DEAR SIR,--In mine of the 12th I informed you I would write to the Attorney General to send on the letter of General Wilkinson of October 21st, referred to in my message of January 22d. He accordingly sent me a letter of that date, but I immediately saw that it was not the one desired, because it had no relation to the facts stated under that reference. I immediately, by letter, apprized him of this circumstance, and being since returned to this place, he yesterday called on me with the whole of the papers remaining in his possession, and he assured me he had examined carefully the whole of them, and that the one referred to in the message was not among them, nor did he know where it would be found. These papers have been recurred to so often, on so many occasions, and some of them delivered out for particular purposes, that we find several missing, without being able to recollect what has been done with them. Some of them were delivered to the Attorney of this district, to be used on the occasions which arose in the District Court, and a part of them were filed, as is said, in their office. The Attorney General will examine their office to day, and has written to the District Attorney to know whether he retained any of them. No researches shall be spared to recover this letter, and if recovered, it shall immediately be sent on to you. Compiling the message from a great mass of papers, and pressed in time, the date of a particular paper may have been mistaken, but we all perfectly remember the one referred to in the message, and that its substance is there correctly stated. General Wilkinson probably has copies of all the letters he wrote me, and having expressed a willingness to furnish the one desired by the Court, the defendant can still have the benefit of it. Or should he not have the particular one on which that passage in the message is founded, I trust that his memory would enable him to affirm that it is substantially correct. I salute you with friendship and respect. TO GEORGE BLAKE, ESQ. WASHINGTON, June 24, 1807.