Year: 1886

page_text: Date of Application, 24th June, 1885
Complete Left, 10th Mar., 1887
Complete Accepted, 15th Apr., 1887.
[Communicated from abroad by ALEXANDER MACMILLAN, a British Subject, at present
residing in Tokio, in the Empire of Japan, Engineer.]
I, WILLIAM PHILLIPS THOMPSON, Fel. Inst. P.A. of the Agency for Foreign Patent
Solicitors, 6 Lord Street, Liverpool in the County of Lancaster, and 323 High Holborn
in the County of Middlesex Civil Engineer do hereby declare the nature of this
invention to be as follows:-
This invention has reference to improvements in the ordinary slide valves for steam
engines whereby a greatly increased area of steam admission can be obtained without
increasing the area of the slide valve exposed to pressure, or increasing the stroke of
slide valve, and is specially designed to retain the advantages of early opening and
closing of exhausts incidental to ordinary slide valves, cutting off steam by means of
their own lap, whose defect is that the large amount of lap required to cut off at an
ordinary rate of expansion, seriously diminishes, the area of steam admission to the
cylinder.
This defect is overcome in this invention by the novel combination of valves,
multiplying the number of ports for steam admission to the cylinder.
Again, if in order to avoid the excessive steam lap, and obtain as nearly as possible
the full amount of port opening due to the stroke, a separate expansion valve is used
in conjunction with a slide valve having very little steam lap, then owing to the want
of steam lap on the slide valve, the slide eccentric is necessarily very little in advance
of right angles (90 degrees) to crank, and to obtain the necessary cushioning, con-
siderable exhaust lap has to be provided thereby diminishing the exhaust passages,
and making the opening of exhaust very late.
In these improved valves, as a large amount of steam lap can be and is employed,
the slide valve eccentric can be placed well in advance of the crank, say about
135 degrees, when set to cut off at seven twelfths of the stroke, thus obtaining an
early release and closing of exhausts, and securing full area of exhaust ports.

page_text: This advantageous arrangement of exhausts can be and is retained even when steam
admission is prolonged as herein-after mentioned.
The steam lap is provided at the ends of the slide valve to open and close the steam
admission as in an ordinary slide valve, and further, through the lap of slide valve
face covering the top and bottom cylinder ports, a steam port is formed in connection
with a steam passage on the back of the slide valve, which steam passage is provided
with any required number of auxiliary steam ports, the steam admission through these
ports being opened and closed by what may be termed an auxiliary valve.
This auxiliary valve can be a stationary plate free to bear against the back of the
slide valve, and provided, with ports having suitable steam lap to admit and cut off the
steam through the auxiliary ports on back of slide valve, precisely as the lap on end
of slide valve does.
The slide valve itself can be actuated by any known arrangement of valve gear.
The auxiliary valve can be made in top and bottom halves if desired, so as to readily
admit of the lap being altered.
In this way with a double ported cylinder face in which there are two exhaust
ports top and bottom it is easy to obtain three additional steam poris in the valve top
and bottom besides the ordinary steam admissions, without increasing the ordinary
length of the valve beyond what is rendered necessary in making the cylinder port or
ports of sufficient area for the increased admission due to the auxiliary steam ports.
Another modification of the new slide valve is made by giving a certain motion to
the auxiliary valve, whereby without affecting the steam lead, or opening and closing
of exhausts, the steam admission through the auxiliary valve can be prolonged beyond
the normal cut off which would be produced by the lap of a stationary auxiliary
valve.
The same steam lead is preserved in the case of a direct acting engine throughout
the normal and prolonged cut offs, by placing the eccentric which gives motion to the
auxiliary valve, exactly at right angles to the crank, so that on the top and bottom
centres of piston, the auxiliary valve is always in the same central position as it would
be when stationary, whatever the variation of its siroke may be, and thus the steam
lead is the same, whether the auxiliary valve is stationary or moving.
One method of obtaining the variable cut off would be by actuating a rocking slotted
lever in which the bottom end of auxiliary valve spindle connecting rod could be
shifted by means of a travelling block and screw.
When exactly over the fulcrum of rocking lever, the valve would be stationary, and
the normal cut off obtained, and as the block was shifted out along arm of lever,
motion would be given to the auxiliary valve, so as to decrease the lap, and a longer
admission of steam with increased area of same would be produced, proportionate to
the amount of travel imparted to the auxiliary valve by the rocking lever.
