[Enclosure]

The impossibility of imediately fortifying our Bays & Harbours on the plan of European Engineers has led me to reflect on the possibility of finding a substitute comporting with the thinness of our population and the necessary economy of the Government.

The progress of improvement in the arts of attack & defence since the invention of artilery appears to have been extreemly slow; yet from time to time improvements have been made, and this emboldens me to make the attempt.

The first object of an Engineer in planing the defence of a Harbour is ground suitable for his commanding & razing Batteries, here he finds himself soon controled by various circumstances of locality, such as Distance, Command, Dirrection, Cross-fires, Water, Communication & Retreat; and when he is so fortunate as to unite most of these requisites, the obstacles that he is able to oppose to a naval force are very inconsiderable compared with the means employ’d, a single view of the Goulet of Brest, the Mole of Cherbourg, or the Dardanells shows the small comparitive effect of an immense artilery opposed to Ships in motion, each gun not being able to fire more than once or twice at the same object, and that gun to do effect must be dirrected with more elementary and practical knowledge than falls to lot of every Gunner. To remedy these inconveniences in part is the object of this speculation. Gentlemen of more practice than myself will be better to judge how far I have succeeded.

I propose to construct floating batteries, a Diagram of which is annexed3 the first apparent advantages of these Batteries over stationary forts, are the choice of position, following the Ennemy, or Retreating; The second is to bring all the guns to bear at once and to follow the progressive motion of a Ship by a circular movement of the battery on its ax. 3°. The Guns being fixed in sliding grooves converging to a center at the usual range of the calibre that may be employed, requires only that the center of the battery be pointed to the center of the Ship to carry all the shot in a proper dirrection, one skillfull Gunner perfo[r]ms this service by means of springs on the cables or a pivot in the ground where the water is shallow. 4°. The battery being only three feet above the surface of the water, or less in smooth water presents but a small mark for the Enemy, and being coverd by a wooden glacis or very gentle inclined plane not more than 6° elevation, and shod with Iron, the Shot by recochet or point-blanc must scale over it, therefore the men and guns are protected. A floating parapet of wood protects the front & flanks. The Embrasures need be no larger than the diameter of the guns as no variation is required of them.

The service of the guns is performed beneeth them, after recoil, the muzzel of the gun is drawn down spunged and Loaded, then rises by its own counterpoise. The loading and fireing a twenty four pounder is performed by three men; Nine such guns I think may be worked in a battery of 36 feet by 24. So that a Frigate presents a surface of Hull alone of 4000 feet compared to 108 of the battery.

If we consider that by converging nine guns to the focal distance of about 1000 Yards we reduce to so small a fraction any probable deviation in the dirrection of the center that every shot must hit the mark, as may be infered from a bare inspection of figure No 5 of the Diagrams where the just proportions of distance and magnitude are observed, Wheras the smalest deviation at the departure of a gun from the Ship would diverge at the distance of 1000 Yards more than the length of the battery. The visual marks on the Battery are three times longer than those of a Gun, and of course in the same ratio less subject error.

The grooves are gently inclined towards the embrasures for the double purpose of retarding the recoil and facilitating the advance of the guns, whose carriages are on iron cylinders.

I conceive that parts of this principle are applicable to land batteries and in situations not otherwise suceptible of fortification; perhaps allso may the lower Decks of Ships be improved on this plan. Batteries of 12lbs. and under may have three guns cast together or strongly united with iron ligaments, this would be what Military men aim and call consolidating power.

A Battery of Nine 24lbs. would cost I presume about one half the value of a Gunboat and be worked with half the men. They may have a mast, or be towed by gunboats or other Craft. Enemies ships might be decoied by one of our Frigates into situations where they know that no batteries exist, and be so disabled as to be unmanageable.

Placeing these batteries and various other details relative to their employment have not escaped my attention, but I thought it superflous to burthen this primary sketch with tecnical definitions and minute details; Military Gentlemen who understand and aprove the principle, will supply this defficiency, and will be as familiar with the thing as myself.

Some late experiments of the Rockets invented in this town, and which range 2000 Yds. induce me to think that they might be combined usefully with the batteries.

The two flank guns may be on swivels to defend the flanks & rear from boats