HEADQUARTERS HOOKER'S DIVISION,.

Camp Baker, Lower Potomac, Maryland, December 15, 1861.

Brigadier General S. WILLIAMS,.

Adjutant-General, Army of the Potomac:.

To-day the enemy have exposed a battery of two pieces on a bluff bank, nearly midway between Cockpit and Shipping Points. It is directly across the river from the head of Stump Neck. The battery is concealed from view by the forest in which it is planted, but from the reports of the pieces and the accuracy of fire it is the opinion that the guns were taken from what is called the Maryland field battery of 12-pounders, which is encamped in the vicinity. We will know more of this in a day or two. The river is narrower at this point by a quarter of a mile than at Shipping Point, but as the channel hugs our shore a little closer than at Budd's Ferry, the difference, of range cannot be material. I am not yet prepared to say that it will add to the annoyance of vessels navigating the river..

I desire to call the attention of Major-General Commanding to the hazards of my position from the closing of the river by ice. From the present time until the 1st of March the navigation is liable to be interrupted from this cause, and in 1855 it was continuously suspended for a period of six weeks. It is not an unusual occurrence for the Potomac to be frozen over to its month. This will prevent supplies reaching us either from Washington or Baltimore..

I have not visited Liverpool Point for several days, but learn that our mechanics are making good progress with our store-house..

Very respectfully, &c.,.

JOSEPH HOOKER,.

Brigadier-General, Commanding Division..

[WHELLING,] December 15, 1861.

Brigadier General L. THOMAS, Washington, D. C.:

I have the honor to report, for the information of the Commanding General, my return to this place. The general orders of the 30th have been executed, except as to the four more regiments to Kentucky. The state of affairs now existing should be brought to the General's attention, as it may require his orders for a delay. There is a strong force reported on the headwaters of Sandy, not in my department. There is a direct turnpike road from Charleston to Sandy and from Sandy to Raleigh. Our stores are ordered up to Fayette, Gauley, Charleston, &c. Would it not be well not to thin still more the scattered forces until we see if an expedition cannot be arranged to cut off this rebel force? Sandy region ought, it seems to me, to belong to this department. Will the Commanding General allow me to come to Washington and see him in reference to these and army other details relating to the good of our service?.

W. S. ROSECRANS..

ADJUTANT-GENERAL'S OFFICE,.

Washington, D. C., December 16, 1861.

Brigadier General B. F. KELLEY, U. S. Service, Romney, Va.;.

The news from Virginia is that you are to be attacked by some 7,000 or 8,000 men, probably from Winchester. It is supposed troops enough to repel them have been ordered to join you..

L. THOMAS, Adjutant-General..