SIR,--On receiving tenders of service from various military corps, I have usually addressed the answer to the officer commanding them. Observing in the address of the Master Mariners of Baltimore of July 16th, that being probably unorganized, no commanding officer was named, I considered the first person on the list of subscribers as a kind of foreman, and therefore addressed my answer to him. I now, with pleasure, correct, on reflection, that error, by enclosing a duplicate of the answer to yourself, as the chairman whom they had chosen as the channel of communication, having nothing more at heart than to prove my respect for yourself and the Master Mariners of Baltimore. Accept for yourself and them the assurances of my high consideration. TO THE SECRETARY OF THE NAVY. MONTICELLO, August 9, 1807. DEAR SIR,--Soon after my arrival here I received a letter from Governor Cabell, requesting me to give such instructions for regulating the intercourse with the British squadron as might enable the officers to act correctly. I accordingly undertook to digest the rules of practice, as to flags, as well as I could, and so as to meet all cases, in a letter to the Governor, a copy of which I now enclose you. Soon after sending it, I learnt from Mr. Madison that the arrangement at Washington had not been known or understood to exclude the officer commanding on shore from the right of communicating by flag, and that some particular orders from the War office, respecting Mr. Erskine's letter, might produce a collision. I have therefore written to Governor Cabell, making the correction stated at the foot of the enclosed letter, which is the safer. As Mr. Newton (of Congress) is the Major Commandant ashore, you will see by the letter that I meant to send a copy of it to Captain Decatur, but have thought it more proper to send it you, with a request to forward it, or a copy, to him. Mr. Newton receiving also a copy, they will be enabled to act by one uniform rule. I salute you with affection and respect. TO THE SECRETARY AT WAR. MONTICELLO, August 11, 1807.