IMPROVEMENTS IN ENGINES TO BE WORKED BY AIR OR GASES
Year: 1844

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
LOUIS FELIX FRANCHOT, of Paris, in the Kingdom of France, Engineer, send
greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twelfth day of December, in the eighth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Charles Louis Felix Franchot, Her especial licence, full power, sole privilege
and authority, that I, the said Charles Louis Felix Franchot, my executors,
administrators, and assigns, and such others as I, the said Charles Louis Felix
Franchot, my executors, administrators, or assigns, should at any time agree
with, and no others, from time to time and at all times during the term of
years therein mentioned, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, and in all
Her Majesty's Colonies and Plantations abroad, and in the Islands of Jersey,
Guernsey, Alderney, Sark, and Man, my Invention of "IMPROVEMENTS IN
ENGINES TO BE WORKED BY AIR OR GASES;" in which said Letters Patent is
contained a proviso, obliging me, the said Charles Louis Felix Franchot, by
an instrument in writing under my band and seal, particularly to describe and
ascertain the nature of my said Invention, and in what manner the same is to
be performed, and to cause the same to be inrolled in Her Majesty's High
Court of Chancery within six calendar months next and immediately after the
date of the said in part recited Letters Patent, as in and by the same, reference
being thereunto had, will more fully and at large appear...

page_text: NOW KNOW YE, that in compliance, with the said proviso, I, the said
Charles Louis Felix Franchot, do hereby declare that the nature of my said
Invention, and the manner in which the same is to be performed, are par-
ticularly described and ascertained in and by the following description thereof,
reference being had to the Drawings hereunto annexed, and to the letters and
figures marked thereon (that is to say) :-
Engines or machines for obtaining motive power by the alternate expansion
and condensation of a volume of air or gases have been for some time known
in these kingdoms; but although some of these machines have given favorable
results, and have been found to work tolerably well, still there were certain
points and practical details of importance to the proper economical and con-
tinuous or regular working of this description of engine, which appeared to the
Inventor to be susceptible of improvement. The present Invention, although
founded on the same principle, differs most essentially in the arrangement and
organization of its parts. The principal improvements are a more certain and
niore effectual method of heating the air, by the employment of certain
mechanical arrangements, which will be found more convenient in practice;
and by means of these and other modifications a considerable reduction in the
size, and consequently the weight, of the apparatus takes place, while at the
same time the extent of the surfaces which effect the alternate dilation or
expansion and condensation of the air or gases is considerably increased. As
has been already said, the motive power of the engine is effected by the alter-
nate heating and cooling of a certain volume of air inclosed in a space of a
cylindrical form. The expansion and contraction which arises from these
changes in the temperature of the air or gas is made to act upon a moveable
piston, conveniently situated for the purpose. The air is not allowed to leave
the vessel (which contains it) for the purpose of being heated or cooled; it is
merely displaced or removed from one part of the vessel to the other by
means of a cylinder, which I shall call the displacing cylinder or vessel, and
which vessel or cylinder, by having a reciprocating movement communicated to
it inside the air vessel; effects the displacement or removal of the air or gas
from one end of the air space to the other; as above mentioned. As the dis-
placing cylinder receives its motion from without; one of its extremities is
made alternately to enter the hot end, and the other extremity the cold end,
from both of which it alternately drives the air, which becomes heated or
cooled in the passage from one end of the vessel to the other.
In order to give a clearer notion of the principle upon which this Invention
is founded; I will proceed to explain it more intelligibly by reference to the
diagram, Fig. 1, in Sheet 1 of the accompanying Drawings. a, a, b, b, c, c

page_text: represents a cylindrical vessel, the upper end a, a, of which is supposed to be
heated, and the lower extremity b and c cold. R is the displacing cylinder,
before mentioned, which receives a reciprocating motion by means of the rod t
from any convenient mechanism. When the cylinder R is lowered, the air
in the cold chamber is forced therefrom into the hot chamber a, a, through a
tube D, by which a communication between the two chambers is always
maintained. The air is heated in its passage, and by its expansion forces
back the moveable piston P; and when the displacing cylinder is raised, the
air is driven from the hot chamber C to the cold chamber F, becomes cooled
in its passage, and by its contraction allows the moveable piston P to resume
its original posision. But in order that the expansion of the air should
be effected under the most favorable circumstances, it is necessary that it
should take place in the hot chamber without the volume of the fluid being
separated in two parts of unequal temperature. Now, as it is of importance
that the piston should not be exposed to a tenperature high enough to alter or
injuriously affect its adjustment, it has been proposed either to place it outside
the generator, or in the cold part of this cylinder or vessel, by covering it
during its return by the displacing cylinder, which would act as a guard or
screen, and also become, as it were, a prolongation of the piston itself. This
excellent arrangement, in a theoretical point of view, at first appeared
extremely simple; it has, however, been found in practice to give rise to several
inconveniences, which I will enumerate, in order that the advantage of the new
improvements may be more evident. In the first place, by placing the hot
and cold chambers in the same vessel, it will be necessary to make this latter
of sufficient length to prevent the loss of caloric, which would be occasioned
by the conductibility of the metal, especially if the air is allowed to pass'
between the sides of the displacing cylinder and the generating vessel in the
annular space marked & in the Figure. On the other hand, the distance that
the displacing cylinder will have to travel will be increased, and its motions
complicated and connected with the piston, which it must accompany on its
return, in order that a separation of the volume of air into two portions of
unequal temperatures may be avoided. Lastly, in the arrangement pointed
out in the diagram, Fig. 1, the process of heating and cooling are inconvenient
and defective. Upon examining the new or improved plan of constructing
air engines, it will be seen that all these defects and inconveniences are
avoided, and that several considerable and particular advantages are obtained.
I will now proceed to explain the construction and arrangement of a
stationary engine with two cylinders connected together. We will first
examine the construction and functions of the parts which constitute the
Q

