With a view to this there was a survey made by Colonel Tatham, which was lodged either in the war or navy office, showing the depth and length of a canal which would give them a retreat from Lynhaven river into the eastern branch of Elizabeth river. I think the distance is not over six or eight miles, perhaps not so much, through a country entirely flat, and little above the level of the sea. A cut of ten yards wide and four yards deep, requiring the removal of forty cubic yards of earth for every yard in length of the canal, at twenty cents the cubic yard, would cost about $15,000 a mile. But even doubling this to cover all errors of estimate, although in a country offering the cheapest kind of labor, it would be nothing compared with the extent and productions of the country it is to protect. It would, for so great a country, bear no proportion to what has been expended, and justly expended by the Union, to defend the single spot of New York. While such a channel of retreat secures effectually the safety of the gun-boats, it insures also their aid for the defence of Norfolk, if attacked from the sea. And the Norfolk canal gives them a further passage into Albemarle sound, if necessary for their safety, or in aid of the flotilla of that sound, or to receive the aid of that flotilla either at Norfolk or in Lynhaven river. For such a flotilla there also will doubtless be thought necessary, that being the only outlet now, as during the last war, for the waters of the Chesapeake. Colonel Monroe, I think, is personally intimate with the face of all that country, and no one, I am certain, is more able or more disposed than the present Secretary of the Navy, to place himself above the navy prejudices, and do justice to the aptitude of these humble and economical vessels to the shallow waters of the South. On the bold Northern shores they would be of less account, and the larger vessels will of course be more employed there. Were they stationed with us, they would rather attract danger than ward it off. The only service they can render us would be to come _in a body_ when the occasion offers, of overwhelming a weaker force of the enemy occupying our bay, to oblige them to keep their force in a body, leaving the mass of our coast open.