IMPROVEMENTS IN THE MEANS OF STEERING STEAM VESSELS, AND IN. APPARATUS FOR THE SAME
Year: 1868

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery
Lane, in the County of Middlesex, Patent Agent, for the Invention
of "IMPROVEMENTS IN THE MEANS OF STEERING STEAM VESSELS, AND IN.
APPARATUS FOR THE SAME."-A communication from abroad by Corrado,
Trinchieri, of 13, Boulevart St. Martin, Paris.
Sealed the 12th January 1869, and dated the 25th July 1868..
PROVISIONAL SPECIFICATION left. by: the said Alexander. Melville
Clark at the Office of the Commissioners of Patents, with his;
Petition, on the 25th July. 1868.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN THE MEANS OF STEERING STEAM
VESSELS, AND IN APPARATUS FOR THE SAME," to be as follows:-
This Invention relates to the application of the principle of equality
of pressure of fluids on the sides of their containers for the production.
of circular motion in vessels provided with steam power.
In manoeuvring under steam the rudder is the only means available
for turning the vessel, and its action being due to the pressure of the.
water displaced in the wake of the vessel is entirely dependent on the

page_text: speed of the latter, that is to say, it is greatest when the vessel moves
at a high speed and nil when the vessel is at rest. Experience further
proves that even when the engine developes its full power and the
rudder is placed in the most favorable position, a vessel cannot make
an entire revolution without traversing the circumference of a circle
the diameter of which is from five to ten times the length of the
vessel at its water line, occupying a time from four to eight minutes
according to the power of the engines, the dimensions and form of the
keel and rudder surface. There are many disadvantages attending
this system, such as in manoeuvring vessels in a limited space during
an engagement where it is impossible to change position in order to
turn and deliver blows in time on given points, and these objections
are still more apparent at the present time when war ships present an
evident tendency to become enormous masses of iron, the facilities for
turning and moving in all directions are of the highest importance in a
military point of view.
Vessels of war whose rudders have become disabled are rendered
helpless and are often lost, thereby proving the great necessity there,
exists of some means being provided if possible of governing their
movement in a more certain manner so, that in case of necessity they
may be steered independent of the rudder. The employment of twin
screws placed on either.-side of the stern and the encasing of the upper
part of the rudder (above the water) are both steps in the right direction,,
although they give rise to complications and great additional expense,
and are not free from objections while they fail to completely answer
the purpose desired,
According to the mode of steering or manoeuvring vessels of this
Invention I dispose a pipe of suitable diameter, if possible, along the
longitudinal axis of a vessel on along one side, as shown by the dotted
lines in Figure 8 of the Drawing annexed, which pipe branches off at
the stern in opposite directions AB, A C, communicating, if desired,
by means of a cock placed at A. Supposing a centrifugal or other
pump to be placed in the pipe A D, and driven by the engine, and
water be admitted in sufficient quantity to produce a continuous jet,
a means is, thus obtained of moving the vessel either to the right or
left according as one or other of the branch pipes A B, A C, is placed
in communication with the longitudinal tube. If this tube be further
extended to the bows at E and have two lateral branches E F, EG,
with a cock placed at the junction of the pipes, and by placing one or

