sorties, &c. It is not entirely completed. At the Chain Bridge the position is enveloped by a well-arranged system of rifle-pits. The line commences again at Fort Alexander, and continues to the Eastern Branch; from the first-named point to Fort Massachusetts being of dimensions enough to cover entirely a man standing in the trench, and to contain two ranks. From Fort Massachusetts to the Eastern Branch the pits are intended only for one rank. The Commission recommend that the dimensions be increased to admit two ranks. Fort Mahan is surrounded by rifle-pits, and some have been constructed in connection with other works over the Eastern Branch. The Commission recommend the construction of rifle-pits in connection with each work,or system of works, of this group, so as to view and defend its own approaches, a continuous line not being necessary.

Wells. - Generally the works are (in some cases at great expense of labor) provided with copious wells. There are yet some, however, where they are wanted, and where they should be provided.

Roads. - On the south side of the Potomac there are roads enough, or nearly so; but they require much work, such as widening, raising, constructing of culverts, &c., to make them practicable for winter. A new military road has been constructed from Fort Alexander to Fort Massachusetts, having branches connecting with the different works. The roads along the line thence to Fort Lincoln (partly made by the engineers) make the chain complete. Much work, however, is required on the main stems leading from the city, to make them practicable in the winter. A military road has been made to Fort Stanton; another is in construction behind the ridge from Fort Baker to Fort Meigs, to enable succor to be given promptly to the works. The communications with Forts Carroll and Greble are probably sufficient. It has been estimated that the work on roads about Washington requires ten regiments for twenty days, and efforts have been made to obtain this or an equivalent

of labor in some other shape. The Commission further state their opinion that the Defenses of Washington cannot be considered complete without the defense of the river against an enemy's armed vessels. Foreign intervention would bring against us maritime forces, and we could not depend upon being always in superior naval force on the Potomac, and we are, even now, threatened with Confederate iron-clads fitted out in English ports. Fort Washington is too distant for defense of the river under existing circumstances,for the superiority of the enemy in the field, which would drive us behind the Washington lines, would prevent our supporting that work if attacked by land. The Commission believe that a satisfactory defense may be afforded by placing on Jones' Point, near Alexandria, a battery of six guns of the heaviest caliber, say four 200-pounders and two 15-inch guns in casemates, and by constructing a battery of ten guns and a covering work on the opposite shore of the Potomac, at or near Rozier's Bluff. An examination has been made, revealing a most favorable and strong position on that side, easily communicated with by water. Surveys are in progress. The occupation of a point on the other shore in this vicinity will likewise protect Alexandria from cannonade, to which it would be exposed if left open to the enemy. The Commission recommend,as an additional security to Washington, the establishment of two heavy guns on Giesborough Point.

The Commission conclude their report by expressing their convictions of the great importance of this system of defenses to Washington, and by urging upon the War Department and Congress to take steps and provide means for a full and early completion of the work.