The Sun.
London, England, 1866-10-20 00:00:00

103 104

lier Majesty's Ship Waterwitch.

It has been said by one of the most eminent of
living authorities on marine engineering that there
is very little novelty in the idea of propelling vessels
by water. This is true in the main, as in 1661 a
patent was taken out for an application of the kind,

and was followed by many others,-but without any
marked success being obtained untillB39, when Mr.
Ruthven, of Edinburgh, patented a greatly im-
proved application of the principle, which was fur-
ther improved upon and a new patent taken out by
him in 1839. A small boat was constructed and
fitted with the Ruthven machinery and placed on

the Thames, and a working inod..:lof the boat and
machinery was also placed in the Gr..at Exhibition
building of 1851, but the principle of hydraulic pro-
pulsion of vessels was viewed with evident disfavour
then by the majority of engineers; the chief objec-
tions urged against its adoption being the large
amount of rubbing surface the water has to encoun-
ter, the cost of producing the propelling power be-
yond a certain rate, and the liability to choke the
perforated bottom- of the ship in shallow water, and
shut out the water supply. On the other hand, the
invention offered the not inconsiderable advantages
of a power of propelling the vessel forwards or back-
wards, Or of turning her on her centre, stopping sud-
denly in her course, going on ahead again or astern,
all without stopping or reversing the engines. It is
also claimed for the invention that a greater power
can be obtained from the same amount of fuel burnt,
as compared with the paddle or the screw ; that the
power of the engines is uniform, producing smooth
motion with perfect freedom from vibration or noise ;
no reaction on themachinery with the ship plunging
in a heavy sea ; an independence of rudder aid in
steering or turning a circle ; a power of relieving
the vessel of any water entering by a leak or shot
damage by simply shutting off the ordinary water
entrance thro ugh th e perforated bottom of the vessel's
hull, and a complete. control over the movements of
the vessel by tit's _officer in charge, and on the upper
deck, by a valve lever without communication with
the engineers below, the engines never being required
to " ease," " stop," or " reverse," the engineer
simply keeping the engines straight at their work,
and the officer in charge of the ship controlling the
propelling power they create by opening or closing a
valve with his lever. The majority of these seemingly
somewhat sanguine expectations proved to be correct
but it was 1853 before the first vessel was built and
fitted with Ruthven hydraulic propelling machinery
for commercial purposes. The vessel was built partly
at the expense of the Prussian Government, and is
said to be still running satisfactorily on the Oder.
The first independent testimony we find in this coun-
try to the valae of the hydraulic propeller lies in the
evidence given before Lord Justice Knight Bruce in
September, 1863, onthe hearing of a petition of Mr.
Ruthven, of Greenock, for an extension of the pa-
tent granted to his father in 1849, Mr. A. Murray,
the chief engineer of Portsmouth dockyard, stating
that the Ruthven propeller afforded extraordinary
facilities for manoeuvring a ship of war understeam,
and he saw no reason why the speed with the Ruth-

yen propeller should not equal that to be obtained
with the paddle or screw. Mr. Murray also stated
that he hadbeen on official duty to Belgium by order
of the Admiralty to inspect and report upon a vessel
called the Seraing, built by the Messrs Cockerell,
and fitted with the Ruthven propeller. His re-
port was favourable to the principle, and from ex-
periments carried out betweien the Seraing and a
paddlewheel vessel of the same form, tonnage, and
horse power of engine the difference in speed was
found to be about 10 per cent. in favour of the
Ruthven propeller. Mr. Murray further stated that
he considered the principle of so much value that he
pressed it on the attention of the Admiralty, and
orders were consequently sent down from the Admi-

ralty to Portsmouth dockyard for the lines of a
vessel to be prepared for building, of sufficient ton-
nage to insure a full and practical trial of the inven-
tion and its suitability as a propelling power for
vessels of war. Mr. Murray's evidence thus gives
an official history of the causes which originally led
the Admiralty to sanction the building of the Water-
witch and the application to her of the Ruthven sys-
tem of hydraulic propulsion, the first official trial of
which by the officers of the Admiralty took place
yesterday in the trial trip of the IVaterwitch down
the Thames.

