AN IMPROVED. ROTATIVE ENGINE
Year: 1863

page_text: LETTERS PATENT to Michel Emile Eyth, of No. 60, Boulevart de Stras-
bourg, Paris, France, Civil Engineer, for the Invention of "AN IMPROVED.
ROTATIVE ENGINE."
Sealed the 29th December 1863, and dated the 4th July 1863.
PROVISIONAL SPECIFICATION left by the said Michel Emile Eyth at
the Office of the Commissioners of Patents, with his Petition, on the
4th July 1863.
I, MICHEL EMILE EYTH, of No. 60, Boulevart de Strasbourg, Paris, France,
Civil. Engineer, do hereby declare the nature of the said Invention for "AN
IMPROVED ROTATIVE ENGINE," to be as follows:-
The rotative engine of my Invention is composed of a. circular hollow ring.
or steam channel, the section thereof being of a circular shape, it could,
however, be of any other regular shape. A piston made as usual of one or
two springy metallic rings is fitted and plays in the circular steam channel,
where it is pushed forward by the steam introduced once at each revolution:
at a proper time. The main shaft is placed at the central part of the ring-:
shaped steam channel; it is provided with a rather thin crank or forked cam,
which enters and runs freely in a groove cut all around the inner part of the..
steam channel where it is caught and actuated by the back part of the piston:
which thus causes the shaft to rotate. To prevent the steam introduced into
the channel escaping through the inner circular groove a tight joint is made?

page_text: by means of an endless chain composed of compact links fitting exactly in the
groove; this chain is raised up by the forked end of the cam or crank as it
passes, and directly after the said chain is pressed back down to its place-in
the groove by the piston as it runs in the channel, thus there can be no escape
of the steam. A moveable partition in the steam channel is raised up by
the piston as it runs, and the steam escapes at these times through an outlet
suitably placed. After the passage of the piston the partition falls back, and
the steam entering betwixt the said partition and piston pushes the latter
forward. The same motions take place for each revolution of the piston
and shaft.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Michel Emile Eyth in the Great Seal Patent Office on the
2nd January 1864..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MICHEL
EMILE EYTH, of No. 60, Boulevart de Strasbourg, Paris, France, Civil
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourth day of July, in the year of our Lord One
thousand eight hundred and sixty-three, in the twenty-seventh year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Michel Emile Eyth, Her special licence that I, the said Michel Emile
Eyth, my executors, administrators, and assigns, or such others as I, the
said Michel Emile Eyth, 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 "AN
IMPROVED ROTATIVE ENGINE," upon the condition, amongst others, that I, the
said Michel Emile Eyth, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should par-
ticularly 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 Michel Emile Eyth, do hereby declare
the nature of my said Invention, and in what manner the same is to be

page_text: performed, to be particularly described and ascertained in and by the following
statement:-
Rotative engines as hitherto constructed are all liable to the same drawback,
viz., the expense of steam, which being greater than for reciprocating engines,
has prevented their general use. This great expenditure of steam is owing
more especially to the difficulty of making steam-tight joints in the groove of
the circular channel, in which runs the crank embodied with the piston. In
order to have a circular motion imparted to the piston by the steam introduced
within the engine, it is necessary that an obturator of an appropriate shape
should stop the passage of the steam in the circular ring channel at a given
point, and that obturator must have an intermittent motion, so as to recede
once in each revolution of the main shaft, and thus leave a free passage to the
piston. The said obturator can be arranged in several ways, and be of any
convenient shape, its action being ever the same. Now, the steam works
generally in such engines in the following manner :-In the beginning of the
piston's motion the obturator being shut and the steam inlet open, the piston
must of course start under the pressure of the steam since the steady obturator
is holding fast in the opposite side. The piston carries along the main shaft in
its rotative motion through the interference of the crank. When the piston
has almost completed a revolution in the circular or ring channel, the obturator
moves back and opens the passage of the said channel which it was shutting,
allowing a free passage to the piston; at this very moment the escape of steam
takes place, and the obturator recloses the channel behind the piston; then a
second revolution of the machine is produced under the same conditions.
The rotative engine of my Invention is planned on this very system, and
I have contrived to produce a practical working machine by lessening the
friction and the waste of steam. The chief piece of the rotative engines, that
which fills the place of the cylinder in reciprocating engines, is a circular or
ring-shaped channel, the straight sectional shape of which can be either round,
square, or of any other regular form. The rotative engine of my Invention
is represented on the two annexed Sheets of Drawing forming part of this my
Specification, in all the Figures of which the same pieces are pointed out by
the same letters.
The Figures 1 and 2 are general views, Figure 1 elevation, taken on the
side opposite to the fly wheel, Figure 2 vertical section taken through the axis
of the. main shaft. The circular or ring-shaped channel is made of two
separate pieces A and B, strongly united together by several screw bolts f;
near the said bolts a tight joint is made all around the flange K in the usual
way, to prevent any escape of steam. The piece B is provided with two

