CERTAIN IMPROVEMENTS IN STEAM ENGINES
Year: 1839

page_text: ARROWSMITH'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
ARROWSMITII, of Bilston, in the County of Stafford, Engineer, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent, under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-fifth day of June, in the third year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto me, the said John
Arrowsmith, Her especial license, full power, sole privilege and authority, that
I, the said John Arrowsmith, my exors, adññiors, and assigns, or such others as
I, the said John Arrowsmith, my exors, adiñiors, or assigns, should at any time
agree with, and no others, from time to time and at all times during the term
of years therein expressed, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, my
Invention of "CERTAIN IMPROVEMENTS IN STEAM ENGINES;" in which said Letters
Patent is contained a proviso that I, the said John Arrowsmith, shall cause a
particular description of the nature of my said Invention, and in what manner
the same is to be performed, to be enrolled in Her said Majesty's High Court
of Chancery within six calendar months next and immediately after the date
of the said in part recited Letters Patent, as in and by the same, reference
being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John Arrowsmith, do hereby declare that my Invention consists in arranging
and combining two steam cylinders, with their passages and valves so disposed
as to allow the steam to pass from one to the other in such manner as to
obtain and apply a greater amount of effective force than is rendered available

page_text: in steam engines of any previously known construction, and hence there results
a considerable saving in the consumption of fuel, and the employment of a
boiler of considerably less dimensions and weight than ordinary. From the
peculiar properties this new engine possesses I have denominated it the high-
pressure, low-pressure, double expansive, and double condensing engine. It is
especially advantageous as a pumping engine, also to mills, forges, and blast
furnaces. It is readily adapted to steamboat engines, and is capable of many
other applications in substitution of ordinary engines. In further accordance
with the aforesaid proviso, I will now proceed to describe the manner of carrying
my said Invention into effect (with reference to the accompanying Drawings.
Figures 1 and 2 are vertical sections, and Figures 3 and 4 are plans of one
of my pumping engines, supposed to be placed perpendicularly over the shaft
of a pit, and having the piston rods working through the bottoms of the
cylinders. (In each of the Figures where the same letters of reference occur
they are used to denote the same parts.) At a, Figure 1, is the induction pipe
for steam, in which is placed a throat valve to regulate the supply of. steam to
the engine. B; Figure 1, is a valve now open for allowing the steam to pass to
the under side of the piston C in the small cylinder, by which means the engine
takes its up-stroke; tlien the valve B closes, and the valves D and E open.. The
valve E. opens to allow-a part of the steam to pass on to the top side of the
piston C, (but this valve can be closed at any part of the stroke of the engine,
say a 3rd, 4th, or 5th, as may be found necessary by practice,) then that steam
expands, and when the down-stroke is finished the same steam is then so weak
as to be in a fit state for condensation; then the valve Fopens to the condenser
G, by which means the steam is condensed above the piston C in the small
cylinder, which of course causes a vaccuum, by which means the pressure on
the under side of the piston C is sixty pounds per inch instead of forty-five
pounds (or as far as the vacuum is good), so that by allowing part of the steam
to pass to the top side of the piston C after it has taken its up-stroke, it places
the piston C in equilibrium, and the valve D opening at the same time as the
valve E, the same steam acts with all its force on the under side of the
piston H in the large cylinder, and by its expansive force (in conjunction with
the vacuum hereafter explained, causes the up-stroke of the piston H; then the
valve D closes, and the valve I opens to allow the steam to pass from the under
side of the piston H to its upper side during its down-stroke; then the valve I.
closes, and at the same opens a passage to the condenser G, and so on alter-
nately. When the piston C has finished its up-stroke the valve E opens, the
passage of which, having a communication with the under side of the piston
.C, allows the steami to pass to the top side of the piston C, consequently, the

page_text: pressure is the same above the piston as below it, having a vacuum on the top
side of the piston H in the large cylinder in taking its up-stroke, and the piston
C descending at the same time in equilibrium, gives to the piston of the large
cylinder all the power of the steam in the small cylinder which has already
been once employed in raising the piston C, without there being any impedi-
ment to the motion of the latter in its down-stroke, because the force of the
steam on each side of the piston is equalized; hence the full effect of the
expansive force of the steam is made to bear against the under side of the
piston on its up-stroke. The steam may be made in a manner to expand three
times, and it may be necessary, if the engine should be above its work, at
times, by closing the valve B at any part of the up-stroke of the piston C; but
I think this engine will act more powerfully by allowing the steam to act with
all its force during the whole of the up-stroke of the piston C in the small
cylinder, that is, with four atmospheres, or sixty pounds per square inch; then
allowing a part of that same steam to pass to the top side of the piston C, then
closing the valve E, it would leave the remaining portion of that steam to act
and expand under side of piston H in the large cylinder.
I now proceed to explain the other parts of the engine. represented in the
Drawings, which do not, however, possess any peculiarity of construction that
is unknown to persons familiar with steam engines in general. J is the educ-
tion pipe connecting the condenser with the boxes of the valves F and I, as
seen in Figures 1, 2, 4; K, injection pipe; L, a cock to regulate the supply of
water to the condenser; M, pipes connecting the cistern N with the condenser
G, which cistern is elevated at least 20 feet above the bottom of the con-
denser, in order that the hydrostatic pressure may force the water into the
condenser, and thereby cause a quick condensation; O, in Figs. 1 & 2, are
views of the foot valve, the condenser and air pumps; P, the discharge valves,
through which the hot water is forced into the hot wells, from whence a part
is raised by a small force pump to feed the boilers, and the overplus runs off
by the waste pipe Q; R, Figures 1 and 2, air pumps, with their piston rods
reversed and attached to the pit pump rod by the bracketts S. I put two air
pumps for the purpose of dividing the work of the air pumps on the two cylin-
ders, and as both draw from one condenser there will always be a good vacuum
when at work. One air pump would do for this engine, as the condensation is
alternate in the two cylinders, and similar to a double-acting engine; T,
Figures 1 and 2, are racks attached to the piston rods; and the wheel U,
working into each, causes a more uniform action of each piston; as one
cannot move without the other, the rollers V are to prevent them forcing
out of gear.
The racks and wheels are not absolutely necessary, as the

