HEADQUARTERS ARMY OF THE POTOMAC,
April 21, 1863.

Respectfully returned.

Captain Comstock will make the necessary arrangements for the balloon to be placed at the disposal of the War Department and advise the Assistant Secretary of War, as herein directed.

If it is possible for him to spare an aeronaut he will name the one selected in his communication concerning the balloons.

By command of Major-General Hooker:

S. WILLIAMS,

Assistant Adjutant-General.

HEADQUARTERS ARMY OF THE POTOMAC,
Camp near Falmouth, Va., April 15, 1863.

Honorable P. H. WATSON,

Assistant Secretary of War, Washington, D. C.:

SIR: Your letter of the 13th instant is received, and in answer would respectfully state that the weight and bulk of the apparatus and supplies necessary for the balloon to be sent South or West are as follows: Two balloons and appendages, about 500 pounds, in a basket three feet by five and two feet deep.

One set of gas generators to go in two army-wagon running gears, same dimension as wagon body and five feet high, weithing about 1,000 pounds each. Material to keep one balloon inflated day and night for two months will consist of 100 carboys of sulfuric acid, weighing about 16,000 pounds, and twenty barrels of iron turnings, weighing about 10,000 pounds. The cost of the above amount of gas material, as now purchased, is about $350 - less than $6 dollars per day. The acid can be obtained from Messrs. Savage & Stewart, Numbers 18 North Front street, Philadelphia, Pa.; the iron at the Washington Navy-Yard. The aeronaut, Mr. James Allen, will be in Washington on Monday next, with everything complete and ready to start from that point, provided the quartermaster procures the acid and iron above mentioned. The salary required by Mr. Allen is $5 per day with rations, or $5.75 per day without rations, and all necessary transportation.

I remain, sir, with great respect, your most obedient servant,

T. S. C. LOWE,

Chief of Aeronautics, Army of the Potomac.

BALLOON CAMP,

Near Falmouth, April 14, 1863.

Professor LOWE,

Chief of Aeronautics:

An extensive camp seven miles southwest of Sherwood's forest; one extensive camp southeast of Sherwood's forest, about five miles; one southwest of the left of our picket line, about four miles from the river; one extensive camp eight miles from the left of our picket line in a scout-southwesterly direction. About ten miles from Sherwood's forest in a westerly direction I saw a large column moving to our right, or the left of the enemy.

I am, sir, yours, respectfully,

JAMES ALLEN,

Aeronaut.

HEADQUARTERS AERONAUTIC DEPARTMENT,
Camp near Falmouth, Va., April 14, 1863.

Captain V. B. COMSTOC,

Chief Engineer, Army of the Potomac:

CAPTAIN: On hearing that Mr. Allen saw a column (whole in the balloon near White Oak Church) moving to the right, I immediately went up in the balloon near Falmouth Station to observe if any extra camp smoke or fires could be seen to the west, but was unable to notice any change, except a few camp-fires not noticed before, on the road from Fredericksburg toward Chancellorsville, I should judge about six miles. All the rest of the camps remain the same as usual.

This p. m. three regiments were drilling on the flats, tow to the south and one to the right of Fredericksburg.

The following are the compass bearings of the various camps, as seen by Mr. E. S. Alen from balloon near Falmouth Station.

Extreme right to extreme left: Numbers 1, 3, to 4 miles west; Numbers 2, 2 miles west by south; Numbers 3, 2 miles southwest by west; Numbers 4, 2 to 3 miles southwest; Numbers 5, 2 to 3 miles southwest by south; Numbers 6, 2 miles south; Numbers 7, 4 to 5 miles south; Numbers 8, 8 to 10 miles south.