Ruthven's Hydraulic Propeller. 57 
ever short continuance; this alone creating a great saving 
of fuel on long sea voyages. 
g. Should the vessel be pierced with shot, or spring a 
leak, the regular supply of water from the canals may be 
shut off, and the water from the leak taken up instead to 
supply the centrifugal pump—thus discharging the leak 
and propelling the vessel at the same time. With a 500 
horse-power engine, 1,000 tons of water per minute might 
be discharged through the nozzles. 
10. In construction this propeller differs from the paddle. 
or screw in the following respects:—On the one hand, the 
paddle-wheels and boxes, sponson beams, and paddle-shaft 
are dipensed with; on the other, the screw shaft, screw- 
tunnel, and add to these the solid wrought iron double 
stern-post, so costly in large screw vessels. In lieu of 
these, the hydraulic propeller requires the turbine-wheel, 
water-chamber, and nozzles, the cost of constructing which 
need not exceed that of those parts dispensed with in the 
paddle or screw. 
I1. From the foregoing it will be readily perceived that 
the important element of safety is almost completely 
attained by this invention. It is not too much to say that. 
had the unfortunate Loudon been fitted with this propeller, 
she could have discharged with a few strokes of her engine 
all the water which flooded her engine-room. 
In order to bring this invention before the public, a vessel 
called the Wautilus has been built, at Blackwall, by the 
patentee, at the expense of private gentlemen, for the pur- 
pose of practically proving the advantages of this mode of 
propulsion. A trial-trip was made on Saturday, March 24, 
1866, when the superiority of this invention was fully 
proved. This vessel, fitted with engines of 20-horse power, 
was able, with a less expenditure of steam, to distance a 
paddle-boat of 24-horse power. This vessel has made 
many trips on the river, and very many persons, scientific, 
practical builders, and others, have witnessed her perform- 
ance. Oneand all, however, expressed their approbation, and 
many their astonishment at the results. On the 8th of 
April a trial trip of a more formal character was made, on 
which occasion one of the best of the up-river paddle- 
boats was hired for the purpose of racing with, and fairly 
testing the merits of, the hydraulic, as compared with the 
paddle-wheei propeller. The Volunteer, the vessel referred 
to, was a smaller vessel, of much finer lines for sailing, and 
of greater horse-power. The Nautilus had, moreover, over 
