IMPROVEMENTS IN STEAM ENGINES AND THE WORKING THEREOF
Year: 1875

page_text: LETTERS PATENT to George Basil Dixwell, of the State of Massa-
chusetts, of the United States of America, for the Invention of
“IMPROVEMENTS IN STEAM ENGINES AND THE WORKING THEREOF, AND IN
Sealed the 4th May 1875, and dated the 19th March 1875.
COMPLETE SPECIFICATION filed by the said George Basil Dixwell
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 19th March 1875, pursuant to the
9th Section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
BASIL DIXWELL, of the State of Massachusetts, of the United States of
America, send greeting.
WHEREAS I am in possession of an Invention of "IMPROVEMENTS IN
STEAM ENGINES AND THE WORKING THEREOF, AND IN THERMOMETRIC APPARATUS
THEREFOR," and have petitioned Her Majesty Queen Victoria to grant
unto me, my executors, administrators, and assigns, Her Royal Letters

page_text: Patent for the same, and have made solemn Declaration that I am
the true and first Inventor thereof.
NOW KNOW YE, that I, the said George Basil Dixwell, do hereby
declare that the following Complete Specification, under my hand and
seal, fully describes and ascertains the nature of the said Invention and 5
in what manner the same is to be performed in and by the following
statement, reference being had to the accompanying Drawings making
part of this my Specification, of which Drawings,—
Figure 1 denotes a top view, Figure 2 a front elevation, and Figure 3
a rear elevation of a steam engine cylinder and boiler,
with my In-
vention, the cylinder, piston, and valve chest being exhibited in Figure 2
in vertical section.
Figure 4 is herein-after described.
1
Figure 5 is a section of the engine piston and the cylinder with its
steam chest, valve, and variable cut-off, the latter being one form of 1
cut-off for which any other proper and well known kind may be
substituted.
The other or remaining Figures will be herein-after referred to and
explained.
My Invention has for its object a peculiar use of superheated steam, 2
whereby all cylinder condensation is suppressed, and such farther
advantage is obtained from the superheating as can be gained without
danger to the working parts of the engine.
It is well known that the loss arising from cylinder condensation in
engines using saturated steam is great, and that it becomes greater as 2
the measures of expansion are increased.
To understand why the condensation increases with the expansion we
must examine the action of the steam in the cylinder, which appears to
be as follows:-The work done up to the point of cut-off is chiefly done
in the boiler, and the condensation arising from the conversion of heat 30
into power takes place almost entirely in the boiler. But the heat which
is equivalent to the work done during expansion must be derived from
the steam in the cylinder, and the condensation must therefore be
greater with a greater measure of expansion. But the actual amount of
condensation is found to be several times as great as that which would 3
counterbalance both radiation and the heat converted into work, although

page_text: bearing a very close ratio to the sum of these. This appears to be
caused in the following manner, viz. :-The refrigeration which occurs
during the first stroke of the piston causes a certain amount of dew or
mist to be formed in the cylinder, which dew or mist evaporates in part
during the expansion and the return stroke and chills the interior sur-
faces, so that these upon the next stroke condense a portion of the steam
which enters from the boiler; but besides this condensation from
chilled surfaces, there will be, upon the second stroke, a fresh conden-
sation growing out of radiation and work done, so that the quantity of
dew or mist to be evaporated, and the quantity of consequent chilling
of interior surfaces, will be greater on the second stroke than on the first,
and so with each subsequent stroke.
The action of the metallic surfaces is cumulative, and the condensation
must go on increasing until it is so great that the portion or percentage
of mist which remains unevaporated and passes out as spray equals the
amount formed at each stroke by radiation and work performed.
Explain it as we may the fact remains that the actual condensation in
cylinders cutting-off short is about five times the equivalent of that
caused by radiation and by the conversion of heat into work, and if we
could superheat the steam to the precise amount required to balance the
refrigeration in question, we should suppress cylinder condensation at a
comparatively trifling expense. This has been already attempted, but
hitherto with very partial success, which is accounted for as follows:-
With a small measure of expansion only a slight refrigeration has to be
met, while with a large measure of expansion a great amount of refrige-
ration takes place, so that the superheating, which is necessary for an
engine cutting-off at one-eighth stroke is about three times that which
suffices at half stroke. If then we use the latter measure of super-
heating, namely, that sufficient for half stroke, condensation must take
place when the larger ratio of expansion is used, and the advantage
sought from the larger expansion will not be secured. If, on the other
hand, we use the amount of superheating required for the larger rate of
expansion the cylinder will be overheated and the working parts injured
or destroyed whenever we revert to the fuller stroke. Both these
accidents have occurred in practice. A moderate degree of superheating
has been used and been found not to suppress cylinder condensation,
and on the other hand a high degree of superheating has been tried
and many valuable engines have been injured thereby.