page_text: other of these branches in communication with the longitudinal
pipe A D E, a power may be obtained at either end of the vessel for
overcoming its inertia and moving it to the right or left.. Lastly, if
the two branch pipes ABEF, or ACEG, be open at same time
the vessel will move in a parallel direction to itself to the right or left,.
certainly at a low speed but still sufficient to be of use in some cases..
In this manner a vessel may be readily moved in any direction desired.
If the boilers could furnish a jet of steam capable of overcoming the
inertia of the vessel and of imparting sufficient motion thereto for the
purpose of turning the same, the question would be much simplified
as it would only be necessary to regulate the position of the pipes and
the admission of the steam to pipe ADE, and from it to the lateral
branches. However, in consequence of the great speed at which the
steam from its want of density would flow out of the pipes, the boilers
would be deprived of steam before the vessel had well begun to move;.
as may be readily proved if one considers the ordinary size of a boiler.
and the quantity of steam it will produce in a given time. Thus
this simple mode is unsuitable in case great speed is. required,
such as in war vessels for example, but apart from the objections.
inherent to all steam jets it may be applied to steam boats requiring.
to bo towed in and out of harbour, that is to say, when the engines are
not acting and the whole of the steam in the boiler may be rendered.
available.
1st, the resistance to turning; 2ndly, to lateral motion; and,
3rdly, the proportion of motive power required to work the pump
in manoeuvring the vessel in one or the other case may be readily
calculated.
The annexed Drawing shows one of the various ways in which the
Invention can be carried into effect..
Figure 1 is a transverse section of a vessel on line X, Y, Figure 3,..
which is a longitudinal section of same.
A double-acting pump with compressed air chamber, Figure 2, is
employed, the pistons of which pumps are connected by means of cranks
to an extension of the screw shaft capable of being. disconnected when
desired. This pump takes in sea water at two or more openings in the
stern and injects it into the longitudinal pipe in the form of a continuous
jet. The stroke and diameter of the pump pistons are regulated according
to the number of revolutions ordinarily made by the screw, so as to take:

page_text: in a sufficient volume of water per second to produce the two reacting
jets, the diameter of the pipes being previously determined relatively
with the speed attainable. I will suppose the pistons to move at the
rate of three feet per second, and as space on board ship is very limited
the dimensions of the pump may be greatly reduced and the speed of the
pistons increased proportionately. Supposing the screw to be driven at
the rate of fifty revolutions per minute when the pump is not working,
and that the diminution of speed produced by the latter is approximately
equal to that resulting from the maximum action of the rudder, the
number of revolutions will be reduced to. about forty, and consequently
the number of strokes of the piston will be 80 per minute. Two sliding
couplings M M, Figures 1, 2, and 3, are employed for connecting or
disconnecting the three parts of the horizontal shafts M N, M M, M P,
Figure 3, so. as to. permit of the pump acting whether the vessel be
stationary or in motion for the purpose of turning. the same, it being
only necessary to slacken the rotary motion of the shaft in some cases, or
to, keep the pump, working in order to prevent damage to the engine by
starting or stopping too suddenly. Two cocks, shown in elevation and
section at Figures 4 and 6 of the Drawings, are placed at the ends of the
longitudinal pipe for supplying the water pumped into one or other of
the two reaction tubes. Supposing that the whole or both of these cocks
were to be accidentally closed while the pump is in work, and the water
should do some injury from the want of an outlet owing to its incom-
pressibility, I avoid any danger from this cause by adapting a tube
QR, Figure 1, to the compressed air chamber provided with a safety
valve opening, outwards under a pressure, a little above that normally
existing in said chamber when the pump is acting. The numbers 1, 2, 3,
on the hand wheel shown in Figure 5 serve to indicate the positions in
which the wheel should be placed in order to turn the vessel to the right or
left or move it in a straight line in a parallel direction, a fourth of a turn, as
indicated, being sufficient to obtain these three results. In order to turn
the cock in one or other direction, it is simply necessary to use a tele-
graphic apparatus or other suitable signal in order to render the steering
as easy as with a rudder. If the cock is of too large dimensions to be
turned by hand, gearing may be provided for the purpose. In the case
of vessels having revolving. turrets where the commander requires to
have at hand everything necessary for manoeuvring the vessel, the cocks
may be placed in the central position shown in Figure 7 or otherwise.
In order to operate both cocks simultaneously from any part of the

