IMPROVEMENTS IN STEAM ENGINES
Year: 1862

page_text: LETTERS PATENT to Edward Alfred Cowper, of. No. 35, Great George
Street, Westminster, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN STEAM ENGINES."
Sealed the 9th December 1862, and dated the 15th October 1862.
PROVISIONAL SPECIFICATION left by the said Edward Alfred Cowper at
the Office of the Commissioners of Patents, with his Petition, on the
15th October 1862.
I, EDWARD ALFRED COWPER, of 354, Great George Street, Westminster,
in the County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
It is well known that it is highly advantageous to have the cylinders of
steam engines enclosed in outer casings containing steam supplied direct from
the boiler, as proposed by James Watt, and commonly known as "steam
jackets, and for more than twelve years it has been known that in engines
working with high-pressure steam acting first in one cylinder and afterwards
in another or low-pressure cylinder, it is also advantageous to let the steam
pass out of the first cylinder into a reservoir or vessel surrounded by a steam -
jacket, and also to have steam jackets to the cylinder covers and cylinder
bottoms, so that as far as possible the temperature of the steam should be kept
up to the temperature at which it left the boiler during the whole time of its
acting on the pistons, until it is allowed to escape into the atmosphere or into
a condenser, whether the pistons act upon one crank or different cranks placed
at any angle with each other.

page_text: Now, the present improvements have for their object the maintaining more
uniformly the temperature of the steam during its action on the pistons, and
my Invention consists in constructing for this purpose a steam jacketted
reservoir of the following arrangement: - I construct a steam jacketted
reservoir having a lining of metal inside it placed at a small distance from the
sides, which lining has a large opening in it through which the steam enters
into the central space without coming into very extensive contact with the
steam jacketted sides of the reservoir, whereas on the contrary when the steam
is withdrawn from the reservoir it is caused to pass through a hole or holes in
the lining at one part, and to pass between the lining and the steam jacketted
sides of the reservoir for some distance before it leaves it, so that as far as
possible it should be maintained at the temperature at which it left the boiler;
or the reservoir is made of any other form, composed of cylinders, tubes, or
plates, with a space or capacity for the steam to enter it freely without coming
into extensive contact with the steam jacketted parts, and then is so arranged
that the steam on leaving does come into contact with such parts, so that as
far as possible it should be maintained at the temperature at which it left tho
boiler. This mode of constructing a reservoir with a space or capacity into
which the steam may enter freely from the first working cylinder, whilst means
are provided for maintaining it as far as possible at the temperature at which
it left the boiler as it leaves such reservoir, is applicable to engines in which
either natural or superheated steam is used.
In applying this improvement to engines having arrangements by which the
heat of a fire is made to act on the steam to superheat it as it passes from one
cylinder to another, the reservoir for the steam to pass into from the first
working cylinder must be placed between that cylinder and the superheater on
the line of pipes, and the superheater be placed between the reservoir and the
second working cylinder, so that the steam shall not be superheated on passing
out of the first cylinder, but may be superheated only as it passes into the
second cylinder. The capacity of the reservoir may be varied to a considerable
extent, but it will be found generally to answer the purpose best if it is made
equal in capacity to the large or low-pressure working cylinder, though if
it is required that there should be a very small variation in pressure in the
reservoir, it must be made larger in proportion; whilst, on the other hand, if
a large variation in pressure is to be allowed, it must be made smaller.
These improvements are applicable to high and low pressure cylinders,,
whether working at the same or different speeds, or making their strokes at
the same or different intervals of time, but care must be taken that the capacity.
of the reservoir be increased in proportion to the time that the steam is to be.

page_text: stored up in it, as otherwise the variation on the pressure of steam in it will
increase.
These improvements are not only applicable in all cases in which the steam
is worked first in one cylinder and then in another, but are especially adapted
for application in cases where a high-pressure cylinder is arranged. first to uso
high-pressure steam and then to supply it to an old low-pressure engine, in
which it would not be safe to use high-pressure steam, as the large capacity of
the reservoir in which the steam is stored up as it comes from the high-pressure
cylinder, (and which may even in such case be made somewhat larger than
the proportions above given), prevent the possibility of any sudden rise in the
pressure of the steam, and a safety valve on it loaded to the proper pressure at
which the old low-pressure engine may safely be worked prevents any great
rise in pressure by providing for the escape of any accidental continued excess
in the supply of steam.
SPECIFICATION in, pursuance of the conditions of the Letters Patent, filed
by the said Edward Alfred Cowper in the Great Seal Patent Office on
the 14th April 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
ALFRED COWPER, of No. 35, Great George Street, Westminster, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of October, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Edward Alfred Cowper, Her special licence that 'I, the said
Edward Alfred Cowper, my executors, administrators, and assigns, or such
others as I, the said Edward Alfred Cowper, 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 STEAM ENGINES," upon the condition (amongst
others) that I, the said Edward Alfred Cowper, 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