page_text: Experiments on a large scale have shown that a temperature of
400° F. may be safely used within the cylinder, but a heat much above
this point appears to decompose the oils now used in lubrication and
to destroy the working parts. With better lubricators a higher heat
may perhaps be used hereafter, but 400° F. appears to be the practical
limit at present. The temperatures however to which it is necessary
to superheat in order to balance the refrigeration occurring at a short
cut-off are very high, much above 400° F., and it would therefore
appear, and in fact it has come to be generally considered exceedingly
dangerous, to employ such temperatures, even when a short cut-off
alone is to be used. Experiment however has shown this to be an
erroneous opinion. The steam may be heated to the necessary tem-
perature in the superheater, and yet no such high temperature will
ever appear in the metal of the cylinder, for a thin film of the metal
takes up instantly the heat of the entering steam, and the weight of the
film in question exceeds by so many times the weight of the steam that
the joint temperature is reduced almost to that of saturated steam.
This is what takes place up. to the point of cut-off. During the
remainder of the stroke the metal gives off its extra heat to the
expanding steam, and maintains it in the superheated state to the end.
There is no danger then in adding to the normal temperature of
saturated steam an amount of heat equivalent to the refrigeration
which takes place in the cylinder at the cut-off we are using. This
will bring the steam at the cut-off only to about the temperature of
saturated steam, and we not only need have no fear of the amount
of heat in question, but we may go on superheating still farther until
the steam at the point of cut-off has a temperature of 400° F. Here
we meet the limit of safety under existing conditions. For instance,
let us suppose an engine to be cutting-off at one-tenth, we may super-
heat the steam to such a temperature as will suppress all condensation,
and also bring the steam in the cylinder to 400° F., and provided no
change is made it will work on indefinitely in safety; but if for any
purpose the cut-off be changed and the engine be set to working at a
cut-off of, say, one-half, the interior of the cylinder will be immediately
exposed to a heat of over 600° F., and will be speedily injured. My
Invention therefore is for regulating the temperature of superheated
steam, so that (whatever cut-off be used) the heat within the cylinder
shall not exceed 400° F., or such other temperature as may be selected
as perfectly safe. This may be done by first ascertaining by experiment

