IMPROVE- MENTS IN STEAM ENGINES
Year: 1858

page_text: LETTERS PATENT to William Marshall, of Leith Walk, in the County
of Mid Lothian, North Britain, Engineer, for the Invention of "IMPROVE-
MENTS IN STEAM ENGINES."
Sealed the 18th January 1859, and dated the 19th November 1858.
PROVISIONAL SPECIFICATION left by the said William Marshall at
the Office of the Commissioners of Patents, with his Petition, on
the 19th November 1858.
I, WILLIAM MARSHALL, of Leith Walk, in the County of Mid Lothian,
North Britain, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN STEAM ENGINES," to be as follows, that is to say :-
This Invention relates to the arrangement and construction of steam engines
of various kinds, and suitable for various purposes, marine'as well as stationary,
but particularly those of the double cylinder expansive class.
As applied for marine purposes in screw propelling, each engine of the
improved kind consists of a large and a small inverted.steam cylinder disposed
in line athwart ship; the larger cylinder is inverted upon the top of an open
supporting frame, the connecting rod working down direct to the crank or
screw propeller shaft. To the piston rod joint there is also connected the
inner end of a horizontal lever working upon a fixed centre, the other end
of such lever being jointed to the top of a connecting rod working the air
pump bucket or piston. The air pump is disposed on the engine sole plate.

page_text: or foundation to one side of the keel line of the ship; and directly above it is
placed the small inverted steam cylinder carried on a suitable open frame or
pedestal; the piston rod of this smaller cylinder is connected, in any con-
venient way, to the air pump lever beneath, so that the piston moves in concert
with the air pump bucket. The steam at its normal working pressure is
primarily supplied to the smaller or high-pressure steam cylinder, and it is
then expanded into the larger one in the usual manner of double cylinder
expansive engines.
Instead of placing the high-pressure steam cylinder directly above the air
pump, the lever working the latter may be prolonged outwards, for connection
with the piston rod of a high-pressure cylinder, either inverted or not, set at a
correspondingly increased distance from the main steam cylinder or keel
line. In this latter arrangement the smaller piston of course has a longer
stroke than the air pump piston.
For marine purposes it is proposed to use two sets of these cylinders, that
is, a double engine of a large and small cylinder each; the two cylinders of
the same kind being in line fore and aft the ship. In this way any
required number of cylinders may be disposed to work in concert; and, if
found convenient, the smaller cylinder of one engine may be set on one side
of the keel line, and that of the other on the opposite side.
This arrangement of steam engine may be modified to suit paddle steamers,
and the cylinders, pistons, and air pumps may either be of the "trunk" kind,
or of the common class; and they may be inverted or not.
These improved engines are also applicable for general stationary purposes.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Marshall in the Great Seal Patent Office on the
17th May 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MARSHALL, of Leith Walk, in the County of Mid Lothian, North Britain,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters.
Patent, bearing date the Nineteenth day of November, in the year of our
Lord One thousand eight hundred and fifty-eight, in the twenty-second year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said William Marshall, Her special license that I, the said William
Marshall, my executors, administrators, and assigns, or such others as I,

page_text: the said William Marshall, my executors, administrators, or 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 STEAM ENGINES," upon the condition (amongst others)
that I, the said William Marshall, by an instrument in writing under my
hand and seal, 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 William Marshall, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying Drawings, and to the
letters and figures marked thereon, that is to say:-
My said Invention relates to the arrangement and construction of steam
engines of various kinds, and suitable for various purposes, marine as well as
stationary, but particularly those of the double cylinder expansive class. As
applied for marine purposes in screw propelling, each engine of the improved
kind consists of a large and a small inverted steam cylinder disposed in line
athwart ship. The larger cylinder is inverted upon the top of an open
supporting frame, the connecting rod working down direct to the crank or
screw propeller shaft. To the piston rod joint there is also connected the
inner end of a horizontal lever working upon a fixed centre, the other end of
such lever being jointed to the top of a connecting rod working the air pump
bucket or piston. The air pump is disposed on the engine sole plate or
foundation to one side of the keel line of the ship, and directly above it. is
placed the small inverted steam cylinder carried on a suitable open frame or
pedestal. The piston rod of this smaller cylinder is connected in any con-
venient way to the air pump lever beneath, so that the piston moves in
concert with the air pump bucket. The steam at its normal working pressure
is primarily supplied to the smaller or high-pressure steam cylinder, and it is
the expanded into the larger one in the usual manner of double cylinder
expansive engines. Instead of placing the high-pressure steam cylinder
directly above the air pump, the lever working the latter may be prolonged
outwards for connection with the piston rod of a high-pressure cylinder, either
inverted or not, set at a correspondingly increased distance from the main

