IMPROVEMENTS IN ENGINES WORKED BY HEATED AIR AND BY OTHER SUITABLE HEATED GAS OR GASES
Year: 1867

page_text: LETTERS PATENT to Alphonse Louis Normandy, of No. 17, New Park
Road, Stockwell, in the County of Surrey, Engineer, for the Invention
of "IMPROVEMENTS IN ENGINES WORKED BY HEATED AIR AND BY OTHER
SUITABLE HEATED GAS OR GASES."
Sealed the 3rd September 1867, and dated the 7th March 1867.
PROVISIONAL SPECIFICATION left by the said Alphonse Louis Normandy
at the Office of the Commissioners of Patents, with his Petition, on the
7th March 1867.
I, ALPHONSE LOUIS NORMANDY, of No. 17, New Park Road, Stockwell, in
the County of Surrey, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN ENGINES WORKED BY HEATED AIR AND BY OTHER
SUITABLE HEATED GAS OR GASES," to be as follows:-
Hitherto the hot air in hot-air engines has been caused to actuate a piston
accurately fitting a cylinder so as to move air-tight therein, the piston being
lubricated to diminish friction and wear, and also to keep it air-tight, but
such an arrangement has not been found to answer well, the lubricant being
soon destroyed by the heat and the piston very soon getting out of order; it
has also been found difficult to properly regulate such engines. Now my
improvements have for their object to produce engines worked by heated air
or. other suitable heated gas or gases which shall not be liable to get out of
order, and be capable of proper regulation, thus rendering available the great
A

page_text: economy in fuel, which it has been proved by Joule, Rankine, and others,
should result from an efficient engine worked by heated air, gas, or gases,
instead of steam, even when the steam is employed in the best possible
manner.
I prefer working my improved engines with heated air, it being most
readily obtainable, and in the following description of my improvements I
assume that air is employed, but I wish it to be understood that they may
also be worked with any other suitable heated gas or gases, except in such
cases as those in which the hot discharged air is employed to consume the
fuel as herein described.
My improvements may be divided into two parts, namely, firstly, as applied
to reciprocating engines; and, secondly, as applied to rotary engines.
Description of the First Part.-My improved engines may be made either
single acting or double acting, and when double acting the pistons may be
made in the form of an inverted cylinder closed at the upper end, and
dropping easily over an upright fixed central core of somewhat smaller
diameter than the piston, which core is surrounded by any suitable fluid
reaching nearly to the top of it, and into this fluid the piston dips to a sufficient
depth. The piston is itself surrounded by another fixed inverted cylinder
closed at the top, and of somewhat larger diameter than the piston, so that
the piston may move in it easily; and this outer cylinder also dips a sufficient
depth into the before-mentioned fluid. The piston being at its lowest position
hot air at a suitable pressure and temperature is admitted through the core by
means of a suitable admission valve to beneath the piston, and the pressure
air thus admitted will depress the narrow column of fluid between the piston
and the core, but not sufficiently for it to escape past the piston, which it will
also cause to rise in the fluid somewhat similar to an ordinary gasholder, and
the air above the piston escapes through a suitable discharge valve. The
before-mentioned admission valve, should close and cut off the supply of
pressure air to beneath the piston, so that when enough has been admitted it
may by expanding continue to actuate the piston, and be eventually discharged
therefrom at a sufficiently low pressure to prevent loss of power. When the
piston is at its highest position another suitable admission valve opens and
admits hot pressure air above the piston, which pressure air will depress the
narrow column of fluid in between the outer cylinder and the piston, but not
sufficiently to escape past the piston, which it will also force down again into
the fluid, the air beneath the piston escaping through the core by means of a
suitable discharge valve, and the supply of pressure air to above the piston
should be cut off as described above when the piston was making the up

page_text: stroke. It will be seen that by this arrangement the piston need not
accurately fit either the core or the outer cylinder, and that no packing is
required for the piston, for all leakage past it is prevented by the resistance of
the fluid due to the depression thereof, as above described; it is advisable,
however, to leave but little space between both core and cylinder and the piston,
so that very little of the pressure air admitted at each stroke may find its way
down these spaces in depressing the fluid as above described, and yet be sufficient
to fill them, as otherwise this would occasion a loss of power. For the same
reason the closed end of the piston when at its highest position should
nearly touch the closed end of the surrounding cylinder, and when at its
lowest position it should nearly touch the end of the core, so as to leave but
little space or clearance at either end to be filled by the pressure air when
first admitted at each stroke. Any suitable fluid may be employed for the
piston to work into, as above described, but the greater the density thereof
the less will be the extent of immersion necessary to prevent leakage past
the piston of the heated air at any given pressure employed to actuate it, and
it is also desirable that the fluid should be capable of being heated to a
sufficiently high temperature without sensibly volatilizing, for which reasons I
prefer employing melted lead. The temperature I prefer heating the air to
is about 6500 or 700 Fabrenheit, and the pressure about 10 or 20 lbs. per
square inch, depending upon the size of the engine, but other temperatures
and pressures may be employed. I prefer admitting and discharging the
heated air through vertical lift valves, actuated by suitable cams, and to con-
struct the discharge valves so that they may open freely should any vacuum
be formed by the piston in consequence of excessive expansion of the air
actuating it, thereby preventing the fluid employed from being drawn up by a
vacuum to above the proper level. I also prefer placing the admission valves
so as to open from the piston and against the pressure, which will then assist
to keep them closed when not opened by the cams. The fluid above men-
tioned is contained in a casing heated outside by the heat from a furnace,
which heat may also be employed to heat the cold air forced by an air pump
into a suitable heater, from whence the air in a heated state is drawn off to
actuate the piston, as above. The heater may be of any suitable construction,
but I prefer making it of pipes in such a manner that the cold air to be
heated may pass through them in a contrary direction to the hot gases from
the furnace passing outside of them, and for such heaters I prefer using pipes
such as are sometimes used for heating buildings by hot water, that is, stout
pipes having their ends coned and faced, and screwed right and left, so that
the ends may be forcibly drawn against each other by means of a socket in
A 2