page_text: vessel the system of hydraulic steering apparatus used for working the
rudders of ships may be employed.
As before mentioned if the lateral motion is not required one of the
cocks and one half of the longitudinal pipe may be dispensed with;
retaining only the stern portion for example, and making the reaction
tube and cock double the size. In this case, by suitably lengthening the
longitudinal tube and modifying the cock, a third aperture may be made
at the stern in a line with the axis of the vessel for receiving a safety
valve, and for imparting forward motion to the vessel in certain cases:
Figure 8 of the Drawings shows this arrangement. Centrifugal and
rotary pumps working at high speeds which are required in this case will
answer almost as well as ordinary pumps for injecting the water into the
reaction tubes, and may be driven by means of gearing, band pullies,
or otherwise; they further possess the advantage of occupying less space.
In order to lessen the length of the tubing reduce the friction and
number of bends and prevent the loss of pressure consequent thereon.
The pumps might be placed at the stern near the lateral emission orifices,
but as these parts require constant attention to keep them in working
order it is preferable that they form part of the engine, and so be under
the eye of the engineer. I would add that the hull is generally narrowed
towards the stern, and in order to obtain the necessary room for the
pumps or turbines they must be placed some distance therefrom, thus
requiring tubes of some length for carrying the reaction jets as near as
possible to the stern, otherwise they would lose a considerable portion
of their effect, which increases in proportion to the rate of discharge.
In the present case the resistance to overcome increases as the square
of the speed of rotation, which is always less than that of the flow;
consequently it is of importance to prevent as much loss as possible,
which is effected by placing the reacting orifices as far as possible from
the axis of rotation.
There now only remains the third part of the problem, viz., to
determine the proportion of engine power required for producing the
circular motion of the vessel at the desired speed. For this purpose, if
when the pumps are at rest all the cocks for introducing and discharging
the water be opened at the same time, as also the several valves, the two
columns of water arriving on opposite sides of the pistons will balance
each other, and the latter will remain stationary, whatever may be the
depth below the water line of the admission and discharge orifices:

page_text: The latter may be in any suitable position provided they are below the
water line, for if they were placed above the motive power employed to
raise the water such a height would be evidently wasted.
The motive power required for working the pump pistons at the desired
speed (of three feet per second for example), may be divided into two
parts, viz.-1st. The power necessary for raising three cubic yards of
water per second to a height of thirty feet in order to maintain the desired
rate of flow in the reaction tubes. 2ndly. The power necessary for over-
coming the passive resistance and loss of pressure due to the friction of the
water on the sides and bends of the tubes, and the inertia of the valves.
All these resistances are the cause of a diminution of the effective power
of the pumps; their coefficient however when in proper condition seldom
falls below 60 per cent.
In conclusion I would observe that a rudder not only produces the
circular motion of the vessel, but also presents an immersed resisting
surface which serves as a brake and absorbs a considerable portion of the
motive power of the engine, which is a pure loss, while in the present
case there is also a loss of power due to the tubes, but as the immersed
:section remains the same considerable power may be thereby economised.
This Invention possesses the further advantage of producing circular
motion of the vessel (independently of its progressive movement) even
when stationary, and of being placed below the water line.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 23rd January 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of July, in the year
of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her

page_text: special licence that I, the said Alexander Melville Clark, my executors,
administrators, and assigns, or such others as I, the said Alexander
Melville Clark, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN THE MEANS OF STEERING STEAM VESSELS,
AND IN APPARATUS FOR THE SAME," a communication to me from abroad by
Corrado Trinchieri, of 13, Boulevart St. Martin, Paris, upon the con-
dition (amongst others) that I, the said Alexander Melville Clark, my
executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in
the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Alexander Melville Clark, do
hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the Sheet
of Drawings hereunto annexed, and to the letters and figures marked
thereon (that is to say) :-
This Invention relates to the application of the principle of equality
of pressure of fluids on the sides of their containers for the production
of circular motion in vessels provided with steam power.
In manoeuvring under steam the rudder is the only means available
for turning the vessel, and its action being due to the pressure of the
water displaced in the wake of the vessel is entirely dependent on the
speed of the latter, that is to say, it is greatest when the vessel moves
at a high speed and nil when the vessel is at rest. Experience further
proves that even when the engine develops its full power and the
rudder is placed in the most favorable position, a vessel cannot make
an entire revolution without traversing the circumference of a circle
the diameter of which is from five to ten times the length of the
vessel at its water line, occupying a time varying from four to eight
minutes according to the power of the engine, the dimensions and
form of the keel and rudder surface. There are many disadvantages

