IMPROVEMENTS IN DOUBLE CYLINDER STEAM ENGINES
Year: 1865

page_text: LETTERS PATENT to Joshua Rooke, of Pimlico, in the County of Middle-
sex, Engineer, for the Invention of "IMPROVEMENTS IN DOUBLE CYLINDER
STEAM ENGINES."
Sealed the 26th September 1865, and dated the 27th March 1865.
PROVISIONAL SPECIFICATION left by the said Joshua Rooke at the
Office of the Commissioners of Patents, with his Petition, on the 27th
March 1865.
I, JOSHUA ROOKE, of Pimlico, in the County of Middlesex, Engineer, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN DOUBLE
CYLINDER STEAM ENGINES," to be as follows:-
My Invention consists in a new arrangement of the high-pressure and
expansion cylinders, and of the slide valves, for admitting the steam from the
boiler into and for its exit from the high-pressure into the expansion cylinder.
In order to prevent the steam from losing any portion of its power in
travelling from one cylinder to the other, I place them close together, as
represented in horizontal section in Figure 1, in which A is the high-pressure
cylinder, and B the expansion cylinder. And I either employ a trunk and
annular piston in the expansion cylinder, as seen at C, or I use an ordinary
piston and piston rod.
My improved slide valve is represented in sectional elevation at Figure 2,
and in sectional plan at Figure 3, through the line A, B, of Figure 2. The
arrows colored black represent the passage of the steam from the boiler,
while those colored red shew its exit from the high-pressure cylinder into the

page_text: port leading to the expansion cylinder. For the exhaust from the expansion
cylinder I use an ordinary double-ported valve with sufficient lap to ensure
shauction of the steam only at the proper times
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joshua Rooke in the Great Seal Patent Office on the
27th September 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSHUA
ROOKE, of Pimlico, in the County of Middlesex, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of March, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-eighth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Joshua Rooke, Her special licence that I, the said Joshua Rooke, my
executors, administrators, and assigns, or such others as I, the said Joshua
Rooke, 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
DOUBLE CYLINDER STEAM ENGINES," upon the condition (amongst others) that I,
the said Joshua Rooke, my executors or administrators, 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 Joshua Rooke, 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 Drawings hereunto annexed, that is
to say:-
My Invention consists in a new arrangement of the high-pressure and
expansion cylinders, and of the slide valves for admitting the steam from the
boilers into and for its exit from the high-pressure into the expansion
cylinders.
In order to prevent as far as possible the loss of effective power caused by

page_text: the expansion of the steam in the passages which lead from one cylinder to
the other, I place them close together, as represented at Figure 1, which is a
horizontal section of so much of a steam engine as is necessary to explain my.
Invention. A is the high-pressure cylinder, and B the expansion cylinder,
and I either employ a trunk and annular piston in the expansion cylinder, as
seen at C, or I use an ordinary piston and piston rod. ...
My improved slide valve is represented on a larger scale in sectional elevation
at Figure 4, and in sectional plan at Figure 5, through the line A¹, B¹, of
Figure 4. The arrows colored black represent the passage of the steam from
the boilers, while those colored red shew its exit from the high-pressure cylinder
into the port leading to the expansion cylinder. For the exhaust from the
expansion cylinder I use an ordinary double-ported valve with sufficient lap to
ensure the exhaustion of the steam only at the proper times.
In arranging the cylinders I always so contrive that the piston of the high-
pressure cylinder shall be moving in a contrary direction to that of the
expansion cylinder, as is usual in engines of a similar class. This may be
done either through the intervention of cranks placed opposite to each other,
or by means of an intermediate beam lever, as shewn at Figure 1. The
cylinders may be placed vertically, horizontally, or at any angle with the
horizontal.
My valve is a many-ported slide valve in which a certain number of the
ports a, a, a, admit and cut off the steam from the boilers, and the remainder
of the ports c, c, and d, d, serve for the eduction from the high-pressure
cylinder and induction into the expansion cylinder. By these arrangements
after the steam. has acted on the piston of the high-pressure cylinder it is
allowed to pass through the passages c, c, and d, d, in the interior of the slide
valve into the expansion cylinder, and after expanding in the latter it passes
to the condenser through an ordinary double-ported slide valve D, shewn in
the transverse section, Figure 2, and sectional plan, Figure 3, constructed to
ensure the exhaustion of the steam at the right periods. By these means and
with great simplicity of construction I shorten the passages between the two
cylinders, thereby reducing the cubic contents of the passages, considerably
diminishing the unprofitable expansion of the steam therein, and consequently
obtaining a corresponding saving in the consumption of fuel.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim as my improve-
ments in double cylinder steam engines,―
First, the arrangement of double cylinder steam engines, as herein-before
described and represented in the accompanying Drawings.

page_text: And, second, the construction and arrangement of slide valves having ports
combined with passages in the interior of the valve, substantially in manner
herein-before described and represented in the accompanying Drawings.
In witness whereof, I, the said Joshua Rooke, have hereunto set my
hand, and seal, this Twenty-seventh day of September, One thousand
eight hundred and sixty-five.
JOSHUA ROOKE. (L.B.)