eral Heintzelman, Major-General Augur has been placed in command of teh department. Your past promptness and diligence give me assurance that you need no fresh admonition.

EDWIN M. STANTON,

Secretary of War.

BALTIMORE, MD., October 13, 1863. (Received 9 p. m.)

Major General H. W. HALLECK,

General-in-Chief:

Have instructed Captain Duvall as to guard at Hog Island Light-House. Ordered (Saturday) a cavalry guard from Drummondtown to Assateague Light-House. Have no other troops but three cavalry companies on the Eastern Shore of Maryland and Virginia Cannot get any information from General Kelley as to General Lockwood or regiments ordered here.

ROBT. C. SCHENCK,

Major-General.

HEADQUARTERS CHIEF ENGINEERS OF DEFENSES, Washington, October 13, 1863.

Honorable E. M. STANTON,
Secretary of War:

SIR: All the officers to whom the Government has committed the defense of harbors, from General Totten, Chief Engineers, down to his lowest subordinate, and all those who represent the interests of cities to be defended or the civil power of these municipaties or States, are unanimous as to the necessity of providing obstructions in channels to be defended, to arrest and detail iron-clad vessels under the fire of the shore batteries.

For the last six months or more the matter has been undergoing investigation in New York, but as yet, no practical result has flowed from it, and in the case of engineer officers, while all lay down the necessity of the thing, none can answer what it shall be. That the problem is one of exceeding difficulty all admit, but if nothing is decided as to plan even, what shall we do when the time for its use arrives?

The collection of materials alone is an immense undertaking; the fabric must be the result of time. I have devoted some thought to the matter, and have had the assistance of very able engineer officers to sketch out a project of obstructions. I believe the only way to solve the problem is to go at it practically.

An efficient barrier in the Potomac at Rozier's is estimated at about &300,000. If we should get into a war with a maritime power while the rebellion is yet powerful, Washington is, next to New York, a probable point for attack through the Potomac. It has now no formidable batteries, as New York and Boston have. The guns which will be mounted in the two new earth-works (sixteen in all) appear to be the only thing likely, for a long time, to oppose an enemy's reaching Washington through teh Potomac. Should the emergency occur, therefore, the engineers and the navy would both be called on to make their opposition efficient by providing the only thing that can do so, viz, obstructions.