page_text: 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 Edward Alfred Cowper, 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 thereof, reference being had to the accompanying Draw-
ings, and to the figures and letters marked thereon (that is to say) :-
It is well known that it is highly advantageous to have the cylinders of
steam engines enclosed in outer casings containing steam supplied direct from
the boiler, as proposed by James Watt, and commonly known as "steam
jackets," and for more than twelve years it has been known that in engines
working with high-pressure steam acting first in one cylinder and afterwards
in another or low-pressure cylinder, it is also advantageous to let the steam
pass out of the first cylinder into a reservoir or vessel surrounded by a steam
jacket, and also to have steam jackets to the cylinder covers and cylinder
bottoms, so that as far as possible the temperature of the steam should be
kept up to the temperature at which it left the boiler during the whole time of
its acting on the pistons until it is allowed to escape into the atmosphere or
into a condenser, whether the pistons act upon one crank or different cranks
placed at any angle with each other. Now the present improvements have
for their object the maintaining more uniformly the temperature of the steam
during its action on the pistons, and my Invention consists in constructing for
this purpose a steam jacketted reservoir of the following arrangement:-
I construct a steam jacketted reservoir having a lining of metal inside it placed
at a small distance from the sides, which lining has a large opening in it,
through which the steam enters into the central space without coming into
very extensive contact with the steam jacketted sides of the reservoir, whereas,
on the contrary, when the steam is withdrawn from the reservoir, it is caused
to pass through a hole or holes in the lining at one part, and to pass between
the lining and the steam jacketted sides of the reservoir for some distance
before it leaves it, so that as far as possible it should be maintained at the
temperature at which it left the boiler; or the reservoir is made of any other
form composed of cylinders, tubes, or plates with a space or capacity for the
steam to enter it freely without coming into extensive contact with the steam
jacketted parts, and then is so arranged that the steam on leaving does come
into contact with such parts, so that as far as possible it should be maintained
at the temperature at which it left the boiler. This mode of constructing a
reservoir with a space or capacity into which the steam may enter freely from

page_text: the first working cylinder, whilst means are provided for maintaining it as far'
as possible at the temperature at which it left the boiler as it leaves such
reservoir, is applicable to engines in which either natural or superheated steam
is used. In applying this improvement to engines having arrangements by
which the heat of a fire is made to act on the steam to superheat it as it
passes from one cylinder to another, the reservoir for the steam to pass into
from the first working cylinder must be placed between that cylinder and the
superheater on the line of pipes, and the superheater be placed between the
reservoir and the second working cylinder, so, that the steam shall not be,
superheated on passing out of the first cylinder, but may be superheated only.
as it passes into the second cylinder.
The capacity of the reservoir may be varied to a considerable extent, but it
will be found generally to answer the purpose best if it is made equal in
capacity to the large or low-pressure working cylinder, though if it is required
that there should be a very small variation in pressure in the reservoir, it must
be made larger in proportion, whilst on the other hand, if a large variation in
pressure is to be allowed, it must be made smaller. These improvements are
applicable to high and low pressure cylinders, whether working at the same or
different speeds, or making their strokes at the same or different intervals of
time, but care must be taken that the capacity of the reservoir be increased in
proportion to the time that the steam is to be stored up in it, as otherwise the
variation in the pressure of steam in it will increase.
These improvements are not only applicable in all cases in which the steam
is worked first in one cylinder and then in another, but are especially adapted
for application in cases where a high-pressure cylinder is arranged, first to use
high-pressure steam, and then to supply it to an old low-pressure engine, in
which it would not be safe to use high-pressure steam, as the large capacity of
the reservoir in which the steam is stored up as it comes from the high-pressure
cylinder (and which may even in such case be made somewhat larger than the
proportions above given), prevents the possibility of any sudden rise in the
pressure of the steam, and a safety valve on it, loaded to the proper pressure at
which the old low-pressure engine may safely be worked, prevents any great
rise in pressure by providing for the escape of any accidental continued excess
in the supply of steam.
;
Having now stated the nature of my Invention, and the manner of putting
the same into practice, I will further give a few examples of engines having
the same applied to them, though the manner of applying the Invention in any
case will readily occur to a scientific engineer acquainted with the best forms
of marine, land, pumping, locomotive, or agricultural engines. In order,

