Order Howe's battery, Fourth Artillery, to Washington, to join the Army of the Potomac..

The two Virginia regiments will be furnished with guns by the Ordnance Department. Orders will be given here for five regiments to report to Brigadier-General Kelley at Romney. Instruct General Kelley, on their arrival, to order the eight Ohio regiments to Camp Chase, to be reorganized and then sent to Kentucky..

The general staff officers at Cincinnati will be no longer under your command. The affairs of the depot there will be regulated by the bureau here. Your requisitions for supplies will be made ont hat depot as usual. Captain McLean, assistant adjutant-general, has been ordered. The recruiting service for volunteers will be conducted according to General Orders, Numbers 69. There are mustering officers at Cincinnati, Columbus, and Cleveland..

As far as possible you will avoid sending your sick beyond your department limits. A general hospital may be established at Wheeling. If the regimental surgeon give proper attention to sanitary precautions in the camp the sick list may be reduced..

You can continue the depots at Bellaire and Marietta, or move them within the limits of your department, as you deem best..

I am, sir, &c.,

L. THOMAS,.

Adjutant-General..

Memorandum for General McClellan..

[Made on or about December 1, 1861.]

The idea of shifting the theater of operations to the James, York, or Rappahannock has often occurred. The great difficulty I have found in the matter is that of moving a body as large as necessary rapidly, and of making the necessary preparations for such a movement, so that they should not in themselves give indication of the whereabouts of the intended operations in time to meet them..

The first thing to be considered is the old danger attending all similar operations. In cutting the enemy's line of operations you expose yourself, and a bold and desperate enemy, seeing himself anticipated at Richmond, might attempt to retrieve the disaster be a desperate effort upon Washington..

Leaving, then, as we should do, the great mass of the enemy in front of Washington, it would not be safe to leave it guarded by less than 100,000 men; that is, until we became certain that he had withdrawn from our front so far as to render his return upon it impracticable. It seems to me, too, that the roll garrisoning of the works up to the standard fixed upon should be completed without delay. These works will but imperfectly serve their purpose if they are not defended by troops who have some familiarity with their positions and duties. (Lieutenant McAlester asks urgently for the regiment of Colonel Poe, Heintzelman's division, to be added to the 600 men under Colonel Christian at Fort Lyon; in the first place to give an adequate and efficient garrison to that important work; in the second, to enable him to get fatigue parties large enough to finish if off.)

The works between Potomac Eastern Branch [?] are finished and armed (with exception of the three small works above Chain Bridge, not quite done). Of those over Eastern Branch, Forts Greble, Carroll, Stanton,.