DEPARTMENT OF STATE, Washington, December 3, 1861.

Major General JOHN A. DIX, Baltimore:

GENERAL: Herewith I have the honor to inclose for your information a copy of a letter received at this Department from P. T. Barnum, esq., in reference to correspondence between ex-Senator Mallory, now at Richmond, Va., and his daughter, Mrs. Bishop, who resides at Bridgeport, Conn., which it is supposed passes through Baltimore. Will you please adopt such measures for the suppression of this correspondence as in your judgment are necessary and proper?

I am, sir, very respectfully, your obedient servant,

F. W. SEWARD,

Assistant Secretary.

[Inclosure.]

LINDENCROFT, Bridgeport, Conn., November 29, 1861.

Hon. SIMON CAMERON.

DEAR SIR: The daughter of ex-Senator Mallory resides here with her husband, who is brother to our late ex-member of Congress, William D. Bishop (secesh). Of course Mr. Mallory (Secretary of the Navy in secesh) resides in Richmond. the daughter, Mrs. Bishop, is in constant correspondence with her parents and their letters are mailed to her in Baltimore. Of course the letters are brought from Richmond to Baltimore by some private hand. Such a letter arrived here last night and they continually arrive at intervals of two or three days.

Your obedient servant,

P. T. BARNUM.

DEPARTMENT OF STATE, Washington, December 3, 1861.

Right Hon. Lord LYONS, &c.

MY LORD: I have the honor to acknowledge the receipt of your lordship's note of the 30th of November last in which you review the explanations of the Secretary of the Navy which I had submitted to you concerning the cases of two seamen of the British schooner REvere and two other seamen of the British schooner Louisa Agnes, which two schooners were captured, though at different times, in attempts to break the blockade of the ports held by theinsurgents. I have read your objections to those explanations with great care and as I trust with candor, inspired by a sincere desire to concede to the complainants whom you represent any redress to which they might be found entitled, and to preserve the best possible understanding with the Government of Great Britain.

The Secretary's explanations do in fact show as you have assumed that the two seamen of the schooner Revere were confined for two or three days in single irons in the daytime and in double irons during the night, and that after the period thus passed they were left at liberty during the greater part of the day but confined at night. I cannot admit, however, that you are perfectly just in calling this confinement "hard treatment. " You notice the explanation that confinement of the seamen with irons to the extent practiced was resorted to in order to prevent their rising and retaking the vessel; but you object that no information is given from which an opinion can be formed as to the reasonbableness of the precaution, and that no evidence is adduced of there having been ground for suspecting the men of a design to retake the vessel or for apprehending that they had the means of executing