page_text: for each particular engine what heat in the superheater corresponds to
400° F. at each different cut-off. Then upon changing the cut-off the
heat in the superheater is varied to correspond, and this may be done.
by varying the fire and the draft of the superheater, or by mixing
saturated steam with the superheated steam, &c., &c.; but these are
imperfect methods, and I prefer to keep watch over the temperature
of the steam in the cylinder by means of a thermometer or pyrometer
placed within the clearance space, or in an adjacent cavity, and to
diminish the heat of the steam when the pyrometer indicates a higher
temperature than 400° F., or such other temperature as may be selected,
and to increase the heat of the steam when a lower temperature is
indicated. This regulation of the temperature of the steam I prefer to
effect by means as represented in the accompanying Drawings, such
consisting of a boiler, a superheater, and an apparatus for automatic
regulation. This last may not always be used, as the engineer on duty
may sometimes adjust the regulating valves according to the indication
of the pyrometer.
Having thus premised, I will now proceed to describe my Invention.
In the Drawings A denotes the steam engine cylinder with its piston B,
valve C, and steam chest D.
In Figure 5 the variable cut-off applied to the valve C is represented
at C'. A boiler for said cylinder is shown at E with its upper part
removed in order to exhibit the cooler or conduit F within such boiler.
This boiler may be supposed to be one of a series as generally used for
large engines. The said conduit is to serve the purpose of a cooler to
the superheated steam.
The flue or conduit F may be either above or below the water surface,
but I prefer to place it below the said surface, so that the heat given up
by the superheated steam will evaporate a certain quantity of water and
nothing be lost. Behind the boiler is seen the superheater G (or boiler
for generating superheated steam) from which a pipe H proceeds directly
to the steam chest D. In this pipe there is a throttle valve b, the
position of which in the pipe is indicated by an index finger a upon the
outside of the pipe, and fixed on the valve spindle.
Figure 4 is a section of the pipe H, its branch pipe c, and their valves.
When the valve is closed no steam passes directly from the super-
heater to the steam chest, but the whole of it makes a detour through a

page_text: branch pipe c nearest the superheater, thence through another pipe d to
the cooler F, from whence it escapes through another branch pipe e into
the pipe H from the superheater, and thence into the steam chest. It
may appear strange to use one of the boilers of an engine as a cooler, but
an example will show that the device is not unreasonable. Let us
suppose that steam of sixty pounds pressure is being used at a cut-off of
one-third, the temperature of the boiler would be 292° F., while the
temperature of the superheater must (in order to balance radiation and
conversion of heat into work) be about 480° F., and this will only
prevent condensation and keep the steam within the cylinder at the
point of cut-off at about 300° F. In order to keep the steam within the
cylinder at the point of cut-off at 400° F., we should have to add still
another 100° F., so that the total heat in the superheater would be about
590° F. It is then evident that a flue passing through the water of a
boiler of which the temperature is 290° F., will be a very efficient cooler
for steam of nearly double its temperature, and it is calculated that the
flue in the boiler need not exceed in surface the aggregate of piston and
cylinder surfaces to which steam is subjected when working at a cut-off
of one-third.
The method proposed has the advantage of keeping a constant flow
of steam through the superheater, which is thereby prevented from
becoming red-hot and a farther advantage of loosing no heat, inasmuch
as what is taken from the superheated steam goes to evaporate a quantity
of water.
I would suggest that the cooling flue could, when exceptional
circumstances require it, be made to traverse a feed water heater instead
of a boiler. It would very seldom be necessary or desirable to do this.
Within the branch pipe c is another throttle valve f, which is adjusted to
work in connection with the valve b, already described, in such a manner
that as one closes the other opens, and when one is entirely shut the
other is entirely open.
We have already considered the case of the direct pipe from the
superheater to the steam chest being closed, and have seen how the
steam then takes a circuitous course through the cooler, and so
diminishes the quantity of heat carried into the cylinder. In the
opposite case (when the valve in the direct pipe is open and the other
closed), all the steam passes direct from the superheater to the steam
chest, and so increases the quantity of heat carried into the cylinder.