page_text: order to join them, such joints not being liable to be affected by high tem-
peratures. The heater may also be in the form of a jacket surrounding the
casing containing the fluid, and the cold air being forced into the bottom of
this heater is drawn off from the top of it in a heated state, having become
heated during its passage upwards in the heater by the hot gases from the
furnace passing downwards either outside of it or through tubes or flues
traversing it. The expanded air expelled by the piston at each stroke still
retains a considerable quantity of heat which it is very desirable to utilize, and
it is also desirable that the heat passing from the furnace shall not be so
intense as to be injurious to the engine or heater, and both these conditions
may be fulfilled by leading a portion of the hot discharged air to beneath the
fire so as to consume the fuel, while the remainder is discharged above the
fire so as to moderate the intensity of the heat passing therofrom to heat
the casing containing the fluid and the heater as above described. By thus
consuming the fuel with hot instead of cold air it is evident that a greater
amount of heat will be-rendered available by the consumption of the same
amount of fuel. The relative quantities of the hot expanded air discharged
below and above the fire may be regulated by means of a damper or valvo
elosing more or less a passage leading it to below the fire so that more or less
of the discharged air may be compelled to raise a second valve, closing a passage
leading it to above the fire, and this second valve may close simply by its own
weight-so as to offer but very little resistance to the passage of the discharged
air. The first damper or-valve in the passage leading to below the fire may
be actuated by an inverted tube containing air and closed at the upper end,
which-tube is sufficiently immersed in the before-mentioned fluid surrounding
the core, so that variations in the temperature of this fluid, by causing
variations in the volume of the air contained in the tube, may cause the latter
to rise or fall in the fluid, and thereby-regulate the position of this first damper
or valve; this valve might also be regulated by a thermostatic band of well
known construction. The heat in the discharged air may also be utilized and
the intensity-of the heat from-the furnace regulated by causing the hot dis-
charged air to pass through a cooler, so that it may part with its heat to a
cooling current of air also passing through it in a centrary direction, which
current becoming beated is led partly to below the fire so as to consume the
fuel, and partly to above the fire to regulate the intensity of the heat passing
therefrom, as more fully described in the second part of my improvements,
and the cooled discharged air may either be allowed to escape, or, preferably,
be again compressed by the air pump and forced into the heater, so that the
same air may constantly circulate through the engine to actuate it. The

page_text: air
power and speed may be regulated by actuating the hot air admission valves
by means of graduated cams made to bear at the right grade either by band
or by a governor, so that they may close the valves and cut off the supply of
hot air to the piston at the right point; the quantity of cold air forced by the
pump into the heater being also regulated by causing it to force up a tube
some suitable fluid, such as mercury, thereby raising a float situate therein in
such a manner that should the pressure rise above a certain point the float
will bear against an inlet valve to the air pump and keep it open more or less
during the forcing stroke thereof, and consequently allow more or less of the
air contained in the air pump to be thrown back through the inlet valve
instead of being forced into the heater, so that the pressure therein conse-
quently remains nearly constant; this might also be accomplished by causing
a similar float to keep open-more or less a delivery valve on the air pump, so
that more or less of the air at first forced out might return into it during the
return stroke instead of passing to the heater. The air pump may be of
any suitable form, and I prefer placing in between it and the heater a
small receiver into which the air is first forced, so that any lubricant which
might pass over with the air from the pump may be intercepted, and this
receiver may also be fitted with a valve to prevent air from the heater
returning into it. I sometimes also cover the surfaces of the suitable fluid
employed, and into which the piston dips, with a layer of some suitable
material, so that it may not be in direct contact with the hot air admitted to
work the piston, and powdered plumbago may be employed for this purpose.
When the hot air from the piston is caused to consume the fuel, as before
described, both the furnace and ash-pit are provided with doors, which should
be kept closed when the engine is at work, but at other times the ash-pit door
is left open, so that air may enter to feed the fire, and by means of a suitable
damper the heat may, when desired, be allowed to pass direct to the chimney
without passing through the heater, and so as only to heat the casing
containing the fluid, and a damper may be fitted in the chimney, which
I prefer to actuate by the-before-mentioned heat regulators, so as to prevent
undue beating at such times when the: ash-pit door is left open; and the
damper may be prevented from altogether closing the chimney, and possibly
eausing the fire to go out by opening more or less the fire-door, so as to admit
some cold air above the fire, and thereby reduce the heat passing from it:
These engines may be made'single acting on the up stroke only by dispensing
with the inverted cylinder surrounding the piston, and also with the admission
and discharge valves to the top side of the piston, as before described,
and when required to be single acting on the down stroke only, then by

page_text: dispensing with the admission and discharge valves to the bottom side of the
piston, and the core before mentioned may then be of any convenient size and
open at the top; but in either case the passage for the expanded discharged
air from the piston should be in communication with that side of it on which
the pressure does not act, so that the discharged air may pass freely to and
from that side of the piston, so that the motion of the latter may not be
resisted, Two or more single or double acting pistons may be connected to
the same shaft, and when it is desired to have the power of reversing the
motion of the engine this may be done by means of backward and forward
cams actuating the valves through links, as is usual in ordinary reversing
gear to steam engines.
bo
Instead of constructing reciprocating engines as above, the piston may
made in the form of an inverted cylinder closed at the upper end, and
immersed in a suitable fluid, preferably melted lead, to such an extent that
when the piston is at its lowest position the pressure of the fluid above the top
of the piston is nearly equal to the pressure of the air intended to actuate it.
An orifice for admitting hot pressure air beneath the piston is situate inside of
and as close as possible to the top of it, so that the pressure air whon admitted
will only slightly depress the fluid beneath the piston, and will consequently
exert its force in causing the piston to rise, and as it rises more pressure air
will flow into it, so that the power of the piston, which is at first nearly
balanced by the pressure of the fluid above it, will gradually increase. When
sufficient pressure air has been admitted beneath the piston the supply should
be cut off, so that the portion admitted may continue to actuate the piston
and become expanded until it is finally discharged at a sufficiently low pressure
during the descent of the piston into the fluid when making the return stroke.
The expanded low pressure air may be discharged from the piston through
suitable valves opening inwards placed in the top of it, and made so as to
close by coming in contact with the fluid employed when the piston has
sufficiently descended into the fluid, and during the up stroke the hot pressure
air will keep them closed until they again open ready for the down stroke
either by their own weight becoming greater than the pressure exerted upon
them by the expanded air or by coming in contact with a stop at the end of
the top stroke. The heated air may be admitted beneath the piston through
a pipe ascending inside it nearly to the top of it, the end of this pipe being
again bent down a short distance and fitted with a valve opening outwards
from it, and made so that the density of the fluid will keep it closed except
when forced open by bot pressure air admitted to the tube by another
admission valve actuated by a cam, as in the above-described engines; the