page_text: generator, which is composed, of three cylinders, placed one above another, as
seen in Figs. 2 and 4, which represent vertical sections taken through the
machine at different lines.
Fig. 3, Sheet II., and Fig. 5, Sheet I., represent horizontal sections of
part of an engine taken at different levels. Fig. 3 also represents a plan
view of a portion of the engine, one cylinder being shewn in section, and the
other in plan or top view. Of the three cylinders before mentioned, 1, 1, 2, 2,
in Figs. 2 and 4, represent the cold one, in which the pistons 3, 3, of the dis-
placing cylinder 3, 4, 5, works. The second or middle cylinder 6, 7, 8, is
heated directly by the fire in the furnace 18, see Fig. 4. The third or upper-
most cylinder is seen at 9, 9, 10, 10; it is in this cylinder that the piston
11, 12, works. The temperature of this cylinder is not allowed to exceed
that which the piston can support without being injuriously affected. For
this purpose, it may, if required, be surrounded with a jacket of water, so
as to limit the temperature to 212°. The piston is, however, preserved from
the immediate action of the heat by a screen or drum 12, which is filled with
some material that is a bad conductor of heat. To connect the cylinders,
which are placed one upon the other, without allowing them to experience
any very considerable changes of temperature, I make use of what I call a
disconnecting or insolating joint, a, a, b, b, which may consist simply of a ring
or ferrule of thin or plate iron, adapted to grooves, cut by means of a lathe on
the edges of the cylinders, and held firmly by bolts. The thinness of this
ring or ferrule does not allow the temperature of one cylinder to be affected
by that of the adjoining one.. Another means of retarding or preventing the
variations of temperature, and cutting off the communication between the hot
and cold cylinders, consists in mounting the displacing vessel or cylinder upon
a piston 3, 3. which prevents any circulation of air in the annular space. The
displacing cylinder is composed of two parts; first, the portion 3, 4, which
forms the piston; this part may be formed hollow, or with a double bottom,
in which a current of cold water may be made to circulate, by means of the
tubes or hollow rods 64, 65. The other portion 5 of the displacing cylinder is
hot, and serves as a screen; it enters the hot chamber 6, 8, situated imme-
diately above. These two parts are connected together by insolating o
disconnecting joints, and they are filled inside, as seen at 4, 5, with matters
that are bad conductors of heat. The circulation or passage of the air from
the hot to the cold chambers is effected by means of a central concentric tube
14, 15, 16, upon which the piston of the displacing cylinder 3, 3, is accurately
fitted, and which serves and assists to guide it. The air passes from the col
chamber 24 to the central tube 14, 15, 16, through the copper tubes 13, 13