When fitted to a compound engine high pressure cylinder having double. exhaust
ports top and bottom the main slide valve will also have double, exhaust ports top and
bottom, and four separate steam admissions, i.e. one over the end of slide valve face as
in an ordinary valve, and three additional through the back, communicating with the
port formed in slide valve face through the lap covering top and bottom cylinder
ports.
If considered necessary, a second similar port could be formed in slide valve face
through the lap, covering the two inner cylinder ports, or another ordinary steam
admission to the inner ports might be provided, but these are preferably dispensed
with so as to leave the exhausts from top and bottom ports quite free.
The admission of steam at the ends of the valve is governed by the amount of lap in
the ordinary way, and the admission of steam through the three ports top and bottom
in back of slide valve is governed by the auxiliary valve, against which the back of
slide valve works, the auxiliary ports having the same steam lap as the slide valve face,
and this auxiliary valve can be either stationary so that the steam is cut off at back
and front of slide valve at the same point, or by giving the auxiliary valve motion in
the required direction; the steam admission through back of slide valve, can be
prolonged at pleasure.

page_text: The auxiliary valve may have a spindle projecting through botion of casing, but if
no motion of the auxiliary valve is considered necessary, the spindle can be a fixture,
or dispensed with altogether, and the auxiliary valve supported and secured inside the
casing in any suitable manner, but always so that it is perfectly free to bear against
the back of slide valve.
'Suitable springs are provided on back of auxiliary valve, to prevent it from falling
off the face when the steam pressure is removed.
The steam lap on the back and front of the slide valve is the same. There are two
ordinary steam admissions and three additional improved admissions at each end..
When the crank is on top centre, the slide valve eccentric owing to the large amount
of steam lap employed is placed about 135 degrees in advance of the crank, and the
auxiliary valve eccentric being 90 degrees behind the crank.
The auxiliary valve is on its central position, in fact in the same position it would be
if stationary and the slide valve is equally open to steam lead at the two ordinary
steam admissions at slide valve face as at the three improved admissions at back of
slide valve.
Whatever amount of travel is imparted to the auxiliary valve, so long as its
eccentric is placed in relation to the crank described, the auxiliary valve will always
be in its central position when the crank is on top or bottom centre, and therefore the
steam lead remains unaltered when prolonging the steam admission by means of the
motion given to auxiliary valve.
Also as the motion of the slide valve itself is not affected in any way, the opening
and closing of exhausts when prolonging the steam admission is unaltered.
If it is necessary to cut off the steam admission earlier than the normal cut off for
which the slide valve is set the stroke of slide valve can be reduced by any of the
ordinary methods such as linking up or otherwise, and a corresponding shorter cut off
effected.
In such cases the auxiliary valve would be stationary and the steam admission
would be cut off at back, and front of slide valve at the same point.
Although cylinders with double ports top and bottom are mentioned, it is to be
understood that the improvements are equally applicable to cylinders having single or
any number of ports.
It is also to be understood that the invention is equally applicable to the intermediate
and low pressure cylinders of compound engines, as to the high pressure cylinders, and
equally to cylinders of marine stationary, land, and locomotive engines.
Dated this 23rd day of June 1886.
WM. P. THOMPSON & Co.,
Agents for the Applicant.

page_text: Improvements in and Connected with Slide-valves for Steam
Engines.
A communication from abroad by ALEXANDER MACMILLAN, a British Subject, at
present residing in Tokio, in the Empire of Japan, Engineer.
WILLIAM PHILLIPS THOMPSON Fel. Inst. P.A. of the Agency for Foreign Paient
Solicitors 6, Lord Street, Liverpool in the County of Lancaster and 323 High
Holborn in the County of Middlesex, Civil Engineer, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
-
This invention has reference to improvements in the ordinary slide valves for steam
engines, whereby a greatly increased area of steam admission-can be obtained
without increasing the area of the slide valve exposed to pressure, or increasing the
stroke of slide valve, and is specially designed to retain the advantages of early
opening and closing of exhausts incidental to ordinary slide valves cutting off steam
by means of their own lap, whose defect is that the large amount of lap required to cut
off at an ordinary rate of expansion, seriously diminishes the area of steam admission
to the cylinder..