page_text: When one valve is partly closed and the other partly open, a greater or
less degree of heat will reach the cylinder in proportion to the relative
positions of the valves.
I shall now proceed to describe what I term the pyrometric regulator
or governor for the two valves and f, such governor operating
automatically.
In the Drawings, g denotes a gear wheel which works into two
smaller gears h, i, that are fixed on the spindles of the valves b and f.
They move the valves in suchwise that as the large gear g moves in one
direction the valve leading to the cooler is closed and the other opened,
and in proportion as the large gear moves in the other direction the
valve leading to the cooler is opened and the other closed.
Extending over the periphery or teeth of the larger gear g, is an arcal
shield carried by an arın k that turns on the pivot or journal 7, for
supporting the said gear g, such journal being projected horizontally
from a bracket m extending down from the conduit H.
Over the arcal shield are two pawls n, o, arranged as shown, and
pivoted to an arm p that turns upon the journal 7, and at its upper end
is jointed to a connecting bar 9, that is also jointed to a bent or right
angular lever having its fulcrum s supported by a standard t. The
longer arm of the lever is or may be pivoted to the stem of the
cylinder valve C. As the valve stem has a positive motion when
the engine is in operation, a reciprocating motion will be imparted to the
arm p, and the two pawls n, o, each of which is provided with a spring v
for forcing it downward.
It will be observed that when the shield lever pis vertical the pawls
slide back and forth on the shield without actuating the gear g, but
when the shield is carried to the right or left one of the pawls will be
forced down into action upon the gear, that is, when the shield is moved
to the right the left pawl catches and moves the large cog wheel to the
left, and when the shield is moved to the left the right-hand pawl
catches and moves the large cog wheel to the right.
The shield is to be worked by a mechanism which is attached to a
pyrometer I. This last is a copper tube lying in the clearance space of
the cylinder and firmly attached to the left-hand side of the cylinder,
but playing freely within. To the bottom of this tube an iron rod wis
attached in such manner that when the copper tube expands with, heat

page_text: towards the right the iron rod follows, and when the copper tube
contracts from loss of heat the iron rod moves towards the left. In thus
moving the iron rod works a system of levers x and y attached to its
outer end and connected with the levers or arm of the shield, as shown.
This moves the shield in one or the other direction. The connection
piece K, by which the system of levers proceeding from the pyrometer
to the shield is connected with the lever p, is made in two parts a¹, b¹,
connected by a set screw c¹ going through a slot d¹ in one of them. The
connection K is thus capable of being lengthened or shortened by means
of the slot and screw, and this enables us to adjust the shield and pyro-
meter so that the large cog wheel will be uncovered and moved
whenever the desired temperature is reached.
The shield should be graduated. A. stationary pointer e¹ arranged in
front of it serves to indicate the temperature existing in the cylinder.
The connection K may be in one piece, but I prefer to have it in two,
made and connected as described. The graduation can easily be effected
by introducing into the bottom of the cylinder and around the pyro-
meter cold water, and afterwards hot water or steam up to 300° F, and
from the graduations up to 300° F. Those of a higher temperature (as
our present limit of cylinder heat being 400° F.), may be inferred.
Behind the steam pipes, and extending above them, may be a steam
whistle L, which on being opened gives an alarm whenever the valve f
leading to the cooler is entirely opened, thus indicating that the tempera-
ture selected as a maximum has been exceeded. The valve of the
whistle may be connected with the index pointer of the lower throttle
valve by a connection rod g' so applied as to cause the whistle to open
when the throttle valve f may be opened.
It may be stated that the top and bottom of the piston and the top
and bottom of the bore of the cylinder may be covered with a sheet of
wire gauze, shown at ,, k, k¹. This will not be necessary in small
and medium engines not using an excessive expansion, but it will be
highly useful to thus increase the surface and weight of absorbing and
radiating metal when a high rate of expansion necessitates a high
temperature in the superheater.
Having now described my Invention, I would observe that it is based
upon four facts or principles which I have discovered from experi-
ments,―