page_text: object of bending the pipe down again and fitting it with a valve is to prevent
the fluid passing down the admission tube. A simpler way, however, of
preventing this is to construct the piston with a chamber on the top reaching
above the level of the fluid,, so that the hot air admission pipe may be carried
up inside the piston, and this chamber to above the level of the fluid, the
upper part of the admission pipe being surrounded by an inverted fixed tube
closed at the upper end, and of a suitable length to lead the pressure air
down again to the same level as the top of the piston when at its lowest
position before it can flow into the piston. The passage between the admission
tube and the inverted tube over the end of it must be large enough to allow
the pressuro air. to pass freely. to the piston; but the space between the
inverted tube and. the chamber in the piston dropping over it should be as.
small as possible when the piston is at its lowest point, so that but little pressure.
air may find its way into this space, and so prevent loss of power.. The air is.
admitted to the admission tube by a separate valve and cam, as above described,
and the object of the inverted.tube is to prevent, the loss of power which would.
result from the discharge of the pressure air in the admission tube at each.
stroke; it may be dispensed with where this loss is unimportant, in which.
case the expanded air may escape back through the admission tube by means
of a discharge valve actuated by a cam instead of through valves in the top.of
the piston, as above described. The other parts of engines having pistons
thus constructed need not be here described, as they would be very similar to
those of engines having pistons as. first described, which I consider preferable.
The second part of my improvements relate to the application of the before
described expansive force of heated air or other gases to actuate rotary
engines. For this purpose I construct these engines in such a manner that
the hot air at a suitable temperature and pressure may actuate a suitable
bucket wheel or endless chain of buckets immersed a sufficient depth in
melted lead or any other suitable fluid and rotating therein,, the hot air being
admitted direct into the fluid employed and immediately below the lower
inverted buckets into which it rises so as to displace more or less of the fluid
with which they were filled, thereby rendering that side of the wheel or chain
buoyant so as to cause it to rotate, and the air in the buckets will continue
to actuate the wheel or chain during its expansion consequent upon the rise.
of the buckets in the fluid until the air is at last discharged from the buckets
at about the same pressure as the air supplied to the air pump, so that tho
power given out by the pressure air during its expansion is rendered available,
which would not be the case had the hot air been caused to operate as in a
Barker's mill rotating in a suitable fluid as has been suggested. The pressure

page_text: air may be admitted into the fluid employed either intermittently by means
of suitable valves and cams for actuating them or else in a continuous stream
which I prefer, and the buckets should be of such a size that the admitted
pressure air may be all collected in the lower buckets, and not pass from
them to the upper ones, which would cause a loss of power proportionate to
the height of such useless rise, for which reason it is best to employ numerous
small buckets rather than fewer large ones, and to give them the necessary
capacity by making them wide rather than deep, which can easily be done
by employing a wide bucket wheel or chain. The bucket wheel or chain
and the suitable fluid may be contained in a casing heated by the heat from
a fire, which heat may also be caused to heat the air forced by an air pump
into a suitable heater, which I prefer to construct of tubes as described in
the first part of my improvements, and the hot air discharged from the buckets
may either escape into the atmosphere or be caused to consume the fuel also
as before described; but I prefer cooling it by means of a suitable cooler so
that it may be again compressed by the air pump and forced into the heater.
The cooler may be very similar in construction to the heater, but preferably
also of tubes, as above described, in which case the hot discharged air
from the buckets passing through the tubes is cooled by a current of cold air
passing in a contrary direction outside of them, and it is then led to the air
pump. The cooling current of air passing through the suitable cooler
becomes gradually heated as it progresses, and may be employed to consume
the fuel so as to economize the consumption thereof, in which case it is
desirable to regulate the amount of this current of air so that enough may
pass to properly absorb the heat of the discharged hot air from the buckets,
but not so much as to be unnecessarily cold when entering the furnace, as
this would occasion a loss of heat, this may be effected by means of two
dampers, one in the heater chimney or flues leading thereto, and the other
placed so as to admit more or less of the heated current of air from the
cooler either above or below the fire; the first or heater damper will regulate
the quantity of the current of air passing through the cooler and heater, and
the second or cooler damper will regulate the relative quantities of the
current of air passing above and below the fire so as to regulate the combustion,
and consequently the quantity of heat passing through the beater, that portion
of the current of air admitted above the fire also moderates the intensity of
the heat passing therefrom. These dampers may be actuated by thermostatio
bands, so that should the temperature of the air escaping from the heater fall
below a certain degree; the first thermostatic band will more or less open the
heater damper so that more air may pass through the cooler and furnace so