The building of the hull of the Waterwitch was
consigned by the Admiralty to the Thames Iron-
works and Shipbuilding Company, and the design
and construction of her engines and the construc-
tion of the enormous turbine wheel, which is the
Ruthven propeller, was consigned by the Admiralty
to the Messrs:J. and W. Dudgeon, the firm whose
name has been so intimately associated with the ex-
position and success of the independently-working
twin-screw system of propulsion in England. The
hull of the Waterwitch is built of iron, of 778 tons'
measurement, 162 ft. in length by 32ft. in breadth, and
13ft. 9in. in depth. She is flat in the bottom, broad
in her midship section in proportion to her length,
and is " d3uble-ended"—fitted with a rudder at each
end—similarly to some of thesmallThames steamers.
Her defensive power as a g,tinboat consists in a belt
of armour-plating, of 4} inches in thickness, at
the water-line and centrally on her broadside, with
walls of iron, or athwartship armour-plated bulk-
heads, across her upper deck, the object being to
fight guns over her deck in linewith her keelthrough
gunports in the athwartship bulkheads as well as
through broadside ports.
The armour-plating is
backed with ten inches of teak, and is further
strengthened by the usual inner skin of an iron-built
vessel. In the bottom of the vessel, and centrally,
is a raised space extending to a good breadth on each
side of the centre of the vessel, and still further
longitudinally, and which maybe termed, for the sake
of plainness of description, a long and shallow iron
box. The lower side of this
box is fitted with an
immense number of small rectangular orifices, which
give admission to the water from outside and under
the vessel's bottom, but the further passage of the
water from the box is controlled by four sluice
valves, which, it is scarcely necessary to say, are only
opened when the machinery is at work and help
from the outer water is required to propel the vessel.
Division plates lead the water from the sluice valves
to the next portion of the machinery which is the
" Rathven," " Hydraulic," or " Turbine" wheel,
which draws the water in through the bottom of the
vessel and ejects it out through the copper propul-
sion pipes and nozzles through an aperture on each
side of the ship,, a little above the water line. The
hydraulic wheel is fixed immediately over the four
sluice valves and the water-box or canal. It revolves
in a cast-iron circular case, 19ft. in diameter, which
has been turned carefully throughout its interior
surface, the object of this being to reduce the fric-
tion to a minimum point of the water driven over
its'surfaces. The wheelitself is 14ft. 6in. in diameter,
and weighs eight tons. It is made of boiler-plate,
and is divided into 12 sections by arms or blades
fixed vertical and radial (although only vertical at
their extreme diameter, forming a tangent from the
surface). From their outer edge they begin to alter
in shape and position, and at their centre turn spi-
rally, like the blades of a Griffiths' propeller, and
thus obtain a " grip" upon the water upon their
i
first suction upon it on issuing from the canal.
twoOn therec •ts‘alilgeeull-acra_ssihnagpeedd dscharge pipes, in each ofge in opposite positions, are
which is fitted a large parallel two-way plug for
diverting the water as it rushes from the wheel into
the propulsion pipes and thence into the nozzles
outside the ship. The copper propulsion pipes have
a spiral twist given them to reduce friction in the
passage of the water through them, and are about
2ft. Sin. by 2ft. lin., interior measurement. The
nozzle pipes on the exterior of the vessel's sides are
continued about Bft. on each side of the centre, and
orifices 24iu. by 18in.
protected by armour-
or the hydraulic wheel
horizontal and direct,
Theypm; at
isnugr
.e
are
Taht
of e their
brass,dri
driving
ndgias
lc; discharge orifices f
angle of 120 degrees.
The connecting rods from the crank shaft of the
isstacnodmi npgristeod eachint three horizontal
a
wheel are connected direct from the cylinder piston
in single guide blocks. The
engine is 3ft. 6in., and the
rods,dlengthia m
ettheoerf loasf tt
ttobekr: working
cylinders
38iu.
The three steam
slides are worked by one eccentric, cutting off the
steam at about 11-16ths of the stroke, the action
being exceedingly good. in, every other respect,