page_text: The first is that superheated steam unlike the gases gives up its
heat to metallic surfaces and receives heat from them with immense
rapidity.
The second is that the metallic surfaces of the piston and cylinder
absorb with immense rapidity the excess of heat existing in superheated
steam brought into proximity to them, and by their great weight convert
a high temperature of steam into a much lower temperature of metal.
Fifty pounds of iron heated 20° F. takes up about the same amount of
heat as one pound of steam heated 232° F.
The third is that the said metallic surfaces give back to the expanding
steam the heat previously absorbed in such manner as to supply the heat
which is converted into work and the heat withdrawn by radiation, and
thus prevent condensation in the cylinder.
The fourth is that different quantities of heat are thus absorbed and
given out with different measures of expansion, so that the steam must
and safely may be superheated to temperatures proportioned to the said
measures of expansion plus the heat withdrawn by radiation.
From the above it will be seen that my Invention, or an important
part thereof, for operating a steam engine piston by superheated steam
used expansively in the cylinder, provided with a variable cut-off or
mechanism for arresting at different parts of the stroke of the piston the
admission of steam to the cylinder is a novel art or method, which
consists in elevating the temperature of the steam of the generator or
superheater as the cut-off may be lessened, and lowering the temperature
of the said steam as the cut-off may be increased, the same being so as
to maintain, as described, in the cylinder a safety temperature such as
will prevent condensation of the steam therein and obtain all the
advantages from superheating consistent with safety under existing
conditions.
It will also be seen that I have combined a pyrometer or heat measurer
with a steam engine cylinder provided with a piston, valve chest, valve,
and a cut-off, all being for the purpose or purposes as explained.
In further carrying out my Invention, one object of which is to obtain

page_text: with safety to the working parts, I have represented by Figures 6, 7,
and 8, other changes or improvements.
Of these last-mentioned Figures, Figure 6 is a top view, and Figure 7.
a front elevation of a steam boiler and engine cylinder with my said
last-mentioned improvements.
In such Figures 6 and 7 A. denotes the cylinder, and B the
boiler and furnace of an ordinary steam engine, the boiler being
for the production of superheated steam to be used expansively in the
cylinder, which is to be supposed to be provided with a cut-off. The
pipe for conveyance of the steam from the generator to the steam chest:
of the cylinder is shown at C. A pyrometer D is arranged in the lower
part of the cylinder, its stem a being to project through the cylinder,
and being jointed to an index pointer to operate with a graduated arc
or scale c to indicate the temperature of the steam in the cylinder.
Another such pyrometer E is similarly applied to the steam generator 1
or superheater, and has its index pointer & projected over a wooden scale
or platform e.
I work the engine at a given cut-off, say, for instance, one-third, and
note the temperature indicated by the pyrometer in the cylinder, noting
also at the same time the temperature in the superheater. If I find the
temperature in the cylinder to be 400° F., while that of the superheater
is, say, 600° F., I mark upon the pyrometer scale board of the super-
heater against 600° F. the words one-third cut off. I next work the
engine at another cut-off, say, for instance, one-half; and if I find that
with 400° F. in the cylinder the pyrometer of the superheater shows, 2
say, 560° F., I mark against 560° F. of the pyrometer scale of the super-
heater the words one-half cut off; and I so proceed until the pyrometer
of the superheater is, so to speak, graduated for the different cut-offs.
I next, if disposed, withdraw from the cylinder the pyrometer placed in
it, and rely thereafter upon the pyrometer of the superheater graduated a
as described.
Figure 8 denotes the pyrometric scale provided with the divisions for
temperatures, and the marks to indicate the cylinder temperatures for
different cut-offs, as set forth.
In order to audibly indicate the temperature of the superheater I
apply to the scale of the pyrometer an adjustable metallic slide f fixed

