AN IMPROVEMENT IN STEAM ENGINES
Year: 1836

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DAVID
FISHER, of Wolverhampton, in the County of Stafford, Mechanic, send
greeting.
WHEREAS I did, by petition, represent unto His most Faithful Majesty
King William the Fourth that I had invented "AN IMPROVEMENT IN STEAM
ENGINES;" and whereas His said Majesty, by His Letters Patent under the
Great Seal of Great Britain, bearing date at Westminster the Seventeenth
day of May in the sixth year of His reign, did, for Himself, His heirs and suc-
cessors, give and grant unto me, the said David Fisher, my executors, admini-
strators, and assigns, His especial licence that I, the said David Fisher, my
executors, administrators, and assigns, or such others as I, the said David
Fisher, my executors, administrators, or assigns, should at any time agree with,
and no others, from time to time and at all times during the term of fourteen
years therein expressed, should and lawfully might make, use, exercise, and
vend my said Invention within England and Wales and the Town of Berwick-
upon-Tweed; in which said Letters Patent is contained a proviso obliging me
particularly to describe and ascertain the nature of my said Invention, and in
what manner the same is to be performed, by an instrument in writing under
my hand and seal, and to cause the same to be inrolled in His Majesty's High
Court of Chancery within six calendar months next and immediately after the
date of the said recited Letters Patent.

page_text: NOW KNOW YE, in compliance with the said proviso, I, the said
David Fisher, do hereby declare the nature of the said Invention to consist
in the working two separate steam engines by means of one sliding or other
valve. And in further compliance with the said proviso, I do particularly
describe and ascertain in what manner the said Invention is to be performed
by the following statement, that is to say:―
I place the two cylinders of the said steam engines so that the bottom of
one cylinder may be parallel to the bottom of the other cylinder, and so that
the axis or piston of one cylinder may be in the same straight line as the axis
or piston of the other cylinder, and so that the aperture for admitting the
steam into the bottom or lower-part-of-one cylinder may be directly opposite to
the aperture for admitting the steam into the bottom or lower part of the other
cylinder, whereby a line drawn from the centre of one of such apertures to the
centre of the other of such apertures will be parallel to the axis or piston of the
cylinders. The distance between the outer surfaces of the bottoms of the cylin-
ders is about equal to the sum of the diameter of the apertures for the
admission of the steam into the bottoms or lower parts of the cylinders, but
the precise distance is immaterial. I admit the steam from the boiler or
boilers, by means of a pipe into a nozzle or oblong steam box, the bottom
whereof is fitted with three apertures, two for the passage of steam into the
cylinders, and one for the waste steam, and on the bottom whereof is worked,
by means of an eccentric, a valve, in the same manner as is usually the case
in ordinary steam. engines, but each aperture must be sufficiently large
to allow sufficient steam to pass for the working the two pistons, and tho
central aperture thereof is the one I prefer to be connected with the waste pipe
for the exit of the steam in the usual way; and one of the said last-mentioned
apertures, which I prefer not to be the central aperture, communicates with a
pipe, one end whereof is fitted into the upper part of one of the said cylinders,
and the other end whereof is fitted into the upper part of the other of the said
cylinders, so that when such aperture is uncovered the steam passes from the
boiler or boilers through the said pipe and into the apertures at the upper parts
of both cylinders at the same time to the upper part of both the said pistons,
and forces down both the said pistons at the same time; the other of the said
apertures in the nozzle or steam box, which I also prefer not to be the central
aperture, is in like manner connected and communicates with the apertures
for the admission of steam' into the lower parts or bottoms of the said cylinders,
and in like manner the steam passes into the lower parts of both the said
cylinders at the same time to the lower parts of both the said pistons, and
forces up both the said pistons at the same time; the steam from the boiler
.2.

page_text: is alternately admitted into and excluded from each of the said end apertures in
the said nozzle or steam box by the motion of the valve in the usual way, and the
steam from the cylinders makes its exit through the waste pipe, which I prefer to
be connected with the central aperture in the usual way, and may be permitted
to escape when the Invention is to be applied to high-pressure engines only, or
may be conducted into a condenser when the Invention is to be applied to
condensing engines in the usual way with condensing engines. Having, as
herein-before described, generated one uniform motion of the two pistons, such
motion may be applied in any of the usual modes as may be most convenient.
When I wish to communicate the motion from both engines to one main shaft,
I generally fix in the same plane a similar and similarly sized cross head per-
pendicularly to each of the piston rods. To one and to the corresponding end of
each of the said cross heads I attach a similar and similar sized connecting rod
or arm, which works a crank in the usual way, and to the other end of each of
such cross heads I attach another similar and similarly sized connecting rod or
arm, which being fixed to the outer rim or edge of a cogged wheel, whose
radius is equal to the radius of the crank arm, works such cogged wheel and
turns the same round in the same time as the other arm completes a revolu-
tion of the crank. The two wheels turned round by the action of the said two
pistons are similarly cogged and of equal size; and in the same plane and
between the same, and in the same plane and with its centre in the same
straight line, is placed another similarly cogged wheel between the said two
wheels; the action of each of the two outer cogged wheels tends to turn round
the central cogged wheel in the same direction; the axis of this wheel forms
the main shaft whereon works the fly wheel; it is not essential that the cylin-
ders should be placed in the position herein-before described, but that is the
position which I usually adopt, and, if convenient, the nature of the communi-
cation between the pipes connected with the end apertures of the nozzle or steam
box may be varied, and the pipe connected with one of such end apertures of
the said nozzle or steam box, and admitting the steam into the top of one of the
said cylinders, may communicate with the pipe connected with the bottom of the
other of the said cylinders, instead of with the pipe connected with the top
thereof, and the pipe connected with the other end aperture of the said nozzle
or steam box, and admitting the steam into the bottom or lower part of one
cylinder, may in like manner communicate with the pipe connected with the top
or upper part of the other cylinder, and in such case one of such pistons will be
moving upwards and the other of such pistons at the same time will be moving
downwards, and the motion from such pistons may be applied by any of the
usual mechanical modes, or the position of the waste pipe may be varied.

page_text: DAVID (LS.) FISHER.
AND BE IT REMEMBERED, that on the same Seventeenth day of
November, in the year above mentioned, the aforesaid David Fisher came be-
fore our Lord the King in His Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained, in form above written.
And also the Specification aforesaid was stamped according to the tenor of
the Statute in that case made and provided.
Ova