BATTERIES AND RIFLE-PITS.

Auxiliary to Fort Whiplle four batteries-mounting respectively seven, four, ten, and four; aggregate, twenty-five guns-have been built, and 800 yards of rifle-pit or infantry covered way has been thrown up.

Across the valley of Four Mile Run, about 550 yards of heavy covered way has bee thrown up, with wet ditch in front.

Around and auxiliary to Fort Williams, 1,200 yards of rifle-pit or infantry covered way have been thrown up, and two batteries, mounting five guns each, have been built.

Between Forts Williams and Ellsworth, two batteries, mounting respectively seven and eight guns, have been built, and 100 yards of infantry parapet thrown up.

A battery mounting five guns has been built to right of Fort Lyon, together with fifty yards of rifle-pits.

NEW FORTS.

A new fort between Forts Strong and Woodbury, having 322 yard of crest line and mounting fifteen guns, has been nearly completed and is now nearly ready for its armament. it has one magazine, three traverses, and a bomb-proof, just commenced, 150 feet long.

A new fort between Forts Whipple and Albany, on interior line, having 539 yards of crest line and a proposed armament of thirty-three guns, has been commenced. The parapets are about half thrown up and some 100 yards of pole revetment completed.

A stockade, with gateway, has been built across the Leesburg turnpike to right of Fort Marcy, and some 150 yards of abatis laid in front of rifle-pit to the Potomac River.

A stockade, with gates, has also been built across approach to Aqueduct Bridge, and some seventy-five yards of rifle-it thrown up in connection therewith.

MILITARY ROADS.

The following military roads have been built during the year: Aqueduct Bridge to Fort C. F. Smith, one mile and a third; Fort c. F. Smith to Fort Strong including branch, two-thirds of a mile; Aqueduct Bridge to Fort Whipple, one mile and a half; Camp Barnard to Fort whipple, one mile and a quarter; Fourth-Mile Run to Fort Ward, two miles and a half; total, seven miles and a quarter.

Two large block-houses have been commenced and nearly completed in valley of Hunting Creek These have been built by the quartermaster department, under the direction of the chief engineer of the defenses.

CONDITION OF THE WORKS.

With a few exceptions, the first south of the Potomac are now very complete as to their interior arrangements. Most of them are provided with good bomb-proofs, magazines, implement and filling rooms, and traverses where required. In nearly all of them the platforms and embrasures have been repaired during the past season and are now in good order. The exterior slopes on the line from Fort Smith to Fort Berry (nine forts), inclusive, have been built up on 45-degree slopes