IMPROVEMENTS IN ROTARY ENGINES WORKED BY STEAM, SMOKE, GASES, OR HEATED AIR, AND IN THE MODE OF APPLYING SUCH ENGINES TO USEFUL PURPOSES
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, COLIN
MACRAE, of Cornhill, in the County of Perth, Scotland, Gentleman, send
greeting.
WHEREAS I did by Petition humbly represent unto Her present most
Excellent Majesty Queen Victoria that, by communication from a foreigner
residing abroad, I had become possessed of an Invention of "IMPROVEMENTS IN
ROTARY ENGINES WORKED BY STEAM, SMOKE, GASES, OR HEATED AIR, AND IN THE
MODE OF APPLYING SUCH ENGINES TO USEFUL PURPOSES," and Her said Majesty,
being willing to give encouragement to all arts and inventions which may be
for the public good, was graciously pleased, by Her Letters Patent under the
Great Seal of the United Kingdom of Great Britain and Ireland, bearing date
at Westminster, the Fifth day of August, One thousand eight hundred and
forty, in the fourth year of Her reign, for Herself, Her heirs and successors, to
give and grant unto me, the said Colin Macrae, my exors, adññiors, and assigns,
Her especial licence, full power, sole privilege and authority, that I or they,
by myself or themselves, or by my or their deputies, servants, or agents, or
such others as I or they should agree with, and no others, during the term of
fourteen years from the date of the said Letters Patent, should and lawfully
might make, use, exercise, and vend the said Invention within that part of
Her said Majesty's Dominions called England, Her Dominion of Wales, and
Town of Berwick upon Tweed, and also in all Her Majesty's Colonies and
Plantations abroad, in such manner as to my exors, adññiors, and assigns
shall seem meet, and as I or they shall enjoy the whole profit and advantage
A

page_text: arising by reason of the said Invention during the said term of fourteen years;
and for that end Her said Majesty requires and strictly commands all Her
subjects whatsoever within England, Wales, and Berwick upon Tweed, and
also in the Colonies and Plantations abroad, aforesaid, that they shall not
directly or indirectly make, use, or put in practice the said Invention or any
part thereof, nor in anywise counterfeit, imitate, or resemble the same, nor
make any addition thereto or subtraction therefrom, whereby to pretend
himself or themselves to be the Inventor or Inventors thereof: And whercas
the said Letters Patent contain a proviso, obliging me, the said Colin Macrae,
particularly to describe and ascertain the nature of the said Invention, and in
what manner the same is to be performed, by an instrument in writing under
my hand and seal, 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 Letters Patent, as in and by the same (reference
being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Colin Macrae, do hereby declare that the nature of the said Invention is
described and ascertained in manner following, and by the aid of the three
Sheets of Drawings hereunto annexed (that is to say):-
The rotary engines to which the said improvements relate are of that kind
or description wherein the revolving part of the engine consists of two wheels,
fixed side by side, on a hollow revolving axis, and enclosed within a case or
box, so as to be capable of revolving therein, but without touching the interior
of such case or box, the lower part of which contains mercury or fluid metal
or other heavy liquid, and each wheel is formed of a hollow pipe joining to the
hollow at one end of the hollow axes, and proceeding therefrom with a spiral
curve to reach to the circular circumference of the wheel; and then the further
continuation of the same pipe conforms to a large portion of such circular
circumference in the manner of the felloe or rim of a wheel, and the extreme
end of such pipe is left freely open into the case or box, so that when the
wheel revolves that open end dips beneath the mercury or heavy liquid. The
said two wheels are both exactly alike, and have their aforesaid spiral curves
curled round in the same direction of spiral convolution as they proceed
respectively from the hollow axis at the centre of the wheel outwards towards
the circumference of the wheel; but the two wheels are so disposed upon the
hollow axis, one with respect to the other, that the said spiral curve of one
wheel sets out from the hollow axis and arrives at the circular circumference
at points diametrically opposite (or across the centre or axis) to the corre-
sponding points of the other wheel, and consequently the aforesaid open ends

page_text: of the circumferential portion of the two pipes or wheels are also at opposite
sides of the circumference across the centre or axis, so that whenever one of
the said open ends belonging to one wheel is at the lowermost part of the case
or box, and consequently dipping beneath the surface of the mercury or heavy
liquid contained in that lowermost part of the box or case, the other open end
belonging to the other wheel will then be at the uppermost part of the box or
case, and freely open to the interior thereof; and that interior of the said
box or case above the surface of the mercury or heavy liquid is kept always
filled with the steam or other elastic fluid, whereby the rotary engine is to be
impelled and put in motion, so as that the surface of the mercury or heavy
liquid shall be constantly subjected to the pressure caused by the elastic force
of such steam or other elastic fluid; but at the same time the hollow axis of
the two wheels, and the interior of the spirally curved pipes which proceed
from the said axis, and which form those wheels, is kept in open communi-
cation with the atmosphere, or else with a condensing apparatus, so as that
the surface of as much mercury or heavy liquid as is contained within those
spirally curled pipes shall be subjected to much less pressure than the surface
of the mercury or heavy liquid contained in the box or case is subjected to,
and in consequence of the difference between the greater and the lesser of
such pressures, a column of the mercury or heavy liquid will be caused to
mound upwards within each of the curved pipes, which constitutes each wheel,
in the manner of a barometric column in each wheel, and which column will
have the effect of constantly loading each of the wheels with a heavy side,
giving the two wheels a constant tendency to turn round within the box or
case with a continuous revolving motion, and they will carry round with them
the hollow axis whereon the two wheels are both affixed, and the ends of that
axis pass out through central stuffing boxes to the outside of the box or case,
in order to give motion to the machinery which the rotary engine is appointed
to drive; and the revolving motion so given to the two wheels will be in that
direction of revolving motion in which the aforesaid open ends of the curved
pipes move foremost, so as, when either of those open ends dips into the
mercury or heavy liquid at the lower part of the box or case, a portion thereof
will be taken up, in order to mount up into the interior of such curved pipe,
and fill the same to such a level or height above the surface of the mercury or
heavy liquid in the box or case as will constitute a barometric column, as
already mentioned, within each wheel, in order form a heavy side thereto; and
when, by the revolution of the wheels, the portion of mercury or heavy liquid
so taken into each of the curved pipes arrives at the spirally curved part
thereof, it will be conducted by such spiral curve into the hollow axis, and will

