To Benjamin H. Latrobe Washington, Nov. 2, 1802
-- The placing of a navy in a state of perfect preservation, so that at the beginning of a subsequent war it shall be as sound as at the end of the preceding one when laid up, and the lessening the expence of repairs, perpetually necessary while they lie in the water, are objects of the first importance to a nation which to a certain degree must be maritime. The dry docks of Europe, being below the level of tide water, are very expensive in their construction and in the manner of keeping them clear of water, and are only practicable at all where they have high tides: insomuch that no nation has ever proposed to lay up their whole navy in dry docks. But if the dry dock were above the level of tide water, and there be any means of raising the vessels up into them, and of covering the dock with a roof, thus withdrawn from the rot and the sun, they would last as long as the interior timbers, doors and floors of a house. The vast command of running water at this place, at different heights from 30 to 200 feet above tide water, enables us to effect this desirable object by forming a lower bason into which the tide water shall float the vessel and then have its gates closed, and adjoining to this, but 24 feet higher, an upper bason 275 feet wide, and 800 f. long (sufficient to contain 12 frigates) into which running water can be introduced from above, so that filling both basons (as in a lock) the vessel shall be raised up and floated into the upper one, and the water being discharged leave her dry. Over a bason not wider than 175 feet, a roof can be thrown, in the manner of that of the Halle au ble at Paris, which needing no underworks to support it, will permit the bason to be entirely open and free for the movement of the vessels. I mean to propose the construction of one of these to the National legislature, convinced it will be a work of no great cost, that it will save us great annual expence, and be an encouragement to prepare in peace the vessels we shall need in war, when we find they can be kept in a state of perfect preservation and without expence.
The first thing to be done is to chuse from which of the streams we will derive our water for the lock. These are the Eastern branch, Tyber, Rock creek, and the Potomak itself. Then to trace the canal, draw plans of that and of the two basons, and calculate the expence of the whole, that we may lead the legislature to no expence in the execution of which they shall not be apprised in the beginning. For this I ask your aid, which will require your coming here. Some surveys and elevations have been already made by Mr. N. King, a very accurate man in that line, and who will assist in any thing you desire, and execute on the ground any tracings you may direct, unless you prefer doing them yourself. It is very material too that this should be done immediately, as we have little more than 4 weeks to the meeting of the legislature, and there will then be but 2 weeks for them to consider and decide before the day arrives (Jan. 1) at which alone any number of labourers can be hired here. Should that pass either the work must lie over for a year, or be executed by day labourers at double expence. I propose that such a force shall be provided as to compleat the work in one year. If this results, as it will receive all our present ships, the next work will be a second one, to build and lay up additional ships. On the subject of your superintending the execution of the work it would be premature to say any thing till the legislature shall have declared their will. Be so good as to let me hear from you immediately, if you cannot come so soon as you can write.
Accept my best wishes and respects.