page_text: attending this system, such as in manoeuvring a vessel in a limited
space during an engagement where it is impossible to change position
in order to turn and deliver blows in time on given points, and these
objections are still more apparent at the present time when war ships
present an evident tendency to become enormous masses of iron, the
facilities for turning and moving which in all directions are of the
highest importance in a military point of view.
Vessels of war whose rudders have become disabled are rendered
helpless and often lost, thereby proving the great necessity there exists
of some means being provided if possible of governing their movements
in a more certain manner, so that in case of necessity they may be
steered independent of the rudder. The employment of twin screws
placed on either side of the stern and the casing of the upper part
of the rudder (above the water) are both steps in the right direction,
although they give rise to complications and great additional expense
and are not free from objections while they fail to completely answer
the purpose desired.
According to the mode of steering or manoeuvring vessels of this In-
vention I dispose a pipe of suitable diameter, if possible, along the
longitudinal axis of a vessel or along one side, as shown by the dotted lines
in Figure 8 of the Drawing annexed, which pipe branches off at the stern
in opposite directions A B CD, communicating, if desired, by means of a
cock placed at A. Supposing a centrifugal or other pump to be placed in
the pipe A D, and driven by the engine and water be admitted in sufficient
*quantity to produce a continuous jet, a means is thus obtained of moving
the vessel either to the right or left according as one or other of the
branch pipes A B, A C, is placed in communication with the longitu-
dinal tubes. If this tube be further extended to the bows at E and have
two lateral branches EF, EG, with a cock placed at the junction
of the pipes, and by placing one or other of the branch pipes in
communication with the longitudinal pipe ADE, a power may be
obtained at each end of the vessel for overcoming its inertia and moving
at to the right or left. Lastly, if the two branch pipes AB, EF, or
AC, EG, be opened at same time the vessel will move in a parallel
direction to itself to the right or left, certainly at a low speed, but still
sufficient to be of use in some cases. In this manner a vessel may be
readily moved in any direction desired.
If the boilers could furnish

page_text: a jet of steam capable of overcoming the inertia of the vessel, and of
imparting sufficient motion thereto for the purpose of turning the same,
the question would be much simplified, as it would only be necessary
to regulate the position of the pipes and the admission of the steam to
pipe AD E, and from it to the lateral branches. However, in
consequence of the great speed at which the steam from its want of
density would flow out of the pipes the boiler would be deprived of
steam before the vessel had well begun to move as may be readily
proved if one considers the ordinary size of a boiler and the quantity
of steam it can produce in a given time. Thus this simple mode is
unsuitable in case great speed is required, such as in war vessels for
example; but apart from the objections inherent to all steam jets it may
be applied to steam boats requiring to be towed in and out of port, that
is to say, when the engines are not acting and the whole of the steam
in the boilers may be thus rendered available.
1st. The resistance to turning; 2ndly, to lateral motion; and, 3rdly,
the proportion of motive power required to work the pump in manœu-
vring the vessel in one or the other case may be readily calculated.
In the next place it is necessary to determine, 1st, what is the
resistance opposed by the water to the rotation of a vessel at different
speeds, and also the diameter of the reaction pipe and the rate of delivery
necessary for overcoming such resistance; 2ndly, the most suitable
arrangement of apparatus by the aid of which the desired movements
may be produced; 3rdly, the proportion of motive power required for
obtaining the speeds desired in order to compare it with the proportion
of the same power absorbed by the rudder, and also to ascertain the
effect of both engine and rudder and their respective utility. The side
of the ship is always of convex form varying according to its nature and
purpose. The resistance opposed by water to the movement of a flat
surface or of an immersed float has already been established in theory
more or less approximately, which however is not the case with bodies
terminating in curved surfaces.
Newton with the impulse of his analytical genius decomposed each
curved surface into several infinitesimal elements to be considered as
planes by the integration of these elemental resistances. From this
sprung a theory, which after being long accepted by mathematicians has
been disproved by the diligent researches of Borda, and this problem,