page_text: as to increase the combustión, and consequently the heat passing through
the heater, and should the current of heated air from the cooler become too.
cold, the second thermostatic band would actuate the cooler damper so that
more of the heated current of air may pass below and less above the fire so
as to increase the combustion, which would have the effect of causing more
beat to pass through the heater to the chimney, which would cause the first
thermostatic band to more or less close the heater damper, and thereby
regulate the quantity of the current of air passing through the cooler and
furnace. Instead of these thermostatic bands, which I prefer, the dampers
may be actuated by the expansion of air in an inverted tube immersed
in a suitable fluid as described in the first part of my improvements.
When the hot pressure air is admitted intermittently into the buckets by
means of a valve, the power and speed may be regulated by means of a
graduated cam actuating the valve, as described in the first part of my
improvements, and when the hot pressure air is admitted into the buckets
in a continuous 'stream, which I prefer, the power and speed may then be
regulated by causing the air from the air pump to pass into a reservoir, and
from thence through a cock or throttle valve actuated either by hand or by
a governor to the heater, the quantity of air supplied by the air pump being
also in either case regulated by its own pressure, keeping open more or less
the inlet or delivery valve of the air pump, as described in the first part of my
improvements. When it is desired to reverse the motion produced by these
bucket engines this may be done by any suitable known arrangement of
reversing gearing.
All the above improved engines described under the first and second parts
may be provided with a suitable valve or plug for drawing off the fluid
employed when desired, and in such cases where the discharged air is cooled
and again forced with the heater, I sometimes work the engines so that the
cooled air supplied to the pump is at a more or less high pressure before it
is further compressed by the air pump and forced into the heater, and when
the air is thus cooled I prefer fitting a valve so as to open and admit air should
any vacuum be formed in the cooler, and another valve for discharging air
should the pressure rise too high therein or in the heater. I prefer also providing
in all cases a separate reservoir containing air at a high pressure, which air may
be discharged by means of a cock into the heater at starting, should the pressure
therein not be sufficient, and this high pressure reservoir may be kept full
by means of a small pump worked either by hand or by the engine, or by
both.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alphonse Louis Normandy in the Great Seal Patent Office
on the 7th September 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALPHONSE
LOUIS NORMANDY, of No. 17, New Park Road, Stockwell, in the County of
Surrey, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of March, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Iler
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Alphonse Louis Normandy, Her special licence that I, the said Alphonse
Louis Normandy, my executors, administrators, and assigns, or such others as
I, the said Alphonse Louis Normandy, 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 ENGINES WORKED BY HEATED AIR AND BY OTHER SUITABLE
HEATED GAS OR GASES," upon the condition (amongst others) that I, the
said Alphonse Louis Normandy, 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 Alphonse Louis Normandy, do hereby
declare the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the accompanying Sheet of
Drawings, and to the figures and letters marked thereon, that is to say :-
Hitherto the hot air in hot-air engines has been caused to actuate a piston
accurately fitting a cylinder so as to move air-tight therein, the piston being
lubricated to diminish friction and wear, and also to keep it air-tight,
but such an arrangement has not been found to answer well, the lubricant
being soon destroyed by the heat, and the piston very soon getting out of
order, it has also been found difficult to properly regulate such engines. Now
my improvements have for their object to produce engines worked by heated
air or other suitable heated gas or gases which shall not be liable to get out

page_text: of order and be capable of proper regulation, thus rendering available the
great economy in fuel which it has been proved by Joule, Rankine, and others,
should result from an efficient engine worked by heated air, gas or gases,
instead of steam, even when the steam is employed in the best possible
manner.
I prefer working my improved engines with heated air, it being most
readily obtainable, and in the following description of my improvements I
assume that air is employed; but I wish it to be understood that they may
also be worked with any other suitable heated gas or gases, except in such
cases as those in which the hot discharged air is employed to consume the
fuel, as herein described,
My improvements may be divided into two parts, namely, firstly, as applied
to reciprocating engines; and, secondly, as applied to rotary engines.
Description of the First Part.-My improved engines may be made either
single acting or double acting, and when double acting the piston may be
made in the form of an inverted cylinder closed at the upper end and dropping
easily over an upright fixed central core of somewhat smaller diameter than
the piston, which core is surrounded by any suitable fluid reaching nearly to
the top of it, and into this fluid the piston dips to a sufficient depth; the
piston is itself surrounded by another fixed inverted cylinder closed at the top,
and of somewhat larger diameter than the piston, so that the piston may
move in it easily, and this outer cylinder also dips a sufficient depth into the
before-mentioned fluid. The piston being at its lowest position hot air at a
suitable pressure and temperature is admitted through the core by means of a
suitable admission valve to beneath the piston, and the pressure air thus
admitted will depress the narrow column of fluid between the piston and the
core, but not sufficiently for it to escape past the piston, which it will also
cause to rise out of the fluid somewhat similar to an ordinary gasholder, and
the air above the piston escapes through a suitable discharge valve. The
before-mentioned admission valve should close and cut off the supply of
pressure air to beneath the piston, so that when enough has been admitted it
may by expanding continue to actuate the piston, and be eventually discharged
therefrom at a sufficiently low pressure to prevent loss of power.
piston is at its highest position another suitable admission valve opens and
admits hot-pressure air above the piston, which pressure air will depress the
narrow column of fluid in between the outer cylinder and the piston, but not
sufficiently to escape past the piston, which it will also force down again into
the fluid, the air beneath the piston escaping through the cover by means of
a suitable discharge valve, and the supply of pressure air to above the piston
When the

page_text: should be cut off as described above when the piston was making the up
stroke. It will be seen that by this arrangement the piston need not accu-
rately fit either the core or the outer cylinder, and that no packing is required
for the piston, for all leakage past it is prevented by the resistance of the fluid
due to the depression thereof, as above described; it is advisable, however; to
leave but little space between both core and cylinder and the piston, so that
very little of the pressure air admitted at each stroke may find its way down
these spaces in depressing the fluid as above described and yet be sufficient to
fill them, as this otherwise would occasion loss of power. For the same
reason the closed end of the piston when at its highest position should nearly
touch the closed end of the surrounding cylinder, and when at its lowest
position it should nearly touch the end of the core, so as-to-leave but little
space or clearance at either end to be filled by the pressure air when first
admitted at each stroke. Any suitable fluid may be employed for the piston
to work into, as above described, but the greater the density thereof the less will
be the extent of immersion necessary to prevent leakage past the piston of the
heated air at any given pressure employed to actuate it; and it is also desir
able that the fluid should be capable of being heated to a sufficiently high
temperature without sensibly volatilizing, for which reasons I prefer employing
melted lead. The temperature I prefer beating the air to is about 650° or
700° Fahrenheit, and the pressure about 20 lbs. per square inch, depending
upon the size of the engine, but other temperatures and pressures may be
employed. I prefer admitting and discharging the heated air through vertical
lift valves actuated by suitable cams, and to construct the discharge valves so
that they may open freely should any vacuum be formed by the piston in
consequence of excessive expansion of the air actuating it, thereby preventing
the fluid employed from being drawn up by a vacuum to above the proper
level; I also prefer placing the admission valves so as to open from the piston
and against the pressure, which will then assist to keep them closed when not
opened by the cams. The fluid above mentioned is contained in a casing
heated outside by the heat from a furnace, which heat may also be employed
to heat the cold air forced by an air pump into a suitable heater, whence the
air in a heated state is drawn off to actuate the piston, as above. The heater
may be of any suitable construction, but I prefer making it of pipes in such a
manner that the cold air to be heated may pass through them in a contrary
direction to the hot gases from the furnace passing outside of them; and for
such heaters I prefer using pipes such as are sometimes used for heating
buildings by hot water, that is, stout pipes having their ends coned and faced,
and screwed right and left so that the ends may be forcibly drawn against

