IMPROVEMENTS IN THE PROPULSION OF VESSELS
Year: 1863

page_text: LETTERS PATENT to Alexander Johnston, of Comely Bank, near Edin-
burgh, (late of Craigleith,) in the County of Mid Lothian, North Britain,
Esquire, for the Invention of "IMPROVEMENTS IN THE PROPULSION OF
VESSELS."
Sealed the 28th July 1863, and dated the 6th February 1863.
PROVISIONAL SPECIFICATION left by the said Alexander Johnston at the
Office of the Commissioners of Patents, with his Petition, on the
6th February 1863.
I, ALEXANDER JOHNSTON, of Comely Bank, near Edinburgh, (late of
Craigleith), in the County of Mid Lothian, Esquire, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE PROPULSION OF VESSELS,"
to be as follows:-
This Invention relates to a method or system of propelling vessels by means
of submerged cylinders fitted with water-tight pistons moved by steam, and it
consists of the adaptation and use of one or more pairs of cylinders and their
pistons placed water-tight below light-load water-line in the stern or other
suitable part of the ship in connection with a working beam which forms part
of the machinery of a steam engine placed in the ship, by which the piston
propellers are worked. The pistons have long noses extending out of the
cylinders into the water outside the ship when making the outward stroke.
They are used in pairs, each pair being connected (one at each end) with the
working beam above mentioned, by which they are worked alternately, the

page_text: one being moved outwards while the other moves inwards, and vice versa.
As the pistons bear the full weight and pressure of the water outside
the ship, they should, in each pair, be made of the same size, so as to press
equally on each end of the working beam, by which they are balanced and
kept in their relative positions. To propel the ship forward one or more pairs
of the cylinders and their pistons and relative apparatus are placed in the
stern or after part of the ship, and they may also be placed in the bottom and
sides of the vessel. To give the ship a backward motion and also to assist in
turning it round, one or more pairs of the apparatus are placed in the bow or
forward part of the ship. By working one or more pairs of the cylinders and
their pistons placed at one side of the stern of the vessel at a higher rate of
speed than those at the other side (or by working the one and turning off the
steam from the other) the steering of the vessel may be assisted and the use of
the rudder in a great measure superseded. When placed in the stern of the
ship the piston propellers have the advantage of working in the back water
which pours in on each side or follows after the ship in the forward motion of
the vessel. The apparatus may be constructed to work at a much higher rate
of speed by means of attached machinery to be moved by the steam engine
placed in the ship, and which can be accomplished either by a wheel and
pinion or by a system of levers to be attached for that purpose.
It has not been thought necessary to shew in detail any of the other well-
known methods of working or moving the propelling pistons and of increasing
their speed so as to give greater speed to the vessel. All these will be known
to the makers of the machine.
The apparatus is calculated to give full force of the steam in propelling the
vessel, and is well suited for steam tugs and other vessels where power is required
rather than speed. Where speed is desired rather than power it can be obtained
by the said apparatus by applying the mechanical gearing above referred to.
The apparatus may be made with parts easily removeable and easily replaced.
The cylinders may be of any convenient and suitable size, and may be made
of cast iron or other suitable material strengthened by means of malleable iron
hoops placed as close together as circumstances will permit. The propelling
pistons and their noses may also be made of cast iron, hollow within,
and should have weight of metal as near as may be equal to the weight of
water which they displace in order that they may as it were float or swim in
the water outside the ship, and thus have no extra strain upwards or down-
wards on the cylinders when the pistons are extended outwards at the full
length of the stroke. The noses of the propelling pistons in front of the piston
head and packing should nearly fill up the whole area of the cylinders, leaving

page_text: just space enough to avoid friction or rubbing against the inner surfaces of
the cylinders, and should be slightly hollowed at the outer end so as to take a
better hold of the water.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may explain that it has not been thought necessary to show in
detail more of the many and well-known methods of working or moving the pro-
pelling pistons and of increasing their speed so as to give greater speed to the
vessel, I do not, however, intend to confine myself to the precise arrangements
or details herein-before described, deviations may obviously be made thereupon
without departing from the nature and objects of my Invention, and I do not
consider it necessary to enter further into details of my Invention, but what I
believe to be new and claim is,-
First, the simple and compact method of propelling a vessel by means of
pistons contained in cylinders placed water-tight below light-load water-line
in the stern or other suitable part of the ship, the pistons moved by steam
having noses extending out of the cylinders into the water outside the ship
when the piston is making its outside stroke, thus effecting the immediate
motion of the vessel and consequently effecting the forward or backward (as
the case may be) propulsion of the ship.
Second, the general form, arrangement, and combination of parts, or any
mere modification thereof, whereby the objects above mentioned are to be..
effected as herein-before described.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Johnston in the Great Seal Patent Office on the
6th August 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
JOHNSTON, of Comely Bank, near Edinburgh, (late of Craigleith, in the County
of Mid Lothian, North Britain, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters.
Patent, bearing date the Sixth day of February, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Alexander Johnston, Her special licence that I, the said Alexander
Johnston, my executors, administrators, and assigns, or such others as I, the
said Alexander Johnston, my executors, administrators, and assigns, should