page_text: pass out through such hollow axis, but will be returned from the end thereof,
so as to run down again to the lower part of the box or case from whence it
was taken up. The hollow axis has a partition across it, situated between those
two places where the spirally curved pipes of the two wheels proceed out from
the axis, so that the hollow within one end of the axis belongs to and connects
with the spiral pipe of one wheel, and the hollow within the other end of the
same axis belongs to and connects with the spiral pipe of the other wheel;
wherefore all the mercury or heavy liquid which has been conducted, as before
stated, by the spirally curved part of the pipe of each wheel into the hollow
axis will pass out by turns, first at one end and then at the other end thereof,
and such mercury or heavy liquid will be returned from each of the said ends
of the hollow axis to run down again to the lower part of the box or case by a
suitable branch pipe joining with a turning joint to each such end of the
hollow axis; and the reason for having two wheels on the same hollow axis is
to avoid any cessation of the force wherewith that axis is turned round; for
whilst the curved pipe of one wheel is emptying itself (through its spiral part
and hollow axis) of the mercury or heavy liquid, which the same curved pipe
had previously taken in at its open end, and which formed a loaded side to the
wheel, then the open end of the curved pipe of the other wheel will be
receiving a new charge of mercury or heavy liquid to mount up therein in the
manner of a barometric column, and thereby give a loaded side to that other
wheel, as soon as (or before) the other wheel, by emptying itself, as aforesaid,
ceased to be loaded at one side. And rotary engines of the above description
are part of improvements in the production of motive power, for which a
Patent was granted by Her present Majesty to John Alexander Elzear
Degrand, on or about the Twelfth day of December, One thousand eight
hundred and thirty-eight, and whereof a Specification stands duly inrolled in
the High Court of Chancery, and, by reference to that Specification, in
addition to what has been herein-before described, the nature of the rotary
engines to which the present improvements relate will become clearly under-
stood. And for the explanation of the said present improvements, which are
the Invention of the said M. Degrand, conjointly with a friend of his,
communicated to me by the said M. Degrand, I shall proceed to describe,
with the aid of the Sheet I. of the Drawings hereunto annexed, a complete
rotary engine constructed according to part of the present improvements.
Figure 1 is a vertical section, taken longitudinally through the axis of the
engine; and Figure 2, a corresponding vertical section, taken transversely
across the axis. The same letters of reference are used in both Figures to
denote the same or corresponding parts. The revolving part of the rotary

page_text: engine consists of two wheels, formed of circularly and spirally curled pipes,
and put together side by side on a horizontal axis which is common to both
wheels, but the direction in which the spiral of one wheel curls is reversed
in respect to that of the other wheel. Both wheels are enclosed within a box
or case, but the interior capacity thereof is divided by a vertical partition into
two compartments; one of the wheels being in one of those compartments,
and the other wheel being in the other of those compartments, a large hollow
axis which connects the two wheels passing through the partition. Each com-
partment is a close air-tight vessel, and each one is made air-tight in respect
to the other compartment by means of the said partition.
The lower part of the box or case contains mercury or fluid metal or other
heavy liquid, into which the circumforences of both wheels dip, and they
revolve therein; and there is an open communication through the lowest part
of the partition, by which the mercury or heavy liquid can freely pass from
one compartment to the other; but the said communication being immersed
beneath the mercury or heavy liquid, the same will not permit any elastic
fluid to pass from one compartment to the other. The steam or gas or other
elastic fluid, by force whereof the engine is to be impelled, is constantly sup-
plied into one of the compartments, so as to fill the interior space thereof and
constitute a plenum, wherein one of the wheels revolves; whilst the other
compartment has an open communication to the atmospheric air, at which the
steam, gas, or other elastic fluid can freely escape; or else an open communi-
cation to a suitable condensing apparatus, by which an exhaustion or vacuum
is kept up within such compartment; wherefore the interior capacity of the
compartment wherein one wheel revolves may be considered as being main-
tained in a constant state of plenum, whilst the interior capacity of the other
compartment wherein the other wheel revolves may be considered relatively to
that plenum, as being maintained in a constant state of exhaustion or partial
The rotative motion of the two wheels is produced by the mercury
or heavy liquid being forced, by the elastic pressure of the steam, smoke, gas,
heated air, or other elastic fluid, to mount up in the manner of a barometric
column within the hollow of the curled pipe, which constitutes each wheel, so
as to produce a constant load at one side of each wheel, tending to turn them
both round in one direction with forcible motion. The direction of spiral convo-
lution of the curled pipe which constitutes one wheel is, as already mentioned,
reversed to the direction of spiral convolution of the curled pipe, which con-
stitutes the other wheel, and each curled pipe is open at both its ends; the
open end of the outermost part of each curled pipe (most remote from the
centre of the wheel) opens into that compartment in which the same wheel is
vacuum.

page_text: enclosed, and that open end dips into the mercury or heavy liquid as the
wheel revolves. The other open end of the same curled pipe, at the inner-
most part thereof, nearest the centre of the wheel, opens into the interior of
the large hollow axes, by which, as before mentioned, the two wheels are con-
nected together. The mercury or heavy liquid is forced to pass from that
compartment which is, as aforesaid, in a state of plenum, so as to enter into
the open end of the outermost part of the curled pipe of the wheel, which
revolves in that said compartment, and which wheel presents the open end of
the outermost part of its curled pipe foremost as it revolves; and the portion
of mercury or heavy liquid which so enters into that curled pipe is forced to
mount up therein in the manner of a barometric column, whereby it loads
one side of that wheel, and gives it a tendency to turn round; and when by
revolving motion of the wheels the said portion of mercury or heavy liquid
arrives at the open end of the innermost part of the curled pipe, it will be
conducted by such open end into the interior capacity of the large hollow axis
by which the two wheels are connected together, and then from that hollow
axis the same mercury or heavy liquid enters into the open end of the inner-
most part of the curled pipe of the other wheel, which is contained within the
exhausted compartment, and which wheel presents the said open end of its
said innermost part foremost as it revolves, and the portion of mercury or
heavy liquid which so enters is forced to mount up within the curled pipe of
the last-mentioned wheel, in the manner of a barometric column, whereby it
loads one side of that wheel, giving it a tendency to turn round, in aid of the
like tendency of the other wheel, as before mentioned; and such tendencies
of the two wheels will cause both of them to turn round in the same direction.
because the barometric column which loads one side of cach wheel is on the
same side of the centre of motion in both wheels, although in that wheel
which is within the plenum the portion of mercury or heavy liquid which is
contained in the curled pipe of such wheel is progressing therein from the
outermost open end of the said pipe towards the innermost open end thereof;
whilst in the other wheel, which is in the exhausted compartment, the portion
of mercury or heavy fluid which is contained in the curled pipe of such wheel
is progressing therein from the innermost open end of the said pipe towards
the outermost open end thereof.
And note, whereas by continuance of such operation of the rotary engine
mercury or heavy liquid will be continually taken out from that compartment
of the box or case wherein there is the plenum (by the wheel in that com-
partment) and introduced into the other or exhausted compartment (by the
wheel therein), nevertheless the communication, before mentioned, through