This defect is overcome in this invention by the novel combination of valves
multiplying the number of ports for steam admission to the cylinder.
Again, if in order to avoid the excessive steam lap and obtain as nearly as possible
the full amount of port opening due to the stroke, a separate expansion valve is used
in conjunction with a slide valve having very little steam lap, then owing to the want
of steam lap on the slide valve, the slide eccentric is necessarily very litile in advance
of right angles (90 degrees) to crank and to obtain the necessary cushioning con-
siderable exhaust lap has to be provided, thereby diminishing the exhaust passages
and making the opening of exhaust very late.
In these improved valves as a large amount of steam lap can be and is employed,
the slide valve eccentric can be placed well in advance of the crank, say about
135 degrees, when set to cut off at of the stroke, thus obtaining an early release
and closing of exhausts, and securing full area of exhaust ports.
This advantageous arrangement of exhaust can be and is retained even when steam
admission is prolonged as hereinafter mentioned.
According to one form of this invention the steam lap is provided at the ends of
the slide valve to open and close the steam admission as in an ordinary slide valve,
and further through the lap of slide valve face covering the top and bottom cylinder
ports, a steam port is formed in connection with a steam passage on the back of the
slide valve, which steam passage is provided with any required number of auxiliary
steam ports, the steam admission through these ports being opened and closed by
what may be termed an auxiliary valve.

page_text: This auxiliary valve can be a stationary plate free to bear against the back of the
slide valve and provided with ports having suitable steam lap to admit and cut off
the steam through the auxiliary ports on back of slide valve, precisely as the lap on
ends of slide valve does.
The slide valve itself can be actuated by any known arrangement of valve gear.
In this way with a douche ported cylinder face, in which there are two exhaust
ports top and bottom, it is easy to obtain three additional steam ports in the valve,
top and bottom, besides the ordinary steam admissions without increasing the ordinary
length of the valve, beyond what is rendered necessary in making the cylinder port
or ports of sufficient area for the increased admission due to the auxiliary sicam
ports.
The auxiliary valve can be made in top and bottom halves if desired, so as to readily
admit of the lap being altered.
Another modification of the new slide valve is made by giving a certain motion to
the auxiliary valve, whereby without affecting the steam lead, or opening and closing
of exhausts, the steam admission through the auxiliary valve can be prolonged beyond
the normal cut off, which would be produced by the lap of a stationary auxiliary valve.
The same steam lead is preserved in the case of a direct acting engine throughout
the normal and prolonged cut offs, by placing the eccentric which gives motion to the
auxiliary valve exactly at right angles to the crank, so that on the top and bottom
centres of piston, the auxiliary valve is always in the same central position as it would
be when stationary, whatever the variation of its stroke may be, and thus the steam
lead is the same, whether the auxiliary valve is stationary or moving.
One method of obtaining the variable cut off would be by actuating a rocking.
slotted lever in which the bottom end of auxiliary valve spindle connecting rod could
be shifted by means of a travelling block and screw.
When exactly over the fulcrum of rocking lever, the valve would be stationary, and
the normal cut off obtained, and as the block was shifted out along arm of lever,
motion would be given to the auxiliary valve so as to decrease the lap, and a longer
admission of steam with increased area of same would be produced, proportionate to
the amount of travel imparted to the auxiliary valve by the rocking lever. Any
suitable known arrangement can be employed to impart motion to the auxiliary
valve.
In order that the invention may be more clearly comprehended the accompanying
drawings are appended hereto.
Figure 1. is a sectional elevation of the improved valve fitted to cylinder of
compound engine having double exhaust ports top and bottom.
Figure 2. plan of same.
Figure 3. similar valve with the addition of an equilibrium ring on back of
auxiliary valve to reduce the friction of the slide valve faces.
Figure 4. plan of Figure 3.
Figuro 5. sectional elevation of valve arranged for slide valve with treble exhaust
ports and six separate steam admissions.
Figure 6. plan of Figure 5.
Figure to 14. indicate the relative position of the valve and the cranks and
eccentrics at certain portions of the stroke.
Throughout these like letters refer to like parts.
A is the engine cylinder. B the steam ports, C the exhaust port. D the slide valve.
