morning, the 10th instant, with a lighter (formerly the G. W. P. Custis) towed out by the steamer Coeur de Lion, having on board competent assistant aeronauts, together with my new gas generating apparatus, which, though used for the first time, worked admirably. We located at the mouth of Mattawoman Creek, about three miles from the opposite or Virginia shore. Yesterday I proceeded to make observations, accompanied in my ascensions by General Sickles and others. We had a fine view of the enemy's camp-fires during the evening, and saw the rebels constructing new batteries at Freestone Point. I was under the necessity of returning for some necessary articles this morning, and will go back immediately to continue in person the reconnaissance.

After making all necessary arrangements below, and leaving a competent aeronaut and assistants in charge, I shall return and place the other balloons wherever the general desires them. I have now a competent aeronaut for each of the new balloons, and in the course of a few days they can all be in active operation. I will call and see you on my return.

Your obedient servant,

T. S. C. LOWE,

Aeronaut.

HEADQUARTERS OF THE ARMY,
November 16, 1861.

Professor LOWE:

General McClellan desires me to say that he desires, to have the first balloon kept ready to be sent to Port Royal; the second one he desires to have sent to Brigadier-General Stone, at Poolesville as soon as it is ready.

I am, sir, very respectfully, your obedient servant,

A. V. COLBURN,

Assistant Adjutant-General.

HEADQUARTERS OF THE ARMY,
Washington, November 16, 1861.

Professor LOWE:

General McClellan desires that you have a balloon ready to be taken to Port Royal by the first opportunity. It is impossible to tell exactly when it can be sent, but I will try to give you three or four days" notice.

Very respectfully,

A. V. COLBURN,

Assistant Adjutant-General.

A report was circulated that the enemy were advancing their forces, and I was ordered to make a reconnaissance, of which the following was the result:

NATIONAL HOTEL,

Washington, November 21, 1861.

Lieutenant Colonel A. V. COLBURN:

DEAR SIR: Yesterday I inflated one of the balloons, the Intrepid, and moved it to Minor's Hill. It being too late for taking observations last night, I ascended at daybreak this morning, and remained up until 8 o"clock, which was sufficient to ascertain that the enemy is not in force this side of Centerville. Judging from our own camp-fires and smokes, I should say there may be three or four regiments at Fairfax Court- House; twice that number at Centerville and more at Manassas, but nothing like the amount of smokes from our own camps in General Porter's division.

Their line of picket smokes near the line of the Leesburg turnpike was quite regular, and occasionally pickets could be seen in the roads and clearings, but owing to the haziness of the atmosphere no moving bodies of troops or their tents were visible. The balloon for the South is all ready. Can you tell me from what place I shall ship the materials for making gas? If from here I must have them sent from Philadelphia to this city, that they may be ready.

I intend going down the river to-morrow to reinflame the balloon at Budd's Ferry. By that time the apparatus for Poolesville will be ready, and I will station one there also.

Very respectfully, your obedient servant,

T. S. C. LOWE.