The usual amount of smoke arose from all the above camps this evening.

It is evident, from all appearances, that the enemy have not made any considerable move as yet.

The balloons will be up at daybreak if the weather will admit.

Very respectfully,

T. S. C. LOWE,

Chief of Aeronautics, Army of the Potomac.

CAMP NEAR FALMOUTH, VA., April 17, 1863.

Captain C. B. COMSTOCK,

Chief Engineer, Army of the Potomac:

CAPTAIN: During my observations to-day I was unable to discover any changes in the position of the enemy. The following is the compass bearing, taken of the enemy's position by Mr. Allen, from the Phillips house, which I find to be as near correct as is possible to get from that point.

Position of the enemy's camps as observed from balloon Eagle, April 17, 1863, beginning with the most distant one, west from Phillips" house, Va.:

Numbers 1, west 5 miles (large camp); Numbers 2, west by south 3 miles; Numbers 3, west by south 6 to 8 miles Numbers 4, southwest by west 2 miles (large camp); Numbers 5, southwest by west 12 to 15 miles (large camp); Numbers 6, southwest 3 miles; Numbers 7, southwest by south 3 miles; Numbers 8, southwest by south 10 to 12 miles (large camp); Numbers 9, south 2 miles (large camp); Numbers 10, south 3 to 4 miles; Numbers 11, south 8 to 10 miles (large camp). Three or four small camps near the river bank, south by east.

Very respectfully,

T. S. C. LOWE,

Chief of Aeronautics.

CAMP NEAR FALMOUTH, VA., April 18, 1863.

Captain C. B. COMSTOCK,

Chief Engineer, Army of the Potomac:

CAPTAIN: Inclosed is Mr. Allen's report of observations taken to- day. I ascended this p. m. (the atmosphere being cleared inthe west) and could see no change. The camp smoke arose from the usual places as far as I could see.

I could not get very high, however, in consequence of the strong breeze blowing t the time.

Very respectfully,

T. S. C. LOWE.

HEADQUARTERS ARMY OF THE POTOMAC,
April 19, 1863.

T. S. C. LOWE,

Chief Aeronaut:

Please inform me what has been the custom when on the march. Have the balloon guard moved with the balloon trains? And are two escorts, namely, the two details we now have needed, or only one, or none, in case of a movement?

Please let me know what material you think should go when we move.

These things should all be thought of and arranged, my approval only being needed.

Very respectfully,

C. B. COMSTOCK,

Captain of Engineers and Chief Engineer Army of the Potomac.

CAMP NEAR FALMOUTH, VA., April 19, 1863.

Captain C. B. COMSTOCK,

Chief of Engineers, Army of the Potomac:

CAPTAIN: In answer to yours of this date asking what has ben the custom when on the march, and whether the present escort are needed or not, O wild state that it has been customary for the men detached on the balloon service to accompany the aeronautic train in order that balloon observations may be taken along the route when required.

I would recommend that the details for both balloons be retained, inasmuch as considerable pains have been taken to instruct them in the requirements of the department. This will enable us to tow the balloons along as the army advances and take observations whenever required; and should bad weather compel us to discharge the gads, sufficient material should be taken along to reinflame, which can be done in the night, and observations taken of the enemy's position and the roads