page_text: or which is the same thing, the determination of the minimum resistance
to the immersed section, which is such on important question in naval
construction still remains unsolved.
In order to simplify the question of the resistance opposed by the
water to the movement of bodies having curved ends I will suppose
A BOD, Figure 9, to be a rectangle corresponding to the immersed
section of a vessel, in which A C, B D, is the mean draft at the bow and
stern and ABCD, the length at the water line. Let EF be the
vertical central axis in a plane passing through the centres of pressure
of the two lateral immersed surfaces, and suppose the vessel to be turned 1
on the axis at a speed indicated by 10.
Leaving out for the moment the thickness of the hull and the
convexity of the vessel's sides, I will consider the resistance to be equal
to that which the water would oppose to the rotation of the moving flat
vertical plane, that is to say, equal to the rectangle ABCD. Let 1
K be the number of pounds corresponding to the resistance opposed
by the water to the motion of a vertical paddle float, having a square
yard of surface and moving at the rate of three feet per second.
It is in fact admitted, as proved by close approximation in experiments,
that for ordinary speeds this resistance is proportionate to the surface of 2
the float and to the square of its speed. Taking the half E F B D of
the immersed section the resistance opposed to its turning will be equal to
that which would support the other half A C E F in a contrary sense.
This hypothesis is not however quite exact in consequence of the
difference of immersion at the bow and stern and of the form of the fore 2
and after part of the hull. Taking a small portion of the lateral
immersed surface extending from the central axis to the point x, let h
be its depth, its linear speed of rotation, and I the half length of A B,
the surface will thus be indicated by h, d, x, the resistance opposed
to its motion by the water being
Khdxxv Khw³ xdx.
The momentum of this elementary resistance in relation to the axis of
rotation, E, F, will thus be
Khwxdxxx=Kh w³ ³ d x, and consequently
K
3

page_text: In this equation Lwhgow are the known quantities in each particular
case, or which are capable of receiving a priori a determinate value; K is
a numerical co-efficient which may be directly determined for each vessel.
What remains undetermined is, r, the radius of the pipe, the rate of
discharge, and H, which is a well-known function of ', so that by
assigning an arbitrary value to r or v¹ it is possible to determine the other
of the two known quantities with the equation [a.]
Passing to a particular case I will suppose the reaction engine to
be applied to an armour-clad vessel of form and dimensions equal to
those represented in the annexed Drawing fitted with two horizontal

page_text: cylinders direct acting at about 750 nominal horse power, equal to
4000 effective.
The value in equation [a] will be h=6, K=40, and K in default
of more exact data may be supposed to equal 33,000 yards, that
is, nearly three-fifths of the maximum limit given by Bourgois as before,
referred to in relation to the motion of immersed planes. Supposing the
linear speed of rotation at the water line at the bow and stern to be.
three feet per second, so that the vessel will perform an entire revolution
in a number of seconds represented by 2×40=251 sec. =4 min. 11 sec.,
that is to say, the minimum time occupied by the Bellerophon. This
gives w ==0.025.
14'
Supposing the orifices of the reaction pipe to be placed at about 13 feet.
(4 inches) below the water line m=0·90, and v=0·90, g=9-088=3.1415.
Lastly, as regards the two indeterminate quantities r and v³, taking the
latter as equal to 14 metres (15 yards), H being the depth due to this
speed will equal 10 metres or about one atmosphere of pressure.
By substituting these particular values for those in the equation [a]
I have 4000x3.1415xx14(0.90/19.61×10+0.81-0·81)=30×6×
9.8088 × 1×40, from which may be readily deduced ³=0·034.341,
and 1= ✔0.034341-0-185, and adding about half an inch for incrusta-
tions of the fluid I may take 8 inches as the internal radius of the
reaction pipe, the determining of which forms the first part of the
problem.
2ndly. The reaction engine must be varied in its arrangements to
suit the exigencies of each case.
The annexed Drawing shows one of the various ways in which the
Invention can be carried into effect.
Figure 1 is a transverse section of a vessel taken on line X, Y,
Figure 3, which is a longitudinal section of same with compressed
air chamber.
A double-acting pump seen in section at Figure 2 is employed,
the pistons of which pumps are connected by means of cranks to
an extension of the screw shaft capable of being disconnected when
desired. This pump, takes in sea water at two or more openings in the
stem and stern and injects it into the longitudinal pipe in the form of a
continuous jet. The stroke and diameter of the pump pistons are.
regulated according to the number of revolutions ordinarily made by the

