What the Nautilus accomplished. The British design compared with that of the Nautilus. Folding propeller. Horizontal propeller. Details of machinery. Effectiveness of the vessel. Screening the Channel.

However interesting from an academic point of view may be Fulton’s views on philosophy, free trade and social problems, and his personal peculiarities as displayed in his negotiations with government officials, the animating question of historical bearing relates to the boat itself. Was the design practical, would it as developed have been able to serve a useful purpose, or was it only a single step in a long process of evolution?

The Nautilus, defective as she was in many particulars which Fulton admitted, clearly demonstrated certain facts: firstly, that a boat could be made to plunge and rise at will; secondly, that it could remain under water with a crew of three men for several hours; thirdly, that it could be manoeuvered and steered by the compass under water as well as on the surface. These features are the essence of the principle of successful submarine practice, and so much Fulton accomplished.

It is a far cry from a little vessel like the Nautilus, no bigger than a ship’s boat that is carried at the davits, to a modern submarine capable of keeping the seas for many weeks, of crossing and recrossing the ocean without replenishing either stores or fuel, and of carrying not only torpedoes and apparatus for their discharge but also a 12–inch long-range gun firing a projectile weighing nearly one-half ton. Except as to size, which is not really a basic feature of principle, the modern submarine differs from Fulton’s proposals in that it possesses an engine actuated when on the surface by a fuel (oil) whose activity can be instantly stopped preparatory to plunging, and by a power (electric storage battery) that neither generates heat nor vitiates the air while submerged. For that combination of motive power the world had to wait another hundred years.

The Nautilus, as a matter of fact, was something vastly more than a toy or experimental model. It possessed real offensive powers, and a fleet of them, as Fulton proposed and as the British navy officials feared, would have been able to do real havoc. In estimating the offensive power of Fulton’s design, the picture of the modern submarine must be kept out of sight. The latter is called on to meet conditions of mechanical development and types of hostile vessels that are as much in advance of those existing when Fulton lived, as is the complicated mechanism of a present-day submarine over the hand-driven propeller proposed by him.

At the beginning of the last century, a ship-of-the-line was a very unwieldly affair. She was bluff bowed and high sided and consequently could be handled satisfactorily only when “off the wind.” Even under these favorable conditions, speed was comparatively slow. With a light wind, especially with a light adverse wind, she could make but little headway. Such a wind rendered capital ships practically helpless. That they were not destroyed by the opposing force was because at such times the opposing force was helpless too. A boat that had offensive power of attack and had means of locomotion enough to overcome tidal currents would have been an effective menace. As Fulton pointed out, the only measure of defense by a large vessel at anchor would lie in a cordon of small boats. But a boat fully, or even partially, submerged would have had an excellent chance to get through a cordon and destroy her prey. In spite of the limitation of speed and cruising range that today would condemn any such boat as absolutely worthless, these limitations were sufficiently generous when compared with the status of naval architecture that prevailed in 1800–1806 to make Fulton’s submarine, when he proposed it, a factor of actual and positive value.

If that can be said of the Nautilus, all the more it is true of the design that he submitted to the British Government. Between the Brest experiments in 1801 and his proposals in 1804, as evidenced by his “Drawings and Descriptions,” it is clear that he had given the matter considerable thought and to some purpose. The specifications as submitted to the British agent called for a boat 35 feet long and 10 feet beam as compared with the similar dimensions of the Nautilus of 21 ft. 3 in. and 6 ft. 4 in., respectively, giving at least three times the tonnage. It was to carry a crew of six instead of three men with provisions sufficient to enable her to be kept at sea for 20 days. The offensive capacity was 30 submarine bombs (or mines) as against a single trailing one with the Nautilus. The vessel designed for the British Government was a real sea-going boat that could independently navigate the Channel while the little Nautilus could not venture far from land or from some large vessel acting as a base.

An examination of the details, particularly those on Plates First and Second will disclose many improvements over the French prototype, shown facing page 26. In the first place the hull is that of a seagoing boat, equipped with a well-developed sail plan for propulsion when on the surface and not the queer contraption that the French marine architects condemned. On the surface this boat could have been handled as easily and she would have sailed as fast as any sloop of the same size. The mast could have been laid back on the deck and the sails disposed of in a few minutes preparatory to plunging.

