FALMOUTH, VA., August 26, 1862.

(Received 1 a. m.)

Major-General HALLECK, General-in-Chief:

The following dispatch just received from General Porter:

FROM ADVANCE.

My aide has just returned from Bealeton. He says Birney is there with two regiments, one at Rappahannock Station. Pope's headquarters are at Warrenton; Kearny is at Sulphur Springs; Reynolds at Warrenton. Banks and Sigel are at Sulphur Springs; there is fighting there to-day. A deserter came over to-day, crossing at this way are their regiments which have been cut up in the battles. At Brandy Station are 500 wagons, guarded by a small force of infantry and a squadron of cavalry. At Rappahannock Station the river is fordable for all arms. Are my arrangements satisfactory?

I have answered him as follows:

Your arrangements are satisfactory. I have not telegraphed because General McClellan is here and we have been waiting instructions from Washington. Hold everything below Rappahannock Station, and, if necessary, re-enforce that. Weed's and Randol's batteries go to you at once. If you want more artillery, it will be sent as soon as Sumner lands. We will forward his troops to your support. As soon as the supply train can be loaded I will send it to you. Your wagons shall be sent as they arrive. Let me know what you want, and, if possible, it shall be supplied. I will send you 150 cavalry to-morrow and more as soon as I get them. Much obliged for your full information.

A. E. BURNSIDE,

Major-General.

FROM ADVANCE, SIX MILES FROM BEALETON.

(Received August 26, 1862.)

General PARKE:

I dispatched you from Bealeton, under the impression that Sykes was 3 miles off. I went to Barnett's. All is well at the first two. Griffin is at first. Morell, with two divisions, at the second, I have decided to post Sykes at Bealeton, and picket, with strength from infantry and artillery, Rappahannock Station, and patrol with cavalry. The Rappahannock is fordable everywhere, and if the enemy desired to cross he could do so with a larger force than I have. Cam, for want of water, cannot be found nearer, except within gun-shot. I have sent back cavalry as fast as I could, and ordered them from the divisions, and directed Morell to use those at the fords. This I had done before receiving your telegram. The 150 cavalry will be a good thing. Send grain. Provisions can be brought from Bealeton to Warrenton. Please send up the wagons and ambulances, and have the drivers directed to pick up sick in a house about 9 miles from Bealeton, on right-hand side, and bring them here. The supply train must go to Barnett's and Kelly's Fords; ambulances also which belong to Morell's. Please have sent up to-morrow an operator and instrument for Bealeton o\to work the other lines; also the corps' mail.

F. J. PORTER.

BEALETON STATION, VA.,

August 26, 1862-2.30 p. m.

General MCCLELLAN, Aquia, and General BURNSIDE, Falmouth:

Have been to Rappahannock Station, and find it in possession of General Kearny, whom I will relieve to-morrow. No enemy in front.