HEADQUARTERS DEPARTMENT OF THE SOUTH, Hilton Head, S. C., July 29, 1864.

General WESSELLS:

MY DEAR GENERAL: I have just received authority to exchange the prisoners in my hands, rank for rank, or their equivalents, according to the cartel. I send an aide-de-camp to make arrangements for the exchange.

Yours, truly,
J. G. FOSTER.

HEADQUARTERS DISTRICT OF FLORIDA, Jacksonville, July 29, 1864.

Lieutenant Colonel U. DOUBLEDAY,

Commanding Third U. S. Colored Troops:

COLONEL: I am directed by the brigadier-general commanding to give you the following instructions for your guidance at Palatka:

First. Build a strong inclosed earth-work, with good abatis, with well inside, and large enough to accommodate 300 men conveniently.

Second. Patrol with strong parties, and with cavalry as far as Orange Creek, near the site of old Fort Brooke. If you find that there is no force of the enemy in that quarter you might push as far as Silver Springs, or even Ocala, taking care to seize upon the Ocklawaha bridges near Silver Springs in order to secure a retreat by way of Fort Gates or Volusia.

Third. When you have cleared the rebels from your front, or found there are none, send a party in the Hattie or in boats to the Ocklawaha, and up that stream as far as safe, to cut away the trees felled over it, to seize on the Silver Springs a steamboat on that river, and to take possession of all lighters, ferry-boats, wherries, dugouts, and other craft of every description.

Fourth. Make inquiries of the whereabouts of the light-house lenses taken by the rebels at the beginning of the war and stored somewhere between Palatka and the town of Ocala. They are worth some $50,000.

Fifth. Get all the contrabands, horses, and all other lawful prizes of war, including mules, wagons, cotton, &c., making a full report of property taken and giving proper receipts for the same.

These instructions are for your general guidance, but may be modified by you accordingly to the exigencies of your position.

Very respectfully, &c.,

WM. A. BAILEY,

Captain and Assistant Adjutant-General.

HDQRS. DISTRICT OF FLORIDA, DEPT. OF THE SOUTH, Jacksonville, July 29,1 864.

Colonel WILLIAM H. NOBLE,

Commanding U. S. Forces at Baldwin, Fla.:

COLONEL: In obedience to orders, I leave for Hilton Head at 12 o'clock. You will be in command. The force you left at Picolata I have ordered to Palatka. I shall re-enforce them to-day with 300 men from the Third U. S. Colored Troops, under command of Colonel U. Doubleday, also with Captain Morton's cavalry. Captain Weiss