Positions of guns and emplacements for guns in the fortress of Yorktown, beginning with water battery and going around the entire main works of Yorktown from east to west.

Water battery of one 8-inch columbiad; one 64-pounder gun; two 8-inch columbiads, and one 42-pounder carronade. (Lower or beach battery; two or three of its guns would see our battery-Numbers 14, perhaps Numbers 13 also.)

Three 9-inch Dahlgren guns and one 10-inch columbiad. (Water battery is on left flank of front of attack, drawn on siege sketch, with embrasures, but the embrasures had been filled with guns mounted en barbette. The 10-inch columbiad would probably have borne on our Battery Numbers 14.)

Front of attack.-One 6 1/2-inch rifled gun (burst); one 9-inch Dahlgren occupying place of next, i. e., one 6 1/2-inch rifled (burst); one 8-inch columbiad; two barbettes for field guns (guns gone); one 32-pounder; two barbettes for field guns (guns gone); one 32-pounder, navy (burst); one 8-inch columbiad; on 8-inch siege mortar; one 244-pounder gun; one barbette for field gun (gun gone); one 8-inch columbiad; one 32-pounder, navy; one 24-pounder gun; one 32-pounder navy; one barbette for field gun (gun gone); one 4 1/2-inch rifle; one barbette for field gun (gun gone); one 32-pounder navy; one 24-pounder gun; one 7 3/4-inch carronade; one 24-pounder; one 8-inch columbiad, and one 12-pounder gun.

On parts of works not seen by our approaches.-One barbette for field gun (gun gone); one 24-pounder gun; one 12-pounder gun; one 6-pounder gun; one barbette for field gun (gun gone); one breech-loading rifle, 2 8/10-inch caliber; six barbettes for field guns (no guns); one 42-pounder carronade; three barbettes for field guns (no guns); one 42-pounder carronade; four barbettes for field guns (no guns); one 42-pounder carronade; four barbettes for field guns (no guns); one 42-pounder carronade, and three barbettes for field guns (no guns).

Redoubt of five 8-inch columbiads; battery of four 8-inch columbiads; battery of four 32-pounders; battery of three 32-pounders; (two-thirds at least of these guns would have borne upon our battery Numbers 14, some on battery 13); battery of two 32-pounders (gone, probably removed since siege began and mounted elsewhere); flanking battery to ravine of one 42-pounder carronade (to sweep to beach.).

Battery for two guns (no guns in place) and battery for five guns (no guns in place) on beach (upper battery.)

Total arrangement for guns 94, of which we captured 53 guns in good order; 3 guns burst. Total number of guns, 56. Barbettes for field guns 31, and 7 embrasures for navy guns.

J. G. BARNARD,

Brigadier-General and Chief Engineer.

Numbers 21. Report of Lieutenant Cyrus B. Comstock,

Corps of Engineers, U. S. Army, of Confederate works at Gloucester Point, Va.

CAMP WINFIELD SCOTT, NEAR YORKTOWN, VA.

May 5, 1862.

SIR: In compliance with your instructions I have to-day visited

22 R R-VOL XI