page_text: however, to enable any workman to apply the Invention in the best manner,
I will mention the points chiefly to be aimed at in constructing an engine of
the most perfect kind with my Invention applied to it.
Firstly, when great economy is desired in the consumption of coal, large
expansion of the steam must be practised, say, from five to nine times, and a
pair of engines must be used, one having a small cylinder and the other a
large cylinder.
Secondly, the cranks of the two engines must be placed at right angles to
each other, or nearly so, or the cylinders and cranks must be so placed as to
work nearly at alternate times, and the steam having first been used in the
small cylinder (which should be steam jacketted around its sides and ends)
must be made to pass into a vessel or reservoir so constructed as to preserve
it for a very short time at about the temperature at which it entered, that is
to say, although the reservoir is to be steam jacketted wholly or in part, it is not
to be formed so as to increase the "back pressure" on the small piston to any
great extent by heating the steam before the proper time when it is required
for use, namely, when the piston of the large cylinder begins to take it, but
when the large piston is ready to begin its stroke and receives steam from the
reservoir, such steam must then pass in close contact with the steam-jacketted
surfaces of the reservoir, by which means it will approach more nearly to the
temperature of the steam in the boiler, and will not fall off in pressure nearly
so fast as the expansion goes on into the large cylinder as it would have done.
were it not so treated, thus a much heavier low-pressure figure is obtained
than would otherwise be the case, as has been proved by the working of a pair
of experimental engines of fifteen-horse power each. It is convenient to ensure
the safety of the low-pressure engine to put a safety valve on the reservoir.
Thirdly, to obtain the greatest possible economy with a given degree of
expansion, the capacity of the small cylinder should have a proportion to the
large cylinder as the square root of the number of times it is desired to expand
is to that number; thus, if nine times is decided on, the large cylinder should
have a capacity of nine, and the small cylinder a capacity of three, and then
the steam should be cut off at about one-third of the stroke of the small
cylinder, so as to be expanded three times in the small cylinder, and again
three times in the large cylinder, or nine times in all.
Fourthly, to obtain the greatest possible uniformity in the rotative power,
and at the same time sacrifice but a very small portion of the economy of the
engines, the steam must be cut off at particular points of the strokes, depend-
ing partly on the length of the connecting rods, such points being clearly set
out in Figure 13, Sheet II., for a pair of engines having connecting rods.

page_text: .
equal in length to four times the crank, and it is easy from this to set out the
points for any other lengths of connecting rods, the principle being that of
setting out the exact rotative power of each cylinder at each part of the stroke
(one on each side of a baso line) by multiplying the virtual leverage due to the
position of the crank and connecting rod at such point by the pressure on the
piston at such moment, and then adding the ordinates of the two curves. so
obtained, and setting them out on another base line, when it will be at once
seen whether the excess in rotative power of one cylinder fits in the best
manner into the deficiencies in rotative power of the other cylinder, and such
alterations in the time of cutting off or in the size of cylinders as may be
advisable can at once be seen.
It may be here observed that, whereas the rotative power of a pair of
ordinary engines having their cranks at right angles, and using full steam
throughout their strokes, varies from the average power as much as thirty-one
per cent., and would vary far more when expanding even only three or four
times in each cylinder, yet an engine may readily be constructed (by closely
following the above directions) in which the variation in the rotative power
may be brought down to fourteen per cent., and that too when expanding eight
or nine times, so that it may be said that nearly uniform rotative power is
thus obtained with as high a degree of expansion as it is desirable to go to
with steam of fifty or sixty pounds pressure per square inch or more, and at the
same time the engines are of the simplest and most economical character that
it is possible to make.
The uniformity in the rotative power is of the highest importance in marine
engines driving screw propellers (tending largely to prevent vibration in the
stern post, as well as to preserve the shaft and other parts from undue and
varying strains), in paddle-wheel engines, in cotton mill engines. (particularly
when spinuing high numbers or weaving fine cloths), in flour mills, in paper
mills, lace mills, &c., &c.
Fifthly, to obtain the greatest possible uniformity of pressure throughout
the stroke, for the purpose of working pumping engines in the best and most
economical manner, and avoiding the necessity of very heavy balance. weights
in the case of Cornish engines, or of heavy fly wheels in the case of rotative
pumping engines, (which great weights are now commonly required when
working very expansively, for the purpose of storing-up the extreme amount
of surplus power at the commencement of the stroke, and in order to give it
-out again toward the end of the stroke when the power of the steam from
great expansion has fallen far below the "load,") the steam should be cut off
even later than half strokes, so as to have as little variation in pressure in

