a mile beyond Silver Spring; one had entered the ground half a mile farther to the north and exploded; others exploded just this side of the turnpike, and, as I learned from a citizen resident near by, caused at least a division of the enemy to transfer their camp to a woods beyond. Ten 100-pounder shells were thrown at a house about 1,700 yards to the north and this side of Rock Creek for the purpose of firing it, as the enemy's sharpshooters were reported there in great numbers. Two shells exploded a little short from defective fuses. The balance passed through and to the right of the house, exploded a little beyond. There were also fired at the house this side of Rock Creek ten 30-pounder percussion-shells were thrown at a body of the enemy advancing down a strip of timber about 2,800 yards distant and drove them back. Shots well directed. Seventeen time shells, 39 percussion-shells, and 3 case-shot were fired at squads of the enemy as they emerged from the woods and charged across grain fields at the time of the advance of our skirmish line on the afternoon of Tuesday, and at squad of cavalry in lane beyond, and had the effect to drive them back. These shells were thrown at ranges from 2,200 to 2,400 and up to 2,800 yards, but few of the percussion-shells exploded. With a few exceptions the time shells with paper fuses exploded at the desired points. Eight spherical case were used in Numbers 3 (32-pounder sea-coast gun) on enemy's line of skirmishers, at ranges of 1,600 and 1,700 yards, and exploded in air over their line, but with what effect I had not the means of knowing. In the lane above referred to lies the carcass of a fine stallion killed by one of our shells, and by the location of the wound his rider did not escape a severe wound. The body of one rebel was found at a distance of 2,600 yards in the direction of our firing badly mutilated by a piece of shell, and I am informed that a number of the severely wounded left at Silver Spring were wounded by our shells.