To plunge and again come to the surface of the water, ballast tanks, sea valves and hand pumps provided ample facilities readily to overcome or restore excess of buoyancy. The brass cylinder with the hemispherical ends would suffice to withstand the exterior hydrostatic pressure. The required thickness of shell was a matter of computation, one readily made with certainty even in those days.

The difficulty with all early submarines was motion beneath the surface. In the British plan, Fulton proposed to obtain motion by a manually operated crank turning a propeller. The boat was larger than the Nautilus, but so also would have been the crew. For short distances he could undoubtedly have driven the boat at his estimated speed. The propeller was a two-bladed affair of modern type. Fulton had now definitely abandoned the full helical or Archimedes screw that Bushnell used and which he had himself tried in his first experiments.

Reference to Plate First and its description will show, however, an exceedingly interesting addition that Fulton had made in the British boat. He reasoned correctly that a propeller when not turning would cause a considerable drag to the boat when sailing, and thus reduce her speed. He, therefore, arranged that his propeller could be folded so as to lie horizontally. This he proposed to do by a hand crank and gearing operated from within the boat. On Plate Seventh it will be seen that the propeller when folded lay well above the water surface and so would not have been an impediment to the motion of the boat. When it is recalled that the propeller was not generally adopted as a means of vessel propulsion until after 1845, when the steamship Great Britain crossed the ocean between England and New York, the first vessel driven by a screw propeller to accomplish the feat, and that a propeller that could be folded or hoisted above water was not introduced until about 1850, because at that period steam was merely an auxiliary to sails, it will be seen how far ahead of his time Fulton was in the design that he made in 1804.

Another radical innovation was a horizontal propeller, Marked B in Plate First, attached near the bow of the boat. This propeller, also actuated by a crank from within the boat, was to give the boat vertical motion when submerged and so enable it to be kept at any depth that might be desired. This principle of the horizontal propeller is that of the helicopter, the device now being experimented with by airplane designers in order to give planes a vertical motion or permit them to hover stationary in the air. It was precisely those same results in the water that Fulton undertook to accomplish with his submarine.

The other mechanism in the interior of the boat is simple and self-explanatory. There were two anchors with windlasses, one anchor to hold in the usual manner against drifting, the other to regulate depth when lying stationary. There were pumps for emptying the water ballast chambers. On deck was a conning tower quite similar to the tower on a modern submarine, which served when closed as a lookout for the helmsman, and when open as means of ingress and egress for the crew. This conning tower had glass windows through which an observer could watch big prey, or steer his course when the boat was partially submerged. Plate Fifth shows how the conning tower could be used when it should be the only part of the vessel above the surface. This particular plate is of peculiar interest in that Fulton has drawn a picture of himself looking through the glass-covered ports. In the original drawing the head is full size.

Attached to the conning tower were two pipes marked F and G in Plate Second. These pipes led to the interior of the boat and permitted fresh air to be drawn in, and the vitiated or mephitic air (as Fulton called it) expelled. These pipes permitted the boat to be submerged so that the deck was just awash, the only part above the surface being the upper half of the conning tower and the air pipes. This is the situation as shown in Plate Fifth. So operated, the boat did not differ materially from a modern submarine under similar conditions with her periscope out of water.

From Fulton’s small conning tower he had only direct vision. A periscope enables the boat to be wholly submerged with vision obtained by reflecting mirrors. But a boat submerged so as to be just awash, with only the conning tower showing, and driven by a hand-operated propeller could have entered at night unseen almost any harbor, because in those days there were no powerful searchlights to illuminate the surface of the water at a distance.

The British were right in the secret note that they sent to the naval commanders that Fulton’s boat, even without the later improvements that he showed the British Government, could in the hands of the French have made an attack with very serious results upon an open roadstead such as the mouth of the Thames.

According to modern phraseology, Fulton’s British boat was a submersible rather than a submarine. The latter term defines a vessel that has powers of offense under water by torpedoes that in turn have means of locomotion. With such a torpedo neither Fulton nor the art was acquainted. His torpedoes or “bombs” were immobile affairs intended to be anchored, dragged by a boat or allowed to drift with the tide and to explode by concussion.