page_text: horizontal brackets J embodied with it, and strengthened by ribs E. The
piece B bears the steam chest h and slide valve, the settle ring of the induction
pipe is shewn at k on the steam chest. The frame D carrying the whole
engine is of a rectangular shape, hollow in the middle for the passage of the
lower part of the circular channel. The bearings P of the main shaft are
fitted on the frame, and also two chairs p, to fasten the piece B by means of
the brackets J'and bolts e. This arrangement reduces the heighth of the
engine, and especially of the bearings (Figure 2). The circular or ring-
shaped channel could be placed outside of the sole plate D, especially in small
engines, when this plate could be cast in a single piece with the piece B. The
crank F is keyed fast in the middle part of the main shaft M; the piston G
is attached to its end. Between the two parts A and B of the circular channel,
towards the centre, there is a circular groove d of a regular width (Figure 2),
so as to allow the crank to travel freely within; the width of the said groove
must be proportionate to the force of the engine. In several trials which
have been made with rotative engines of similar systems, the crank was a
comparatively thin plate, on which the piston was attached, and this plate ran
in a groove somewhat similar to the groove used in my engine. The joints
were made either with metallic rings or with tow, requiring a constant and'
special lubrication, and the said cranks absorbed a considerable portion of the
force of the engine by working as a brake. I endeavoured especially to
supersede the imperfect joints just spoken of by a better mode of stopping the:
groove d, and it is this improvement which constitutes the principal feature of
my Invention. I believe I have got the result, which is necessary to have a
rotative engine working with advantage by making a steam-tight joint almost
without any friction by means of a metallic chain of a special description.
The said chain is composed of a number of links R as long as possible, which
are plainly shewn in the Figures 2, 6, 7, 8, 9. I can say that this chain fills
up exactly the groove which is between both parts of the circular channel
by its bearing exactly on the crowns 6 and b', Figures 2 and 9.
The section of the chain shewn Figure 9, is so thick that its upper part is
level with the inner surface of the circular steam channel broken in two parts
by the groove
d whatever may be the sectional shape of the steam channel.
The chain of my engine is somewhat similar to "Gall's" chain, but the links of
the former are quite full when it is mounted and fitted in the space where it is
to work, it is as it were a ring of a single piece. It is formed by a number of
identical links R, Figures 6, 7, 8 and 9, attached to each other by metallic pins
or axis n, the links should be as long as possible in order to make it cheap
and to lessen the causes of steam escaping which could arise from bad work-