page_text: each cylinder as is convenient, and thus suit the power to the work to be dono
as nearly as possible; the construction of the reservoir should be the same as
before described to receive the steam, and give it up as before stated, but in
cases of Cornish engines without crank shafts, it will be necessary to connect
the valve gearing or "cataract" of one engine with the other, so that the two
engines may work at uniform speed, as otherwise the second engine might be
supplied with steam of rather too high a pressure for its "load" at times if
the first engine went a little faster, or too low a pressure if the first engine
went slow. By such arrangements there will be less variation in the power
throughout the stroke, when working on the whole .very expansively, than can
be accomplished by any other means.
Sixthly, to construct engines of this kind of the most compact and
economical form, it is only necessary to adopt a convenient space anywhere
near or about the cylinders, and to place there a reservoir of any convenient
shape of the construction pointed out above, for the purpose of receiving and
giving out the steam as it comes from the small cylinder and passes into the
large cylinder; then to arrange each engine with one slide valve of any
approved construction, and without the addition of any expansion valve, unless
it be desired to cut off much sooner than half stroke. It may here be
observed, that although all slide valves ought to be made longer inside than
the length between the ports, this is particularly desirable when cutting off at
about half stroke with one slide, and it gives the further advantage of an early
"exhaust," and better average "vacuum" throughout the stroke, whilst the
very slight loss near the end of the stroke, owing to the difference between the
expansion curve and the curve formed in consequence of an early "exhaust"
is not so much as the improvement in the indicator figure due to a good and
early vacuum. Another advantage of making the slide long inside consists in
its reducing the "compression," so as to be entirely unobjectionable..
DESCRIPTION OF THE DRAWINGS.
Figures 1, 2, and 3, on Sheet I. of the accompanying Drawings, shew so
much of a vertical inverted direct-acting marine engine for working a screw
propeller as is requisite to shew one example of the manner in which my
Invention may be applied; Figure 1 shews a part plan of the same, and part
sectional plan on line X, X, Figure 2; Figure 2 shews a part front elevation
and part sectional elevation on line Y, Y, Y, Y, Figure 1; Figure 3 shews
an end elevation. The same letters of reference indicate the same parts in
each of the Figures.
The high-pressure cylinder A and the low-pressure cylinder B, which are

page_text: both steam jacketted on all surfaces, are bolted together, as shewn, and are
supported, firstly, between the two piston rods (indicated by the dotted lines a
and b) by the box-shaped framing C, and, secondly, by the columns D, D, D', D',
both the framing C and columns D, D', being fixed to the foundation framing E;
F is the crank or propeller shaft, the cranks f, f¹, respectively to the high-
pressure and low-pressure cylinder being placed at right angles to each
other, so that when the piston of the high-pressure cylinder is nearly at half
stroke, that of the low-pressure cylinder is at end stroke, and vice versâ. The
box-shaped framing C forms the steam reservoir, and contains, firstly, the
steam jacketted vessel G, closed at its lower end, and open at the upper end,
and, secondly, a receptacle formed by the lining H placed within the vessel G,
with which it communicates at the lower extremity, but does not do so at tho
upper extremity. This receptacle H is so formed as to leave a narrow
space 9, 9, all round between its sides and that of the steam jacketted
reservoir G, which space communicates with the space 9' between the upper
surface of the receptacle H and the steam jackets of the cylinders A and B,
constituting the upper surface of the reservoir C. The high-pressure cylinder
A communicates with the receptacle H through the eduction passage I and
the aperture h, whilst the low-pressure cylinder B communicates with the
reservoir C through the induction passage J and the aperture g. From this
arrangement it will be seen that the high-pressure steam entering the
cylinder A through the inlet pipe K and slide valve box L, will, after having
done its duty in this cylinder, pass thence through the passage I into the
receptacle H, as shewn by the arrows, without being at the time brought to
any material extent in contact with superheated surfaces, whilst when at the
required time it has to be conducted from this receptacle into the low-pressure
cylinder B, it is caused to pass through the narrow spaces g, g, g', between the
sides of the receptacle II and those of the steam jacketted vessel G, whereby
the whole of the steam is brought into intimate contact with steam jacketted
surfaces, and consequently becomes heated to the requisite degree before
entering the cylinder B through the aperture 9, passage J, and slide valve
box M, as shewn by the arrows; N is the eduction pipe conducting the steam
from the low-pressure cylinder to the condenser. The above described
arrangement of marine engines are, on account of their compact, simple, and
consequently inexpensive construction, and the great economy in their working,
particularly adapted for use as auxiliary engines in sailing vessels where
economy in the space occupied, as also in first cost of the machinery and in
the consumption of fuel, are such great desiderata. -
Figure 4 on Sheet 2 shews a transverse section through a pair of horizontal

