IMPROVEMENTS IN PROPELLING VESSELS, AND APPARATUS THEREFOR
Year: 1874

page_text: LETTERS PATENT to James Edwards Wilson, of Bromley, in the
County of Kent, Civil Engineer, for the Invention of "IMPROVEMENTS
IN PROPELLING VESSELS, AND APPARATUS THEREFOR.”
Sealed the 11th December 1874, and dated the 12th June 1874.
PROVISIONAL SPECIFICATION left by the said James Edwards Wilson
.
at the Office of the Commissioners of Patents, with his Petition,
on the 12th June 1874.
I, JAMES EDWARDS WILSON, of Bromley, in the County of Kent,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
PROPELLING VESSELS, AND APPARATUS THEREFOR," to be as follows:-
Propelling vessels by the direct action of the pressure of steam either
alone or mixed with hot gases against the water through which the
vessels travel without the intervention of any engine or moving parts,
effecting thereby economy in construction, working and maintenance,
reduction of wear and tear, and increase in the space available for
freight.

page_text: A tube or tubes, preferably bWO,
along the bottom or sides of the vessel parallel to the axis thereof and
either inside or outside the vessel. The tubes are circular, by preference
in cross section, and have one end of considerably greater diameter than
the other; they may either taper conically from the one end to the
other, or parabolically, the latter being the best. If only one tube is
employed it is placed along the centre line of the vessel. With two
tubes one is placed on one side and the other on the other side of the
centre line, equidistant and as far therefrom as possible. The ends of
the tubes are square to their axes, and each tube is laid with its large
end towards the stern of the vessel. When the tubes are laid within
the vessel the large ends must pass through the sides thereof into the
water. The small end of each tube is introduced and fixed hermetically
into either the smoke box itself of the boiler, or a separate box her-
metically connected with the smoke box. No special form of boiler is
involved, but the tubular form of the locomotive system is preferable.
Whatever may be however the system of boiler adopted there must be
a movable damper, by which, when required, the chimney may be
partially or entirely closed.
To the small end of cach tube is adapted, within the smoke box or
continuation thereof, a steam jet. The axis of the jet is the axis of the
tube, and the jet is preferred of a form similar to that of an "Argand"
gas burner, but with an annular slit for the passage of the steam. The
steam jet does not entirely fill up the end of the tube, and the annular
space left between the two is made adjustable so as to be increased or
diminished as may be required. The construction of the jet is also, such
as that the width of the annular slit for the passage of the steam may
be varied as required. The steam pipe from the boiler supplying steam
to the jet is placed entirely within the smoke box, or continuation
thereof, to avoid contact with the external air. Steam being allowed to
issue from the jet it rushes into the small end of the tube, and in its
progress along the tube has its velocity gradually reduced until at the
large end, which must have a duly proportioned area, its force becomes
such as to overcome the resistance of the vessel with the desired speed.
As the steam rushes out of the jet into the small end of the tube it
causes a rarefaction in the smoke box, and this causes the products of
combustion to enter through the annular adjustable space between the
jet and the end of the tube as well as through the central fixed opening

page_text: of the jet, and pass along with the steam through the tube. The amount
of hot gases thus drawn into the tube may be modified either by the
ash pan, damper, or by a special valve or flap in the smoke box or con-
tinuation thereof, and may be increased beyond the quantity actually
necessary for the due combustion of the fuel. This arrangement of
drawing in the products of combustion into the tubes along with the
steam while affording a convenient and economical means of blowing the
fire has the great advantage of extracting from those products heat that
would otherwise be thrown away. Consequently the steam in its
expansion from the jet into the rarefaction of the smoke box or con-
tinuation thereof finds the heat necessary for that expansion not out of
itself but out of the products of combustion, and does not therefore
losc velocity as it would if it found the heat out of itself. This is an
important consideration, as the effect of the jet varies with the square
of the velocity of the steam.
To avoid loss of heat in the tubes by conduction and radiation cach
tube is enclosed in an outer case hermetically attached to the smoke box
or continuation thereof with a certain space between the tube and the
outer case through which of course the products of combustion are free
to circulate.
The large ends of the tubes being in the water are provided with doors
closing them tight when the vessel is at rest. It is almost unnecesary
to state that when the pressure of the steam at the large ends of the
tubes is sufficient to overcome the resistance of the vessel the doors
are opened, the steam as it meets the water being condensed, and the
products of combustion passing up to the surface of the water in
bubbles.
To provide against the accidental entrance of the water through the
tubes there is placed in the smoke box or continuation thereof a valve
or flap to be closed by the water itself should it penetrate so far.
When vessels are required to move astern as well as ahead another
set of tubes and steam jets must be provided, but with the large ends of
the tubes set towards the bows of the vessel instead of the stern.
As by this Invention none of the heat produced by the combustion of
the fuel is expended in moving any machinery or working parts and the
steam and products of combustion being given off at the lowest possible