page_text: manship, but the links must not binder, by too great a length, the passage of
either the piston or the crank. By inspecting a link R, it will be seen that at
both ends there are pins or axis n and n' running through; on the side of the
pin n there is a notch or recess cut into the link at right angle with the pin,
whilst on the other side it is cut as a tenon to fit exactly in the notch; each
link is shaped in the same manner with a recess on one side and a tenon on the
other. The Figures 6 and 7 shew that two links may be inclined over one
another by hinging around the pin n, and that the whole chain can be undulating,
and the joints formed by the links are perfectly steam-tight. When the chain
is mounted, viz., when its links are united by their pins or axles, both faces A'
and B' must be perfectly straight and in parallel direction, and the surface r, s,
shewn in section, Figure 9, must be shaped exactly as the circular groove or
channel left for the passage of the crank. The surfaces A¹ and B¹ are snugly
adjusted over the edges of the groove d of the circular channel already men-
tioned, (see Figure 2,) and when the rotative engine is set up the surfaces A¹
and B' of the chain must softly slide over the corresponding surfaces of the
groove..
The Figures 6, 7, 8, 9, shew a chain intended for a rotative engine in which
the circular steam channel is round in section, if the section of the said channel
was of a different shape the surface r, s, would be modified so as to agree
exactly and form the continuation of the surface of the channel divided by the.
groove. Within the links tow, leather, india-rubber, or any other suitable.
packing for joints may be applied, the said joints should be made either for the
purpose of lubricating in a better manner the pieces composing the chain, or
to lessen the friction and consequent wear of the said pieces.
In the Figures 3 and 10, which are sections made in the middle of the
circular steam channel across the main shaft, it is to be remarked that the
chain is thrown out of shape in a certain portion of the circumference, it runs
out of the groove near the piston as it passes, crossing then through the crank
under the pressure of a roller T, on which it is bearing. This roller which is
inserted in the said crank, can revolve freely on its axle t, which is parallel to
the main shaft. It will be easily understood that the chain remains motionless
in the greatest part of its length, and that the smaller portion which moves
does it only by sinking in the groove d, under the pressure of the piston as. it
passes, then rising before the passage of the crank, being lifted up by the
roller of the said crank. Each link is removed once for each revolution of the
engine, and it is to be remarked that the vibrating angle of each link is hardly
noticeable, and the wear of the chain is almost nil. I have applied and
experimented the system of chain which has just been described, but I mean

page_text: to modify its shape, as well as the shape of the links, if I think it proper, and to
make them either with metals or any other suitable material, so I could make
a chain with a band of india-rubber or a kind of a strop, and cover it to receive
the friction of the piston, with metallic plates. The crank F which can be made
either with a single piece, or with several pieces suitably disposed together, is
provided with a recess to receive the roller T, and above it the chain which
enters freely into it as shewn Figures 3, 4, 5. The Figure 4 is a section
made through the crank by the line A, B, and Figure 5 is a section of the
same crank through the line C³, D. The piston G, which is made with
metallic spring rings, is similar in its arrangements to the pistons used in
reciprocating engines, it is attached by bolting to the end of the crank, as
shewn Figure 3. It can be made with one or several rings in the case of two
rings, as shewn Figure 3, the nearest one to the crank Y is hollowed in the
portion which should touch the chain so as not to hinder the motion of the
said chain. The rubbing surface of the piston must bear exactly over
the portion of the inner surface of the steam channel where it is touching, so
as to be in the same workable conditions as in ordinary steam engines. It is
advantageous to make the piston as thin as practicable, so as to lessen the loss
of power owing to the friction of its surface against the inner surface of the
circular steam channel. I have already mentioned the obturator and its mode
of working in rotative engines. The steam exerts its pressure against the said
obturator just as against the top and bottom of cylinders in the reciprocating
engines. The obturator which I have adopted is a steam gate or moveable
partition V, on which is attached a cylindrical rod c, Figures 2 and 3; this
gate can slide freely in a groove ✗, and in the extension of the groove which
is a kind of metallic box Z, provided on its top with a stuffing box i, in which
plays the rod c. The groove for the passage of the steam gate is cut by
half in each part of the circular steam channel, and its middle plan runs
through the axis of the main shaft. The side of the steam gate V, which is
opposite to the piston when it begins to move, must be perfectly straight
and snugly adjusted upon the corresponding edges of the groove, this
precaution is necessary so as to prevent the escape of steam behind the
said gate.
Its lower part ought to rest exactly upon the chain, and
for this purpose the part which touches must be furnished with leather
or any other suitable material for making joints. The steam gate is so
disposed that it stops perfectly the circular steam channel, being in the
same conditions as the bottom of the cylinder of ordinary steam engines.
The rod of the steam gate c is actuated by a system of lever and rods C³, D,
E', F, driven by the cam Q, which impels the connecting rod G. The cam

