Dear Sir, ー

In your last you requested I would give you an account of the progress of our machine, and whether anything may be expected of it. I now sit down to give you a succinct but imperfect account of its structure, which is so complicated that it is impossible to give a perfect idea of it.

The Body, when standing upright in the position in which it is navigated, has the nearest resemblance to the two upper shells of a Tortoise joined together. In length it doth not exceed 7½ feet from the stem to the higher part of the rudder: the height not exceeding 6 feet. The person who navigates it enters at the top. It has a brass top or cover, which receives the person's head as he sits on a seat, and is fastened on the inside by screws. In this brass head is fixed eight glasses, viz. two before, two on each side, one behind, and one to look out upwards. In the same brass head are fixed two brass tubes, to admit fresh air when requisite, and a ventilator at the side to free the machine from the air rendered unfit for respiration. On the inside is fixed a Barometer, by which he can tell the depth he is under water; a Compass, by which he knows the course he steers. In the barometer and on the needles of the compass is fixed fox-fire, i.e. wood that gives light in the dark. His ballast consists of about 900 wt. of lead which he carried at the bottom and on the outside of the machine, part of which is so fixed as he can let run down to the Bottom, and serves as an anchor, by which he can ride ad libitum. He has a sounding lead fixed at the bow, by which he can take the depth of water under him; and to bring the machine into a perfect equilibrium with the water, he can admit so much water as is necessary, and has a forcing pump by which he can free the machine at pleasure, and can rise above water, and again immerge, as occasion requires.

In the bow, he has a pair of oars fixed like the two opposite arms of a wind mill, with which he can row forward, and turning them the opposite way, row the machine backward; another pair fixed upon the same model, with which he can row the machine round, either to the right or left, and a third, by which he can row the machine either up or down; all which are turn'd by foot, like a spinning wheel. The rudder by which he steers, he manages by hand, within board. All these shafts which pass through the machine are so curiously fix'd as not to admit any water to incommode the machine. The magazine for the powder is carried on the hinder part of the machine, without board, and so contrived, that when he comes under the side of the Ship, he rubs down the side until he comes to the keel, and a hook so fix'd as that when it touches the keel it raises a spring which frees the magazine from the machine and fastens it to the side of the Ship; at the same time, it draws a pin, which sets the watchwork agoing which, at a given time, springs the lock and the explosion ensues.

Three magazines are prepared; the first, the explosion takes place in twelve, the second in eight, ー the third in six hours, after being fixed to the ship. He proposes to fix these three before the first explosion takes place. He has made such a trial of the effects of the explosion of gunpowder under water, since Dr. [Benjamin] Franklin did me the honor to call upon me, as has exceeded his most sanguine expectations, and is now convinced his magazines will contain three times so much powder as is necessary to destroy the largest ship in the navy.²

I now write with the greater freedom, as I conclude by the time this reaches you the machine will be in camp. Lately he has conducted matters and his designs with the greatest secrecy, both for the personal safety of the navigator as to produce the greatest astonishment to those against whom it is designed, ー if this projection succeeds, of which I make no doubt, as I well know the man and have seen the machine while in embryo, and every addition made to it fills me with fresh astonishment and surprize. And you may call me a visionary, an enthusiast, or what you please, ー I do insist upon it, that I believe the inspiration of the Almighty has given him understanding for this very purpose and design. If he succeeds, a stipend for life, and if he fails, a reasonable compensation for time and expense is his due from the public.

What astonishment it will produce and what advantages may be made by those on the spot, if it succeeds, is more easy for you to conceive than for me to describe.³

I congratulate you and my country in the begun success of our Arms to the northward, and the prospects of further success. Make my most respectful compliments to Dr. Franklin and our Delegates, your associates; and am, most respectfully Your sincere friend and most humble servt,