page_text: to the scale by a clamp screw g going through a slot in the slide. To
this said slide f I attach a wire h of an electro-magnetic circuit, whose
electro-magnet is shown at i, and battery at k. The armature 7 has an
elevating spring m, and is in effect a hammer to strike a bell n, arranged
over it as shown. From the bell a circuit wire ¹ extends to and through
an electric non-conductor m¹ fixed upon the index pointer of the pyro-
meter of the superheater, and thence is turned toward the slide f.
When the index pointer may arrive at the position for which the slide
is to be touched by the end of the current wire carried by the said index
pointer, a galvanic circuit will be completed, and the alarm bell will be
rung.
When the engine may have been set to work at a particular cut-off
the adjustable slide f is to be arranged so that before the circuit may
be completed the index pointer may have passed a little beyond the
indicating division of the cut-off, and whenever this point is reached
the electric bell will give the alarm, and the temperature of the super-
heater will be easily diminished by partly closing the damper, or by
diminishing the fire, or by opening the door of the furnace, or any other
of the usual means.
There is also applied to the pyrometer scale another such adjustable
slide f, arranged as shown. It purpose may be thus explained :—
To this auxiliary slide f', and to the non-conductor m² of the index
pointer, circuit wires o, p, are attached and arranged as shown, they
leading to the electro-magnetic alarm apparatus, or another such, having
a bell of a tone differing from that of the other bell.
When it may be desired to have an alarm indicate that the heat in
the superheater has descended below the equivalent of a previously
selected minimum (say, for instance, 370° F), the auxiliary slide ƒ³ is to
be adjusted properly to the scale, so that when the degree of temperature
may have been reached the wire of the index pointer may be brought
into contact with the auxiliary slide, and thus cause closure of the
circuit and the sounding of the alarm.
My Invention further embraces an improved cylinder pyrometer or
heat measurer, or thermometric apparatus for steam engine cylinders,
which I have represented in the remaining Drawings, of which,―
Figure 9 exhibits a perspective view of the lower part of a steam
engine cylinder with such part of my Iuvention applied to it.

page_text: Figure 10 is a vertical section of the tubular expander and the
cylinder.
By means of the said apparatus the temperature of the steam or vapor,
and consequently the temperature of the internal surfaces of the cylinder,
may be promptly and correctly ascertained in engines using superheated 5
steam or vapor.
From the above it will be perceived to be a matter of primary
importance to possess an instrument by which the temperature of the
steam in the cylinder may be watched and accurately and expeditiously
ascertained; an instrument which, if it differ at all from the steam, shall 1
differ in the same direction and to the same extent as the internal
metallic surfaces of the cylinder differ, for it is in reality their tem-
perature which it is necessary to maintain at a safe point.
Murcurial thermometers have been found to be exceedingly unreliable
(sometimes showing a very much lower temperature than the truth) and 1
being always sluggish; and the usual metallic pyrometer does not give
settled indications until sufficient time has clapsed for the external
cylinder to communicate its temperature to the internal rod which is of
a different metal.
Neither of these instruments are satisfactory for the purpose in view,
and I had spent much money, labor, and time in vain efforts to find one
that would fully answer the purpose, when the following form of
pyrometer suggested itself:-It is very necessary to have in combina-
tion with the cylinder a thermometric apparatus of extreme s ensility,
one readily affected by very slight changes of temperature. A metallic
rod will not answer as its beat absorbing and conducting powers are
generally too slow for the purpose. I therefore make use of an extremely
or very thin mass of metal having extensive surfaces; and although a
thin and wide plate of metal will in most cases suffice, I prefer to use the
expander in the form of a tube, open so that the steam can gain ready
access to its inner as well as to its outer surfaces. In said Figures 9
and 10 this feature of my Invention is shown. In such Drawings A is
a horizontal and transverse section of a steam engine cylinder with the
pyrometer or thermometric apparatus attached; B is the pyrometer or
expander, it being in part a thin metallic tube open at the end c next to
where it is fixed to the cylinder head a, and also pierced laterally with
numerous holes b, b, &c., through which and through the open end c the