page_text: each other by means of a socket in order to join them, such joints not being
liable to be affected by high temperatures; the heater may also be in the
form of a jacket surrounding the casing containing the fluid, and the cold air
being forced into the bottom of this heater is drawn off from the top of
it in a heated state, having become heated during its passage upwards in
the heater by the hot gases from the furnace passing downwards either outside
of it or through tubes or flues traversing it. The expanded air expelled by
the piston at each stroke contains a considerable quantity of heat which it is
very desirable to utilize, and it is also desirable that the heat passing from
the furnace shall not be so intense as to be injurious to the engine or heater,
and both these conditions may be fulfilled by leading a portion of the hot
discharged air to beneath the fire so as to consume the fuel, while the
remainder is discharged above the fire, so as to moderate the intensity
of the beat passing therefrom to heat the casing containing the fluid and
the heater, as above described. By thus consuming the fuel with bot
instead of cold air it is evident that a greater amount of beat will be
rendered available by the consumption of the same amount of fuel. The
relative quantities of the hot expanded air discharged below and above
the fire may be-regulated by means of a damper or valve closing more or less
a passage leading to it below the fire, so that more or less of the discharged
air may be compelled to raise a second valve closing a passage leading it to
above the fire, and this second valve may close simply by its own weight, so
as to offer but very little resistance to the passage of the discharged air. The
first damper or valve in the passage leading to below the fire may be actuated
by an inverted tube containing air and closed at the upper end, which tube is
sufficiently immersed in the before-mentioned fluid surrounding the core, so
that variations in the temperature of this fluid, by causing variations in the
volume of air contained in the tube, may cause the latter to rise or fall in
the fluid, and thereby regulate the position of this first damper or valve; this
valve might also be regulated by a thermostatic band of well-known con-
struction, or by the expansion of a rod of metal actuating suitable levers, and
this regulating rod or band may be placed so as to be acted upon by the hot
gases from the fire, so as to properly moderate their temperature. Instead of
having two valves or dampers, the first valve might be constructed so as to
control two openings, one to below and the other to above the fire. The heat
in the discharged air may also be utilized, and the intensity of the heat from
the furnace regulated by causing the hot discharged air to pass through a
cooler, so that it may part with its beat to a cooling current of air also passing
through it in a contrary direction, which current becoming heated is led partly

page_text: to below the fire, so as to consume the fuel, and partly to above the
fire to regulate the intensity of the heat passing therefrom, as more fully
described in the second part of my improvements, and the cooled discharged
air may either be allowed to escape, or preferably, be again compressed by
the air pump and forced into the heater, so that the same air may constantly
circulate through the engine to actuate it. The power and speed may be
regulated by actuating the hot air admission valves by means of graduated
cams made to bear at the right grade, either by hand or by a governor, so
that they may close the valves and cut off the supply of hot air to the piston
at the right point; the quantity of cold air forced by the air pump into the
heater being also regulated by causing it to force up a tube some suitable fluid,
such as mercury, thereby raising a float situate therein in such a manner
that should the pressure rise above a certain point the float will bear against
an inlet valve to the air pump and keep it open, more or less, during the
forcing stroke thereof, and consequently allow more or less of the air contained
in the air pump to be thrown back through the inlet valve instead of being
forced into the heater, so that the pressure therein consequently remains
nearly constant; this might also be accomplished by causing a similar float
to keep open more or less a delivery valve on the air pump, so that more or
less of the air at first forced out might return into it during the return stroke,
instead of passing to the heater. The air pump may be of any suitable
form, and I prefer placing in between it and the heater a small receiver, into
which the air is first forced, so that any lubricant which might pass over with
the air from the pump may be intercepted, and this receiver may also be
fitted with a valve to prevent air from the heater returning into it; I some-
times also cover the surfaces of the suitable fluid employed, and into which
the piston dips with a layer of some suitable material, so that it may not be
in direct contact with the hot air admitted to work the piston, and powdered
plumbago may be employed for this purpose. When the hot air from the
piston is caused to consume the fuel, as before described, both the furnace
and ash-pit are provided with doors which should be kept closed when the
engine is not at work; but at other times the ash-pit door is left open, so that
air may enter to feed the fire, and by means of a suitable damper the heat
may, when desired, be allowed to pass direct to the chimney without passing
through the heater, and so as only to beat the casing containing the fluid,
and a damper may be fitted in the chimney, which I prefer to actuate by the
before-mentioned heat regulators, so as to prevent undue heating at such times
when the ash-pit door is left open, and the damper may be prevented from
altogether closing, and possibly causing the fire to go out, by opening more or

page_text: less the fire-door, so as to admit some cold air above the fire, and thereby
reduce the heat passing from it. When the engine is not at work undue
heating may also be prevented by causing the heat regulator to close -more or
less the ash-pit door, instead of a damper in the chimney, as above described.
These engines may be made single acting on the up stroke only by dispensing
with the inverted cylinder surrounding the piston, and also with the admission
and discharge valves to the top side of the piston, as before described, and
when required to be single acting on the down stroke only, then by dispensing
with the admission and discharge valves to the bottom side of the piston, and
the core before mentioned may then be of any convenient size and open at the
top, but in either case the passage for the expanded discharged air from the
piston should be in communication with that side of it on which the pressure
does not act, so that the discharged air may pass freely to and from that side
of the piston, so that the motion of the latter may not be resisted. Two or
more single or double acting pistons may be connected to the same shaft, and
when it is desired to have the power of reversing the motion of the engine
this may be done by means of backward and forward cams actuating the
valves through links, as is usual in ordinary reversing gear to steam engines.
Instead of constructing reciprocating engines, as above, the piston may be
made in the form of an inverted cylinder, closed at the upper end and
immersed in a suitable fluid, preferably melted lead, to such an extent that
when the piston is in its lowest position the pressure of the fluid above the
top of the piston is nearly equal to the pressure of the air intended to actuate
it; an orifice for admitting hot pressure air beneath the piston is situate inside
of and as close as possible to the top of it, so that the pressure air when
admitted will only slightly depress the fluid beneath the piston, and will con-
sequently exert its force in causing the piston to rise, and as it rises more
pressure air will flow into it, so that the power of the piston, which as at first
nearly balanced by the pressure of the fluid above it, will gradually increase.
When sufficient pressure air has been admitted beneath the piston the supply
should be cut off, so that the portion admitted may continue to actuate the
piston and become expanded until it is finally discharged at a sufficiently low
pressure during the descent of the piston into the fluid when making the
return stroke. The expanded low pressure air may be discharged from
the piston through suitable valves opening inwards placed in the top of it,
and made so as to close by coming in contact with the fluid employed, when
the piston has sufficiently descended into the fluid and during the up stroke
the hot pressure air will keep them closed until they again open ready for the
down stroke either by their own weight becoming greater than the pressure