E the auxiliary. F the valve chest. G steam ports or passages in the slide valve.
openings in back of slide valve for admission of steam to the passages G. H steam
space at back of auxiliary valve. openings in face of auxiliary valve for passage of
steam, I slide valve rod. J auxiliary valve rod. K springs on back of auxiliary valve.
Lequilibrium ring on back of auxiliary valve in Figures 2 and 3.
Figures 1 and 2 show sectional elevation and plan of improved valves as fitted to a
compound engine high, pressure cylinder having double exhaust ports top and.
bottom.

page_text: The main slide valve D has also double exhaust ports e¹ top and bottom, and four
separate steam admissions, that is to say, one over the end of slide valve face as in an
ordinary valve and three additional through the openings, the back communicating
with the port G formed in slide valve face through the lap covering top and bottom
cylinder ports.
If considered necessary, a second similar port could be formed in slide valve face
through the lap, covering the two inner cylinder ports, or another ordinary steam
admission to the inner ports might be provided, but these are preferably dispensed
with in the example given so as to leave the exhausts from top and bottom ports quite free.
The admission of steam at the ends of the valve is governed by the amount of lap
in the ordinary way, and the admission of steam through the three ports g top and
bottom in back of slide valve D is governed by the auxiliary valve E, against the face
of which the back of slide valve works, the auxiliary ports having the same steam lap
as the slide valve face. The auxiliary valve E can be either stationary so that the steam
is cut off at back and front of slide valve at the same point or, by giving the auxiliary
valve motion in the required direction, the steam admission through back of slide valve
can be prolonged at pleasure.
In these figures 1 and 2 the auxiliary valve E is shown with a spindle J projecting
through bottom of casing, but if no motion of the auxiliary valve is considered
necessary the spindle can be a fixture, or dispensed with altogether, and the auxiliary
valve supported and secured inside the casing in any suitable manner, but always so
that it is perfectly free to bear against the back of slide valve.
Suitable springs K are provided on back of auxiliary valve E, to prevent it from
falling off the face when the steam pressure is removed.
Figures 3 and 4 show sectional elevation and plan of the same slide valve and
auxiliary valve as in Figures 1 and 2, with the addition of an equilibrium ring L on
back of auxiliary valve E to reduce the friction of the slide valve faces. Any known
arrangement of equilibrium ring can be used for this purpose. With this arrangement
the auxiliary valve E can be either stationary, or movable as desired.
In Figures 1 and 3 the auxiliary ports g in back of slide valve and also the ports c
in cylinder face are shown of the proportions suitable for a stationary auxiliary valve,
but in Figures 7 to 14 both inclusive, the ports are shown suitable for the increased
admission of steam resulting from the motion given to auxiliary valve. E when
prolonging the steam admission.
•
In order more clearly to explain the action of the valves, they are here shown in
eight different positions. Figure 7 showing the valves in their central positions from
which it will be seen that the steam lap on back and front of slide valve is the same,
and Figures 8 to 15. showing the action of the valves during the downward stroke of
piston, diagrams of the position of crank and eccentrics being appended to each view.
There are two ordinary steam admissions and three additional improved admissions
at each end. Figure 8 shows crank on top centre, slide valve opening on top for
steam lead equally at ordinary ports and improved ports. The slide valve eccentric
owing to the large amount of steam lap employed is placed about 135 degrees in
advance of the crank, and the auxiliary valve eccentric, 90 degrees behind the crank.
It will be seen that the auxiliary valve E is in its central position, in fact in the
same position it would be if stationary, and the slide valve D is equally open to steam
lead at the two ordinary steam admissions at slide valve face as at the three improved
admissions g at back of slide valve; The passage through slide valve face being quite
free and exercising no control whatever in the opening or closing of the steam
admission.
It is also clear that whatever amount of travel is imparted to the auxiliary valve E
so long as its eccentric is placed in relation to the crank as shown in the diagram, that
is to say at right angles to crank, the auxiliary valve will always be in its central
position when the crank is on top or bottom centre, and therefore the steam lead
remains unaltered when prolonging the steam admission by means of the motion 5
given to auxiliary valve.

page_text: Also as the motion of the slide valve itself is not affected in any way the opening
and closing of exhausts when prolonging the steam admission is unaltered.
Figure 9. shows crank moved short distance on down stroke the slide valve at bottom
of its stroke, and therefore full open for top steam. Opening of auxiliary ports
increased by movement of auxiliary valve.