page_text: the lower part of the partition allows the mercury or heavy liquid to run back
again from the exhausted compartment to the other one as fast as is requisite,
to prevent any undue deficiency of mercury or heavy liquid in one compart-
ment, or accumulation thereof in the other compartment. The box or case
of the rotary engine represented in Figure 1 is marked A, B, C, D, being a
hollow cylinder or drum, with its two ends A, B, and C, D, rather concave
at the inside of the drum. The horizontal axis Q, R, of the two revolving
wheels M, m, P, p, and U, u, S, s, occupies the central part of the box or
case, and that axis passes through stifling boxes at the centres of the two
concave ends, A, B, and C, D. E, F, is the vertical partition by which the
interior capacity of the box or case is divided into two compartments, A, B,
F, E, and E, D, C, F; the former of those compartments containing the
revolving wheel M, m, P, p, within it, and the latter compartment containing
the wheel U, , S, s, within it. The partition E, F, has a large central hole
through it, to admit the large hollow axis H, I, K, L, of the two revolving
wheels to pass through the partition, which partition makes a close junction
around the said hollow axis, in order to prevent any elastic fluid passing by the
partition, so as to get from one compartment to the other; but nevertheless
the hollow axis can turn freely round in the said central hole through the par-
tition E, F, and the hollow axis IT, I, K, L, connects the two wheels together
like one wheel, although cach wheel is, as already stated, enclosed within its
own distinct compartment of the box or case. X is the induction passage through
which steam or other clastic fluid by which the engine is to be worked is con-
tinually supplied into the compartment A, B, F, E, so as to keep up a plenum
therein around the revolving wheel M, m, P. p. Y is the eduction passage,
by which such clastic fluid is conveyed away from the compartment E, D, C, F,
either to make its escape into the open air, or else to be condensed in a con-
densing apparatus, so as to leave the interior of that compartiment in a state
of exhaustion relatively to the state of plenum which is kept up in the other
compartment A, B, F, E. The lower part of the interior capacity of the case
contains a due quantity of mercury or fusible metal, or amalgam of metal,
with mercury or other heavy liquid, and the lower part of each revolving
wheel is immersed therein. G is an opening at the lower part of the par-
tition E, F, to allow such mercury or heavy liquid to pass freely from one
compartaient to the other; but clastic fluid cannot pass, because the opening
G is always immersed beneath the mercury or heavy liquid.
Note. to avoid useless words, I shall mention only mercury; but it is to
be understood that other heavy liquid, before mentioned, may be used; also,
that to keep such heavy liquid in a fluid state, the outside of the case may

page_text: have heat applied to it, if heat is requisite for that purpose. The curled pipe
which constitutes the wheel M, m, P, p, and which wheel is enclosed within
the plenum compartment of the box or case, is represented in the transverse
section, Figure 2, which shews that the greatest part of the curl J, h, i, j, l
is a circular curve, and concentric with the axis of the wheel, that concentric
curve forming the greater part of the circumference of the wheel; but the
spiral portion of the curl occupies only a small portion of that circumference
at J, 1. The said curled pipe is open at both its ends, which are marked J
and I, whereof respectively the open end J is the outermost portion of the
curl (or that end which is most remote from the centre), and the said
outermost open end J moves foremost when the wheel revolves, and there-
fore that outermost open end J dips into the mercury contained in the
plenum compartment A, B, F, E, so as to take in the same into the curled
pipe J, h, i, j, l. The innermost open end of the curl which is nearest
to the centre opens into the interior of the large hollow axis H, K, so
as to deliver or discharge into that hollow all the mercury which, as
before mentioned, has been taken into the curled pipe. The uppermost
row of five small figures, marked Figure 3, represent the said wheel M, m,
P, p, or Figure 2, in five different positions, which it assumes in succession
during each of its revolutions, in order to explain the action of the mercury
within the curled pipe at cach of those positions, and the manner in which
it is caused to mount up in the curled pipe, like a barometric column, so as
to load one side of the wheel, and give it a tendency to turn round in the
direction of the arrows. The other wheel U, u, S, s, Figure 1, which is
enclosed within the exhausted compartment E, D, C, F, of the box or case, is
composed of a curled pipe, exactly the same as that of the first-mentioned
wheel, except that the spiral portion of the curl is reversed in the direction of
its obliquity, and the two wheels are so put together that the open ends J
and of the curled pipe of one wheel are at a part of the circumference of the
wheels, which is one-fourth part of that circumference (or ninety degrees)
distant from the corresponding open ends of the other wheel. It is the
innermost open end of the curled pipe of the wheel U, u, S, s, which moves
foremost when the wheels revolve, and therefore that innermost open end will
take in mercury which has been previously delivered into the interior of the
hollow axis H, K, as already explained, by action of the first-mentioned wheel
M, m, P, p, and the mercury so taken into the curled pipe of the wheel U, u,
S, s, will be ultimately delivered or discharged at the outermost open end of
the same curled pipe into the exhausted compartment E, D, C, F. The
lowermost row of five small figures, marked Figure 4, represent the wheel

page_text: U, u, S, s, in five different positions, corresponding to those of the uppermost
row of five figures, so that each of the five figures in the lower row,
Figure 4, stands immediately under a corresponding figure of the upper row,
Figure 3; and each pair consisting of two figures, one under the other, will
serve to explain the cotemperaneous action of the mercury in the two wheels,
and the manner in which the mercury is caused to mount up like a barometric
column within the curled pipes of the two wheels at the same time, so as to
produce a heavy side to both wheels, in order to give them a tendency to turn
round in the direction of the arrows. The action of the engine may be
explained as follows:-If mercury is used for the heavy liquid it will be
naturally liquid, but if amalgam of mercury with other metal, or if fusible
metal be used, the external case is to be heated, as already mentioned, until
the heavy liquid becomes perfectly fluid, as may be known by a suitable
indicator for that purpose, and the mercury or heavy liquid being in a very
fluid state will stand at the same level in both compartments of the box or
case until steam, smoke, gas, heated air, or other elastic fluid, by which the
engine is to be worked, is admitted at the induction passage X, Figure 1,
and then by the elastic pressure of that elastic fluid the surface of the
mercury or heavy liquid will be pressed downwards within the compartment
A, B, F, E, (wherein the plenum is to be maintained,) probably to the level v,
for instance, and owing to the free communication at G, for the mercury to
pass from one compartment to the other, and owing to the exhaustion or
relative exhaustion which is maintained within the other or exhausted compart-
ment E, D, C, F, by the escape of elastic fluid from that compartment through
the eduction passage Y, the surface of the mercury will be raised within that
exhausted compartment E, D, C, F, probably as high as the level V; in such
case the difference of the two levels and V will be the height of a barometric
column of the heavy liquid, which may be considered as forming a measure
of the pressure of steam or elastic fluid constituting the whole intensity of
impelling force by which the engine is to be worked; and supposing the
interior capacity of the large hollow axis N, H, I, T, u, K, L, t, Figure 1, to
contain only so much of the elastic fluid as will cause an elastic tension,
which is intermediate between the clastic tension of the plenum of such
elastic fluid within the plenum compartment A, B, F, E, and the elastic
tension of the exhaustion or relative exhaustion of such fluid within the
exhausted compartment E, D, C, F; then the mercury or heavy liquid will
be caused to mount up within the curled pipes of both revolving wheels
in the manner of barometric columns therein, as is explained by the several
figures which are disposed one over the other in pairs in Figures 3 and 4;

