2. Having cannon on floating batteries or boats, which may be so stationed as to prevent a vessel entering the harbor, or force her after entering to depart. There are about fifteen harbors in the United States, which ought to be in a state of substantial defence. The whole of these would require, according to the best opinions, two hundred and forty gun-boats. Their cost was estimated by Captain Rogers at two thousand dollars each; but we had better say four thousand dollars. The whole would cost one million of dollars. But we should allow ourselves ten years to complete it, unless circumstances should force it sooner. There are three situations in which the gun-boat may be. 1. Hauled up under a shed, in readiness to be launched and manned by the seamen and militia of the town on short notice. In this situation she costs nothing but an enclosure, or a centinel to see that no mischief is done to her. 2. Afloat, and with men enough to navigate her in harbor and take care of her, but depending on receiving her crew from the town on short warning. In this situation, her annual expense is about two thousand dollars, as by an official estimate at the end of this letter. 3. Fully manned for action. Her annual expense in this situation is about eight thousand dollars, as per estimate subjoined. ‘When there is general peace, we should probably keep about six or seven afloat in the second situation; their annual expense twelve to fourteen thousand dollars; the rest all hauled up. When France and England are at war, we should keep, at the utmost, twenty-five in the second situation, their annual expense fifty thousand dollars. When we should be at war ourselves, some of them would probably be kept in the third situation, at an annual expense of eight thousand dollars; but how many, must depend on the circumstances of the war. We now possess ten, built and building. It is the opinion of those consulted, that fifteen more would enable us to put every harbor under our view into a respectable condition; and that this should limit the views of the present year. This would require an appropriation of sixty thousand dollars, and I suppose that the best way of limiting it, without declaring the number, as perhaps that sum would build more. I should think it best not to give a detailed report, which exposes our policy too much. A bill, with verbal explanations, will suffice for the information of the House. I do not know whether General Wilkinson would approve the printing his paper. If he would, it would be useful. Accept affectionate and respectful salutations. Th: Jefferson. LETTER XX.--TO MR. VOLNEY, February 8, 1805 TO MR. VOLNEY. Washington, February 8, 1805. Dear Sir,