During the time of fire it is very important to know much the shot or shell fall short, if any at all.

Very respectfully, yours,

J. F. McQUESTEN,

Lieutenant and Aide-de-Camp.

[Inclosure.]

SEPTEMBER 24, 1861.

General F. J. PORTER:

If we fire to the right of Falls Church, let a while flag be raised in the balloon; if to the left, let it be lowered; if over, let it be shown stationary; if under, let it be waved occasionally.

W. F. SMITH.

HEADQUARTERS OF BALLOON,
Arlington, September 24, 1861.

Brigadier General F. J. PORTER,

Commanding Division, Fort Corcoran:

SIR: This evening I took the balloon out near Ball's Cross- Roads and remained up nearly two hours. I had a distinct view of the works on a hill about one mile and a half beyond Munson's Hill. There seems to be heavy guns mounted and a pretty heavy force near by. Several tents were visible about there and a number of bodies of men on parade.

To the left of a high bluff, and about ten miles distant to the left, or nearly in a line with Bailey's Croos-Roads, there appeared to be a long line of smoke, as if there were several camps. The smokes of the enemy's pickets are quite numerous and a large body of men were on Upton's Hill, and also what appeared to be a field piece.

The whole distance from Chain Bridge to Falls Church is shown plainly from my new point of observation, and I think a shell could not be fired without seeing where it strikes.

Should it be convenient for you to come and go up in the morning the first thing, I think you will gain some valuable information.

Very respectfully, your obedient servant,

T. S. C. LOWE.

CHAIN BRIDGE, September 24, 1861.

General PORTER:

I am going to Lewinsville to-morrow (Wednesday). Will you let Professor Lowe up at 11, or little before, to watch the road from Falls Church and round to Lewinsville? Can"t practice at fort to- morrow.

W. F. SMITH.

CHAIN BRIDGE, September 25, 1861.

Professor LOWE:

General Smith desires you to go up in the balloon this morning to observe the movements of troops, although we will not fire from the fort. The general is going out with the command, and firing will only be done in case the enemy is met.

C. MUNDEE,

Assistant Adjutant-General.

SEPTEMBER 25, 1861.

PROFESSOR: Look out for a battle at Lewinsville, and movements between us and that point.

F. J. PORTER.

Send me word of anything important.

SEPTEMBER 25, 1861.

PROFESSOR: I am anxious about the movement from Chain Bridge. The enemy has moved north and has all his force between General Smith and Lewinsville, evidently to intercept his return.

I wish to get as much information of his movements, or what is transpiring, as possible before sundown. I expect the return of the enemy, and if much dust be visible wish to know it, that I may send out a force.

F. J. PORTER.

If you can get up against this wind, will be glad. An important move is on foot.