page_text: and in consequence of such barometric columns, both wheels will become
loaded on the same side of their common centre of motion with a preponderating
weight, and their rotative motion will begin, and as long as a sufficiency of
the elastic fluid is supplied at X and carried away at Y (so as to maintain
each of the compartments in the intended state of plenum and exhaustion or
relative exhaustion), the said barometric columns will continue to be kept
mounted up within the curled pipes of the two wheels by pressure of the
elastic fluid, and the masses of mercury constituting those columns will be
pushed along in those curled pipes by the force of the elastic fluid acting
behind those masses, which masses serve for two liquid pistons, whereof the
weight acting at one side of the centre causes the two wheels to turn round,
the motion so induced being a revolving or rotary motion of both wheels
with their curled pipes, the said liquid pistons remaining stationary within
the curled pipes whilst the latter revolve, until by continuance of the
rotary motion the open ends of the curled pipes of first one and then the
other of the wheels arrives (once during each revolution of the wheels) at
the surface of the mercury in the box or case, and then one of the said
masses of mercury which has acted as a piston passes out at one of those
open ends, and at or about the same moment a fresh mass enters into the
other open end of the same curled pipe, and is forced to mount up (by
pressure of the elastic fluid) as a barometric column in that curled pipe,
so as to form another liquid piston, which is made to operate in its turn
exactly as its predecessor had done, for keeping the same side of the wheel
constantly loaded with a preponderating weight; and at every time that a
mass of mercury constituting a liquid piston passes out in that manner from
the open end of that curled pipe wherein it has so operated, then as much
elastic fluid as has been employed in impelling or pushing such liquid piston
along in the said curled pipe in manner aforesaid will also pass out at the open
end of that curled pipe after the said liquid piston has passed out therefrom;
and the operation of both wheels is alike, as regards a succession of masses
of mercury being taken in one after another at one open end of the curled
pipe of the wheel, and being forced (by pressure of the elastic fluid) to mount
up therein in the manner of a barometric column, which acts as a heavy side
to the wheel, tending to turn it round, and which mass of mercury is pushed
forwards in the curved pipe (by pressure of the elastic fluid) in the manner of
a liquid piston until the wheel has gone nearly round the said mass, then
passing out at the other open end of the same curled pipe, and being followed
by as much clastic fluid as has been employed in impelling the said mass
through all the length of the curled pipe; and also another like mass or piston

page_text: of mercury is taken in at the other open end of the curled pipe at or about
the same time that the preceding mass or piston so passes out, the difference
between the manner in which the said operation takes place in the two wheels
being, that the wheel M, m, P, p, which occupies and revolves within the
compartment A, B, F, E, wherein the plenum is maintained, takes in such
masses of mercury at the outermost open end of its curled pipe from the
mercury which is in the bottom of that compartment, and discharges them
(together with the elastic fluid which has impelled them) from the innermost
open end of that curled pipe into the interior of the hollow axis H, I, K, L, of
both wheels; but the other wheel U, u, S, s, which occupies and revolves
within the exhausted or relatively exhausted compartment E, D, C, F, takes
in such masses of mercury at the innermost open end of its curled pipe from
the mercury which is within the interior of the hollow axis H, I, K, L, and
discharges them (together with the elastic fluid which has impelled them)
from the outermost open end of that curled pipe into the exhausted compart-
nient E, D. C, F. The mode of action of the rotary engine represented in
Sheet I. being now explained, the following particulars relative to its con-
struction will convey useful information to the maker of such engines, although
the construction may be greatly varied, at the discretion of the said maker :-
Each of the revolving wheels with its curled pipe is composed of two circular
disks of cast iron, having suitable rims projecting from its flat surface for
fastening long scrolls of sheet iron to those rims, in order to unite the two
lisks together, so as to form the curled pipe by the interval which is left
between the convolutions of the said scrolls, each of which makes nearly two
convolutions, as is sufficiently explained in Figures 1 and 2. One of each of
the said two disks M, N, n, m, and S, T, t, s, is a flat plate, with only a central
hole through its central boss, which hole is adapted to fix fast and with a tight
joint upon the central axis Q, R, by means of cross keys or other suitable
means of fastening a wheel on its axis. The other of each of the said two
disks P, H, K, p, and U, 1, L, u, has such a large central hole through it that
it may be considered as a circular ring; and the part 0, 0, of the former of
those rings P, H, K, p, is adapted to fit over the part II, K, of the latter ring
U, I, L. u, with a tight joint, whereby the two rings become united together
as one ring, and when thus united, they form the large or hollow axis
H, I, K, L, of the two curled pipes or complete wheels, and by which hollow
axis it is that the two wheels are, as already mentioned, connected together,
in addition to the connection that is made in consequence of both the flat
plates N, n. and T, t, being fastened upon the solid central axis Q, R. The
two wheels with their curled pipes, which are thus formed (by four disks of

page_text: cast iron and two long scrolls of sheet iron), constitute one hollow drum,
which is fastened on the central axis Q, R, as is apparent in Figure 1. The
exterior of the hollow axis at and near to O, o, must be made truly circular and
concentric with the axis Q, R, in order that such exterior may fit truly into
the large circular aperture through the partition E, F, and the circular edge
of the overlapping part O, o, of one of the rings already mentioned will apply
closely to the flat surface of the partition around the margin of its said
aperture. The partition E, F, is a strong thick plate, or rather a ring, and
the two compartments of the external box or case A, B, C, D, are put together
with flanges at E, F, which admit the circumference of the partition between
them. The outer circumference of each compartment may be sheet iron,
united to the said flanges at E, F, and united by means of angle iron to the
circumferences of the two ends A, B, and C, D. Those ends may be wrought
iron or cast, with a concave or dish shape, and having the stuffing boxes at
their centres for the ends of the solid axis Q, R, to pass through, but to
prevent any passage of clastic fluid by the axis. The ends of the axis Q, R,
may be sustained in suitable bearings, which are not represented, and any
such wheels or cranks or other suitable means of communicating motion as
may be preferred are to be fixed on one or both ends of the axis, in order to
transmit the power and rotary motion of the revolving wheels which are
within the box or case to any machinery which the engine is appointed to turn.
The centre bosses of the flat plates M, N, n, m, and S, T, t, s, Figure 1, may
be fixed on the solid axis Q, R, by means of two conical tubes of steel,
marked a, a, and b', ', which are fitted on near to each end of the axis with
a slight taper, and are fitted into the central holes in the said bosses with a
more rapid taper; and by means of cross keys inserted and driven tight into
openings made across through the bosses and through the conical steel tubes
and through the axis Q, R, all the aforesaid parts are made fast on that axis.
The said keys (which are not represented) have a wedge-like action to force
the said steel tubes a, a, b, b. tight into their several tapered fittings, as is
apparent from the representation of the said openings, whereof one is marked
d', c, c, d. Against the flat ends of the said steel tubes a', a', b', ', the like
ends of two cylindrical tubes or bushes of steel e¹, e, f, f', are applied with a
close air-tight junction, and the latter tubes or bushes are very closely fitted
to a cylindrical part of the axis Q, R, but so as to allow the same to turn
round within them, and the said bushes e', e', f', f', are fastened into pieces
g', g', so as to be like parts thereof. The pieces g', g¹, are similar to what are
called the glands of stuffing boxes, the steel bushes e¹, e', f¹, f¹, being like
what are called the bushes fixed in such glands. The pieces g', g¹, are fitted