page_text: it
steam cylinder or keel line. In this latter arrangement the smaller piston of
course has a longer stroke than the air pump piston. For marine purposes
is proposed to use two sets of these cylinders, that is, a double engine of a
large and small cylinder each, the two cylinders of the same kind being in a
line fore and aft the ship. In this way any required number of cylinders may
be disposed to work in concert, and if found convenient the smaller cylinder
of one engine may be set on one side of the keel line, and that of the other on
the opposite side. This arrangement of steam engine may be modified to suit
paddle steamers, and the cylinders, pistons, and air pumps may either be of
the "trunk" kind or of the common class, and they may be inverted or not.
These improved engines are also applicable for general purposes.
And in order that my said Invention may be properly understood, I shall
now proceed to describe the several illustrative Figures upon the explanatory
Sheets of Drawings which I have hereunto appended for the purpose of
showing certain modifications under which my improvements may be judiciously
carried out in practice, that is to say:-
Figure 1, on Sheet 1, is a side elevation looking upon the port or larboard
side of one arrangement of a pair of my improved marine engines. Figure 2
is an after end elevation; and Figure 3 is a plan corresponding to Figures 1
and 2. As arranged in this modification the whole of the details of the
engines are carried upon a single cast-iron cellular sole plate A, which is of a
rectangular figure, and is strengthened by deep flange ribs. The sole plate
has bolted to it two pairs of open pillar frames B, these pillars are curved
outwards at the lower part, as shown in Figure 1, in order to obtain sufficient
space for the rotatory movement of the crank. The pillars are arranged
parallel to each other, and to the upper surfaces of each pair is bolted a low-
pressure cylinder C. These cylinders are arranged in an inverted position,
and they have cast on the periphery of each a pair of bearing brackets, which
are strengthened by feather flanges, and these brackets being bolted down to
te upper flanges of the standards B, the whole is firmly bound together.
The forward pair of pillar standards B have cast on each of their front edges
or lateral faces a projecting bracket piece, which serves to partially support
the high-pressure cylinders D, which are cast in one with the valve chests E..
The valve chests E rest on the brackets of the pillar standards B, and the
vertical flanges of the chests are bolted to the contiguous faces of the brackets,
as shown in Figure 1 on the accompanying Drawings. The high-pressure,
cylinders D are supported at the front part by the malleable iron pillar rods F,.
which are carried upon the sole plate A, their upper extremities being passed.
through eyes cast on the peripheries of the cylinders D, and secured thereto.

page_text: by nuts. The high-pressure cylinders D are in this modification of my
improvements arranged so that their upper ends are level with the lower faces
of the low-pressure cylinders C. The piston rod G of each high-pressure
cylinder works downwards through a bottom end stuffing box on the cylinder,
the extremities of the crosshead of the piston rod being connected by the
links to the shorter arms of the horizontal lever beams I. Each horizontal
lever beam consists of two parallel bars which are connected transversely by
stud spindles, these beams work in pedestal bearings that are fitted on brackets
cast on the framing standards B. The longer arm of each lever beam I is
jointed by an upwardly directed pair of links J to the crosshead stud K of
each piston rod L, which works out through an end stuffing box in the lower
covers of the low-pressure cylinders C. Each piston rod L has forged upon it
a crosshead joint and slide block piece M, which traverses in the guides N
that are bolted to the inner faces of the standards B. The cap or joint stud
holder O is bolted on to the block piece M by bolts and retaining nuts, and
the lower extremity of the connecting rod P is fitted in a similar manner for
connecting to the pins of the double crank discs Q and R.. The disc Q on the
propelling shaft S forms a worm-wheel, which can be set round when required
by means of the worm on the short shaft, which is carried in the bearings T
that are bolted to the face of the standards B. The worm, and shaft are
delineated in dotted lines in Figure 1 on my Drawings; the shaft is turned by
means of a hand wheel fitted upon its squared extremity; the arrangement
admits of the propeller shaft S being turned round for the purpose of
inspecting or repairing the screw propeller when the vessel is in port or not
under steam. The air pump U of each engine is recessed into the sole plate A*;
the upper end of the bucket or pump rod is connected, directly to the lower,
end of the piston rod G of the high-pressure cylinder D, which piston rod is
directly in a line with the pump rod.. The crossheads V on the. pump rods are
prolonged outwards on each side for the purpose of working the plungers W
of the pumps X. The valve gearing is actuated by a set of four eccentrics on
the main shaft, the rods Y from which work upwards to a pair of link
motions Z, which are connected directly to the joint studs of the lower ends of
the low-pressure valve spindles a, that work through the stuffing boxes in the
lower ends of the contiguous valve chests. The slide valve spindles a are
continued upwards, so as to extend out through stuffing boxes on the upper
side of the valve chest, where they are linked to a pair of diagonally disposed,
levers 6 working on stud centres carried by the pillar brackets c cast on the
exhaust branch pipes d of the low-pressure cylinders C. The other extremities
of the levers bare jointed to the link rods e, which are attached directly,

