Thomas Jefferson Papers

To Thomas Jefferson from Robert Fulton, 28 July 1807

New York July the 28 1807


General Dearborn will inform you of the experiment for blowing up the Brig. I had arranged the machinery Accurately as in the case when I blew up the Vessel in Walmer Roads near Deal two years ago; I therefore did not Suspect any error or failure, yet both my locks missed fire, in consequence of the pans being turned beneath the Torpedoes, a circumstance which might not take place in One hundred attacks, but which should not be trusted to. And which I have so Correct that it cannot happen Again;    On the second application of the Torpedo to her Bottom, she was rent in two, and went to the bottom in 20 seconds; the quantity of powder was 70 pounds, the effect of which seemed to prove it sufficient to destroy a ship of the line;

It has now been demonstrated to the satisfaction of every reflecting American that a ship can be destroyed by the explosion of powder under her bottom; I have also proved that by a particular Arrangement the Torpedoes must go under the bottom of the vessel if their lines be made fast to her cable or any part of her bow.

To fasten the line or chain to her cable or bow, I have conceived many methods, the two principal of which are as follows;    First, to couple the Torpedoes by a line and chain 100 feet long and let them float, down with the tide across the cable or bow of the Vessel at Anchor; To render such line as little visible as possible it may be arranged thus.


Here the leading line is 8 or 10 feet under water suspended by small twine and corks as 1. 2. 3 &c &c. As attacks of this kind should be made in the night it would be almost impossible to guard against such a line, the enemy would therefore be necessitated to cut cable and run or be blown up, for the locks may be set to a minuet and a half which leaves little time to look for or guard against the Torpedoes; hence this mode would compel the enemy to keep out of our harbors, or should they come in they must be continually under way. I have therefore contrived a mode of destroying them while under Sail, by harpooning them in the bow, Thus

A Small harpoon gun 18 inches long and one inch bore is to be fixed to a swivel in the bow of a good row boat, the harpoon is a single bolt of Iron two foot long with an eye and barbed point, one end of a rope 60 feet long is fixed in the eye of the harpoon, the other end is fastened to the Torpedo


When the harpoon is fired the ring A slides along it to the but end, and lays the rope in a right line to its side, thus.


By this arrangement it will fly almost as straight as a bullet and in this manner I for Experiment harpooned the brig at the distance of 40 feet, and drove it into her oak planks 6 inches deep, in which case a rope united with a chain could not be cleared away In two minuets, the time for which the clockwork would be Set, Having thus proved the facility of harpooning and that if harpooned, the Torpedo must from necessity go under the bottom of the Ship, Let it now be supposed that a ship is under sail at the speed of 4 or 6 miles an hour And in the night to be attacked by 20 torpedo and harpoon boats, ten of which to run at her Larbord and ten at her Starboard bow as in the annexed drawing


Such a number of boats would divide her fire and we instantly see that some of them must harpoon her for it is well known that it is extremely difficult to hit boats in the night time and impossible to hit the whole 20, particularly as they will not be within the range of the Shot more than 3 minuets

Let her now be supposed to have four harpoons in each bow; whichever way She may then turn. Some of them will be pressed under her bottom, for example:


Should she turn to the larboard, then the larboard torpedoes will sheer off from her and the Starboard will come directly under her. Should she turn to the Starboard thus, the Larboard torpedoes will bring her up.


Some persons have inconsiderately asked who has courage to approach a ship of the line in boats, I answer men who have courage, in boats, to rush on to boardage and which has been done hundreds of times, have courage to harpoon a ship of the line.    All courage is founded on the hope of success and calculations of superior Advantages; cowardice is forced upon the mind as soon as it feels inferiority. 200 men in 20 boats would feel confident that few of them could be hit. 500 men in a Ship of the line would be certain of Annihilation if harpooned by only two Boats, the difference in the chances is therefore immense,

Having thus explained to you my principles of practice your capacious mind will readily trace all the happy consequences which will result from the success and general practice of this invention; And I Submit to your consideration whether it Should not be organized into a general System for our own defence, let it be considered if there be any plan so calculated to Strike terror Into the Enemy, will they not calculate the improvement of which it is capable, and its future consequences, is there any mode of defence so cheap, so easy of practice so fitted to common understandings?    At new York for example

20 good Row Boats worth 4.000 dollars
200 Torpedoes with powder complete 20.000 Do

Two hundred Men who on an average with the officers would cost 25 dollars a month or 60 thousand dollars a year in time of war, would be complete security for this City against Ship of war

In time of peace 20 men would be sufficient to keep the boats and engines in order and thus the peace establishment would not be more than 6,000 dollars a year

One Vessel of an enemy blown up with such engines would give the peace you might think proper to demand and if the fear of the torpedoes produced peace the same fear would make the peace eternal;

The people of New york seem well pleased with the experiments and I believe would be happy to see it united with other modes of defence; it will perhaps Require some time to work this subject so into the mind, as to make them feel that it is of itself sufficient security; for it required more than 50 years to give such confidence in flints as to induce the Military in general to adopt it instead of a Match lock. And Matches are Still used for marine Cannon instead of locks; although it has been proved that locks are superior; Such is the effect of habit on the human mind and the fear of Philosophy and common Sense.

With profound Respect I have the honor to be your most obedient

Robert Fulton

DLC: Papers of Thomas Jefferson.

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