page_text: exerted upon them by the expanded air or by coming in contact with a stop at
the end of the top stroke. The heated air may be admitted beneath the piston
through a pipe ascending inside it nearly to the top of it, the end of this pipe
being again bent down a short distance and fitted with a valve opening outwards
from it, and made so that the density of the fluid will keep it closed except
when forced open by hot pressure air admitted to the tube by another admis-
sion valve actuated by a cam, as in the above-described engines. The object
of bending the pipe down again and fitting it with a valve is to prevent the
fluid passing down the admission tube. A simpler way, however, of pre-
venting this is to construct the piston with a chamber on the top of it reaching
above the level of the fluid, so that the hot air admission pipe may be carried
up inside the piston, and this chamber to above the level of the fluid, the
upper part of the admission pipe being surrounded by a fixed tube closed at
the upper end, and of a suitable length to lead the pressure air down again to
the same level as the top of the piston when at its lowest position before it
can flow into the piston. The passage between the admission tube and the
inverted tube over the end of it must be large enough to allow the pressure
air to pass freely to the piston, but the space between the inverted tube and
the chamber in the piston dropping over it should be as small as possible
when the piston is at its lowest point, so that but little pressure air may find
its way
into this space, and so prevent loss of power. The air is admitted to
the admission tube by a separate valve and cam, as above described, and the
object of the inverted tube is to prevent the loss of power which would result
from the discharge of the pressure air in the admission tube at each stroke;
it may be dispensed with where this loss is unimportant, in which case the
expanded air may escape back through the admission tube by means of a
discharge valve actuated by a cam, instead of through valves in the top of the
piston, as above described. The other parts of engines having pistons thus
constructed need not be here described, as they would be very similar to
those of engines having pistons as first described, and which I consider
preferable.
The second part of my improvements relate to the application of the before-
described expansive force of heated air or other gases to actuate rotary
engines. For this purpose I construct these engines in such a manner that the
hot air at a suitable pressure and temperature may actuate a suitable bucket
wheel, or endless chain of buckets immersed a sufficient depth in melted lead
or any other suitable fluid, and rotating therein; the hot air being admitted
direct into the fluid employed and immediately below the lower inverted
buckets into which it rises so as to displace more or less of the fluid with

page_text: which they were filled, thereby rendering that side of the wheel or chain
buoyant so as to cause it to rotate, and the air in the buckets will continue to
actuate the wheel or chain during its expansion consequent upon the rise of
the buckets in the fluid until the air is at last discharged from the buckets at
about the same pressure as the air supplied to the air pump, so that the
power given out by the pressure air during its expansion is render available,
which would not be the case had the hot air been caused to operate, as in a
Barker's mill rotating in a suitable fluid as has been suggested. The pressure
air may be admitted into the fluid employed either intermittently by means of.
suitable valves and cams for actuating them, or else in a continuous stream-
which I prefer, and the buckets should be of such a size that the admitted
pressure air may be all collected in the lower buckets, and not pass from them
to the upper ones, which would cause a loss of power proportionate to the
height of such useless rise; for which reason it is best to employ numerous.
small buckets rather than fewer larger ones, and to give them the necessary.
capacity by making them wide rather than deep, which can easily be done by.
employing a wide bucket wheel or chain. The bucket wheel or chain and
the suitable fluid may be contained in a casing heated by the heat from a fire,
which heat may also be caused to heat the air forced by an air pump into a
suitable heater, which I prefer to construct of tubes, as described in the first.
part of my improvements, and the hot air discharged from the buckets may
either escape into the atmosphere, or be caused to consume the fuel, as before
described; but I prefer cooling it by means of a suitable cooler, so that it
may be again compressed by the air pump and forced into the heater. The
cooler may be very similar to the heater, but preferably of tubes, as above
described, in which case the hot discharged air from the buckets passing through
the tubes is cooled by a current of cold air passing in a contrary direction
outside of them, and it is then led to the air pump. The cooling current of
air passing through the suitable cooler becomes gradually heated as it progresses,
and may be employed to consume the fuel, so as to economize the consumption
thereof; in which case it is desirable to regulate the amount of this current of
air, so that enough may pass to properly absorb the heat of the discharged hot
air from the buckets, but not so much as to be itself unnecessarily cold when
entering the furnace, as this would occasion a loss of heat; this may be
effected by means of two dampers, one in the heater chimney or flues leading.
thereto, and the other placed so as to admit more or less of the heated current.
of air from the cooler, either above or below the fire; the first or heater damper
will regulate the quantity of the current of air passing through the cooler and