page_text: steam has free access to the interior surface of the tube; the outer
part D is solid, but may be tubular and filled with a heat non-conducting
substance to the point where the tube reaches the next adjacent part of
the internal surface of the cylinder. F represents a stuffing box through
which the tubular rod or pyrometer moves, and G denotes a screw by
means of which the tube or expander is attached to the cylinder head;
H is a lever to which the pyrometer B is pivoted in advance of the
fulcrum d; by this lever the expansive movement of the pyrometer is
multiplied and conveyed to a short vertical spindle I surmounted by a
mirror K, which moves with and is turned by the said spindle, the two
being firmly attached together; L is a screen with a vertical slit e
through it, through which a beam of light proceeding from a lamp or
other suitable source may be thrown upon the mirror K and thence
reflected upon a graduated arc or scale M placed upon the wall of the
engine room or upon a screen N for the purpose. Now as the tube B
may be expanded by heat it will move the lever H, which in turn will
move the spindle I and the mirror K so that the beam of light falling
upon the mirror from the slit in the screen will be reflected upon the
graduated are or scale M and there indicate the change of temperature.
Of course a graduated scale provided with a vernier attached to the
spindle I may be used instead of the graduated are on the wall, or the
two may be used together if desirable. So also the spindle I may carry
an arm by means of which the circuit of an ordinary electric bell shall
be completed at the selected maximum temperature, and another be
completed at the selected minimum temperature. The tube B may be
attached to the cylinder by a screw proceeding from the outside, so that
the whole pyrometer may be detached and withdrawn from the cylinder
for examination and repair. The multiplying parts may be of other
forms, as a series of cog wheels or a combination of toggle joints.
The pyrometer itself may be of other forms than the cylindrical, as
for instance it may be a rectangular, or elliptical, or flat tube. All these
are details of construction relating to my Invention, which has for its
object the arrangement of the surface or surfaces exposed to the action
of the steam in a thin and extensive form analogous to that in which
the internal surfaces of the cylinder and piston are exposed to the steam
so as to give prompt and reliable information as to the temperature of
the said surfaces.

page_text: its information by means of the insulated wire proceeding through the
cylinder and completing the circuit of an electric alarm bell when the
maximum temperature is reached, and another circuit of another bell at
the point when the selected minimum temperature is reached. Thus it
will be seen that the registering or heat indicating portion of my appa-
ratus may be variously constructed, and the expander may be varied in
form so long as the described principles of its action be preserved.
Having thus described the nature of my Invention having reference
to steam engines, and the working thereof, what I claim as of such
Invention may be stated as follows:-
With respect to the matters shown in Figures 1, 2, 3, 4, and 5, of the
Drawings, I claim as follows, viz. :-
I claim, the combination of the cooler F with the superheated steam
generator G, the engine cylinder A, their connection pipe H, and a
valve arranged in such pipe, all being substantially as described.
I claim, in combination with the superheated steam boiler or
generator G and engine cylinder A, and their connection pipe H, the
two throttle valves b, f, and the cooler F, all being arranged and applied,
substantially in manner and to operate as described.
]
I claim, the combination of the steam alarm or whistle with the super- 2
heated steam generator G and engine cylinder A, and their connec-
tion pipe H, the two throttle valves b, f, and the cooler F, all being
arranged and applied, substantially in manner and to operate as
specified.
I claim, the pyrometric regulator or governor, substantially as 2
described, consisting of the gears g, h, i, the vibratory shield 2, the
pyrometer I, and the vibratory arm p, and its pawls n, o, all arranged,
applied, and connected, substantially as and to operate as explained.
I claim the combination of the said pyrometric governor with the super-
heated steam generator G and engine cylinder A, their connection pipe H, 3
the valves b, f, and the cooler F, all being arranged and applied, sub.
stantially in manner and to operate as set forth.
I claim, the cylinder and piston, or either, provided with wire
gauze, k, applied to, or arranged therewith, substantially as and for
the purpose specified.
3

page_text: I claim, for operating a steam engine piston by superheated steam
used expansively in the cylinder provided with a variable cut-off or
mechanism for arresting at different parts of the stroke of the piston
the admission of steam to the cylinder, the new art or method sub-
stantially as described, it consisting in elevating the temperature of the
steam of the generator or superheater as the cut-off may be lessened,
and lowering the temperature of the said steam as the cut-off may be
increased, the same being so as to maintain, as described, in the cylinder
a high or maximum safety temperature, such as will prevent conden-
sation of the steam therein, and effect other useful advantages as set
forth.

page_text: In witness whereof, I, the said George Basil Dixwell, have here-
unto set my hand and seal, this First day of March, A.D., 1875.
GEORGE BASIL DIXWELL. (L.S.)