page_text: surrounded with cold water. The central tube conducts the air to beneath
the piston 12. This tube is filled with rings of sheet metal 15, rolled round
concentrically upon themselves, so as to leave sufficient space for the air to
pass. The middle or hot cylinder is composed of three parts, see Figs. 2 and 4;
first, the upper hot chamber 16, into which the screen guard or lower part of
the piston 12 projects; second, the lower hot chamber 17, into which the guard
or upper part 5 of the displacing cylinder projects; third, the intermediate
space 8, in which the heating of the hot chambers 16 and 17, and of the air
which enters there, is effected. Fig. 5 represents a horizontal section taken
through this intermediate space. The flame and heat from a furnace situated
at 18 circulates through the flues 19, 20, 21, 22, and passes completely round
the hot air chambers 16, 17, as seen by the arrows, before it escapes into the
chimney 23. There is no communication whatever between the gases from
the furnace which circulate in the flues 19, 20, 21, 22, and the air contained
in the hot chambers 16, 17. The sides 8, 8, of the flues, and which are seen
in section at Fig. 5 in the forms of arcs of a circle, are connected together at
top and bottom by plates, which separate the two hot-air chambers 16, 17,
from the flues; but these sides 8, 8, are hollow, or pierced with holes, which run
from top to bottom, for the purpose of establishing a communication between
the two hot-air chambers. In the present machine, as in the others upon which
the first experiments have been made, it is proposed that the body of air dis-
placed by the displacing vessel or cylinder should be doubled in volume upon
being heated, that is to say, that each time that the displacement of the air
takes place a variation in the temperature of the air, amounting to about 500°,
is effected; therefore, when the displacing vessel descends, see Fig. 4, the air
leaves the cold chamber 24, passes through the tubes. 13 into the central canal
or pipe 14, 15; where it comes into contact with the rolls of sheet metal, enters
the interstices between the sheets, and takes up a portion of their heat, which
gradually increases from 14 to 16; it then arrives beneath the piston 11, 12,
and passes from thence through the openings 8, 8, made in the sides 19, 20, of
the flues, where the operation of heating is completed, and it then occupies the
the space 17 left by the displacing cylinder in the hot-air chamber. In the
passage that the air has to make from below to above the displacing cylinder,
it acquires a temperature that increases its pressure to double what it originally
was. The result of this is a motive power, which tends to raise the piston
11, 12, until the volume of air displaced by the displacing vessel occupies in
the hot-air chamber 16, 17, a space just double that which it originally did
when cold; then, if the displacing vessel rises, the air returns through the
opens 8, 8, re-enters the central tube, gives back again to the rolls of metal

page_text: contained therein the heat which it took up during it upwards passage, and
finally arrives in the space 14, nearly entirely deprived of its caloric; from the
space 14 it passes up the refrigerating tubes 13, 13, where it loses what little
heat may remain, and when it enters the space below the displacing vessel it
will be found to be perfectly cold; the result of this will be, that the elastic
pressure of the air will be reduced, and consequently a motive power, which will
tend to bring the piston back to its original position, will be obtained. The
sheets of metal which are placed in the central tube are arranged in separate
rolls, and mounted on stages one above another, for the purpose of preventing
as much as possible the transmission of caloric from one roll to the other. It
will be seen, from what has been already said, that in this improved air engine
the motive power is consumed at the same moment that it is produced. It is
therefore of the greatest importance that proper relative and appropriate move-
ments should be established between the organs of production and those of
consumption, that is to say, between the displacing cylinder and the piston, so
that the respective functions of these two moveable parts should be properly
carried out; also, notwithstanding the regularity and continuity of movement
which must be given to the fly wheel of a motive power engine, it is necessary
that the greater portion of the air should be displaced before the alteration in
its volume takes place; and on the other hand, that the change in the volume
of the air thould be effected without displacing the body of air; in other
words, the displacing cylinder should be actuated just when the piston is at
the dead point, which hardly gives a quarter of a revolution of the crank
for the displacing cylinder to perform its motion or stroke. By adopting this
plan or arrangement the displacing cylinder acts as follows during an entire
revolution of the crank: it rises during one quarter of a revolution, remains
stationary during the second quarter, descends during the third quarter, and
again remains stationary for the fourth quarter. As these motions are sym-
metrical, or equal, I am enabled to obtain them without the use of cams, that
is to say, by means of levers connected together at their extremities. Let us
take, for example, an engine with two generators, perfectly similar and connected
together the piston 11 M, Figs. 2, 3, and 4, rises, whilst the other piston
11 N in the other cylinder descends, the two pistons being connected at 28, 75,
to a common vibrating beam 28, 38, which has its centre of motion at 34,
between the two cylinders M, N. The spaces above the piston are placed in
communication with each other by means of a tube 70. This tube is furnished
with a turning or tumbling valve 71, which is connected to and actuated by an
ordinary centrifugal generator 72. In order to diminish the speed of the engine,
it is sufficient, in fact, to intercept or cut off the communication through the tube

