No information of the receipt by Mr. Mallory of the letter of this Department has reached me, but as it was sent to Lieutenant-General Grant, to be forwarded through the lines, it is presumed it reached its destination, and that there will be no obstacle in the way of effecting the exchange of the prisoners now sent down, and of receiving such of ours as are within reach in return.

Accompanying this is a list, but not a perfect one, of our officers of the Navy imprisoned in the South.

As you are doubtless aware, Lieutenant Commander P. Williams has returned home under parole, and the Department, in view of the contemplated general exchange, considered it unnecessary for him to return. Act. Ensign F. W. Sunburn was also permitted to come home in order to effect an exchange for Acting Master Bnneau, the latter of whom goes out in the Circassian. Acting Master Dillingham has likewise returned with the view to effecting an exchange for a Captain Fowler, who was captured at Sabine Pass. There seems to be no satisfactory evidence of Fowler being an officer in the so-called Confederate Navy, and the Department has not included him in those sent down. Any other equivalent can be given for Acting Master Dillingham.

In addition to the Navy officers sent down, there are two officers of the so-called Confederate Army, viz, Major Harold Borland and Major G. A. Preston. The former can be offered in exchange for Major Forbes, of Boston, who was captured near Aldie Gap.

The Department, in a letter to Major Borland, has informed him that he could remain in the Department of the South until an answer is received in reply to the offer, or until Major Forbes should be delivered to you.

Major Preston has been sent out with no view to exchange for any specially-named person, but simply in compliance with his request and at the urgent solicitation of Commander William A. Webb. He can be offered in exchange for an equivalent. Both of the Army officers named were captured by the naval forces.

Among the prisoners on the Circassian is Francis Hernandez, of Saint Augustine, Fla., who was captured in violating the blockade. He is sent down as an act of humanity, being quite old and anxious to return to his family and friends, and is in bad health.

We have in our forts many blockade-runners who have been appealing to the Department to send them with the Navy officers and seamen for exchange, and expressing confidence that they would be received. It is believed that there is or will be a large excess in favor of the South in this exchange of naval officers and seamen, for whom we will have to give equivalents, in accordance with the understanding between this Department and Mr. Mallory. But I have declined to send out the blockade-runners referred to, because we have no assurance that they would be received upon the same footing as the Navy officers and seamen. Most of them were masters of the blockade-runners commanded by officers of the so-called Confederate Navy.

If, as I have informed Commander Webb, they will be received for our officers and seamen, they will be sent to you in the Circassian as she comes along on her next trip to the Gulf.

You will find among the prisoners several who were recently captured at Mobile, and have just been brought North.

Our officers and seamen imprisoned in Texas, and many of whom have been there over eighteen months, deserve our first consideration, and it is hoped the authorities at the South will take the earliest means to place them in our hands.