With the Nautilus it is true that he contemplated dragging a “bomb” beneath the bottom of a ship to be attacked, and in this respect the Nautilus possessed some feature of a true submarine. The plan that he proposed for the Nautilus presented many serious difficulties depending as it did on the fixing of a spike in the bottom of the other vessel. Fulton himself apparently reached the conclusion that this suggestion was impracticable, through actual experiments or further study. The boat that he proposed for the British Government had no such attachment, but instead was designed to carry “bombs” to be deposited secretly in an enemy harbor, and there to be anchored so as to remain beneath the surface when they would come in contact with the bottoms of passing vessels, or to be released in couples held by bridles and thus to be carried by tidal currents across the cables of anchored ships when the “bombs” would be drawn beneath the vessel and explode.

What Fulton called “bombs” are today known as mines. No means are shown in his plans by which these mines could be placed or released while his boat was submerged. The capability to submerge and to move beneath the surface was expected to permit the boat to work into a harbor unperceived, and there to lie in wait beneath the surface until night presented the opportunity to rise unseen, when the mines would be placed or set free. The successful experiment with the Dorothea showed that his mines could be completely effective and that, therefore, his submersible mine layer, as perhaps she can be correctly described, could have been developed into a very effective engine of war.

In Fulton’s bombs, as he calls them, we are not particularly interested because he has fully described these devices in his book that he wrote on Torpedo Warfare. It is, however, in view of subsequent events exceedingly interesting to point out that Fulton foresaw the conditions that actually obtained in the recent war.

On pages 71–2 of the “Descriptions” he explained how hundreds of such bombs or mines could be strewn in the channel of the Thames or along the coast and it would not be in the power of the whole British marine to prevent such practice. This is precisely what the Germans undertook to do, forcing the British, even though they had control of the open seas, to sweep the Channel by daylight, day after day, in order to remove mines that might have been planted during the night. Furthermore, Fulton pointed out that a line of such mines could be strung from Calais to Dover, rendering it “impossible for any vessel to pass without certain destruction.” When the German submarine attack on British commerce became seriously acute, the British authorities put into execution that which Fulton had suggested and strung a line of obstructions across the Channel from Dover to Calais thereby compelling the German submarines to pass around the northern coast of Scotland in order to reach the open sea.

Speaking of the effect of submarines and mines, Fulton’s language is worthy of repetition because the sinister side of his prophecy became so nearly realized between 1914 and 1918:

The moment this System or any other reduces the British marine to Boat fighting, the revered Sovereignty of the Seas will be forever lost; Colonies must be Abandoned and the whole influence which England holds in the scale of nations will Vanish. This is the natural and obvious consequence of this system when reduced to practice and prosicuted by a powerful nation with energy and Spirit. The Wealth of England and the existence of her fleets depend on her immense and uninterrupted commerce, But should France ever possess a means to cut off or interrupt such trade, England would be obliged to submit to any terms which Bonapart might think proper to dictate.

Substituting Germany for France and Hohenzollern for Bonaparte, we have precisely the very situation that existed in 1915, when the naval authorities of Germany expected to break the power of Great Britain, and in which attempt they came so perilously near success.

The Commission charged by the Directory to examine the plan of the Nautilus gave credit in its report on September 5th, 1798, to Fulton for having invented a terrible means of destruction since it acts in silence. That description was merited, but it remained no more than an expression of private opinion. It failed to secure for Fulton the public support to which his device entitled him. The world, perhaps fortunately, had to wait a century for the production of this engine of destruction. In the light of experience an examination of Fulton’s improved plan as contained in his “Drawings and Descriptions,” fully confirms the decision of the French Commission in that:

“LE BATEAU SOUS-MARIN IMAGINÉ PAR LE CITOYEN FULTON EST UN MOYEN DE DESTRUCTION TERRIBLE, PARCE QU’IL AGIT DANS LE SILENCE ET D’UNE MANIÈRE PRESQUE INEVITABLE.”