page_text: temperature a greater amount of that heat is converted into useful
The Invention is
than by any means of propulsion hitherto in use.
therefore an improvement, and the novelty consists in propelling vessels
by the direct pressure of steam acting at the larger ends of tapering
tubes and supplied into the smaller ends thereof by jets, the steam
carrying with it into the tubes the products of the combustion of the
fuel employed to generate the steam.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Edwards Wilson in the Great Seal Patent
Office on the 12th December 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
EDWARDS WILSON, of Bromley, in the County of Kent, Civil Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of June, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said James Edwards Wilson, Her special
licence that I, the said James Edwards Wilson, my executors, adminis-
trators, and assigns, or such others as I, the said James Edwards
Wilson, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times there-
after 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 Inven-
tion for "IMPROVEMENTS IN PROPELLING VESSELS AND APPARATUS THEREFOR,"
upon the condition (amongst others) that I, the said James Edwards
Wilson, 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.

page_text: NOW KNOW YE, that I, the said James Edwards Wilson, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say:-
The Invention consists in the propulsion of vessels by the direct
action of steam together with the hot gases from the fire against the
water through which the vessels travel. This is effected by causing the
steam to issue as a jet through a nozzle of suitable form and opening
into a long tapering tube, the smaller piece of which communicates with
the smoke box of the boiler, and the larger end of which opens into the
water. By this arrangement the steam drags with it into the tube the
hot gases from the smoke box, the two streams of steam and hot gases
becoming combined together at a certain distance along the tube (at
what may be termed the neck of the tube) into one uniform stream,
which expanding thence as it goes rushes against the water with a force
equal, theoretically, to the product of its mass by the square of its
velocity. The body of the tube may be simply conical but more advan-
tageously of a parabolic form similar to the modern bugle. It will
however be expedient in most cases, as will be herein-after explained, to
curve the body of the tube also, making the axis thereof a parabola, or
approaching thereto. When the body is simply conical and the axis a
straight line, the angle of the cone of which it forms part will have to
bc determined specially in cach particular case, the maximum being six
degrees and a half (6° 30') in the case of low steam pressure. When
parabolic with straight axis the most advantageous form is obtained by
making the two tangents which enclose the parabolic segment equal to
cach other, or from that to one and a half to one for the ratio of the
tangent parallel to the axis to the other tangent. With the curved axis
the one tangent to the axis being horizontal, the other tangent should
make an angle therewith as much greater than a right angle as the
length of the body of the tube and the height of the neck of the tube
above the horizontal tangent will permit of. The longitudinal section
of the body of the tube will in this case shew two separate parabolas, the
one above and the other below the axis. The portion of the tube
between the mouth-piece and the neck will not form a portion of the
curve, but will be on the continuation of the upper tangent thereto.
The length of the body of the tube between the neck and the large
end should in no case be less than twenty times the diameter at the

