AN IMPROVEMENT OR IMPROVEMENTS IN CONDENSING STEAM ENGINES
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BOULD, of Overdon, in the Parish of Halifax, in the County of York, Cotton
Spinner, 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 Sixteenth day of December, in the fifth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said John
Bould, Her especial licence, full power, sole privilege and authority, that I, the
said John Bould, my exors, adiñiors, and assigns, or such others as I, the said
John Bould, my exors, adñors, 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
"AN IMPROVEMENT OR IMPROVEMENTS IN CONDENSING STEAM ENGINES;" in which
said Letters Patent is contained a proviso that I, the said John Bould, shall
cause a particular description of the nature of my said Invention, and in what
manner the same is to be performed, to be inrolled 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 Bould, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, are fully described and ascer-

page_text: tained in and by the following statement thereof, reference being had to the
Drawing hereunto annexed, and to the figures and letters marked thereon,
that is to say:-
My Invention relates to the mode of arranging the valves (which slide over
the ports) of condensing steam engines in such manner that the exhaustion
port shall be fully open at the time the piston has completed its stroke at
either end of the cylinder, and at the same time allow of the steam being
worked expansively by means of the same valves. And in order that my
Invention may be most fully understood and readily carried into effect I will
proceed to describe the means pursued by me.
In constructing and applying valves to condensing steam engines, the valves
of which are worked by excentrics, it is..usual to form the valves of such
dimensions that they will only just cover the ports or openings into the cylin-
der, or only very slightly exceed the dimensions of the port; hence, when the
valves are moved, the ports are simultaneously or nearly simultaneously opened
and closed; but, according to my Invention, by enlarging the size of the slides
so that they will be much larger (at least twice as large) as the ports they
work over, the induction valve may remain closed during a considerable length
of movement of the valves; hence, it may be closed at any desired part of the
stroke of the engine, and the exhaustion valve remain open to the condenser;
and what is also very important, the exhaustion valve may be fully open at the
termination of the stroke at either end of the cylinder, so that a good vacuum
may, at the commencement of the stroke, be obtained, and, consequently, at
the time the induction port is open for the flow of steam.
!
DESCRIPTION OF THE DRAWING.
Figure 1 represents a Diagram of a steam cylinder and valves, and also the
excentrics and parts which work the valves. In Figure 1 the valves are shown
in the position they would be at the termination of the stroke at the upper end
of the cylinder; and it will be seen that the exhaustion valve has passed away
from the exhaustion port; and the induction or steam valve has partially
opened the induction port. And I would remark that the steam valve is not
set to open the port completely, as I have found that is not necessary; but, if
desired, it will be evident to the engineer that that might be done, either by
increasing the throw of the excentric, or by shortening the lever e', to which
the excentric rod is attached.
Figure 2 shows a Diagram of a steam cylinder and valves, and the lever
which works them, the excentric which gives motion to the lever not being
shown, the valves in this Figure being in the reverse position to that shown
in Figuro I. The valves a, a, are made of such length as to be equal to three

page_text: times the opening of the ports; and it will be seen that, by tracing the move-
ment which will take place in the parts of Figure 1, that when the struke in
the upward direction has been completed, and the steam or induction valve
opened to the required extent, and steam admitted above the piston, the steam
or induction valve will be closed by the time the piston has moved about one
third of its stroke; but this may be varied, and the exhaustion port will remain
open, and the movement of the excentric, and the parts actuated thereby, will,
near the end of the stroke, close the exhaustion port at the lower end of the
cylinder, and open the exhaustion port at the upper end of the cylinder, and
bring the parts into the positions shown in Figure 2; and it will be seen that
these effects will be consequent on the enlargement of the valves in respect to
the ports over which they work, and the extent of movement given to the
valves, whereby one or other of the valves can be moved for a considerable
length whilst over its port with uncovering that port, allowing the exhaustion
port to be fully open at the time of completing the stroke at either end of
the cylinder. b is the excentric on the main shaft c, and the rod d and levers
e and e' for moving the slides, one of the ordinary construction, allowing only
for the quantity of motion given to the valves. And it is important to call
attention to the circumstance of the distance over which the valves are moved,
as on that circumstance, combined with the length of the valves, depends the
beneficial results obtained. The Diagrams show the parts so arranged as to
cause the valves to move a distance equal to four times the depth of the ports;
and if it were desired that the steam port should be opened fully, then the
valves would have to move five times the length of the depth of the port, and in
case of making the valves less, to the extent of their being twice the length of
the depth of the ports, then the movement given to them is to be four times
the depth of the ports, to fully open the steam port, and the movement ought
not to be reduced below three times the depth of the ports, as the steam port
will then be only half opened. It should be stated that, although I prefer to
work the slides with an excentric, it will be evident that a crank may be sub-
stituted therefor. At the same I would wish it to be understood that I do not
claim the opening of the exhaustion port by the time the piston arrives at
either end of the cylinder, when other arrangements of valves are used or
other means than an excentric (or its equivalent a crank) be employed for
working the valves, my Invention being confined to such engines as work the
valves by excentrics or cranks. And I would further remark that, although
I have shown the valves as being equal to three times the length of the depth
of the ports over which they work, yet I do not confine myself thereto, as they
might be slightly encreased, and even less extensive valves may be used,

page_text: varying the other parts accordingly; but I have found that there is little
advantage to be derived when the valves are not at least equal to twice the
length of their ports, measured in the direction of the movement of the valves.
But what I claim is,―
The mode of constructing the valves of condensing steam engines when
worked by excentrics or cranks, whereby the exhaustion ports may be fully.
opened at the completion of the stroke, and whereby steam may be cut off and
more effectually worked expansively by the same valves, as above described.
In witness whereof, I, the said John Bould, have hereunto set my hand
and seal, this Sixteenth day of June, One thousand eight hundred and