page_text: high and low pressure marine engines, both the high-pressure cylinder, A and
low-pressure cylinder B being in this case provided with two piston rods a, a
and b, b, as in the well-known arrangement of screw-propeller engines, where
the propeller shaft lies close in front of the steam cylinders and the piston rods
pass beyond the same to such an extent as to obtain the requisite length of
connecting rod. It is obvious that any other construction of engines may be
used. The cylinders are steam jacketted, as shewn, and the framing C car-
rying the same is formed of a closed box shape, so as to constitute the steam
reservoir, containing, firstly, the steam jacketted vessel G communicating with
the low-pressure cylinder B, as shewn by the arrows; and, secondly, of the
receptacle H, placed in such a manner inside the vessel G that narrow spaces
intervene between the sides of the two vessels, as also between the side of the
receptacle and steam jackets of the cylinders A and B, which constitute
the upper surface of the reservoir C. The principal difference between the
mode of working in this arrangement and that of the before described one is,
,that here the steam, after passing from the high-pressure cylinder A into the
receptacle H through the aperture h, as indicated by the arrow, subsequently
passes through the same aperture from the receptacle H into the vessel G, as
shewn by the arrows, to which arrangement there is no objection, as the steam
passes into the vessel H at a different time to that at which it passes out of
the same, owing to the cylinder A being open to eduction at a different time
to that at which the cylinder B is open to steam. Although the receptacle H
is here shown extending only partially into the vessel G, yet, if it be requisite
to increase the capacity of the same, the reservoir C and vessel G may be
deepened somewhat, and the receptacle H may be carried beneath the low-
pressure cylinder B; K is the steam pipe, and L is the slide valve box to
the cylinder A; M is the slide valve box, and N is the eduction pipe to the
cylinder B.
Figure 5 on Sheet II. shews a part plan of a steam vessel S having two
screw propellers P, P', each driven by a separate pair of vertical inverted bigh
and low pressure engines, of which A, A', are the high-pressure cylinders,
and B, B', are the low-pressure cylinders. The two pairs of engines have,"
however, one common steam reservoir C, of the before-described construction,
for receiving the steam from the high-pressure cylinders without at the time
heating the same to any material extent, and then causing the same to come
intimately in contact with steam jacketted surfaces on its passage to the low-
pressure cylinders. The propeller shafts Q, Q', are placed at a small angle to
each other in order to provide the requisite space between the propellers for
the stern post whilst keeping the engines close together. Figure 6 shews a

page_text: plan of two similar pairs of engines with the propeller shafts Q, Q, placed at
an angle, in which the high-pressure cylinder A is placed in front of the low-
pressure cylinder B, whilst the high-pressure cylinder A' is placed bebind the
low-pressure cylinder B', by which arrangement a different form for the steam
reservoir C is obtained. Figure 7 shews a similar arrangement of the cylinders
to that shewn in Figure 6, but with the propeller shafts Q, Q', placed parallel
to cach other. Figure 8 shews a similar arrangement of the cylinders to that
shewn in Figure 5, but with the propeller shafts placed parallel to each other
instead of at an angle. It is evident that the reservoir may be constructed of
any form to suit the construction of engines; thus, it may be convenient in
certain cases to place the reservoir immediately at the end of the cylinder or
cylinders, or to separate it from the engines, though in no case it should be far.
removed from the cylinders.
Figures 9 and 10, Sheet II., shew an example of the application of my
Invention to a pair of horizontal high and low pressure land engines; Figure 9
shews a transverse section of the same, and Figure 10 shews a longitudinal
section through the low-pressure cylinder and the steam reservoir. A is the
high-pressure cylinder; B is the low-pressure cylinder; both of which are
steam-jacketted on all surfaces, as shewn; E is the framing fixed upon the
foundation V. This latter is formed with a recess immediately underneath
the steam cylinders, in which recess is placed the steam jacketted reservoir,
consisting, firstly, of the cylindrical steam jacketted chamber G, closed at both
ends, and communicating with the low-pressure: cylinder B through the aper-
ture 9, pipe J',. and inlet passage J, as shown by the arrows; and, secondly,
of the receptacle H fixed inside the reservoir G, with narrow spaces 9, 9, 9',
intervening, which receptacle H.communicates with the high-pressure cylinder
A through the aperture h, pipe I, and eduction passage I, as shown by the
arrows, and is in communication with the reservoir G at the other extremity,.
so that the steam first enters the receptacle from the high-pressure
cylinder A without.coming in contact with steam jacketted surfaces. to any
material extent; and then, on passing thence into the low-pressure cylinder B,
is caused to pass along the narrow spaces 9, 9, 9', being thereby. brought into
intimate contact with the steam jacketted surfaces of the reservoir G, by. which
it becomes heated to the requisite degree whilst passing into the low-pressure
cylinder. K is the inlet steam pipe, and L is the valve box, to the high-
pressure cylinder A; M is the valve box, and N is the eduction pipe, to the
low-pressure cylinder B. The crank f¹ to the low-pressure cylinder is placed
at right angles to the crank f of the high-pressure cylinder,.as indicated.
Figures 11 and 12 on Sheet I. shew an example of the manner in which

