bridge across the Rappahannock is completed, and that a train from Culpeper has arrived (yesterday) at Warrenton Junction. At Fredericksburg only few troops. I expect further news this evening.

F. SIGEL,

Major-General.

WASHINGTON, October 6, 1862.

Colonel J. C. KELTON,

Assistant Adjutant-General:

COLONEL: I am informed, by Captain Sawtelle, that probably about 500 contrabands can be obtained from Fort Monroe. I desire them very much for work on the fortifications of Washington, and request that, if consistent with other requirements of the service, they may be ordered here at once. There are steamers at Fort Monroe, by which they can be brought up immediately..

As everything connected with this subject of the fortifications of Washington is left to my individual will, I take this occasion to state what I am doing, and what, I think, is required.

Before the battle of Bull Run, the idea of the fortifications of Washington was not broached, the works previous to that (Forts Ellsworth, Runyon, Albany, and Corcoran) being for special purposes. Imperfect, as a system of defense, as those works were, they doubtless exercised an important influence in deterring the enemy from following up his success by an assault upon Arlington or Alexandria, and the necessity of completing the fortification of Washington became evident.

It was an immense undertaking, for the line to be held was 35 miles long, through a country extensively wooded and of intricate topography. The work was not fully inaugurated until the latter part of August, and its extension around the northern sides of the city, and over the Eastern Branch, was of later date. During, therefore, the five months of August, September, October, November and December, the entire defensive line, 35 miles in length, consisting of about fifty different works, and mounting four hundred and forty-three guns, was, though not completed essentially brought to the condition in which it was left when the Army of the Potomac commenced its campaign in Virginia.

It is no matter of surprise that a work which, to be thoroughly well done, required so much preliminary study and reconnaissance, and which was executed under the pressure of an enemy in our front, allowing no time for such thorough study, should be found in many respects imperfect; besides, it was necessary to commence works in many cases before the woods could be cleared away enough to give that perfect knowledge of the ground essential to their best location.

As the season of construction drew to a close, the sense of danger to the capital in great measure passed away, and, in making an appropriation to meet liabilities actually incurred, Congress prohibited the application of that appropriation to the commencement of any new works, although there were several gaps to be filled, and much work necessary on some part of the line to five them any real defensive strength.

On resuming charge of these works, in August last, the condition may be briefly stated as follows:

On the south side of the Potomac there were probably works enough, and the woods had been pretty well cleared from the front. A few auxiliary batteries have been judged necessary, as well as the connection of the works by rifle-pits or infantry parapets. A remark should be made about Fort Lyon. It is a very large work, and a very important.