While slide valve D has moved down to this position the auxiliary valve E has
moved up, thus opening up the auxiliary steam ports in excess of what the motion of
slide valve alone would do, equal to the distance the auxiliary valve has moved up
from its central position.
Figure 10. shows crank moved more than halfway down say of piston stroke,
steam shut at ordinary steam ports, but still open at auxiliary ports, thereby prolonging
steam admission. The two slide valve steam ports on its face are in the act of closing,
while the three auxiliary ports on back still remain open on account of the position
of the auxiliary valve E resulting from the motion given to it. If the auxiliary valves
were stationary all the steam ports would close at this point.
It is to be noted that the auxiliary port or passage G in slide valve face is quite
open and does not control the admission or cut off of the steam in any way.
Figure 11 shows crank moved further down say of piston stroke-Auxiliary
steam ports shut and steam admission entirely closed. The three auxiliary steam
ports on back of slide valve E in the act of closing, and this figure compared with
the preceding one shows the prolongation of steam admission resulting from the motion
given to auxiliary valve.
The auxiliary port or passage G in slide valve face still remains open, the auxiliary
cut off being entirely effected at the ports on back of side valve.
Figure 12. shows the top exhaust ports just opening ready to afford free exhaust by
the time down stroke of piston is complete. It is to be noted that this takes place at
a point considerably before the end of piston stroke, thereby giving an early, free and
perfect exhaust.
Figure 13. shows the bottom exhaust ports in the act of closing, giving ample
cushioning for piston when approaching dead point. This takes place well in advance
of ends of piston stroke, thereby compressing the remaining steam in clearance space,
by which saving of steam is effected, and the piston cushioned when approaching the
dead points on top and bottom centres.
Figure 14. shows crank on bottoin centre the auxiliary valve E being again (as on
top centre of crank) in its central position and the slide valve D is equally open to
steam lead at the two ordinary steam admissions of slide valve face and the three
improved admissions at back of slide valve.
9
It is to be noted. that although the crank is only on bottom centre that the top
exhaust ports are already nearly full open, affording a free escape for the exhaust steam.
In foregoing example slide valve stroke is supposed to be 5 inches and auxiliary valve
stroke 2 inches, steam being cut off with auxiliary valve stationary at about of
piston stroke, and with auxiliary valve stroke at 2 inches, the steam admission is pro-
longed to about of piston stroke, the length of admission being varied between these
two cut offs by simply reducing the motion of auxiliary valve by means of a rocking
lever or oilier suitable arrangement.
If it is necessary to cut off the steam admission carlier than the normal cut off for
which the slide valve is set, the stroke of slide valve can be reduced by any of the
ordinary methods such as linking up or otherwise and a corresponding shorter cut off
effected. In such cases the auxiliary valve would be stationary and the steam admission
would be cut off at back and front of slide valve at the same point.
Although in Figures 1 and 3 cylinders with double ports top and bottom are shown
for illustrating the invention, it is to be understood that the improvements are equally
applicable to cylinders having single or any number of ports.
For example Figure 5, shows the same size of cylinder, but treble ported for
exhausts, the slide valve having also treble exhaust ports top and bottom and six
separate steam adimissions, that is to say, one over the end of slide valve face as in an

page_text: ordinary valve, and five additional through the back communicating with two ports
formed in slide valve face through the lap covering the two top and bottom cylinder ports.
The steam admission through these five additional ports top and bottom, being
regulated by the auxiliary valve.
It is also to be understood that this invention is equally applicable to the intermediate
and low pressure cylinders of compound engines, as to the high pressure cylinders and
equally to cylinders of marine, stationary land, and locomotive engines.
The auxiliary valve is left free to bear against the back of the slide valve, and may
either be stationary or have motion given to it in such a manner that although the steam
admission to the cylinder through the auxiliary valve or valves can be prolonged the
steam lead and opening and closing of exhausts to remain unaltered, and when pro-
longing the steam admission the area for same is greatly augmented by the motion
given to the auxiliary valve.