page_text: my Invention may be applied to a high and a low pressure beam engine, suitable
for a large cotton mill or other manufactory; Figure 11 shews a side ele-
vation, and Figure 12 shews a transverse section through the reservoir of the
same, placed between the cylinders, and consisting, as before described with
reference to other arrangements, of the steam jacketted closed reservoir G
communicating with the low-pressure cylinder B through the pipe J and the
receptacle H placed inside the reservoir G, with which it is in communication
at top, whilst at bottom it communicates with the high-pressure cylinder A
through the pipe 1. The passage of the steam from the high-pressure
cylinder A into the receptacle H, and thence through the narrow spaces
between the vessels H and G into the low-pressure cylinder B, takes place, as
shewn by the arrows, in precisely the same manner to that described with
reference to other classes of engines. The reservoir is enclosed to prevent
undue condensation of steam in the steam jacket.
Figure 15 to 26 Sheet III. of the accompanying Drawings are
examples of various arrangements of the reservoir. Figure 15 shews a
longitudinal section, and Figure 16 shews a transverse section through a
steam reservoir, in which the steam passes from the high-pressure cylinder
through the aperture into the receptacle H; G is the heating chamber,
having no connection with the receptacle H, but traversed by a number of
small tubes 9, 9, 9, communicating with the receptacle H at one end, and
with the aperture g³, leading to the low pressure cylinder, at the other end.
The chamber G is supplied with steam from the boiler through the pipe P,
which steam surrounds the outer surfaces of the tubes 9, 9, 9, and consequently
in heating these serves to raise the temperature of the steam from the high-
pressure cylinder as it passes through the interior of the tubes from the
chamber H to the low-pressure cylinder. The chamber H is made of such a
capacity that the steam, on entering it from the high-pressure cylinder, does
not to any material extent come in contact with the tubes g, 9, 9, and therefore
does not at that time become heated. Q is the pipe for drawing off the water
of condensation from the chamber G.
Figures 17 and 18 shew another arrangement, being respectively a longi-
tudinal section and a transverse section through the reservoir. Here the
steam from the high-pressure cylinder enters the inner receptacle H through
the pipe I and aperture h, and passes thence into the surrounding steam
jacketted chamber G through the narrow slit or aperture g¹. A partition p
is fixed in the chamber G, between the slit g' and the opening 9%, conducting
to the low-pressure cylinder, by which the steam is caused to pass right round
the annular space 9, 9, before arriving at the opening 92, by which it is brought