page_text: must raise the steam gate once for each revolution in order to suffer the
piston to pass, but it must at once leave the steam gate which falls back dead
as soon as the piston is through. The steam can be introduced as soon as the
steam gate has fallen back, and it can be stopped when the gate begins to
be raised; this engine would then work without expansion. The whole of the
steam contained within the circular channel can easily escape during the up
motion of the steam gate. If we suppose the steam to be introduced in the
beginning of the travel of the piston, and to be stopped before the rising of the
steam gate, then leaving the steam to work by expansion, this would be an
expansion engine. In both instances the steam will escape at the same point
of the piston's travel. It must be remarked that. the steam gate could fall
back by its own weight when disposed, as in the annexed Drawing, Figures 2
and 3, but the same result could be obtained, the steam gate being in any
other position if it were driven back by a spring. The distribution of steam
is much simplified in my system of engine, because the eduction is effected
naturally without the interference of a slide. The foregoing description relates
only to engines similar to the one shewn on the annexed Sheets of Drawing,
running only on one side, but I apply the chain steam gate and mode of actuating
it and modifying it, if required, to rotative engines running on both sides for
applying especially for marine purposes. This disposition of engine, shewn
Figure 10, will be described hereafter. The steam is let in through a slide
valve worked either by a cam or eccentric. There is but one aperture cut
through the slide valve for letting in the steam which rushes directly in the
circular channel near the groove of the steam gate at S, Figure 3. This
aperture is very short in order to lessen the space by which steam is wasted.
Moreover in the rotative engine running only one way. there is but one
induction of steam for each revolution of the crank, whilst in the common
reciprocating engines two inductions of steam take place for each revolution
of the crank, and besides, the steam ducts are comparatively very long.
There is now the work of the slide valve. As soon as the steam gate has
moved down the slide begins to uncover the inlet and the steam induction can
be stopped at any step of the piston's travel; for instance, to get the steam
expanding of its bulk, the inlet must be stopped at the quarter of the
piston's travel; during the remaining part till the moment the steam gate
moves up the steam works by expansion. If desiring to have an engine
working without expansion the slide must stop the inlet only to the moment
the gate begins moving up. The advantage given by the slide of my system is
evident, because the capacity of the slide box, which is under the same
pressure of steam as in the boiler, may be less, which gives an important

page_text: a
'economy of the power. But the steam let in at each revolution of the piston
ought, of course, either to escape in the atmosphere or run into condenser
according to the kind of engine. In order to leave the steam escaping freely I
place an aperture H in the circular steam channel, being placed near the
steam gate on the side opposite to the induction.. When the steam gate
begins to move up the aperture H is partly uncovered, and it is. more and
more uncovered when the piston moves nearer to the end of its travel; thus
the escape of steam takes place easily through an outlet which can be made as
wide as desired in a comparatively long time, then no connter pressure can
happen on the piston during its travel. When the escape of steam takes
place through the outlet just described it can also run out from the circular
channel through the portion of the groove left open by the raised up chain.
This steam could spread about in the engine room and do injury, which is
to be avoided, and this is easily effected by casting with each half of the
circular steam channel a kind of flange M', with a hole at its center for the
passage of the main shaft, and a steam-tight joint is made against this hole in
style of a stuffing box (Figure 2). The flanges M' just spoken of could be
'dispensed with by applying a double piston (Figure 10); such a piston must
unavoidably be used in the reverted motion engine; the portion of the chain
raised up is then between both pistons. The engine just described is to run
only on one side, but by the addition of a steam gate and piston I can
instantaneously revert the motion in the rotative engines of my system. The
circular groove and chain remaining the same (Figure 10). The crank F
being nearly of the same shape, but two pistons G instead of a single one
are attached to its end part; they are at such a distance from one another
that the portion of the chain raised up by the roller T is betwixt them.
The engine is provided with two slide valves, two steam gates and
six apertures i, ³, ³, i, e, e³, used for letting the steam in or out.
In the Figure 10 the pistons are supposed to stand at the beginning of
their travel. The upper steam gate V is shut whilst the lower one Vis
open, the induction port is open, and the steam escapes through the
aperture ². As soon as the pistons have passed before V₁ this gate is shut,
and the steam enters through the inlet , the steam escaping still out
through the aperture ³, the pistons passing then under the gate V, which
moves up, a second revolution begins and takes place as the first one. For
reverting the motion of the engine the inlet of the steam must be reverted
either by means of slide valves or inlet cocks; and the pressure which was
being produced on one of the pistons is directly transferred on the other piston,
which causes the instantaneous starting motion of the engine in a reverted