The cylinder chosen for illustration is 40 inches diameter x 48 inches stroke of
piston, area being equal to 1256 square inches, and piston speed supposed about
500 inches per minute. The stroke of slide valve is 5 inches. The angle of slido
recedes both ahead and astern about 135 degrees in advance of crank, the mean steam
lap top and bottom being " and mean steam. Iead of an inch, placing the slide"
valve 13 past its working centre at each end of the piston stroke. Consequently the
exhausts both opening and closing are very early, the exhaust lap top being inch and
bottom 0 inch that is to say inch negative lap on top and none on bottom thereby
giving full area to exhaust ports. Exhausts open top and bottom at 39" of piston
stroke and close at 43 inches giving 5 inches for compression and a fuſl and carlý
release.
=
==
The width of the ports being 30 inches and the exhausts double ported, stroke of
slide being 5 inches, then area of exhausts is 30" x 2" × 2=150 square inches
.in
of cylinder and is even more for the top exhausts owing to the inch
negative lap.
Now for the steam ports-The mean steam lap is 1, say 1 for simplicity,
leaving for the steam opening of each steam port (3-14=1"). There being four
steam admissions gives us 31" x 1" x 4 120 square inches as the actual' greatest
steam admission through the ports by which the steam is admitted and cut off. The
steam port in cylinder face is shown deep, and when the valve is opening to steam,
the end bar of the slide valvo which is 1" deep in this case obstructs the steam admis-
sion to that amount. This obstruction can easily be avoided by making the cylinder
port 1 inch deeper, but the constant area of 90 square inches at cylinder face for steam
admission is considered quite enough, being about th of cylinder area from beginning
to end of steam admission which steam admission at the cutting off ports varies from
almost nothing at top and bottom centres of piston to th of cylinder area when valve
is full open, and again to nothing at point of cut off.
=
In the plan referred to, it would be easy to add a second ordinary steam admission
from sides of valve through the inner exhaust port in the usual way, and another
auxiliary port on back, making six steam admissions 30" x 1" x 6"=180 square
inches or area of cylinder. This would no doubt give a cut off approaching to
theoretical perfection, but is not necessary in practice with ordinary piston speeds.
Besides, by giving motion to the auxiliary valve in order to prolong the steam
admission it must be remembered that the area of steam admission is greatly increased,
as for instance if carrying the steam say " longer than the normal cut off produced
by a stationary auxiliary valve, making the point of cut off at 34" of piston stroke in
place of 28", a stroke of about 2" would be given to the auxiliary valve, that is, a
motion of about 1" above and below the centre line. When the slide valve is full
open for steam, the auxiliary valve would be about of an inch above or below the
centre line on the opposite side to slide valve, thus adding this much opening to the
width of each auxiliary port, being for the three a total of 4x32 or rather more
than one additional auxiliary port.
This increased area. of ports when prolonging the steam admission comes in very

page_text: rationally for the increased piston speed resulting from the greater amount of steam
admitted.
I am aware of many varieties of expansion valves' in which motion is given them to
effect an early cut off but in this arrangement the auxiliary valve can be, and as now
arranged and shown is, stationary, when at shortest cut off, and only receives motion to
prolong the steam admission. Other expansion valves do not multiply the number of
ports for steam admission to the cylinder, nor control the opening as well as the closing
of steam admission.
They may and many do, multiply the ports for steam admission to the slide valve
but this admission is again controlled by the amount of opening afforded to the cylinder
by the slide valve itself.
In this valve the slide valve opening fed by the auxiliary ports does not control the
admission or closing of the steam to cylinder in any way, both the admission and
closing of the steam to these ports being effected at the back of the slide valve.
Ordinary expansion valves control the cut off of steam which enters the cylinders
outside the lap covering the steam edge of the cylinder port.
In this improved valve the slide valve itself controls the ordinary steam admission
being furnished with the necessary steam lap to cut off at required point.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed as communicated to me by my foreign
correspondent I declare that what I claim is
The combination of an auxiliary valve with, and on the back of a slide valve, which
latter in addition to the usual steam admissions of ordinary slide valves at cylinder
face is supplied with suitable steam passages at back communicating with a port or
ports formed in slide valve face through the lap, which ordinarily covers the cylinder
ports when the slide valve is in central position, and these steam passages at back of
slide valve are supplied with any number of suitable steam ports through which the
admission of steam to the cylinder, both as regards opening and closing is controlled
by the auxiliary valve thus greatly increasing the area of steam admission to the cylinder
over that obtainable by ordinary methods with equal areas of valves.
11°
1007.
WM. P. THOMPSON & Co.,
Agents for the Applicant.