page_text: smaller end or neck, increasing with the velocity of the steam, to insure the
most gradual expansion of the combined stream of steam and hot gases.
The first portion of the tube, that wherein the steam and hot gases
become blended together, between the mouth-piece and the neck should
be conical with the smaller end at the neck where it joins the body of
the tube and the larger end at the mouth-piece. The areas of these two
ends must be specially determined in each case; they depend principally
on the velocity of the steam and the velocity and amount of the hot
gases. The latter velocity could scarcely under the most favorable cir-
cumstances reach the one-third (3) of that of the steam; however, while
the maximum of the hot gases would be with any kind of combustible
under ordinary perfection of combustion from two and a half to three
times the weight of the steam, the temperature of the hot gases would
generally be in the case of ordinary marine boilers not less than from
300° to 400° centigrade (572° to 752° Fahrenheit). The length of this
portion, or in other words the distance between the mouth-piece and the
neck depends in general upon the amount of the hot gases as well as on
the form of the steam nozzle, and shape of the mouth-piece. With these
latter of the most approved patterns, such as herein-after described, the
best length would be according to the velocity of the steam from three
to six times the diameter of the arca taken as a circle allowed for the
passage of the hot gases at their entrance from the mouth-piece into the
tube. The mouth-piece of the tube should be conical and divergent
from the tube, the angle of the cone practically the most suitable being
in mean about fifty degrees (50°). The mouth-piece must also have
sufficient length to allow of a gradually although rapidly converging
passage for the hot gases through the mouth-piece. This will in general
be adequately insured by making the length about equal to or a little
less than the diameter of the smaller end. The steam nozzle must be in
the axis of the propelling tube and should pass through the mouth-piece
so that its orifice may be close to or just within the end of the tube.
It may be made cither with a plain round hole for the passage,
or with an annular orifice after the fashion of an argand lamp.
The latter is by far the most advantageous as it gives so much larger a
surface of contact between the steam and the hot gases, the movement
of these by the steam being entirely effected by the friction of the
particles of the steam against their particles. And in order always to
obtain the maximum amount of contact possible between the steam and
the hot gases and maintain the thinness of steam jet found to be so

page_text: advantageous, it will be necessary in most cases to adopt two or more
annular orifices for the issue of the steam either placed concentrically
within each other or in any other more convenient way. The steam
nozzles must be adjustable within themselves so as to allow of the width
of the annular steam orifice to be modified, as may be required, even to
the extent of closing altogether the passage of the steam. The nozzles
must also be adjustable along their own axes so that the passage of the
hot gases may be increased, diminished, or entirely shut, as may be
found requisite. I do not go into the details of the construction of
these nozzles, nor explain the manner in which the adjustments thereof
should be carried out, such steam jets being already before the public.
For the propulsion of a vessel, one tube with its accompanying steam
jet is sufficient provided the dimensions thereof be properly determined
and with due, reference to the resistance of the vessel at the required
speed. The tube would of course be laid with its axis along the centre
of the vessel, and its large end meeting the water vertically at the stern
thereof just where the single screw is now placed. The axis of the tube
may be straight, in which case it will be parallel to the keel of the
vessel, or in other words horizontal. This arrangement although
apparently the most simple is attended with. the disadvantage of
rendering possible the entrance of the water within the vessel. Not-
withstanding that a door or cover may be adapted to the tube so as to
close the end thereof perfectly and with facility, and that the adjust-
abilities of the steam nozzle enable both steam and hot air passages to
be shut when required, still an obstacle might at any time occur to the
prompt closing of any one of thesc. No source of danger necessarily
springs therefrom. Still it is found more expedient, all things considered,
such as the saving in the length of the steam and hot air conduits, the
more convenient position of the steam nozzle and mouth-piece of the
propelling tube, and so on, to curve the axis of the tube upwards to such
an extent as to bring the mouth-piece well above the highest water line
of the vessel. This causes no perceptible increase in the cost of the
construction of the apparatus, just as in a large brass wind instrument,
whether the body be straight or curved makes scarcely any difference in
the cost of the instrument.
I would take the opportunity here of pointing out the advantage of
making these propelling tubes in a similar manner to that in which
brass wind instruments are made, thereby insuring accuracy of form,

