In view of the many representations made to me in the case I pray you excuse me for giving this letter to the public.

With great respect, sir, your obedient servant,

WILLIAM H. SEWARD.

54 WALL STREET, NEW YORK, September 10, 1861.

F. W. SEWARD, Esq.

DEAR FRED: I saw by yesterday's papers on my return to town last evening that Mr. Algernon s. Sullivan has been sent to Fort Lafayette. He is comparatively a stranger here and this leads me to say to you what I know of him. I have not seen him or any of his family, relatives or friends for five or six weeks past and write this entirely of my own volition and without the knowledge of any human being. I of course know nothing of what information or evidence the Government may possess in the case and do not mean in any manner to question the propriety of its course. The fact that Mr. Sullivan is a stranger here, a member of the bar ingood standing and that I believe his family to be dependent upon his professional labors coupled with my surprise at the cause of his arrest induces me to write to you.

He is a Virginian by birth. Mrs. S. is also from that State; but notwithstanding these facts and the sympathies which would naturally flow from them Mr. S. has in several conversations with me during the past five or six months, and especially in the last conversation I had with him some five or six weeks since, expressed himself unhesitatingly and unequivocally in favor of prosecuting the war; that the Administration ought to be and must be sustained in so doing. I believe him to be entirely loyal and utterly incapable of intentionally committing any disloyal act. I should not have been more surprised at the arrest for this cause of our mutual friend R. B. Potter or any prominent Republican.

It occurs to me that in some of the letters said in the papers to have been written by him to the South he may have said more than was prudent or proper and may have disclosed more of our plans than he should have done. If so, it may be said for him that he is a lawyer- like many of us wanting clients. His friends are at the South. His anxiety to obtain favor there for this purpose may have led him to careless frankness of disclosure or to the expression of opinions really not his own. Should there be anything pointing to this ould not justice be subserved by administering the oath and giving him his freedom? He would very certainly be sufficinelty purdent in the future. Mr. Sullivan knew me as an old Tammany Hall Democrat. There was therefore no reason why he should have expressed other than his real sentiments to me. Since I began this letter I have seen two lawyers, acquaintances of Mr. Sullivan, one (F. R. Sherman) a prominent Republican, and they confirm the view I have expressed of Mr. Sullivan's sentiments.

This much I feel bound to say for Mr. S., hoping that if there is the slightest doubt of the sufficiency of the proof against him the Government will see the justice of inquiring into his case or of giving him an opportunity to exculpate himself. I will be very glad if you can find the time and inclination to inquire a little into it. I did not mean to ask your attention to so long a letter.

Pardon me, and believe me, faithfully your friend,

JOHN S. SUTHERLAND.