page_text: 70, and an obstacle consisting of a stratum of air is thereby placed before the
descending piston, and the resistance of a rarefaction of air will be found to
exist behind the descending piston. The vibrating beam 28, 38, is connected
by a rod 38, 39, to a crank 39, 41, which transmits a rotary motion to the.
shaft 41 of a fly wheel. The crank 39 transmits its rotary motion, by means of
a second crank 40, 42, of the same radius, to a small shaft 42, which commands
or carries a shorter crank 42, 43, and which I will call the conducting crank..
At each revolution of the shaft 41, this crank 42, 43, communicates a recipro-
cating motion to a tangent connecting rod 43, 44, which is attached by a chain
to a drum 45, by means of which it performs the functions of a rack upon, a
toothed wheel or pinion. The portion of a circle a, b, through which the drum
45 works, is evidently the same length as the diameter of the circle described
by the bolt or pin 43 of the conducting crank 43, 43, and represents more than
half the circumference, that is to say, an arc of about 200°. The result of this
is, that the crank, or rather the lever 46, 47, situated, at the extremity of the.
shaft 47 which carries the drum, describes an arc of the same amount; so as to
communicate a reciprocating motion, by means of the connecting rod 46, 48,
to the lever 48, 49, and consequently to the forked beam 50, 51... It is, this
beam, the axis of which is at 49, which imparts the reciprocating motion to
the displacing vessels or cylinders by means of the hollow rods 3, 64, and 3, 65,
to which it is connected by the links 52. It will be seen that the displacing
vessels of the separate cylinders act as a counterpoise to each other; their
motions are also identical, and they can consequently be acted upon by the
same beam. The consequence of the arrangement above described is, that
the dead point of the conducting crank 48, is added to the dead point of the
crank 46, the action of which is prolonged about 10° on each side beyond half
the circumference;, the consequence of which is, that the displacing vessels
remain stationary, or nearly so, for an appreciable or sensible length of time
during a quarter of a revolution of the main shaft 41. These moveable parts
commence moving by insensible degrees, and they are never left entirely to the
impulsion or motion they have received, nor exposed to the shocks or jerks
which would be the case if cams were employed, for they are connected to the
prime mover by fixed centres, and their motion or action is rigorously limited
by the diameter of the semicircle described by the crank 46. It will be easily
understood that the dead point or time of rest of the displacing vessels may be
shortened or prolonged by lengthening or shortening the conducting crank 43:
The following are accessory movements connected with the principal parts, and
subsiduary to the movements above described: the displacing vessels may
disconnected from the other parts, either for the purpose of putting the machine
be

page_text: in motion by moving it by hand, or for the purpose of reversing its motion. To
effect this object, it is only necessary to disconnect the drum 45 from the clutch
53, to which it is attached by a double spring bolt 54, which may be raised
instantaneously by means of the excentric 55. The shaft 47 becomes free, and
it is made to describe half a revolution by means of the counterbalance crank
56. The displacing vessels are by this means put in motion, and this can be
continued by hand. If it is desired to reverse the motion, it will be necessary
also to reverse or alter the stopping point of the conductor crank 48 upon
the large crank 46, that is to say, to cause the large crank 43 to occupy the
position r, Fig. 2, instead of the position 42, 43, as shewn in the Figure. In
order to re-connect the parts the excentric 55 is turned half round. To the
balance beam 28, 38, the piston rods of a water pump 57 and an air pump 58
are attached. The water pump brings the liquid through the tubes or pipes 59
into the lower part of the vessel or space 60, which surrounds the refrigerating
tubes 13; the water passes from this vessel 60 through an opening 61 into the
jacket 61, 62, where it comes into contact with the external sides of the cold
cylinder; from there it passes through the tube 63 into one of the hollow rods
64 of the displacing cylinder, fills the double bottom 3, 3, and runs out through
another hollow rod 65. The basin 14 serves to empty the engine by means of
the pipe 66. It is kept supplied with water for the purpose of retaining the
dust, metallic oxides, and other impurities, and preventing them from re-
entering the machine. The air pump 58 serves to keep up a greater or less
pressure in the interior of the engine or generator, and upon which pressure
will depend the power of the engine. Above the piston a mean pressure,
between the extreme or maximum and minimum pressure which is produced
below the piston, is kept up. In the above-described machine it is calculated
that by employing a mean pressure above two atmospheres a power equal to
twenty horses may be obtained.
PARTICULAR DESCRIPTION OF THE VARIOUS PARTS FOR CONSTRUCTING A
STATIONARY ENGINE WITH TWO CYLINDERS CONNECTED TOGETHER.
The piston 11, 12, is composed of a metallic spring ring, furnished with four
cross pieces 25, 25, whereby it is connected to a centre tube or cylinder 26,
which serves as a rod and guide. At the bottom of this cylinder, and at the
same level as the ring 25, a rod 27, 28, is, by means of the spherical head 27,
held between two bearings 29, 30. The upper bearing 30 is formed of two
pieces, connected together by a bridle piece 31, which passes round a neck
formed at the lower end of the rod. A hole, somewhat larger than the neck of
the rod, is made in the upper bearing, to allow the rod to oscillate freely.