page_text: engine will work without them. W, Figures 1 and 2, the wood framing to
support the engine. Figures 5, 6, and 7 are plans and sections of an engine
on the same principle as the one described above, but adapted for blast
furnaces and various other purposes. It is unnecessary to describe the action
of this engine, as it is the same as the other, excepting that the steam passes
from the under side of the piston C to the top side of the piston H, and
causes the down-stroke of this engine; thus the condensation is on the top side
of the piston C in the small cylinder, and the bottom side of the piston H in
the large cylinder, or vice versa. The principle of this engine could be adapted
to any condensing engine now at work, by placing the small cylinder behind the
large one, and connecting the nozzels or breast pipes one with another, as seen
in the Drawing, and lengthening out the beam, as in Figure 5. The same air
pump and condenser will serve. The valve may be worked by band gears or
excentric motion, or any of the known methods now in use. I have shewn
this sort of slide valve as being the most simple, but almost any other sort of
valve will do for this engine. The small cylinder may be put under the
large cylinder by having the piston rod lengthened, and passing it through a
stuffing box on the bottom of the large cylinder; then the beam would not
want lengthening out, and the stroke would be the same in both cylinders. I
think it unnecessary to shew parrallel motion and other gearing or parts of the
steam engine, as the present Drawing sufficiently show my Invention and
improvements. Figure 8 is a side elevation of a method that may be adapted
as a steamboat engine. It is unnecessary to describe it, as the Drawing suffi-
ciently shows how it may be put to work, and a steamboat engine may be put
to work with the beam made longer at the cylinder end, as in Figure 5, which
makes the stroke of the small cylinder longer than the large cylinder. Various
other modes can be adapted for connecting these engines with their work.
Figure 9 is another mode of working the said engine. It consists in allowing
a portion of steam to pass from the boiler by the valve E to the top side of the
piston C after it has taken its up-stroke, and then closing the valve E at any
part of the down-stroke of the piston C, as may be found necessary, to cause it
to act in equilibrium as the steam expands on the under side of the piston C,
and in the large cylinder. By this means it allows the whole of the steam on
the under side of the piston to act on the under side of the piston H in the
large cylinder; consequently the large cylinder will require to be of a larger
diameter than the one in Figure 1, which will give this engine more power
at the expense of a little more steam.
Having thus explained the principle or characteristic features of my improve-
ments in the construction and mode of "working steam engines," and illus-

page_text: trated by several examples the method of carrying them in practice, 1 desire
it to be understood that I lay no claim of originality to any of the parts of the
engines or apparatus separately considered, as they are or may be common to
other steam engines. Neither do I claim as original the employment of two
cylinders in an engine for working the same steam through them, because, as
is well known, this has been done by Woolfe and other persons; but I do claim
as my Invention the peculiar arrangements or combination I have described,
by which the pressure of the steam in both cylinders is placed in equilibrium
on each side of the pistons during the descending or returning strokes thereof,
and the condensation of the said steam in both cylinders, so as to obtain the
entire effect of the force of the steam, that is, without the usual counteraction
arising from the reaction of the steam that has passed from the upper to the
under side of the piston of the small cylinder, and which reaction is common
to all previous arrangements of engines having two cylinders of the kind.
I also claim as my Invention the mode of working the same engine as shewn
in Figure 9, which consists in allowing a small portion of high-pressure steam
from the boiler to act on the top side of the piston C during its down stroke;
but the valve E is closed at that part of the stroke which allows the steam to
expand in the same proportion as the steam under the piston C, and when the
down stroke is finished the same steam is condensed above the piston C, as in
Figures 1 and 2.
In witness whereof, I, the said John Arrowsmith, have hereunto set my
band and seal, this Twenty-fourth day of December, in the year of our
Lord One thousand eight hundred and thirty-nine.
JOHN (L.S.) ARROWSMITH.
AND BE IT REMEMBERED, that on the Twenty-fourth day of December,
in the year of our Lord 1839, the aforesaid John Arrowsmith came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according to
the tenor of the Statute made for that purpose.
Inrolled the Twenty-fourth day of December, in the year of our Lord One
thousand eight hundred and thirty-nine.