Third Experiment:—On August 25th I tried to manœuvre the Nautilus by means of wings 4 feet diameter like the sails of a wind-mill; to this end at first I placed on the bridge two men with oars; they took 7 minutes to row about 192 yards, the length of the basin; then I ordered the same 2 men to set the sails and in 4 minutes the Nautilus covered the distance to the starting place;—I proved by this that the speed of sails to that of oars is about 2 to 1 and that these sails are very suitable to manœuvre a boat under water. The success of this experiment has given me several new ideas which I hope will facilitate much the use of carcasses [iron cases] of powder or torpedoes.
Fourth Experiment:—On the 26th of August I tried balancing the Nautilus under water in such a way as to prevent it rising towards the surface or descending to the bottom, meanwhile advancing. This is executed by means of a pair of wings placed horizontally on the front of the Nautilus and which communicates with the interior. By turning these wings from left to right the Nautilus is made to descend below the water, in turning them from right to left, it is raised to the surface. My first trial was unfortunate, in not having placed the boat in the necessary trim in order that the wings could act. The next day I had a decided success and I kept my Nautilus below water at a depth of about 5 feet whilst it covered a distance of 192 yards, about from one end of the basin to the other. This day I made several movements under water and I observed that the Compass acts as well under water as at the surface. The three people who have been my companions during these experiments are so familiarized with the Nautilus and have so much confidence at present in the movements of this machine that they undertake without the least concern these aquatic excursions.
Having thus assured myself of the ease of immersion and submersion of the Nautilus and all its movements as well as the effect on the compass, on the 27th of August I half filled an ordinary barrel and placed it at anchor in the harbour at about 426 yards from the jetty;—I seated myself then in an ordinary boat at the distance of about 160 yards and placed in the sea a torpedo containing about 30 lb. of powder; the torpedo was attached to a small rope 200 yards long; the current going under the barrel, the torpedo passed without touching it; but turning the helm of the boat in which I sat, I made it go obliquely till I saw the torpedo exactly under the barrel; I then drew back the cable till at last the torpedo touched the barrel; at that instant the battery went off, the powder exploded and the barrel was reduced to fragments being lost in a column of water 10 feet in diameter that the explosion threw into the air to the height of 60 or 80 feet.
On the 12th of September I left Havre for La Hogue and in this little voyage my Nautilus sometimes did a league and a half (4½ miles) per hour and I had the pleasure of seeing it ride the waves like an ordinary boat.
On the 15th of September I put into a little harbour called Growan near Isigny at 3 leagues from the islands of Marcou. The next day the equinoctial gales commenced and lasted 25 days. During the time I tried twice to approach two English brigs which were anchored near one of the islands, but both times, whether by accident or design, they set sail and were quickly at a distance. During one of these trials I remained during the whole of one tide of 6 hours absolutely under water, having for the purpose of taking air only a little tube which could not be perceived at a distance of 400 yards.
The weather being bad I remained 35 days at Growan and seeing that no English vessel returned, and that winter approached, besides my Nautilus not being constructed to resist bad weather, I resolved to return to Paris and place under the eyes of Government the result of my experiments.
In the course of these experiments there has come to me a crowd of ideas infinitely more simple than the means that I have employed hitherto and in an enterprise so new and without precedent one ought to expect that new ideas should present themselves, tending to simplify the execution of the great object in view.
As to myself, I look upon the most difficult part of the work as done. Navigation under water is an operation whose possibility is proved, and it can be said that a new series of ideas have just been born as to the means for preventing naval wars or rather of hindering them in the future; it is a germ which only demands for its developement the encouragement and support of all friends of science, of justice and of society.
Health and respect,
(Nov. 7th 1801.)