cover, and parapet to be thickened. Battery for Whitworth gun, near Numbers 14, commenced; boyaux, 2,500 yards, 6 feet wide and four fee deep, completed. Battery for Whitworth gun, near Numbers 5, has one row of gabions up. Lieutenant McAlester reports that his portion of the parallel will be finished to-nigh, including the additional banquette decided upon last night. He reports also that no interest whatever in the work could be excited in the officers, and that the men were therefore generally idle. The detail from the Mozart Regiment accomplished very little. Battery Numbers 11 is complete. Batteries No.s 9 and 12 progressed very slowly from a failure of carpenters and teams to report as expected. Lieutenant McAlester thinks they may possibly be completed to-night. Two-gun (Whitworth) battery located and commenced yesterday; will be ready to-morrow evening. Infantry road up right branch ravine commenced yesterday; will be finished and ready to-day. Redoubt C: the enemy concentrated so heavy a fire upon it that the working party was withdrawn at about 10 a.m. At night work was resumed upon it, but the officers and men from Hooker's division worked badly. Lieutenant McAlester thinks he will be able to finish it to-night. Captain Stewart reports that during a part of the day a party of 100 men was employed in revetting, building traverse, and repairing Battery Numbers 7; 200 men were engaged in making obstructions in its vicinity, and 200 men were at work on Numbers 8. A party of 200 men was engaged yesterday afternoon in forming the parapet of a barbette battery for two 8-inch siege howitzers in peach orchard clearing; also 100 men cutting timber in its vicinity. General Woodbury reports 255 of his command at work on bridges over Wormley's Creek; 100 on Battery Numbers 4; over 300 men on detached service, and the remainder variously employed. Two hundred and forty-two gabions were made yesterday and 485 issued, leaving 1,131 on hand. A large force will be employed in making fascines to-morrow. The road covering of bridges over south branch of Wormley's Creek is complete. The earth-covering will probably be done by Sunday night. The sand-spit pontoon bridge will, I hope, be done by Sunday night.

Sunday, May 4.-Battery Numbers 8 is reported as completed; some trees were to be felled to unmask it. A mortar battery near Garrow's Chimneys was being constructed; this would have been completed to-morrow. The parallel between Batteries Nos. 3 and 5 is completed. Battery Numbers 10: one traverse and magazine to finish and embrasures to open. Battery Numbers 13: three traverses to build. Battery Numbers 14: traverse to build and parapet to thicken. Battery for Whitworth guns: interior slope to be reverted. Battery for Whitworth guns, near Battery Numbers 3; parapet three-fourths done. Battery Numbers 5; change completed. Redoubt D commenced last night. Five hundred and seventy gabions and 83 fascines were on hand at engineer depot. No report has been received from Lieutenant McAlester of the work under his charge. Redoubt C was completed, and only a little finishing was required to be done upon the parallel and batteries between the branches of Wormley's Creek. The works upon the batteries, trenches, &c., were suspended on the morning of the 4th, the fortress of Yorktown and the whole line of rebel works, including the fort and batteries at Gloucester, having been evacuated during the preceding night by the enemy.

J. G. BARNARD,

Brigadier-General, and Chief Engineer Army of the Potomac.

General R. B. MARCY, Chief of Staff.

Brigadier General S. WILLIAMS, Assistant Adjutant-General.