page_text: The bearing is compressed and held down by means of a cylinder 32,
which is held in its place by means of the key 33, which passes through
a hole made in the outer cylinder 26 and the rod 28, the hole in this
latter being made sufficiently large to prevent the motions of it from being
in any way interfered with. The balance lever 28, 38, is double, and the
centre pins 34 are supported by standards 35, which rest upon the foundation
plate 36, and are connected to the two cylinders M, N, by bolts 37. All
the bearings and joints of the connecting rods are furnished with spherical
adjustments. The piston rod of the air pump carries a small handle with a
click 67, whereby it is thrown in or out of gear at will. The vessel 60, of
which the lower part of the refrigerator is composed, is cast in one single piece,
and also includes the lower part of the central tube 15, upon which the dis-
placing vessel works, as before mentioned. The top and bottom or opposite
ends of the vessel are pierced with holes, corresponding with each other, and
into which are screwed the copper tubes 13, which extend from top to bottom
of the vessel or chamber. It supports the generator, and rests upon the
foundation plate 36, which is slightly dished below to allow a free passage
for the circulation of the air from the central tube 15 to the small copper
tubes 18. The cavities 45 of the displacing vessel, and which are covered
with discs of sheet iron, are filled with asbestos, or any other substance which
is a bad conductor of heat. On the cold side 4 any combustible material
may be employed without inconvenience. The drum upon which the tangent
rod works is shewn in plan and elevation at Figs. 6 and 7. It has three
grooves, upon which three chains work; one of these chains works from left
to right upon the drum, and is attached by one of its extremities to an ear on
the middle of the drum 68, and by the other extremity it is connected to the
tangent rod 44 at about its middle, and at the side of the conductor crank.
The two other chains work from right to left, and are attached by one of their
extremities to the ears 69 of the drum, and by the other extremity they are
connected to the end of the tangent rod 44. The tangent rod is also main-
tained in its place by two lateral cheeks on the drum 45. It will be seen that
this mechanism is equivalent to a rack and pinion or toothed wheel, which
would occupy the place of the drum. I, however, prefer the plan above
described.
DESCRIPTION OF AN ARRANGEMENT FOR A BOAT ENGINE WITH FOUR CYLINDERS.
Fig. 8, Sheet III., represents the following views:-A plan of the engines
and of the generator A; a horizontal section in the line K, L, (Fig. 9.) of the
cylinder B; a similar section in the line M, N, Fig. 9, of the cylinder D; a view

page_text: of the refrigerator and of the lower reservoir, the generator C¹ being completely
removed. Fig. 9 represents a transverse section of the boat or vessel 78, 79,
and of the generator B, taken in the line E, F, (Fig. 8,) and also an elevation
of one of the engines. Fig. 10, Sheet IV., represents a longitudinal section of
the generator D, taken in the line G, H, (Fig. 8,) and a longitudinal elevation
of the other generator B. In these Figures 8, 9, and 10, I have generally
made use of the same figures of reference as in the Figures 2, 3, 4, 5, 6,
and 7, to represent similar or corresponding parts. of the engines.
CONSTRUCTION OF A GENERATOR FOR BOAT ENGINES..
The advantage which will be found in diminishing the height of the engines
for vessels of light tonnage have induced me to employ for these purposes
generators with the following modifications:-The diameter of the displacing
vessel 3, 4, 5, is increased, as seen in Figs. 9 and 10, so as to present a super-
ficial area of two and a half times as much as the piston, and consequently
the stroke of the displacing cylinder is two and a half times less than that
of the piston. The height of the displacing vessel, as well as the depth of
the cold chamber 24, and of the lower hot chamber 17, will also be lessened
or shortened in the same proportion. Instead of obtaining or effecting the
refrigeration of the air, by causing it to pass through refrigerating tubes,
cold water is injected in small streams into the space below the dis-
placing vessel, through rose heads 65, by means of a circulation. of water,
which will be hereafter explained. It is not, however, impossible to adapt the
vessel with the refrigerating tubes above described to the generator thus
reduced in height, for the reduced height may be compensated by giving it
additional width by increasing its diameter. I only intend to describe a
different or novel combination of parts for effecting the refrigeration of the air.
In order to compensate for shortening the length of the central tube, which
would be the effect of the alterations, I elongate the passage at 66, above the
intermediate space 19, 20, 21, by turning it back or bending it over, as at 72,
by means of a concentric cap 66; a cavity or recess 25 is made in the guard
of the piston 12, in order to receive this prolongation 66, 72, of the central
tube 15. The guard of the piston 12, 25, 73, is composed of two distinct
parts; the one 12, 25, is similar to that which has been already described,
except the cavity or recess just mentioned; the other is composed of two seg-
ments 73, which enter the two circular cavities 74, made between the flues 19
and 22, and which allows me to save nearly the whole depth of the upper hot
chamber, and which, by this means, is in a manner removed to the interior of
the cylinder 9, 10. The piston, composed of a circular ring 11, is connected

