casemates, for reversed flank defense, be prepared in the northwestern angle, and that the exterior covert-way be prepared with platforms and embrasures for a battery of field artillery.

The works thus far mentioned form a group by themselves form a group by themselves, and can scarcely be called "Defenses of Washington, " though doubtless having an important bearing on its defense. To defend Washington, strictly speaking, requires simply that the enemy shall be kept off from the banks of the Potomac to such a distance that he cannot shell the he cannot shell the city, and this object is accomplished by the chain of works from Fort Scott to Fort De Kalb, resting its left on Four-Mile Run and its right on the Potomac. The works in question are, strictly speaking,for the defense of Alexandria and the railroad terminus. It is unnecessary to expatiate on the importance of holding these points; and these remarks are made to show that the lines of works necessarily embrace something more in their objects than the mere defense of Washington.

Fort Scott forms the left interior line covering Washington. That is, in connection with Fort Richardson, it continues the line to the Potomac, thus forming a complete defensive system independent of the works previously mentioned, which over Alexandria. Its position is important and commanding, and the works is well constructed and provided with ample bomb-proofs and magazines. Under circumstances, the Commission do not find cause to recommend any modifications. They would recommend, however, the eventual filling up of the gap between this work and Fort Richardson, by a small work on the elbow of the ridge, and such other additional arrangements as may be necessary to make this interior line complete.

Fort Richardson occupies a very commanding position. It is small, but well built, well armed, and amply provided with bomb-proofs and magazines. The ravines in front will be seen by the rifle-pits in construction. A 100-pounder is being placed in this work, which will sweep a sector from Fort Ellsworth to Fort De Kalb. Considering its position (in a re-entrant) and difficulty of access, the Commission do not judge it necessary to recommend of reversed flank defenses.

Fort Albany is a work partly bastioned, well built, and in admirable condition, the parapets being turfed and scarps reveted with boards. It is well defiladed, and in a very advantageous position to cover the Long Bridge, and look into the gorges of Forts Richardson and Craig. It sees the high ground in front of Fort Tillinghast, and commands the valley between Forts Richardson and Scott. It is well provided with magazines, embrasures, and bomb-proofs. Some heavy rifled pieces are wanted.

Fort Runyon. - Though this work has not the importance it first had, it should not have been permitted to fall to decay, nor to be disarmed, as has very improperly been done. As a tete-de-pont, it should be rearmed, and kept in perfect condition in every respect.

The five works, Forts Craig, Tillinghast, Cass, Woodbury, and De Kalb, extend the line from Forts Richardson and Albany to the Potomac, opposite Georgetown, covering what are usually called the Heights of Arlington, heights from which the enemy would have within long range of rifled guns the most important public buildings of the city. The line would have been better had it been thrown half a mile farther forward; but its location where it is, on ground by no means unfavorable, was not an error of judgment, but a necessity of the circumstances under which it was built. In reference to this part of the line, the following general remarks are made: The line south of Fort Richardson,