page_text: perfection, lightness, and economy. And I might also mention that in
the last experimental boat employed for testing the apparatus portions
of actual wind instruments were adopted for the bodies of the tubes.
It will be found convenient in some cases to employ two tubes instead
of one tube, as in the case of twin screws. The twin tubes would of
course be placed one on each side of the centre of the ship with their
axes parallel to the centre line thereof. Their position towards the stern
of the vessel must always be such that none of the disturbed water or of
the hot gases out of the tubes may impinge or pass too near any part of
the vessel.
The propelling tubes must always be incased within other tubes,
the spaces between the two being open to the hot gases. The pipes
leading the steam to the nozzles, and the flues conveying the hot gases
should in every case be as direct and straight as possible. I enter into
no details respecting these points as nothing new is involved therein, and
the arrangements therefor would of course vary for each particular case.
It is of course indispensable that every vessel moved by the action of
steam should be able to go astern when required. For effecting this
however I am not able just at present to offer any other means than a
duplication of the tube or tubes, such duplicate tube or tubes to be
placed in the contrary direction in any convenient and suitable position
in the vessel.
As the size, form, dimensions, position, and arrangement of the pro-
pelling apparatus must necessarily be for every particular case according
to the size, shape, build, and nature of the vessel as well as the speed,
no general drawing could be given as a guide to the application of the
apparatus to any particular vessel; I shall therefore however add to
the particulars which I have given above of the various parts of the
apparatus an explanation of the manner in which the general dimensions
thereof should be determined.
The resistance of the vessel at the required rate of speed being either
ascertained or ascertainable gives us the product of the area of the large
end of the propelling tube by the specific weight of the combined stream
of steam and hot gases by the square of the velocity of that stream.
First. As regards the Area of the Large End of the Tube.—The area
described by the radius of a screw is generally from one-third to one-

page_text: fourth of the area of the main immersed section of the vessel. Now the
trials made with the apparatus in experimental boats shew that the end
of the propelling tube need not be by a great deal so large. In fact on
the average and for moderate speeds one-twelfth of the area of the main
immersed section would seem to be ample. It must however be
distinctly understood that this figure is subject to correction which it
may receive from further trials with larger boats and at higher speeds.
The area of the large end of the propelling tube being taken as
determined, we have to determine the specific weight of the stream of
steam and hot gases, and the velocity of that stream before we can arrive
at the dimensions of the rest of the apparatus. To estimate the velocity
of the stream of steam and hot gases we must turn to the other end of
the tube. The velocity with which the steam issues from the nozzle is
dependent on the pressure in the boiler and the pressure in and tem-
perature of the place into which it passes. Now the steam in passing
through the first part of the tube carrics along with it the hot gases
from the smoke box which are at a temperature sufficiently higher than
itself to supply the heat it requires for its expansion into the lower
pressure (that of the smoke box with which the mouth-piece of the tube.
communicates) its velocity will be a maximum under the given con-
ditions and can be easily calculated.
As regards the Hot Gases.-The quantity of these varies from twice
to three times the weight of the steam, according to the kind of fuel used
and the particular character of the boiler. The velocity with which
they enter the tube can be brought by proper construction of the steam
nozzle and the mouth-piece of the tube up to one-fourth of the velocity
of the steam. The velocities of the steam and of the hot gases at their
entrance into the tube being thus given, the joint velocity which they
will possess at the neck of the tube can be easily deduced from the
"quantities of movement." From the neck they will rush on, expanding
as they go, until they reach the large end of the tube. They will
thereby lose a great deal of the high temperature they were at at the
neck of the tube, but their velocity must remain the same, for the
process being continuous the "quantities of movement" at all the points
of the tube must be equal, and as the quantities of matter must be the
same at every section of the tube the velocity must necessarily remain
the same.
The velocity of the stream of steam and hot gases being thus
given determines the amount of the steam required. It will of course

page_text: however be required to divide the quantity of steam thus ascertained by
the fraction expressing the ratio of the vis viva of the joint stream of
steam and gases to that of the steam; this fraction can also be estimated
from the respective "quantities of movement." It will also be necessary
to multiply again by a fractional coefficient, allowing for the imper-
fections of the apparatus, and this coefficient will have to be determined
specially for each particular case.
It is scarcely necessary to add that from what has been said the areas
of the ends of the first part of the tube are quite easily calculated, and
it is almost needless to point out that the depth of the large end of the
propelling tube below the level of the water must be such that the
resistance of the boat at the maximum of speed is several times the
weight of the column of water pressing on the large end of the tube.
What I claim in this Invention is, the propulsion of vessels by the
direct action of steam passing together with the hot gases from the fire
through long tapering tubes against the water through which the vessels
travel, substantially as hercin-before described.
I also claim constructing or arranging apparatus, substantially as
hercin-before described, to be employed in propelling vessels, in the
`manner explained.
In witness whereof, I, the said James Edwards Wilson, have here-
unto set my hand and scal, this Eleventh day of December, One
thousand eight hundred and seventy-four.
J. EDWARDS WILSON. (L.S.)