page_text: screw, so as to take in a sufficient volume of water per second to produce
the two reacting jets, the diameter of the pipes being previously deter-
mined relatively with the speed attainable. I will suppose the pistons
to move at the rate of three feet per second, and as space on board ship
is very limited the dimensions of the pump may be greatly reduced and
the speed of the pistons increased proportionately. Supposing the screw
to be driven at the rate of fifty revolutions per minute when the pump
is not working, and that the diminution of speed produced by the latter
is approximately equal to that resulting from the maximum action of
the rudder, the number of revolutions will be reduced to about 40, and
consequently the number of strokes of the piston will be 80 per minute.
Let K be the radius of one of the pistons for determining the volume
of water to be injected into the reaction pipe, viz., ³×¹-3.14x
0-185x14 1.50, thus R=1.50 and R=0.693, or in round numbers
R=0.70. Lastly, if x be the length of the stroke of the pistons
would be the number of strokes per second, as the speed should be one
yard 801, or x=0.75.
**
60
x 80.
60
Two sliding couplings M M, Figures 1, 2, and 3, are employed for con-
necting or disconnecting the three parts of the horizontal shaft M N,
M M, MP, Figure 8, so as to permit of the pump acting whether the
vessel be stationary or in motion for the purpose of turning the same,
it being only necessary to slacken the rotary motion of the shaft in
some cases or to keep the pump working in order to prevent damage to
the engine by starting or stopping too suddenly. Two cocks, shown in
elevation and section in Figures 4 and 6 of the Drawings, are placed at
the ends of the longitudinal pipe for supplying the water pumped into
one or other of the two reaction tubes. Supposing that one or both of
these cocks were to be accidentally closed while the pump is in work,
and the water should cause some injury from the want of an outlet
owing to its incompressibility, I avoid any danger from this cause by
adapting a tube Q P, Figure 1, to the compressed air chamber, provided
with a safety valve opening outwards under a pressure a little above that
nominally existing in said chamber when the pump is acting. The
numbers 1, 2, 3, on the hand wheel shown in Figure 5 serve to indicate
the positions in which the wheel should be placed in order to turn the
vessel to the right or left or to move it in a straight line in a parallel
direction, a fourth of a turn as indicated being sufficient to obtain these

page_text: three results. In order to turn the cock in one or other direction it is
simply necessary to use a telegraphic apparatus or other suitable signal
in order to render the steering as easy as with a rudder. If the cock is
of too large dimensions to be turned by hand, gearing may be provided
for the purpose. In the case of vessels having revolving turrets, where
the commander requires to have at hand everything necessary for
manoeuvring the vessel, the cocks may be placed in the central position
shown in Figure 7, or otherwise. In order to operate both cocks
simultaneously from any point of the vessel the system of hydraulio
steering apparatus used for working the rudders of ships may be employed.
As before mentioned, if the lateral motion is not required, one of
the cocks and one-half of the longitudinal pipe may he dispensed
with, retaining only the stern portion for example, and making the
reaction tube and cock double the size. In this case, by suitably
lengthening the longitudinal tube and modifying the cock, a third
aperture may be made in a line with the axis of the vessel for receiving
a safety valve and for imparting forward motion to the vessel in certain
cases. Figure 8 of the Drawings shows this arrangement. Centrifugal
and rotary pumps working at high speeds, which are required in this
case, will answer almost as well as ordinary pumps for injecting the
water into the reaction tubes, and may be driven by means of gearing
band pullies, or otherwise; they further possess the advantage of
occupying less space. In order to lessen the length of the tubing
reduce the friction and number of bends and prevent the loss of pressure
consequent thereon. The pumps might be placed at the stern near the
lateral emission orifice; but as these parts require constant attention
to keep them in working order it is preferable that they form part of
the engine and so be under the eye of the engineer. I would add that
the hull is generally narrowed towards the stern, and in order to obtain
the necessary room for the pumps or turbines they must be placed some
distance therefrom, thus requiring tubes of some length for carrying
the reaction jets as near as possible to the stern, otherwise they would
lose a considerable portion of their effect, which increases in proportion
to the rate of discharge. In the present case the resistance to overcome
increases as the square of the speed of rotation which is always less
than that of the flow, consequently it is of importance to prevent as
much loss as possible, which is effected by placing the reacting orifices.
as far as possible from the axis of rotation.
There now only remains the third part of the problem, viz., to