page_text: like glands into the hollows of the stuffing boxes A, B, and are held therein
by screws v¹, v', which serve to regulate the pressure wherewith the ends of
the steel bushes e¹, e, f, f, shall be forced to apply against the ends of the
conical steel tubes a, a, b, b; and to prevent leakage, a ring m³, m¹, composed
of four segments is applied within the box A, B, and within the conical inside
of that ring another ring n', n', also composed of four segments, is applied and
held in place by screws ¹, ¹, the joints of the segments of the ring n³, n³,
being interspaced to the joints of the segments of the ring m¹, m¹. The
velocity of motion of the rotary engine is regulated in like manner as in
ordinary steam engines, by a throttle valve, applied to the induction passage X,
to intercept and restrain the influx of elastic fluid into the engine, and such
throttle valve (which is not represented) may be regulated by hand or by a
governor, and by totally closing such throttle valve the influx of elastic fluid
may be wholly prevented, and the motion of the engine will be stopped; and
also for the purpose of expelling air from the interior of the engine (and of its
condenser, if it has one), before settling it to work, as is commonly done in
steam engines, for what is termed blowing through before starting, a valve
may be applied in the partition E, F, as shewn by dotted lines S', Figure 1,
which valve when opened will allow clastic fluid to pass direct from the
plenum compartment to the exhausted compartment; and the rotary engine
may have a fly wheel fixed upon or connected with the axis Q, R, if it is
thought requisite, to regulate the rotary motion very perfectly, because the
power thereof will not operate at all times with a precisely equal force, for at
every time that a liquid piston passes out of one of the curled pipes, and
another of those pistons enters in at the other end of the same curled pipe, as
herein-before described, there will be a short cessation of the preponderating
load which such piston is intended to cause at one side of the wheel in order
to turn the same round; and although such cessation will not happen in both
wheels at the same time, so as to deprive the engine of all its rotary forec, yet
an alteration of the amount of that force must take place, and will render the
motion somewhat variable, unless a fly-wheel or other equivalent regulator is
added to the engine; all which, being the same as in ordinary double-acting
steam engines, requires no farther explanation. And in case it is required to
make the aforesaid rotary engine work in either direction of rotary motion, as
is the case with many steam engines, that is, to turn round either in a back-
ward or a forward direction at pleasure, then the passages X and Y must be
reversed, or made to mutually exchange their respective characters, whereby
the passage Y will become the induction passage, and consequently the com-
partment E, F, C, D, (wherein the wheel U, u, S, s, is enclosed and works)

page_text: will become the plenum; also, the passage X becoming the eduction passage,
the compartment A, B, F, E, (wherein the wheel M, m, P, p, is enclosed and
works) will become the exhausted compartment, and then after that change
all the action which has been herein-before described will take place in the
reverse direction, and will cause the two wheels of the rotary engine to turn
backwards, in the same manner as according to the foregoing description they
turned forwards. The said reversing of the passages X and Y may be easily
performed by means of suitable stop-cocks or valves or sliding valves, such as
are commonly used in steam engines for similar purposes. A convenient
manner of applying a sliding valve for reversing the motion is represented in
Figure 5, Sheet II., which is a section of a rotary engine, nearly the same as
Figure 1, but with some differences, and the same letters denote the same
parts as have been herein-before described. 1, 1, is a close chest, into which
the clastic fluid by which the engine is to be worked is constantly supplied by
a pipe 2, and the two passages X and Y proceed downwards from the flat
bottom of the chest 1, 1, upon which bottom a sliding box valve 3 is applied
with close fitting, so as to slide backwards and forwards thereon by means of
a rod 4, which comes through a stuffing box in one end of the chest to the
outside. When the valve 3 is slided into the position represented in Figure 5,
it uncovers the orifice of the passage X, so as to admit the elastic fluid to pass
freely down out of the chest 1, 1, into that passage X; but the orifice of the
passage Y is covered over by the hollow of the box valve 3, and so is the
orifice of the eduction pipe 5, which is provided for conveying the clastic fluid
away from the engine, either to make its escape into the open air, or (in case
of steam being used) to be condensed in any suitable condensing apparatus,
as lierein-before mentioned; wherefore the interior hollow of the box valve 3
connects the passage Y with that eduction pipe 5, and in such a position of the
valve 3 the action of the engine will be the same as hercin-before described
respecting Figure 1, when the wheels turn round forwards; and in order to
reverse the motion of the engine, the box valve is to be slided endways in the
chest 1, 1, by its rod 4, so far as to uncover the orifice of the passage Y, as is
shewn in Figure V), so as to admit the elastic fluid to pass freely down from
the chest 1, 1, into that passage Y; but the orifice of the passage X will
at the same time be covered over by the hollow of the box valve 3, and so will
the eduction pipe 6, whereby the passage X will be brought into communi-
cation with that pipe 6, and in that position of the box valve 3 the engine will
turn round backwards. The eduction pipe 6 is a duplicate of the eduction
pipe 5, and one such pipe situated between 5 and 6 would be sufficient for
the
purpose now describing; but when there are two eduction pipes 5 and 6

page_text: (as in Figures 5 and V), the orifice of one of those two pipes is completely
closed in either position of the valve 3 by the solid part of that valve, whilst
the orifice of the other of those pipes is covered by the hollow of that valve,
and when the elastic fluid by which the rotary engine is to be worked is steam,
the same is to be produced in any of the kinds of steam boilers which
are used for steam engines, and is to be conveyed from such boiler by a steam
pipe to the induction passage X, Figure 1, or to the chest 1, 1, Figures 5
and V, and either high pressure steam or low pressure steam may be used.
In the latter case, a condensing apparatus of any of the kinds used in steam
engines with a suitable air pump is to be applied to the rotary engine, to draw
off the steam through the eduction pipe and produce a vacuum, the air pump
being worked by the rotary engine; and when high pressure steam is used
such a condensing apparatus and air pump may be employed, or else the steam
which has performed its office may be discharged through the eduction pipe
into the open air as waste steam, so as to produce a relative exhaustion in
respect to the plenum of high pressure steam. The steam boiler must be
supplied with water by a feeding pump worked by the rotary engine; but the
rotary engine may be worked by the smoke, gasses, or heated air which
proceeds from the combustion of suitable fuel within a close furnace, the
combustion of that fuel being kept up by forcing atmospheric air continually
from a blowing machine worked by the rotary engine into the ash-pit of the
furnace beneath the fire-grate whereon the fire lays. The ash-pit being made
close at all parts, the said air is compressed by the action of the blowing
machine, and by passing through the fire in its compressed state becomes in
part converted into gas, and the remaining compressed air is strongly licated,
as well as the smoke or gasses produced by the combustion of the fuel, all
which elastic fuels are greatly heated in their compressed state, and conse-
quently expanded, and the same being conducted from the close furnace by a
pipe which answers to its chimney, and leading to the induction passage X of
the rotary engine, Sheet I. (or to the chest 1, 1, Figures 5 and V, Sheet II.);
consequently the hot and compressed elastic fluid will act therein with expan-
sive force, as high pressure steam would do, to produce a plenum of clastic
fluid in one compartment of the box or case; but such elastic fluid, being
allowed to escape freely through the eduction passage Y from the other com-
partment, will keep the same in a state of exhaustion relatively to the state of
plenum of elastic fluid in the first-mentioned compartment. The furnace must
be built within a strong vessel which will resist the elastic force of the smoke,
gases, or heated air, the fire brick or stone whereof the furnace is built being a
lining to such vessel, so as to protect the same from the full effect of the fire.