page_text: intimately in contact with the steam jacketted surfaces of the chamber G;
the receptacle H is shewn formed with a double casing, which, however,
is not supplied with steam, but merely acts to prevent the conduction of heat.
Figures 19 and 20 show another arrangement, being respectively a longi-
tudinal section and a transverse section. H is the receptacle into which the
steam from the high-pressure cylinder passes through the pipe I. The sur-
rounding chamber G does not communicate with the receptacle H, but, being
supplied with steam from the boiler through the pipe P, serves to heat the
tubes 9, 9, 9, which traverse the same in the annular space surrounding the
receptacle H. The steam passes from this latter through the tubes g, g, g,
becoming thereby heated and arriving in the space g', passes thence to the
low-pressure cylinder through the pipe J; P' is the steam pipe from the boiler
to the steam jacketted end of the reservoir; Q, Q', are pipes for drawing off
the water of condensation.
Figures 21 and 22 show respectively a longitudinal and a transverse section
of an arrangement somewhat modified from the just described one. In this
case the receptacle H is in communication with the chamber G, and the
heating of the steam as it passes from the former through the narrow spaces g. 9,
between it and the latter is effected by the tubes G', G¹, into which steam is
conducted from the boiler through the pipe P and enclosed space G³. The
tubes G, G', communicate at the other extremity, through the circular
channel G³, with the pipe Q, for drawing off the water.
G, is a
Figures 23, 24, and 25 show a longitudinal section and end views of the
most simple manner in which my Invention may be carried out.
steam jacketted pipe, which may or may not be provided with a lining H, into
which pipe the steam from the high-pressure cylinder euters in the direction
shewn by the arrows. At the other extremity of the pipe a number of pieces
of metal H, H', are placed alternately in different positions; by this arrange-
ment the whole of the steam on first entering the pipe is not necessarily brought
into intimate contact with the steam jacketted surface of the same, but on
passing through that part in which the plates H', H', are placed, on its way
to the low-pressure cylinder, it is so thoroughly stirred about as to cause the
whole of it to come into intimate contact with the steam jacketted surface of
the pipe, and thus become heated.
Figure 26 shews an arrangement similar to that shewn at Figures 11, and
12 on Sheet I. A is the high-pressure cylinder, B is the low-pressure
cylinder, G is the reservoir containing the receptacle H, into which the
steam from the high-pressure cylinder. passes through the pipe I' without
at the time being heated to any material extent, and from whence it passes

page_text: into the spaces 9, 9, between H and the sides of the steam jacketted reservoir G,
on its way to the low-pressure cylinder through the pipe J'; P, P¹, are the
pipes from the boiler to the steam jacket; Q, Q', are the pipes for conducting
off the water. S is a safety valve to prevent any undue rise in the pressure
of the steam in the reservoir supplying the low-pressure engine; c is a
casing surrounding the reservoir to prevent loss of heat from the steam jacket.
Figure 27 shews an arrangement in which the steam, after passing from
the high-pressure cylinder into the receptacle I, placed inside the steani
jacketted reservoir G, through the pipe I, passes from thence to the low-
pressure cylinder at a different period of time through the coil of pipes g, g,
placed in a flue F, conveying the products of combustion, whereby the steam
becomes somewhat heated; the flue F may in some cases be that from the
boiler to the chimney. Other arrangements for applying heat from the
products of combustion may be adopted, provided the steam is not heated as
it comes from the high-pressure cylinder, but is heated as it passes to the low-
pressure cylinder.
Figure 13, Sheet II., shows the variation in the rotative power obtained by
using full steam throughout the stroke in two cylinders having cranks at
right angles, and also the variation when cutting off at certain definito
points.
The parts A1, A2, (the outside line) represent the rotative power obtained
from the two strokes of one cylinder, as developed on the path of the crank,
whilst B, B, (the outside line) represent the power obtained from the other
cylinder, also developed on the path of the crank; when using full steam in
both cylinders, the dotted lines V1, V2, V3, V, show the combined rotative
power of the two cylinders, and a variation from the average line O, P, of
thirty-one per cent.; and it should be stated, that if expansion were carried
to any great extent in each of the cylinders separately, this variation would be
much greater.
The full lines A1, A2, and B1, B2, show the rotative power when cutting off
at the points indicated, and the lines v¹, v³, v³, v, show the combined rotative
power of the two cylinders working as just stated, giving a variation from the
average line E, C, of only fourteen per cent., which amounts in practice to
perfect uniformity in effect. It should also be noticed, that when using full
steam, the variations in power are not only large, but long continued; for
instance, in the first quarter of the revolution the power is greatly in excess
of the average, whereas in the third quarter it is greatly below the average.
When cutting off at the particular points before noticed, each quarter has
nearly the same power.