page_text: by two rods 26, 27, to a cross head 27, 28. The circulation of the
gases from
the furnace in the intermediate space (see Fig. 8, cylinder B,) differs but little
from that which has been already explained for the stationary engine. After
having passed between the sides of the flues 19, 20, 21, the smoke and
gases from the furnace come back around the intermediate space by the
external flues 22 to the chimney 23.
The external canal is diminished to the
passage E, F, K, L, so as not to interfere with the motion of the balance
levers or beams. The functions of the various parts of the generator are
not widely different from those which have been described in reference to
the stationary engine. I would only remark, that the lower part of the
central tube is pierced with holes 80, by means of which the refrigerating
water runs off into the lower basin 14. These openings also serve to
admit the air which enters between the sheets of metal 15. When the
air enters 66, it passes into the cap 72 through small openings made at
the
upper part of the central tube 15, when it enters the different compart-
ments 16, 17, of the hot chamber. The four generators consist of two pairs of
generators, connected together on each side of the propellor shaft 41, Figs. 8
and 9; the generators A and B form one engine, and the generators C and D
another engine. The piston of the generator A is not connected to the piston
of the generator B by ordinary beams, nor is the piston of the generator C
connected in this manner to the piston of the generator D, as in the stationary
engine. The cross head 27, 28, is connected by its extremities 28 to the
centre of two links 28, 29, 30, the lower parts of which are attached to side
beams or levers 29, 34, 39, which are connected together by the common shaft
34,. The upper ends 30 of the links are jointed to two levers 30, 31, also
connected to a common shaft 31. Upon referring to Fig. 10, it will be seen
that the distance between the centres 29, 34, being exactly the same as the
distance between the centres 30, 31, a well-known parallelogram will be
described, within which the centre 28 of the links moves in a right line. The
balance levers 29, 34, 39, are bent, so as to form bell-crank levers, in order
that the connecting rods 38, 40, 39, may be inclined forty-five degrees. Each
connecting rod 38, 39, 40, is similar in form and construction to those which
are used in beam engines for marine purposes; each of the cylinders con-
sequently has a separate and distinct connecting rod, which communicates
motion to the paddle wheel or propellor shaft 41, and which are connected to
two pairs of opposite cranks Y and Z. The connecting rods of the generators
B and D, 38, 39, Fig. 10, are connected to the crank Y, and stand at a right
angle to each other. The connecting rods of the cylinders A and C are con-
nected to the crank Z, and also form right angles with each other. The result

page_text: of this arrangement is, that when the two engines are connected together they
are in reality equivalent to four engines; that is to say, supposing that the
connecting rods which are connected to the crank Z are taken away, the con-
necting rods which belong to the crank Y would be amply sufficient to com-
municate as regular a rotary motion to the paddle wheel or propellor shaft as
is now given to the propellor shaft of a steam boat by means of a pair of
engines; the other rods are therefore only to communicate additional power
from the other cylinders. Although the pistons are independant, or not in any
way connected with each other, as in the stationary engine, the displacing cylin-
ders A and B are connected to a common beam or balance lever 49, 51, and
consequently have precisely the same movements as in the other engines above
described. The displacing cylinders C and D are arranged and worked in
exactly the same manner. The displacing cylinders are connected to their beam
or balance lever by means of two crutches or bent pieces 54, see Fig. 10, to
which are attached the rods 53, which pass through stuffing boxes 2, fixed on
each side of the cold cylinder. The crutch pieces 54 descend or project down
into boxes or spaces 64 made below the cold chamber 2, 24, and the rods 53
are connected to the balance lever by means of the links 52. The side beams
or balance levers 49, 51, of each displacing cylinder are mounted upon one
common shaft 49. Upon the inner balance lever is fixed an arch-shaped
lever 50, 48, best seen in Fig. 9, and which serves to communicate a recipro-
cating motion to the two balance levers, either by means of the hand lever 56,
or by a motion obtained from the propellor shaft 41 by means of the toothed
gearing 54, 75. This motion is analogous to that which has been already
described. The red lines in Fig. 9 represent the actual or present position of
the relative parts of the engine A, B, and the green lines the actual or present
position of the various moving parts of the engine C, D; the blue lines indi-
cate the extent of motion. The wheel 54, Fig. 8, is movable upon the shaft
41, so far as to admit of changing the position of the displacing vessel, according
to whether it is required to go forward or to back the vessel, by means of an
arrangement similar to that which is used for the excentrics of boat engines.
The wheel, however, is fixed or fastened while the engine is working by means
of a moveable click and collar 55, worked by a forked lever, so as to avoid or
prevent any shock. The wheel 54 communicates a rotary motion to the two
wheels 75, both of which are adapted to, or connected with, and work one of
the engines; thus, the wheel 75, see Figs. 8 and 9, causes the crank 42, 43,
to rotate, and by this means work the tangent rod 43, 44, which causes the
crank 46, 47, to describe a portion of a revolution, and which thereby transmits
a reciprocating motion to the connecting rod 46, 48, and to the arch-shaped