page_text: The action of the rotary engine, when it is thus worked by smoke, gases, or
heated air, is entirely dependant upon the forcing of a continual supply of com-
pressed atmospheric air through the fire by a blowing machine, which is to be
worked by the rotary engine, as already mentioned, wherefore it requires some
management at the beginning, in order to compress the elastic fluid and to get
up the fire sufficiently hot for commencing the motion, so as to get the engine
to work, unless the blowing machine could be worked by manual labour or
some other power than that of the engine itself, so as to supply compressed
air to the fire, until such time as the fire is got to burn vividly and sufficiently
to start the engine. But if the blowing machine can only be worked by the
engine itself, then to get up the fire sufficiently for starting, the door of the ash-
pit must be set quite open; and also a communication must be made from the
eduction passage Y (by opening a damper passage) into a high chimney, so as
to cause a draft through the engine, in order that atmospheric air may be
freely supplied to allow the fire to be lighted on the grate, and to cause it to
burn up thereon.
Note, the blowing-through valve S, Figure 1, is also to be opened, so as
to communicate freely from one compartment of the engine to the other, and
thereby allow the draft of the said chimney to cause a direct current through
the engine, and that current being heated smoke, air, and gas will give heat
to the whole engine, and will render the heavy liquid quite fluid and very hot.
Then the ash-pit door must be closed, and the blowing-through valve S must
be shut, and at the same instant a small jet of water is to be injected into that
compartment which is to be the plenum, and by the heat of the parts of the
engine and of the heavy liquid, that water will be converted into steam, which
will cause the requisite plenum within the said compartment for commencing
the rotary motion of the engine, and that motion will put the blowing machinery
in action, so as to supply compressed air to the furnace, and give great activity
to the fire, and as much of the compressed air so supplied as is not converted
into gas by the combustion, as well as the smoke and gasses produced by the
combustion, will become heated, and will act with expansive force, so as to
maintain the plenum which has been commenced within one compartment of
the engine, by means of the aforesaid temporary formation of steam, and such
plenum being so maintained by heated air, smoke, and gas in a compressed state,
the action of the rotary engine will go on, as herein-before fully described.
Note, the high chimney before mentioned may be disconnected by its
damper from the eduction passage Y, and that passage made to communicate
more directly with the open air after the engine is thus got to work, or else
such chimney may be kept always in communication with the eduction passage

page_text: Y, in order that the draft of the chimney may facilitate the eduction of the
smoke, gas, and heated air from the exhausted or relatively exhausted com-
partment of the engine. It is manifest that the utmost pressure of elastic
fluid wherewith the rotary engine, herein-before described, can be made to
operate for turning the wheels round is limited by the height of such a column
of the heavy liquid which is employed in the engine as can be contained within
the magnitude of the revolving wheels of the engine; but if a greater intensity
of pressure of elastic fluid is desired to be used, it may be done by employing
a series of two or more rotary engines of the kind herein-before described,
combined together by means of wheel-work fastened on the axes of their
several revolving wheels; or those axes may be otherwise connected (as, for
instance, by means of coupling bores), so that all must go round together, and
the eduction passage Y of the first of such engines is to be connected by a
pipe with the induction passage X of the second engine, whilst the eduction
passage of that second engine is to be connected with the induction passage of
the third engine, if a third engine is used, and so on, for as many engines as
may be desired to be connected, the eduction passage of the last engine of the
series being open to the atmospheric air, or else connected with a condenser ;
then a very strong pressure of elastic fluid being employed in the first engine
will be so much counteracted by its detention in the succeeding engines as to
operate with only a moderate pressure to cause a barometric column of heavy
liquid to mount up within the curled pipes of the first engine, and which pres-
sure may thus be rendered suitable to the height of the column of heavy liquid
which that engine is qualified by its magnitude to work with; and the same
of the second engine (if a third one is used), the pressure of elastic fluid in
that second engine will be moderated by the application of the third engine,
and so on, because that pressure of elastic fluid which is in the state of relative
exhaustion within the first engine is in the state of plenum within the second
engine, and that which is the state of relative exhaustion of the second engine
constitutes the state of plenum of the third engine, and so on.
And note, as to the expression "state of relative exhaustion," which has
been used in this Specification, as being maintained within one of the com-
partments of a rotary engine, it is to be in all cases understood as having no
relation whatever to the pressure of the atmosphere, but only to that state of
plenum of elastic fluid which is maintained in the other compartment of the
same rotary engine. For instance, if steam or compressed heated air, gas, or
smoke is supplied to one of the said compartments so as to keep up therein
(for the state of plenum of elastic fluid) a pressure of forty-five pounds per
square inch above the atmospheric pressure, and in the other compartment of
B

page_text: the same rotary engine a pressure of only thirty pounds per square inch above
the atmospheric pressure is kept up, then that latter is to be termed a state
of relative exhaustion, according to the sense in which the said expression is
used throughout this Specification, and the difference between the plenum and
relative exhaustion (being, in the instance now mentioned, 15 lbs. per square
inch,) is the intensity of elastic pressure wherewith the rotary engine is to be
worked; and when two or more rotary engines are employed in a series, as
above described, the said pressure of thirty pounds per square inch, which is
the state of relative exhaustion in the first engine, is also the state of plenum
in the second engine, and then the relative exhaustion in that second engine
may be an elastic pressure just equal to the atmosphere, in which case the
difference between the state of plenum and of relative exhaustion in the second
engine will be fifteen pounds per square inch for the intensity of elastic
pressure wherewith that second engine is to be worked; and in case there is
no third engine, the eduction passage of that second engine may open to the
atmospheric air, in order to allow the elastic fluid to escape freely from the
said second engine into the open air, for the purpose of maintaining the said
state of relative exhaustion in the second engine at a pressure equal to the
atmosphere; but if the elastic fluid be steam or condensible vapour, then a
third engine may be used, in which case the steam, equal in elasticity to the
atmospheric air, which (as before mentioned) is the state of relative exhaustion
in the second engine, instead of being discharged therefrom as waste steam
into the open air, is conveyed into the third engine, and constitutes a plenum
therein; and that third engine, having a condensing apparatus and air pump
connected to it, its state of exhaustion will be a vacuum or as nearly a vacuum
as usual in ordinary condensing steam engines, so that the difference between
the plenum and exhaustion or vacuum in the third engine will be thirteen or.
fourteen pounds per square inch for the intensity of elastic pressure wherewith
that third engine is to be worked; therefore all three engines are worked with
nearly an equal intensity of elastic pressure by the same steam in different
stages. It is to be observed that the capacity of each succeeding engine to
take in and pass elastic fluid through its curled pipes should be greater than
that of the preceding engine in the same series, in order that the elastic fluid
may be allowed to dilate itself and occupy more space at each time that it is
used over and over again; wherefore the first engine of a series should have
a very small section, and consequently a small capacity of its curled pipe;
the second should have a much larger section, and consequently a larger
capacity of its curled pipe; and the third, a still larger section and capacity
of its curled pipe; but nevertheless the diameters of the wheels of all the