page_text: 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 "IM-
PROVEMENTS IN THE PROPULSION OF VESSELS," upon the condition (amongst
others) that I, the said Alexander Johnston, my executors or adminis-
trators, 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 Johnston, 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: —
My Invention relates to a method or system of propelling vessels by means
of an improved propeller consisting of one or more pairs of submerged
cylinders fitted with pistons of the form herein-after more particularly
described.
In carrying out my Invention I make use of one or more pairs of these
cylinders and their pistons, and I place them water-tight below light-load
water-line in the stern or other suitable part of the ship. The cylinders and
their pistons are used in pairs, each pair of pistons by the piston rods
being connected to each other by means of a rocking beam or beams placed
inside the ship; by reason of being connected to this rocking beam the pistons
are balanced and kept in their relative positions. The propelling pistons
(which I call the water pistons to distinguish them from the steam pistons)
are formed with projections or noses which extend from the piston head and
packing of the water pistons towards the mouth or open end of the water
cylinders. These projections or noses must be made of a size sufficient to fill
up the whole area of the water cylinders when the pistons are drawn back,
leaving just space enough to avoid friction or rubbing against the inner surfaces
of the said water cylinders, and the ends of the said projections should be
slightly dished or hollowed out, as shewn by the dotted line in the Drawings,
so as to enable them to take a better hold of the water. The projections may
be made of cast iron or other suitable material, and should be made hollow,
but they must be made of such weight as to be equal or thereabouts to the
weight of water which they displace, so that when the pistons are extended

page_text: to the full length of the stroke there may be no strain on the water
cylinders.
The method of using my Invention will be better understood by reference to
the accompanying Drawings and the description thereof, in which similar
letters in the several Figures are used to denote similar parts.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a longitudinal plan of the aft portion of a vessel fitted with a
pair of my water cylinders with their pistons and rocking beams in connection
with the parts of the steam engine by which they are to be worked, shewing
the projections or noses of one of the water pistons when at the inward and
the other when at the outward stroke; Figure 2 is an elevation with a portion
of the plating of the ship removed to shew the machinery and propellers
in situ.
A, the water cylinders; B, the water pistons, to which the projections
or noses B are attached; C, water cylinder piston rods; D, framing;
E, steam cylinders; F, steam chest; G, the rocking beam or beams; H,
weigh bar of. valve motion called the tappet motion for moving the valve;
I, cross head; J, motion bars; K, valve rod; L, motion bar framing.
I would here remark that all the machinery is contained within the vessel
except a portion of the water cylinders and the projections or noses of the
water pistons which pass out from the hull of the vessel. As the piston pro-
pellers bear the full weight and pressure of the water outside the ship, they
should, when placed horizontally, be made of the same size in each pair, so as to
press equally on each end of the rocking beams with which they are connected.
They are worked alternately, and while the one is moved outwards the other
is moved inwards.
The arrangement above shewn is the simplest form of application of
my Invention to propel a ship forward by means of one pair of water cylinders
with their pistons and relative apparatus placed in the stern or after part of
the ship, and it is evident that the water cylinders may also be placed in the
bottom and sides of the vessel and the water cylinders with the pistons and
rocking beams may also be arranged in pairs on each side of the vessel so that
the propellers on one side may be worked independently of those on the other
side.
In this arrangement of the apparatus, by working one or more pairs of the
propellers placed at one side of the stern of the ship at a higher rate of speed
than those at the other side (or by working the one and turning off the steam
from the other) the steering of the vessel may be assisted. To give the ship a

page_text: backward motion and also to assist in turning it round, one or more pairs of
the propellers may be placed in the bow or forward part of the ship. The
apparatus may, if desired, be constructed so that the propellers may work at a
higher rate of speed than the engines by which they are driven by means of
any of the known arrangements of multiplying machinery.
Figure 3 represents an arrangement of my apparatus in which two pairs of
water cylinders with their pistons are worked by one steam cylinder with twin
pistons, the steam cylinder being placed across the vessel and at right angles
to the water cylinders, and working the water pistons by means of two-
double bell cranks and connecting rods.
A, water cylinders; B, water pistons, with the projections or noses B¹
attached; C, water cylinder piston rods; D, framing; E, steam cylinder; f.
steam cylinder pistons; G, rocking beams; h, steam cylinder piston rod;
I, cross heads; J, motion bars; M, M, are partitions or fins separating the
water cylinders and water pistons when more than one water cylinder is used
on each side of the vessel.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same is to be performed, I wish it, to
be understood that what I claim as my Invention is. the method of propelling
vessels by means of my peculiar propeller, consisting of water pistons working
in submerged water cylinders, the pistons having projections or noses extending
out of the said cylinders into the water outside the ship, as herein-before
described and represented in the Drawings hereunto annexed.
In witness whereof, I, the said Alexander Johnston, have hereunto set
my hand and seal, this Thirty-first day of July, in the year of our
Lord One thousand eight hundred and sixty-three.
ALEXR. JOHNSTON. (L.S.)