page_text: to the upper ends of the high-pressure slide valve spindle that work through
the stuffing boxes f, on the upper sides of the high-pressure valve chests E.
In this way the whole of the functions of the high and low pressure valves are
performed by the actions of the two link motions, so as to admit of the
reversing and expansive movements by means of very simple and effective valve
gear. Bearing brackets 9 are cast on the standards B, which serve to carry
the horizontal shaft h for the handling movements of the valves; these are
actuated by the hand levers i, which are made so as to be readily slipped on
to the short stud levers j; the motion of the shaft being conveyed to the link
motions Z through or by means of the connecting rods k. The steam from.
the boiler enters by the branch pipe l, and fills the first casing E, and thence
passes by a transverse pipe shown in dotted lines between the cylinders D to
the contiguous casing E. The steam enters the cylinders D by the upper and
lower ports, and after performing its work in actuating the pistons of the
This
cylinders, exhausts through the middle ports into the steam pipe m.
steam pipe is divided into two distinct passages by a central partition or
diaphragm, so that the steam is conveyed in separate volumes or quantities to
the valve chests of the low-pressure cylinders C. From these cylinders the
steam is exhausted through the middle ports, and passes down the exhaust
steam pipes d, to the condenser n, from which the water of condensation is
pumped into the hot well o, and passes off by the pipe p, which is carried
through the ship's side. In this modification of my improvements the levers I,
connecting the high and low pressure cylinders are centred at about two-
thirds of their length, so as to give the high-pressure pistons a stroke of
about one half that of the low-pressure pistons, the diameters of all the
cylinders being equal.
In Sheet 2 of the accompanying Drawings is shown a modification of the
arrangement, in which the high-pressure cylinders are reduced in diameter, but
have a longer stroke. The Figure represents the transverse section of a vessel,
showing one of the engines in side elevation; to avoid repetition of description,
the principal parts of the engine are marked with letters of reference corre-
sponding to those used to indicate similar parts in the Figures delineated on
Sheet 1. In this arrangement the high-pressure cylinder D of each engine is
set further out or away from the centre line of the larger cylinder C. This
increase of distance is obtained by elongating the brackets by which the
cylinder D is connected to the projecting part of the standards B. The high-
pressure cylinder D is supported or four malleable iron pillars F, which spring
from the sole plate A, and pass through eye snugs cast on the cylinder D, to
which they are secured by retaining nuts. The piston rod of the cylinder I

page_text: works in the trunk G, so as to admit of its being jointed directly to the cross
head of the horizontal lever beam I, which is centred on pedestal bearings
fitted on brackets cast on the standards B. The connection of the longer arm
of the lever beam I to the cross head of the low-pressure piston rod L, and
the parts connected therewith, do not differ from the arrangement herein-before
described, and need not therefore be again referred to in detail. Like the
piston of the cylinder D, the air pump bucket is fitted with a trunk V, to
admit of the angular motion of the bucket or pump rod, when connected
directly to the over-head beam I. In this modification the beam I is placed at
a greater distance from the over-head cylinders, so as to obtain a longer stroke;
the beam is also centred nearer the half length than in the arrangement shown
in Sheet I., of the accompanying Drawings. The manner in which the steam
is conveyed to and exhausted from the cylinders, and the arrangement of the
condenser and hot well, are essentially the same as in the modification first
herein-before described. In arranging engines of this class for propelling
paddle wheel vessels, the high-pressure cylinders are placed overhead with the
air pumps immediately beneath or contiguous thereto. The low-pressure
cylinders being placed at the other end of the lever beams, the piston rods
work upwards in the ordinary manner, and are connected in any convenient
way to the paddle-wheel shaft.
With minor modifications an arrangement of this kind may be adapted for
screw propellers, in which the propeller shaft is driven by means of spur
gearing. Engines arranged in the manner delineated in the accompanying
Drawings are compact, well balanced, and easily accessible in all their parts,
so as to be well adapted for marine purposes.
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 observe, in conclusion, that I do not confine
or restrict myself to the precise details or arrangements which I have had
occasion to describe or refer to, as many variations may be made therefrom
without deviating from the principles or main features of my Invention; but
what I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,-
First, the general arrangement and construction of marine steam engines,
as herein-before described and shown in the accompanying Drawings.
Second, the system or mode of arranging the air pump of marine engines of
the class herein-before described in a line with or immediately beneath the
high-pressure cylinder, so that the bucket or pump rod is connected directly
to the piston rod of the high-pressure cylinder, and to the lever beams by

page_text: means of straps, as herein-before described and shown in the accompanying
Drawings.
Third, the modification of the marine engine, as delineated on Sheet 2 of
the accompanying Drawings, in which the high-pressure cylinder is reduced in
size, as compared with the low-pressure cylinder, the length of stroke is in-
creased, and the piston of the high-pressure cylinder and bucket of the air
pump are fitted upon the trunk principle to admit of the piston and pump
rods being connected directly to the lever beams, as herein-before described
and shown on the aforesaid Sheet of Drawings:
In witness whereof, I, the said William Marshall, have hereunto set
my hand and seal, this Sixteenth day of May, One thousand eight
hundred and fifty-nine.
W. MARSHALL. (L.S.)