page_text: lever 48, 50, to which this rod is attached by a notch 48, which catches the pin
of the arched lever 48, 50, which carries it forward, and can be disengaged at
pleasure. In order to work this by hand, it will only be necessary to raise the
notch 48 of the rod 46, 48, by an operation similar to that which is in use for
steam boats, and thereby liberate the arch-shaped lever; but if it be required
to change the direction of the vessel, that is, to make it go backward instead of
forward, it will be necessary to liberate the wheel 54, by means of a treadle
which is connected to a collar 55, in order that this wheel 54 may assume a
proper position. Each engine is furnished with a water pump 57 and an air
pump 58, actuated by the levers 33, fixed upon the shafts 34 of the balance
levers. The air pump 58 serves, as has been before mentioned, to inaintain a
greater or less pressure in the interior of the engine, and upon which the power
of the engine depends. The water pump only serves to draw off from the
cisterns 60 the water which is allowed to enter therein directly through open-
ings made in the sides of the boat, and furnished with cocks.
I will now procced to describe the manner in which the water is forced
or injected into the cold chambers. The lower basins or cisterns 14 of the
generators belonging to the same machine A and B, for instance, commu-
nicate with each other by means of the pipes 59, 61, 64, 13, 65, furnished
with valves 61. The pipes beyond the valves are divided into smaller
branch pipes 13, which are bent round in the lower cold water reservoir
60, and terminate in rose heads 65, which are placed in the bottom of the
cold chamber 24. The object of these worms or bent pipes is to equalize
the temperature of the water that circulates therein with the water that
is in the basin or chamber 60. The circulation or passage of the water
through the worms is effected by the difference of pressure of the air
contained in the cylinders with which these pipes are in communication.
The water leaving the basin or cistern of the cylinder D, for example, where
the pressure preponderates, arrives by the tube 59, see Fig. 10, under the
valve 61, which it raises; it then passes off through the upper branch or side
pipe 63 around the basin C; there this tube becomes divided into four sets
of spirals or worms 13, each of which terminate in a rose bead 65, from
which the water is disperse in the cold chamber 24. When the pressure
preponderates in the generator C, exactly the reverse effect takes place, and
the water returns by other tubes, arranged in the same manner as in the other
cylinder. In order to regulate the quantity of water which it is necessary to
pass through, the opening of the two valves is limited, by means of screws 62,
worked by toothed gearing, as seen in Figs. 8 and 10.
The following are some details explanatory of the mode of constructing the

page_text: improved air..engine for marine purposes, as above described:-The cold
cylinders 1, 2, of the generators A and B, belonging to the same machine, are
in one piece, and form the foundation plate for this engine. The same may
be said of the cold cylinders belonging to the generators C and D. These
double cylinders or plates rest immediately upon the sleepers or masonry 76,
to which they are firmly fixed by tie bolts. Immediately above these plates is
placed the framing or standards 35, which connect the two engines on each
side of the propellor shaft together. There are three framings or standards,
rendered firm, strong, and rigid by means of struts or cross pieces 37. These
standards are placed lengthwise of the boat or vessel, one being on each side
of the engines, and one in the middle between them. The standards support
the axles of the balance levers or beams 34, and an upper foundation plate 36,
placed across, and upon which are fixed the four bearings or steps which
receive the crank shaft 41. This plate also carries or supports the mechanism
which actuates the displacing cylinders. The axles 31 of the parallelogram
levers are attached to the upper foundation plate 36 by means of the bearings
32, as seen in Fig. 10. The tube 70 is for the purpose of effecting a con-
nection or communication between the cylinders A and B, above the pistons.
The cylinders C and D have a similar tube of communication. By adapting
to this tube a tumbling valve or cock, the speed of the engines may be regu-
lated with the greatest facility, or, if required, they may be completely stopped.
The portions 73 of the guard of the piston are composed of two sheets of plate
iron, connected together by cross bolts or rivets; and the space between the
plates is filled with earth, or other substance which is a bad conductor of heat;
or, if it be thought preferable, the part 73 may be made of cast iron, and hollow.
The following are the distinctive characteristics and advantages of the new
generator: The great difference and advantages that distinguish this new
system of an engine from that which was briefly described at the commence-
ment of this Specification will be understood and recognized with facility after
having read the above description. The peculiar features of the first or old
and known plans, or that described in reference to Fig. 1, are,-1st, the cold
chamber is placed and opens between the displacing vessel and the piston;
2nd, the displacing vessel and the piston are placed in the same cylinder;
3rd, the sides of the generator and the displacing vessel are made as long as
possible, and the space between their sides is employed as the passage of circu-
lation for the transmission of the air from the cold to the hot chamber, and
vice versa.
The distinctive characteristics of the new or improved plan, or
that above described and shewn in Figs. 2, 3, 4; 5, 6, and 7, are the following:
Ist, the hot-air chamber is placed and opens between the displacing cylinder

