In all these propellers, we have only an imitation, very often a rude one, of the processes which nature puts in play in fishes and mollusks, and the mode that we now wish to make known is without contradiction that which imitates these the best.

Hydraulic propulsion by reaction consists, in principle, in effecting a movement of boats, by sucking in water at the bow and forcing it out at the stern.  This is a very old idea.  Naturalists cite whole families of mollusks that move about in this way with great rapidity.  It is probable that such was the origin of the first idea of this mode of operating.  However this may be, as long ago as 1661 a patent was taken out in England, on this principle, by Toogood & Hayes.  After this we find the patents of Allen (1729) and Rumsay (1788).  In France, Daniel Bernouilli presented to the Academic des Sciences a similar project during the last century.

Mr. Seydell was the first to build a vessel on this principle.  This ship, which was called the Enterprise, was of 100 tons burden, and was constructed at Edinburgh for marine fishery.  The success of this was incomplete, but it was sufficient to show all the advantage that could be got from the idea.  Another boat, the Albert, was built at Stettin, after the same type and at about the same epoch; and the question was considered of placing a reaction propeller upon the Great Eastern.

About 1860 the question was taken up again by the house of Cokerill de Seraing, which built the Seraing No. 2, that did service as an excursion boat between Liege and Seraing.  The propeller of this consisted of a strong centrifugal pump, with vertical axis, actuated by a low pressure engine.  This pump sucked water into a perforated channel at the bottom of the boat, and forced it through a spiral pipe to the propelling tubes.  These latter consisted of two elbowed pipes issuing from the sides of the vessel and capable of pivoting in the exhaust ports in such a way as to each turn its mouth downward at will, backward or forward.  The water expelled by the elbowed pipes reacted through pressure, as in the hydraulic tourniquet of cabinets of physics, and effected the propulsion of the vessel.  Upon turning the two mouths of the propelling tubes backward, the boat was thrust forward, and, when they were turned toward the front, she was thrust backward.  When one was turned toward the front and the other toward the stern, the boat swung around.  Finally, when the two mouths were placed vertically the boat remained immovable.  All the evolutions were easy, even without the help of the rudder, and the ways in which the propelling tubes could be placed were capable of being varied ad infinitum by a system of levers.

The Seraing No. 2 had an engine of a nominal power of 40 horses, and took on an average 30 minutes to make the trip, backward and forward, of 85 kilometers, with four stoppages.

The success obtained was perfect, and the running was most satisfactory.  It was remarked, only, that from the standpoint of effective duty it would have been desirable to reduce the velocity of the water at its exit from the propellers.