SIR,--Your letter of July 28th, came to hand just as I was about leaving Washington, and it has not been sooner in my power to acknowledge it. I consider your torpedoes as very valuable means of the defence of harbors, and have no doubt that we should adopt them to a considerable degree. Not that I go the whole length (as I believe you do) of considering them as solely to be relied on. Neither a nation nor those entrusted with its affairs, could be justifiable, however sanguine its expectations, in trusting solely to an engine not yet sufficiently tried, under all the circumstances which may occur, and against which we know not as yet what means of parrying may be devised. If, indeed, the mode of attaching them to the cable of a ship be the only one proposed, modes of prevention cannot be difficult. But I have ever looked to the submarine boat as most to be depended on for attaching them, and though I see no mention of it in your letter, or your publications, I am in hopes it is not abandoned as impracticable. I should wish to see a corps of young men trained to this service. It would belong to the engineers if at hand, but being nautical, I suppose we must have a corps of naval engineers, to practise and use them. I do not know whether we have authority to put any part of our existing naval establishment in a course of training, but it shall be the subject of a consultation with the Secretary of the Navy. General Dearborne has informed you of the urgency of our want of you at New Orleans for the locks there. I salute you with great respect and esteem. TO GOVERNOR CABELL. MONTICELLO, August 17, 1807. DEAR SIR,--Your favors of the 11th, 12th, and 14th were received yesterday, being the first day for some days past that the obstruction of the water-courses has permitted the post to come through. I now return you the letters of General Matthews and Captain Hardy; I enclose you also two offers of volunteers from Montgomery and Fauquier counties, because they are expressly made under the late act of Congress. I have received a great number of tenders of service at a moment's warning, which, appearing to me to have relation merely to the repelling invasion in the quarter lately violated, and not to intend an absolute engagement for twelve months, I have only accepted generally and vaguely, without relation to the Volunteer Act.