Robert Fulton to the citizens Monge, La Place and Volney, members of the National Institute, and Commissioners appointed by the first Consul to promote the invention of Submarine Navigation—

Citizens, yesterday on my return from Brest I received your note, and will with pleasure communicate to you the result of my experiments, during the summer, also the mode which I conceive the most effectual for using my invention against the enemy. Before I left Paris I informed you that my plunging boat had many imperfections, natural to the first machine of so difficult a combination, added to this I found she had been much injured by the rust during the winter in consequence of having in many places used Iron bolts and arbours instead of copper or brass, the reperation of those defects and the difficulty of finding workmen consumed near two months. And although the machine remained still extremely imperfect yet she has answered to prove every necessary experiment In the most satisfactory manner.

On the 3d of thermidor I commenced my experiments by plunging to the depth of 5 then 10 then 15 and so on to 25 feet but not to a greater depth than 25 feet as I did not conceive the Machine Sufficiently Strong to bear the Pressure of a Greater column of water, At this depth I remained one hour with my three companions and two candles burning without experiancing the least inconvenience.

Previous to my leaving Paris I gave to the Cn. Gueyton member of the Institute a calculation on the number of cube feet In my boat which is about 212 in Such a Volume of Air he calculated there would be sufficient Oxszine to nourish 4 Men and two small candles 3 hours. Seeing that it would be of great Improvement to despence with the candles I have constructed a Small window in the upper part of the Boat near the bow which window Is only one inch and a half diameter and of Glass 9 lines thick, with this prepared I descended on the 5th of thermidor to the depth of between 24 and 25 feet at which depth I had Suffecient light to count the minuets on the Watch, hence I conclude that 3 or 4 Such windows arranged in different parts of the boat would give suffecient light for any operation during the day each window may be Guarded by a Valve in Such a manner that Should the glass break the Valve would immediately Shut and Stop out the Water, finding that I had air and light Suffecient and that I could Plunge and Rise perpendicular with facility. On the 7th Therd I commenced the experiments on her movements. At 10 in the Morning I raised her anchor And hoisted her Sails which are the Mainsail and Gib the breeze being light I could not at the Utmost make more than about two thirds of a league per hour. I tacked and retacked tryed her before and by the wind And in all these operations found her to Answer the helm And Act like a common dul Sailing boat, After exersising thus About An hour I lowered the mast and Sails and commenced the operation of Plunging this required about two Minuets. I then placed two men at the engine which gives the Rectileniar Motion, And one At the helm, while I governed the machine which keeps her ballanced between two waters. With the bathomater before me And with one hand I found I could keep her at any depth I thought Proper the men then commenced movement and continued about 7 Minuets when mounting to the Serface I found we had gained 400 Matres. I again plunged turned her round under water and returned to near the Same place. I again plunged And tried her movements to the right and left, in all of which the helm answered And the compass acted the same as if on the serface of the Water having continued these experiments the 8, 9, 10 and 12th untill I became fameliar with the movements And confidence in their operation, I turned my thoughts to Increasing or preserving the Air, for this purpose the Cn. Gueyton advised to precipitate the carbonic acid with lime, or to take with me bottles of Oxizine which might be uncorked as need required; but as any considerable quantity of bottles would take up to much room, And as oxizine could not be created at Sea without a Chymical operation which would be Very Inconvenient, I adopted a mode which occured to me 18 months ago which is a Simple Globe or bombe of copper capable of containing one cube foot to (Manuscript is torn here) A Pneumatick Pump by means of which Pump 200 Atmospheres or 200 cube feet of common Air may be forced Into a Bomb consequently the Bomb or reservoir will contain As much oxegine or Vital air as 200 cube feet of common respirable Air, hence if according to Cn. Gueyton’s Calculation 212 feet which is the Volume of the boat will nourish 4 Men and two small candles 3 hours this additional reservoir will give Suffecient for 6 hours—this Reservoir is constructed with a measure and two cocks So as to let measures of Air Into the Boat as Need may require require—

Previous to my leaving Paris I gave orders for this machine but it did not arrive till the 18 of thermidore on the 19 I ordered 2 Men to fill it which was an operation of about one hour I then put It into the boat and with my three companions but without candles plunged to the depth of about 5 feet, At the expiration of one hour and 40 Minuets I began to let off Measures of air from the reservoir and So on from time to time for 4 hours 20 Minuets without experiancing any Inconvenience—

Having thus succeeded

And to Augment the respirable air by a reservoir, which may be obtained at all times, I conceived every experiment of importance, to be proved in the most satisfactory manner hence I Quit the experiments on the Boat to try those of the Bomb Submarine. It is this bomb which is the Engine of destruction the Plunging boat is only for the purpose of carrying the bomb to where it may be used to Advantage. They are constructed of Copper and of different sizes to contain from 10 to 200 Pounds of powder each bomb is arranged with a Gun lock In Such a manner that if it Strikes a Vessel or the Vessel Runs against it, the explosion will take place and the bottom of the Vessel be Blown in or so Shattered as to insure her destruction. To prove this Experiment the Prefet Maritime, And Admiral Vellaret ordered a Small Sloop of About 40 feet long to be anchored in the Road, on the 23d of Thermidor With a bomb containing about 20 Pounds of powder I advanced to within about 200 Matres then taking my direction So as to pass near the Sloop I Struck her with the bomb in my Passage the explosion took Place and the Sloop was torn into Atoms, in fact nothing was left but the buye and cable, And the concussion was so Great that a Column of Water Smoak and fibres of the Sloop was cast from 80 to 100 feet in Air, this Simple Experiment at once Proved the effect of the Bomb Submarine to the Satisfaction of all the Spectators; of this experiment you will See Admiral Villarets description in a letter to the Minister of Marine Marine—

Having Given in a Short Sketch of the Sucession of my Experiments, the mode of using these inventions Against the enemy is now to be considered, on this Point time and experience will make numerous improvements As in all other new inventions and discover modes of operation which could not possibly accur to me; when Powder was Invented Its Infinite applications were not thought of, nor did the Inventors of the Steam Engine conceive the numerous purposes to which It could be applied, in like manner it is Impossible At present to See the Various modes, or the best methods of Using a plunging boat or the bomb Submarine—

But as far as I have Reflected on this point I conceive the best operation to be as follows—