page_text: engines and the rapidity of their revolution may be the same or nearly the
same; for if the same elastic fluid is to be used over and over again, in
passing through a succession of rotary engines the effect of allowing that
elastic fluid to dilate itself and occupy more space at each succeeding time
that it is so used over again will be the same, as is well known to be very
advantageous in the high pressure condensing engines introduced into use
by Mr. Arthur Woolf, and of which engines many have two cylinders and
pistons, viz, a small one, in which the high pressure steam is first used to
impel the small piston, and also a larger cylinder, into which the steam that is
discharged from the small cylinder is conveyed, in order to expand itself to the
state of low pressure steam, and act over again against the large piston during
its expansion, and ultimately, after having so acted a second time, the expanded
steam is condensed in order to get rid of it.
And note, by thus employing a series of rotary engines to be worked by a
moderate pressure of elastic fluid, water, oil, or tar, or other liquid, or melted
tallow, may be used for the heavy liquid, provided that such liquid does not
boil at a low temperature, and is not of a nature to be corrosive of the
materials whereof the engine is constructed; for, notwithstanding that water
is too light a liquid to give much effect by its barometric columnar pressure to
one rotary engine having wheels of moderate diameter, (and it would be
inconvenient to have those wheels of such very large diameter as to employ a
barometric column of water of sufficient height to operate with a strong
pressure,) nevertheless, by employing a series of rotary engines, the height of
the barometric column in one becomes an addition to that in the next engine,
and so on, whereby the aggregate of several such columns (although they are
all columns of water or oil or other light liquid or melted tallow, and of no
considerable height in each one, would in that aggregate produce a con-
siderable effect; and the weight or specific gravity of the water or other liquid
which is so used as the heavy liquid, may be augmented by dissolving in it as
much potash of commerce as it will take up, so as to render the heavy liquid
a saturated solution of potash, which, as well as being heavier than water,
requires a higher temperature to make it boil when retained under a like
compression.
Sheet II. contains representations, at Figures 5, 6, 7, and 8, of a rotary
engine, which is for the most part similarly constructed to the rotary engine
represented in Sheet I., and herein-before fully described, but with some
additions, for the purpose of adapting the engine to operate with a stronger
pressure of elastic fluid than could be used with full effect to work the engine,
Sheet I., (unless the diameter of its wheels was inconveniently large,) because,

page_text: as herein-before mentioned, the utmost pressure of elastic fluid wherewith that
engine, Sheet I., can be made to operate for turning its wheels round, is
limited by the height of such a column of the heavy liquid used in the engine
as can be contained within the magnitude of the revolving wheels of the
engine. But the engine, Sheet II., has vertical pipes added to it for the
purpose of receiving higher columns of the heavy liquid than the revolving
wheels of the engine could contain, and the wheels are adapted to receive and
be turned round by forcible action of elastic fluid, having an intensity of elastic
force proportionate to such higher columns. The two revolving wheels M, m,
P, p, and U, u, S, s, Figure 5, with their large hollow axis N, n, T, t, and solid
central axis Q, R, are all the same, as already described in reference to
Sheet I., and so is the box or case and its two compartments A, B, F, E, and
E, D, C, F, wherein the two wheels are inclosed, and also the partition E, F,
by which the box is divided into those two compartments, excepting that there
is no opening at the lower part of that partition E, F, to give the heavy liquid
a free passage from one compartment to the other, as in Sheet I.; but in
Sheet II. there is no such free communication between the two compart-
ments, and in lieu thereof the ends x, y, of two curved pipes are closely joined
to the lowest parts of the two compartments, and the two pipes turn up and
stand vertically side by side at 11 and 12, see Figures 5 and 8, to a considerable
height, and they join into one at their upper ends at 13, and it is by the junction
of those upper ends at 13 that the communication between the heavy liquid
contained in the two compartments takes place; but instead of being a free
communication it can only take place under compressure of the column of
heavy liquid which stands in the two pipes x, 11, and y, 12. The one pipe, 18,
which stands up above the said junction of the two pipes is really the eduction
pipe, to convey away the elastic fluid whereby the engine is worked, after
such elastic fluid has performed its office. At the upper part of the box or
case is a chest 1, 1, into which the elastic fluid whereby the engine is to be
worked is continually supplied, and within that chest is a box sliding valve 3,
applying to and sliding upon the flat bottom thereof, to cover or uncover the
orifices of the induction passage X and the eduction passage Y, in such
manner, that by uncovering one or other of those passages, it will admit elastic
fluid from the chest 1, 1, into one of the compartments (wherein the plenum
is to be), and at the same time to allow the elastic fluid to pass away through
the hollow of the box valve 3 from the other compartment (which is to be
exhausted or relatively exhausted) into one or other of the two eduction pipes
5, 6. The action of the sliding valve 3 has been already fully explained, as
applied to the rotary engine, Sheet I., for the purpose of causing the wheels

page_text: The lower ends of the eduction
thereof to work either in a backward or forward direction, but then there
need be only one eduction pipe in place of the two, 5 and 6.
In the present
case, as applied to the engine, Sheet II., although the valve 3 is for the same
purpose of enabling the engine to be worked either way round (and it effects
that purpose in a similar manner), yet there are two eduction pipes, 5 and 6,
which proceed from the lower part of the chest 1, 1, and pass down with a
curved course, as represented in Figure 8, in order to join into the vertical
pipes a, 11, and y, 12, at their lowest parts and y, in the centre lino of the
straight vertical part of each pipe 11 and 12.
pipes 5 and 6 pass up into and stand up a little way within the interior of
those pipes 11 and 12, and terminate with upright nosles at x and y. somewhat
in the same manner as the eduction pipes of locomotive engines enter upwards
into the lower parts of the vertical chimnics of such engines with jets called
blast pipes, in order that by discharging a vertical jet of waste steam upwards
in the vertical centre line of such chimney, the ascending current of smoke
and heated air therein may be accelerated. And in the engine now describing,
the elastic fluid, which is to make its escape from the exhausted (or relatively
exhausted) compartment through one or other of the eduction pipes 5 or 6,
(suppose it to be 5, for instance, as in Figure 5,) will be conveyed through
the eduction pipe 5, Figure 8, and thereby emitted in a vertical jet at y
upwards in the vertical centre line of the corresponding vertical pipe 12,
through the midst of a column of heavy liquid contained therein, whereby the
said vertical jet of elastic fluid will operate to raise up the column of that
heavy liquid, and cause the same to ascend in the vertical pipe 12, and also by
causing an admixture of the elastic fluid with the heavy liquid, whilst the
elastic fluid is in the act of making its way upwards through the heavy liquid,
the compound, which is formed of elastic fluid and heavy liquid; within the
vertical pipe 12, will be much lighter or of less specific gravity than the heavy
liquid by itself would be, and as it actually is, in the other vertical pipe 11;
consequently the heavy liquid will exert so much less force of columnar
pressure on the vertical pipe 12 than is due to its height and density, that the
continuance of the action of the same jet of elastic fluid at y will cause the
mixture of heavy liquid and elastic fluid to ascend upwards in the vertical
pipe 12, thereby relieving the interior of the compartment E, D, C, F, which
is connected with the pipe 12, (and which compartment is to be relatively
exhausted,) from the greater part of the pressure which is actually operative
within the interior of the other compartment A, B, F, E, whereof the vertical
pipe 11 stands full of heavy liquid unmixed with any elastic fluid. And by this
means the two opposite states of plenum and relative exhaustion will take place