page_text: heater, and the second or cooler damper will regulate the relative quantities of
the current of air passing above and below the fire, so as to regulate the com-
bustion and consequently the heat passing the heater. That portion of the
current of air admitted above the fire also moderates the intensity of the heat
passing therefrom. These dampers may be actuated by thermostatic bands,
so that should the temperature of the air escaping from the heater fall below a
certain degree the first thermostatic band will more or less open the heater,
damper, so that more air may pass through the cooler and furnace, so as to
increase the combustion and consequently the heat passing through the
heater; and should the current of heated air from the cooler become too cold
the second thermostatic band would actuate the cooler damper, so that more
of the heated current of air may pass below and less above the fire, so as to
increase the combustion, which would have the effect of causing more heat to
pass through the heater to the chimney, which would cause the first ther-
mostatic band to more or less close the heater damper, and thereby regulate
the quantity of the current of air passing through the cooler and furnace. To
further regulate the intensity of the heat from the furnace a third damper
may be fixed, so as to admit more or less of the cooling current above the
fire, which damper may be actuated by a thermostatic band situate in that
part where the heat of the fire is first applied, so as to limit the maximum tem-
perature, and thus prevent undue heating of any part of the engine. Instead
of these thermostatic bands, which I prefer, the dampers may be actuated by
the expansion of air in an inverted tube immersed in a suitable fluid, as
described in the first part of my improvements; but when the temperature
employed is high I prefer actuating the dampers by the expansion of a
metallic rod actuating suitable levers. When the hot pressure air is admitted
intermittently into the buckets by means of a valve the power and speed may
be regulated my means of a graduated cam actuating the valve, as described
in the in the first part of my improvements; and when the hot pressure air is
admitted into the buckets in a continuous stream, which I prefer, the power
and speed may then be regulated by causing the air from the air pump to
pass into a reservoir, and from thence through a cock or throttle valve
actuated either by hand or by a governor to the heater, the quantity of air
supplied by the air pump being also in either case regulated by its own
pressure keeping open more or less the inlet or delivery valve of the air pump,
as described in the first part of my improvements. I prefer a separate
reservoir, as above described, but the cock or throttle valve may be placed
near the point where the air is discharged into the fluid, so as to make the

page_text: heater act as a reservoir. When it is desired to reverse the motion produced
by these bucket engines this may be done by any suitable known arrangement
of reversing gearing.
All the above improved engines, described under the first and second parts,
may be provided with a suitable valve or plug for drawing off the fluid
employed when desired, and in such cases where the discharged air is cooled
and again forced into the heater I sometimes work the engines so that the
cooled air supplied to the pump is at a more or less high pressure before it is
further compressed by the air pump and forced into the heater, and, when the
air is thus cooled I prefer fitting a valve so as to open and adinit air should
any vacuum be formed in the cooler, and another valve for discharging air
should the pressure rise too high therein or in the heater. 1 prefer also pro-
viding in all cases a separate reservoir containing air at a high pressure,
which air may be discharged by means of a cock into the heater at starting
should the pressure therein not be sufficient, and this bigh-pressure reservoir
may be kept full by means of a small pump worked either by hand or by the
engine, or by both.
The annexed Drawings will further explain the nature of my said improve-
ments. Figures 1, 2, and 3, are vertical sections showing my improved single
and double acting pistons; Figures 1 and 2 being surrounded by heaters in
the form of a cylindrical jacket; Figures 4 and 5 illustrate the improvements
described in the second part above mentioned.
'
Description of Figure 1.-a, piston actuating a shaft (not shown on the
Drawing); b, core over which piston.a.drops; c, cylinder surrounding piston a,
and of such a size that piston a may move in it easily; d, hot air inlet valve;.
6, outlet valve for the expanded hot air; f, heater; g.. hot air chamber com-
municating with top of heater f; h, chamber into which the hot expanded air
from the piston is discharged; i, melted lead or other suitable fluid surrounding
core b, and into which piston a and cylinder c dip to a sufficient depth; j, casing
containing fluid i; k, fire; l, m, n, passages leading the heat from the fire k
to a chimney (not shown); o, piston rods, shown broken and in dotted lines,
and actuating a beam or shaft, as in ordinary steam engines; p, thicknesses
of bad heat-conducting materials. From chamber h are two passages (not
shown), one discharging into above and the other into below, the fire k;
9, suitable air pump; r, bent tube containing mercury or other suitable fluid ;.
s, Hoat; t, inlet valve to air pump q. The action, is as follows:-The heat
from fire k passes up passage 1, heating casing and its contents, then down.
passages or tubes m, thereby heating the cold air forced by the air pump q

page_text: into the bottom of the heater ƒ during its passage upwards towards the
chamber g. The piston a being at the top of its stroke the valve d opens by
means of a graduated cam (not shown), so as to admit the hot air at a
suitable pressure and temperature above the piston a, which hot air will
depress the narrow column of fluid contained between the piston a and
cylinder c, but not sufficiently for it to escape past the edges of either, and it
will also force down piston a further into the fluid i, the air beneath it escaping
freely through core 6 communicating with expanded discharged air chamber h.
The cam closes the valve d when sufficient air bas been admitted, and this air
by expanding will cause the piston a to continue its downward stroke. The
piston a makes its return or up stroke by means of a fly wheel, or of another
similar piston coupled to the same shaft, and the valve e opening by means of
another can (not shown) allows the expanded air above the piston a to pass
into chamber h, from whence it passes to above or below the fire k, which is
regulated by means of a heat regulator, as before described. Should the
engine not be working at full power the graduated cam then closes the inlet
valve d sooner, so as to admit less hot air above the piston a, and con-
sequently the air pump will at first supply more air than is used, thereby
causing the pressure in the heater to rise somewhat, which increase of pressure
will force the liquid up in the bent tube r, thereby raising the float 5, so as to
make it bear against the inlet valve t, and thus keep it open more or less
during the forcing stroke of the air pump g, so as to allow some of the air to
flow back again from the pump, instead of all of it being forced into the
heater, thereby regulating the pressure.
Description of Figure 2.- a, piston; b, central core over which piston a
drops easily; c, cylinder surrounding piston a, which can move easily in it;
d, d³, hot air inlet valves; e, e¹, outlet valves for the expanded hot air;
f, heater; 9, g¹, bot air chambers communicating with the top of heater f;
h, h¹, chambers into which the hot expanded air is discharged; i, melted lead
or other suitable fluid surrounding core b, and into which piston a and
cylinder c dip to a sufficient depth; j, casing containing fluid i; k, fire;
l, m, n, passage leading heat from fire k to a chimney (not shown); o, piston
rods, shown broken and in dotted lines; p, thicknesses of bad heat-conducting
materials. Chambers h, h', both communicate with two passages (not shown)
leading one to above and the other to below fire k. In this arrangement the
action is much the same as described with reference to Figure 1, but when
the piston a is at the bottom of its stroke the valve d' opens by means of a
graduated cam so as to admit the hot-pressure air underneath it, which air will