page_text: and the piston; 2nd, the displacing vessel and the piston are placed in separate
cylinders; 3rd, the length of the sides of the generator and displacing vessel
are reduced or shortened as much as possible, and the circulation of air
between the sides of these parts of the apparatus is, as far as possible, com-
pletely prevented. These characteristics rest not only upon certain new prin-
ciples of construction, but they are the results of certain technical processes,
which I will point out and intend to claim. I do not, however, think that it
is necessary to enter into any further comparison of my improved system of
air engine, with other arrangements or constructions more or less analagous,
with regard to the employment of an intermediate canal, for the purpose of
husbanding and economizing the caloric, and making use of the 'alterations
in temperature between the hot and cold air, as I consider that the reciprocal
alterations in temperature and the economy of caloric, which is obtained by
the use of a central passage with multiplated surfaces, is a sine qua non for
a proper economization of fuel, which air engines must effect before they can
be advantageously employed in the place of steam engines.
Having now described my Invention, and the manner of carrying the same
into effect, and having pointed out the principal advantages resulting from
my improvement, I wish it to be understood that although I have shewn
and described the best arrangement of engine with which I am at present
acquainted, yet I do not by any means intend to confine myself to the precise
arrangement of parts herein shewn and described, as they may doubtless be
considerably varied without departing from the nature of my Invention. But
that which I claim to be secured to me under the 'herein-before in part recited
Letters Patent will be found in the following concluding observations:-
1stly, I claim the means above described, or any modification thereof,
for preventing, or, at any rate, reducing to an unimportant quantity, the
waste or escape of caloric from the hot chamber to the cold, even when these
chambers are placed in juxtaposition, and consequently to reduce as much
as possible the length of the displacing vessel, that is to say, to reduce it
in length to the depth of the chambers from which it expels the air. There
are three principal causes which effect the changes in temperature between
the hot and cold chambers: 1st, the conductability of the metallic surfaces
which are used for both the hot and cold chambers; 2d, the passage of air
between the said surfaces when the air or gas passes from the cold to the hot
chamber, and vice versa; 3rd, the radiation from the sides of the displacing
vessel, which: passes alternately from one chamber to the other, and which
gives rise to a loss of caloric. I obviate the effect arising from the first cause
by the employment of the isolating joints, by which the metallic surfaces or

page_text: envelopes are connected together at those situations where the two chambers
are contiguous, and which breaks the continuity of the metal. To obviate the
effect of the second cause, I adapt a piston to the displacing vessel, which
prevents the air from passing up between it and the outside cylinder. In order
to diminish the influence of the third cause as much as possible, I make
the displacing vessel of as large a diameter, and give it as short a stroke
as possible. Furthermore, I either make the sides of the displacing vessel
of polished metal, or the surfaces of the two chambers in which it works
are polished, for which purpose I propose to surround the displacing vessel
with sheets of copper gilt, because polished surfaces absorb less heat than
rough ones. These plans are based upon the fundamental principle which
I have always had in view in carrying out these improvements, and which I
will call the neutralization of the lateral surfaces.
2ndly, I claim placing the fire in such a situation that its heat should act
upon the air between the displacing vessel and the piston, and at about the
middle of the hot chamber, which I by this means double in size, and also
consequently increase the efficacy of the heating surfaces by carrying the
gases arising from the furnace into internal flues, the sides of which are hollow,
and all being continually traversed by the air.
3rdly, I have adopted and claim the new modes of causing the air to circulate
in the interior of the generators, and the different parts which effect the
heating and cooling of the air arranged in a more advantageous manner.
These parts are the tubular refrigerator; the central tube or passage, with
its rolls of sheet metal, whereby the air takes up and gives back a certain
portion of its heat in passing; and also the hollow sides of the flues through
which the air passes, as above described.
4thly, the novel arrangement of the tangent rod, and its appendages for
the purpose of actuating the displacing vessel without the use of cams, and
allowing it a longer or shorter time of rest, according to circumstances. At
the same time I possess the power of detaching the displacing vessels from
this part of the apparatus, and allowing them to be worked by hand, in as
simple and effectual a manner as is employed for working the slide valves of
steam engines.
5thly, I claim the general arrangement of the various parts which constitute
the stationary engine.
Sixthly, in applying my improved air engine for propelling steam vessels.
I am enabled to reduce its length, first, by making the displacing vessel of
greater diameter than the working piston; second, by causing the guard of
the said piston to enter the spaces made between the circulating flues; third,

page_text: by placing a concentric tube around the upper part of the. central tube
through which the air passes, and thereby increasing the length of the passage,
without at the same time materially adding to the length of the said central
tube; fourth, by making use of a method of direct refrigeration, by injecting
water into the interior of the cold chambers.
Seventhly, and lastly, I have adopted a general arrangement of construction,
in which all the parts are closely and compactly arranged, and the various
motions are transmitted in a very convenient manner.
I also claim the manner of managing the engine by hand, which is as
simple and convenient as in the stationary engine.
In witness whereof, I, the said Charles Louis Felix Franchot, have here-
unto set my hand and seal, this Fourth day of June, in the year of
our Lord One thousand eight hundred and forty-five.
CHARLES LOUIS FELIX (L.s.) FRANCHOT.
Taken and acknowledged by Charles Louis
Felix Franchot (party hereto), at Paris,
in the Kingdom of France, this Fourth
day of June, One thousand eight hun-
dred and forty-five,
Before me,
THOMAS PICKFORD,
AND BE IT REMEMBERED, that on the acknowledgement abovesaid,
the aforesaid Specification was inrolled word for word as above written. And
also the Specification aforesaid was stamped according to the tenor of the
Statute made in the fifty-fifth year of the reign of His late Majesty King
George the Third.