page_text: direction. Thus, for operating the reverted motion of the engine instead of:
letting in the steam through the ports e³ and it should be let in through..the
ports and, the apertures and working.successively as escape ports.
Several rotative engines of my system can be disposed on the same shaft, and:
by this means a very regular motion can be obtained without dead point,.this
could allow the fly wheel. to be taken away, or at least using but a very small;
and light one. When employing a single-motion engine it is necessary. to.
have a fly wheel N on the main shaft to get a regular motion, especially when.
working with a long expansion; the size and weight of the fly wheel should
be appropriate to the system of rotative engines, which engines should revolve
with a speed appropriate to the kind of work they are to perform; and, as
I have already mentioned, they can be made to work with or without conden-
sation, with or without expanding the steam, in the hypothesis that it works.
with water steam; but I mean to apply any other kind of steam or gas to
work my rotative engines, such as vapour of ether, ammonia, hot air, expand-
ing mixtures, or any other fluids of the same kind. It is to be understood that
the rotative engines may be disposed according to requirements, either in a
horizontal or vertical position, as is the case with reciprocating engines.
My rotative engine is provided with all the safety organs which are of
general use for reciprocating engines. I have adopted as illustration a regu-
lator or governor of the centrifugal system, as shewn in Figure 1, but I intend
to apply any other kind of regulator, either with spring, magnet, compressed
air, or any other system in use.
My Invention being now described in all its features, together with the
arrangements, fittings, and work of all the organs of this rotative engine,
I would have it understood that I do not confine myself to precise details so
long as the principal character is retained. Indeed, all the organs of this
engine are not new; but the whole of them, the reunion of the known with
the new organs constitutes an Invention of which I claim the exclusive use,
reserving the right to modify any of the parts I think proper, provided that no
departure from the principle on which this engine is built be made, and I claim
particularly,―
First, the use, arrangement, and fitting of a chain inserted in a groove
inside of a circular steam channel working as a steam-tight joint all around the
groove, as described and shewn in the Figures 2, 3, 10, of the annexed Sheets
of Drawings.
Second, the particular disposition of the crank, the end of which is cut with
a rounded recess for the free passage of the chain, which is raised up either

page_text: directly or by means of a roller lodged in a forked recess, as shewn in the
Figures 3, 4, 5, and 10.
Third, using two pistons for engines running both ways, which pistons are
united together by the crank, as shewn Figure 10.
Fourth, the use of several of my rotative engines placed on the same shaft &
in order to get a more regular motion, permitting the use of a fly wheel of
much smaller diameter than ordinary, and even dispensing altogether with
a fly wheel.
In witness whereof, I, the said Michel Emile Eyth, have hereunto set
my hand and seal, this Twenty-fourth day of December, in the year
of our Lord One thousand eight hundred and sixty-three.
Signed and sealed in the presence of
L. D'AUBRÉVILLE, C.E.
M. E. EYTH. (LS.)