to the Chain Bridge, over which it is indispensable to secure a debouch. The position is strong, and well occupied. The lines of rifle-pits which connect the works with each other, and with the banks of the river, afford with the auxiliary batteries, full view and defense of the numerous ravines, and give all the artificial strength which the position needs. The heights from which the works can be commanded, and the approaches to them, are under the fire of the heavy guns (the 100-pounder Parrott, and rifled 42-pounders and 30-pounder Parrotts, and 32-pounder sea-coast guns) of Batteries Cameroon, Parrott, Kemble, Vermont, and of Forts Alexander and Franklin.

The Commission suggest that some defensive arrangements are necessary immediately about the head of the bridge; probably two or three small works, or,perhaps, block-houses would suffice.

Forts on Upton's, Taylor's, and Munson's Hills.- An army falling back on Washington after defeat, or on account of inferiority of numbers, might find it advantageous or desirable on many accounts to occupy temporarily or permanently this advanced position; its left resting on these naturally strong points, its right on the works at Chain Bridge. On the other hand, should Washington be threatened while held merely by a garrison, these works are too far advanced to be held. We recommend that the existing works be preserved from dilapidation, and consider nothing more necessary.

Forts Alexander, Franklin, and Ripley -This group of small works occupies a commanding, but advanced, position. The occupation is indispensable to the security of the Chain Bridge, and protection of the receiving reservoir. The fires from these works add, at the same time, greatly to the strength of the works and position in advance of the Chain Bridge. The salient position of these works them, in great degree, upon their own strength, while there are heights to the northward dangerously near, affording convenient emplacements for the enemy's artillery. The fire from the 100-pounder at Fort Pennsylvania reaches the heights in question; so, too, to a certain degree, that of the rifled guns of Fort Mansfield and adjacent batteries. The fire from the works themselves upon these heights is quite inadequate; the guns (32-pounders) crowded and wholly exposed. The Commission recommend, first, the union of the three works into (essentially) one, by connecting parapets; second, the removal of three 24-pounders now useless, from Fort Ripley, and placing them in battery behind the connecting exterior parapets; third, the buildings of melons, to protect all the barbette guns bearing toward the heights mentioned; fourth,the construction of traverses on the southwest faces of Fort Alexander; fifth, the providing of platforms behind the external parapets for at least a dozen field guns to bear upon the heights; sixth, the introduction of another 100-pounder into Fort Alexander or Fort Franklin. (Part of the matters here recommended are in course of execution.) Between these works just named and Fort Mansfield are two well-constructed and well-located batteries for field guns, for sweeping the ravine in front of Fort Mansfield.

Fort Mansfield. - The name is applied to two considerable redoubts and an exterior battery, connected by a substantial rifle-pit. The works are well located, as connecting links between Forts Ripley and Pennsylvania; are well built, and deemed adequate for their purpose. Still another redoubt (not named) is in construction on this line, near the Great Falls turnpike.

Fort Pennsylvania. - This work occupies a commanding position,at a point where the dividing ridge between the Potomac and Rock Creek