page_text: depress the narrow column of fluid between piston a and core b, but not
sufficiently to escape past the edge of piston a, and it will also force up
piston a, and when expanded it will be discharged through valve e¹ by means
of a cam, and from thence to the fire k in a similar manner to the air from
above the piston a.
Description of Figure 3.-This Figure represents a double-acting piston very
similar to that just described with reference to Figure 2, but the inlet and
discharge valves to beneath the piston a being differently placed. The same
parts are represented by the same letters as in Figure 2, and need not
therefore be again described.
Description of Figures 4 and 5.-The same letters represent the same
parts in both these Figures. a, inverted bucket wheel; b, inverted buckets;
c, shaft carrying wheel a; d, melted lead or other suitable fluid; e, casing;
f, fire; g, flues leading heat from fire f round casing e through the heater
to chimney h; i, suitable air pump; j, reservoir. The pump i forces the
air through pipe k into this reservoir j; 1, pipe leading compressed air from
reservoir to chamber m, and heating tubes n, and from them into the
fluid d, into which the air is discharged against a guard o, so that it may rise
through the fluid into the lower buckets b; p; pipes for cooling the hot dis-
charged air from buckets b, and leading it into chamber q communicating
through piper with the air pump i; s, passages through which passes &
current of cold air in order to cool the hot discharged air passing through
pipes p in a contrary direction, and this current of cold air becoming gradually
heated as it progresses passes through passages t and u to above and below the
fire in proportions depending upon the position of the cooler damper v;
w, thermostatic band actuating damper v, so as to more or less close passage.
and open passage u should the current of air from the cooler passing through
them become unnecessarily cold in consequence of the quantity passing being
too great; x, second thermostatic band actuating the heater damper y, so as
to close it more or less should the temperature of air escaping up the
chimney become too high. These dampers and y are provided with
counterweights and a¹ to keep them always bearing against the thermostatic
bands w and x. When it is desired to further regulate the intensity of the heat
acting on casing e this may be done by having a third damper admitting air
from the cooler to above the fire f, which damper may be actuated by a
thermostatic band or an expansion rod placed in the passage near the fire, so
as to receive the first effects of the heat. The pipe is provided with a cock b¹
for stopping the engine, and with a throttle valve c¹ for regulating it, which
t

page_text: valve may be actuated by a governor, and the reservoir is provided with two
pipes d¹, d¹, dipping into mercury or other suitable fluid, so that should the
throttle valve be partly closed the increasing pressure in the reservoir j will
force up the mercury in the tubes d', d', so as to lift the floats e¹, e', and keep
open the inlet valves f¹, f, of the air pump i during the forcing stroke, so
that more or less air may return through them instead of being forced into
the reservoir j, thus regulating the pressure therein. The reservoir j, also the
beater and cooler chambers m and q, may be provided with inlet valves to
prevent the formation of a vacuum, and casing e may be provided with a
suitable opening for drawing off the fluid when desired; y¹ is a damper for
admitting the heat direct to the chimney when desired. The second reservoir g¹
contains air at a high pressure, which may, when necessary to start the engine,
be discharged into the heating tubes n by means of the cock h¹; this reservoir
is kept full by means of the second small air pump 2, which may be made
with sufficient space between the valves to limit the amount of compression to
the desired point; this reservoir may also be kept full by a small hand air
pump. The air enters reservoir g¹ through pipe o¹; j¹ represents the crank
circle, and the centre line of the connecting rod for working the air
pumps i, . The shaft c revolves in outside bearings, and passes through
stuffing boxes packed with some suitable material to prevent the fluid escaping
when the level of it is above the shaft c. Instead of outside bearings the
shaft may sometimes revolve on inside bearings, or be itself stationary, the
bucket wheel revolving on it, in which case the power may be communicated
by a spur wheel to another shaft; n', thicknesses of bad heat-conducting
materials. The action of these bucket engines will be readily understood
from the foregoing description of the second part of my improvements.
Having now described the nature of my said improvements, and in what
manner they are to be performed, I wish it to be well understood that I do
not confine myself to the precise arrangements herein described; but that which
I claim as my Invention is the following, substantially as herein described,―
First, constructing reciprocating engines worked by heated air or other
heated suitable gas or gases, in such a manner that the heated air, gas, or
gases actuates pistons arranged and operating substantially on the improved
plans herein described.
Second, constructing engines worked by heated air, gas, or gases, wherein
the air or gas is caused to enter the lower inverted buckets of a bucket wheel
or chain of buckets immersed in melted lead or other suitable heated fluid, so
as to produce the rotation of such bucket wheel or chain or buckets by the

page_text: buoyancy of the air operating during its expansion in the buckets due to their
ascent in the fluid, substantially as herein-before described.
Third, regulating the power and speed of improved engines, as described in
the first claim, by means of a graduated cam actuating the valve for admitting
the heated air, gas, or gases, so as to close it and cut off the supply to the
piston at the right point, the quantity of air, gas, or gases supplied by the
pump being at the same time regulated by its own pressure, so that the
working pressure may remain nearly constant, substantially as herein
described.
Fourth, regulating the power and speed of improved engines, as described
in the second claim, by means of a throttle valve and reservoir, the quantity
of air, gas, or gases supplied by the pump being at the same time regulated by
its own pressure, so that the pressure may remain nearly constant, substantially
as herein-before described.
Fifth, constructing improved engines, as described in the first and second
claims, so that the hot discharged air, gas, or gases is cooled by means of a
cooling current of air, and again compressed by the air pump, the cooling
current of air being at the same time employed to consume the fuel and to
regulate the intensity of the heat from the furnace by being discharged below
and above the fire, the total quantity of the cooling current and the relative
quantities of it discharged, below and above the fire being also regulated by
dampers, substantially as herein described.
In witness whereof, I, the said Alphonse Louis Normandy, have here-
unto set my hand and seal, this Seventh day of September, in the year
of our Lord One thousand eight hundred and sixty-seven.
A. L. NORMANDY. (L.S.)