page_text: determine the proportion of engine power required for producing the
circular motion of the vessel at the desired speed. For this purpose,
if when the pumps are at rest all the cocks for introducing and dis-
charging the water be opened at the same time, as also the several
valves, the two columns of water arriving on opposite sides of the
pistons will balance each other and the latter will remain stationary
whatever may be the depth below the water line of the admission and
discharge orifices. The latter may be in any suitable position provided
they are below the water line, for if they were placed above the motive power
employed to raise the water such a height would be evidently wasted.
The motive power required for working the pump pistons at the
desired speed, say three feet per second for example, may be divided
into two parts, viz.: 1st. The power necessary for raising three
cubic yards of water per second to a height of thirty feet in order
to maintain the desired rate of flow in the reaction tubes. 2ndly. The
power necessary for overcoming the passive resistance and loss of
pressure due to the friction of the water on the sides and bends.
of the tubes and the inertia of the valves. All these resistances are
the cause of a diminution of the effective power of the pumps, their
co-efficient however when in proper condition seldom falls below
60 per cent. In the present case, considering the increased size of
the tubes, in order to allow a certain latitude for correcting errors which
may arise in resolving other portions of the problem, I will suppose
that the effective power of the pump will absorb only 40 per cent. of
the motive power, and representing this by M M-3000x10x+
=75,000 kilogrameters, which, divided by 75 gives 1000 as the amount
of effective horse power, that is to say, exactly a fourth of the total
power of the apparatus. On referring to the table of experiments on
the rotation of vessels by the aid of the engines and rudder, the
resistance opposed by the water to the progress of the vessel is. repre-
sented by the formula K, SV, K being a co-efficient dependent on the
speed and form of the keel, S the immersed midship section, and the
speed of the vessel. If be the speed reduced by the action of the
rudder causing a difference represented by K, SV, this will at once give
the proportion of power absorbed by the rudder, and on calculation
it will be found that this is equal to an average of 0.467 of the whole
power. This result would be much nearer than that obtained by the
calculations with regard to the apparatus of this Invention, supposing
that the speed of rotation established in this hypothetical vessel equals

page_text: not merely the average speed of the vessels herein-before referred to but
that of the largest, viz., the Bellerophon.
In conclusion, I would observe that a rudder not only produces the
circular motion of the vessel but also presents an immersed resisting
surface which serves as a brake and absorbs a considerable portion of
the motive power of the engine, which is a pure loss of power due to the
tubes, but as the immersed section remains the same, considerable power
may be thereby economized.
This Invention possesses the further advantage of producing circular
motion of the vessel (independently of its progressive movement even
when stationary, and of being placed below the water line.
Having described the nature of this Invention, and the manner of
performing the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is, the
application of the principle of equality of pressure of fluids on the sides
of their containers for producing the rotary motion of vessels having
steam power. I obtain this result by means of an arrangement of tubes
and cocks and pump operated by the engine discharging a continuous
jet of water at one side of the bow and another at the stern on the
opposite side so as to readily turn the vessel; or I may have two jets,
one at the bow and the other at the stern, either on the port or star-
board side, for moving the vessel parallel to its longitudinal axis, the
whole being arranged substantially in the manner shown and described.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Twenty-third day of January,
in the year of our Lord One thousand eight hundred and sixty-
nine
Witness,
JAMES DAISH,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)