page_text: Figure 14, Sheet II., shows the indicator figures obtained from a pair of
experimental engines of fifteen horse-power each, constructed according to
this Invention. The atmospheric line is shown by a dotted line, and the true
expansion curve is also shown by a dotted curved line, so as to compare with
the expansion curves obtained from the cylinders; it will thus be seen that
there is a considerable gain of power, and that the loss caused by the fall in
the pressure of the steam, as it passes out of the small cylinder into the
reservoir, is but very small, and may be reduced to next to nothing, as
noticed under the head "thirdly." In this case the steam is expanded nearly
nine times (8.82), and the economy may easily be calculately approximately,,
the consumption being about one and nine-tenths (1.9) pounds of coal per.
gross indicator horse-power per hour, or, say, two and four-tenths (2.4)
pounds per horse-power net useful effect, after deducting the friction of the
engine, &c.
To carry out great expansion in one cylinder in an ordinary engine, with a
limited length of stroke (as in a screw engine), a large diameter of cylinder is
required in order to obtain sufficient capacity, and as the high-pressure steam
acts first with full force upon this large diameter, very great strength in the
crank shaft and other parts is required, and thus with large diameter of
bearings, &c., so large an amount of friction is generated as to be very objec-
tionable; indeed, this consideration, together with the great variation in the
rotative power, has prevented expansion being carried out to any very large
extent in marine engines (though some persons have increased the number
of cylinders applied to each engine or to the shaft); but this Invention
renders it possible without loss to carry out expansion to a very large extent
with only one cylinder to each engine (or two in all to one shaft), and without
any very great variation in the pressures, or any risk to the low-pressure
engine, as the safety valve on the reservoir, which is larger than the steam
pipe, prevents at all times any undue pressure on the piston.
It is strongly recommended, wherever convenient, but particularly in
marine engines, that surface condensers should be used with vertical tubes,
and with the cooling water ascending inside them, as by this means the
upward current of water tends very much to brush or rub off the air bubbles
that always form on the cooling surfaces, and so form a non-conducting coat,
which hinders the quick action of the surface. Spiral or other brushes of
bristles or fine wire introduced into the tubes, and moved a little up
and
down occasionally would rub off the bubbles of air which stick very tightly to
the surfaces, but such additions would not always be desirable on the account

page_text: of the complication, though they would increase the effect of the surface
probably thirty per cent., or even more. An occasional large increase in the
velocity or force of the cooling water passing up the tubes would have a very
good effect in brushing off the bubbles of air, say, once in every minute or
oftener; such increase in pressure might be obtained by means altogether
extra to those causing the regular flow of water (whether the motion of a
vessel through water, a centrifugal pump, or any other means); thus steam
or air might be turned on at a considerable pressure for a very short time, or
an extra pump might make a single or several sharp strokes, or water from a
cistern at a high level might be turned on for a short interval by some
mechanism or connection from the engine. Surface condensers give a supply
of distilled water for the boilers, and it is then possible to work at a higher
pressure without fear of incrustation, so that fifty or sixty pounds pressure per
square inch may be as readily and conveniently carried as twenty-five or thirty
now is; but it is absolutely necessary to take proper means to protect the
boilers from the grease or oil used in the engines which comes over with the
distilled water, and by constant and repeated boilings become so acid as to
attack and injure the metal of the boiler; indeed, so seriously has this been
felt where surface condensers have been used without proper precautions being
taken, that parties have even gone back to the use of salt water in the boilers,
not knowing how otherwise to prevent the injury, whereas the remedy is
simply to put sufficient chalk or other neutral base into the boiler for the
grease or oil which has become acid to unite itself with, when it becomes per-
fectly harmless and insoluble, and can be taken out at any time in lumps
when the boiler is cleaned.
It is a convenience in some engines, such as marine engines, for example,
to be able to work one engine quite independently of the other in case of
accident, and if this is wished, it is simply necessary to provide a branch
steam pipe to the large cylinder and a branch vacuum pipe to the small
cylinder with shut-off valves, and to shut off all connection with the reservoir
by valves, when either or both engines may be worked, together or separately,
without the reservoir.
steam from the cylinder of a steam engine previous to its passing into the
cylinder of another steam engine, which reservoir is so arranged that the
steam, when first received, does not pass over steam jacketted surfaces to any

page_text: large extent, but, on passing from the same, is brought intimately into contact
with steam jacketted surfaces by passing over the same in thin or divided
stream or streams.
Secondly, I claim the employment of a vessel or reservoir for receiving
the steam from the cylinder of a steam engine previous to its passing into.
the cylinder of another steam engine (which vessel may or may not be
steam jacketted) in combination with a second vessel or coil, or series of pipes
heated by the products of combustion in the boiler or other flue, through
which vessel, or coil, or series of pipes the steam passes on its way to the
second cylinder.
In witness whereof, I, the said Edward Alfred Cowper, have hereunto
set my hand and seal, this Fourteenth day of April, in the year of
our Lord One thousand eight hundred and sixty-three.
EDWARD ALFRED COWPER. (L.s.)