constitutes an entirely different mode, and should not figure in our
enumeration, considering the essentially variable character of the force
utilized.

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 Académic 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