page_text: in the two compartments, and will be maintained therein in a suitable manner
for producing the operation of the engine to turn its wheels round; for the
elastic fluid, wherewith that compartment which is in the state of plenum is
filled, presses equally on all parts of the exterior surface of the revolving
wheel, which is enclosed within that compartment, excepting at the area of
the open end of the curled pipe of that wheel; wherefore the absence or
deficiency of the said pressure at that part gives the wheel a tendency to turn
round by virtue of the counter pressure, which is operative against the part
that is opposite to that open end; and in like manner the other wheel, which
is enclosed within the compartment which is relatively exhausted, must sustain
the pressure of so much elastic fluid as is contained within the large hollow
axis M, n, t, T, that pressure acting against all parts of its interior surface
excepting at the area of the open end of the curled pipe of that wheel, and
the absence or deficiency of the said pressure at that part gives the wheel a
tendency to turn round in the same direction as the first-mentioned wheel has
a tendency to turn; and as to any excess of heavy liquid which gets into the
compartment that is relatively exhausted, in the same manner as already
explained respecting the rotary engine, Sheet I., and which excess in that
engine can flow freely through the opening G, Figure 1, in the partition E, F,
in order to get from the relatively exhausted compartment to the plenum
compartment, so as to avoid accumulation in the former or deficiency in the
latter, it is to be observed, that all such excess in the engine, Sheet II., over-
flows at 13 from the upper end of that upright pipe 12, wherein the jet of
elastic fluid is for the time operating to raise the heavy liquid in the said pipe
(and which pipe belongs to the exhausted or relatively exhausted compart-
ment), and the overflow falls into the upper end of the adjacent upright pipe
11, which connects with the plenum compartment and the elastic fluid which
has ascended upwards through the midst of the heavy liquid in the pipe 12
ascends freely up the pipe 13, which is open to the atmospheric air, or else is
connected to a condenser with an air pump, and is therefore, in fact, the real
or ultimate eduction pipe of the engine.
And note, although there are two eduction passages and pipes 5 and 6, only
one of them is operative at the same time, because the solid part of the box
valve 3 closes the orifice of the other one, as already stated, and as is shewn
in Figure 5, where the eduction pipe 6 is so closed, and the other, 5, is open;
consequently no jet of elastic fluid is thrown into the upright pipe 11, but
only into the upright pipe 12 at y, and in that position of parts the engine
will work by turning one way round; but if it is desired to make it work the
other way round, nothing more is necessary than to move, the sliding box

page_text: valve 3 into the position represented in Figure V, and then it will cause an
exchange in the conditions of the two compartments, making that one which
was the plenum become the relatively exhausted compartment, and vice versa;
also the orifice of the eduction pipe 5 will be closed, but the orifice of 6 will
be opened, by which means the jet of elastic fluid will be thrown at x into
the vertical pipe 11, which belongs to the compartment that is now the
relatively exhausted compartment, and all that had been herein-before stated
respecting the kind of elastic fluid wherewith the rotary engine, Sheet I., may
be worked, whether it be steam of high or low pressure, or whether it be
smoke, gas, or heated air proceeding from the combustion of the fuel within
a close furnace, is equally applicable to the engine, Sheet II. But for further
explanation of the mode of working with the last-mentioned kinds of elastic
fluids, Figures 5 and 6 are represented as being disposed over a close furnace
15, which is supplied with a constant influx of air, forced by a blowing
machine worked by the engine (but not represented) into the close ash-pit 16,
beneath the fire grate R, W, whereon the burning fuel lies. The heat excited
by the combustion acts beneath the lower part C, B, of the case, to keep the
same hot, and maintain the heavy liquid in a very fluid state.
And note, if the full action of the fire will be too great for that purpose,
the furnace may have an arch of fire brick interposed between the fire and the
bottom B, C, of the case. The smoke, gas, and heated air proceeding from
the fire passes away through the pipe Z, 2, which goes up and joins to the
top of the chest 1, 1, so as to supply that chest with a constant influx of
clastic fluid, as has been already mentioned to be requisite for producing the
motion of the engine, either to work by turning round backwards or by turning
round forwards, according as the sliding box valve 3 is placed by means of its
rod 4, either in the position represented in Figure 5 or Figure V.
And note, as there will be a strong pressure of elastic fluid within the close
furnace 15 and ash-pit 16, the same must be surrounded with metal casing, as
already mentioned, and the fire door and ash-pit door must be fitted tight
and kept securely shut by screws, which may be done in the manner of the
doors of gas retorts; and there should be two fire doors, one beyond the other,
in order that one may be kept shut whenever the other is opened for intro-
ducing fuel to the fire; and the manner of first lighting the fire and getting
the engine to begin to work, by injecting a small dose of water to form steam,
is to be the same as already described respecting the engine, Sheet I.
And note, whenever it is requisite to give a momentary accession of force
to the rotary engines which are worked, as herein-before stated, by smoke, gas,
or heated air produced by combustion within a close furnace; a small quantity

page_text: of water may be injected into that compartment of the box or case wherein the
plenum is to be kept up, and that water, by falling upon the hot surface of the
heavy liquid and of the hot parts of the revolving wheel, will produce a sudden
evolution of steam, which, by mixing with the elastic fluid, will augment its
elasticity, and give more force of action to the engine, in the same manner as
is directed to be done for first starting the engine into motion, when, from the
fire door having been left open for lighting the fire, such elastic fluid, smoke,
gas, or heated air cannot by itself have acquired any more clastic force than
the atmospheric air. And respecting the mode of applying the rotary engines
which are constructed according to the present improvements to useful pur-
poses, they may be applied to locomotive engines which are to travel on
railways, or for propelling vessels on water, the solid central axis Q, R, being
prolonged sufficiently to have the running wheels of the locomotive engine or
the paddle wheels of the vessel fixed on the two ends of the axis Q, R; or for
propelling vessels, two, three, or more such engines may be placed with their
axes Q, R, in a line across the vessel, the ends of those axes being connected
by coupling boxes, so that they will all go round together. And when two or
more rotary engines are so combined, they may be worked as a series by the
same elastic fluid passing first through one and then through the next, as
already described, provided that an elastic fluid is provided of sufficient force
to be capable of being used over and over again, in the manner and under the
conditions herein-before explained; and two or three rotary engines so com-
bined in a series may be used for locomotive engines on railways, by applying
one of the combined engines to work one pair of the wheels and the other
engine to work another pair of the wheels of the same locomotive engine; the
same steam or elastic fluid which works one of those rotary engines and pair
of wheels passing away therefrom into the other rotary engine, in order to
work that and the other pair of wheels also, in the manner already explained;
and the same system may be used on board vessels by using four paddle
wheels.
Sheet III. represents another kind of rotary engine which has only one
revolving wheel or curled pipe, and that placed in a horizontal position at the
bottom of a box or case A, B, C, D, wherein the wheel is enclosed, which case
may also serve for the steam boiler, and it contains a heavy liquid (which may
be fluid metal) in the lower part of it, and in that heavy liquid the wheel p, q,
r, s, is wholly immersed, its hollow axis R, Q, P, being in a vertical position,
and standing up through a stuffing box at Q', at the upper or dome part A, B,
of the boiler. The upper part P of the hollow axis above that stuffing box is
within an upper. reservoir Y, which is kept constantly filled with the heavy

page_text: liquid, and which liquid can enter from Y by a side opening into the hollow
axis Q, R, and then descend therein, so as to get into the central hollow of
the wheel p, q, r, s, which with its curled pipe is the same in its structure as
Figure 7, Sheet II., already described; wherefore the heavy liquid, descending
from Y through R, will exert a columnar pressure within the hollow of the
wheel p, q, r, s, which greatly exceeds the pressure of the heavy liquid wherein
the wheel is immersed and by which it is surrounded, so that the heavy liquid
within the hollow of the wheel will have a strong tendency to pass into the
innermost open end of the curled pipe of the wheel, and to flow through the
whole length of the curl, and then to make its escape from the outermost open
end thereof; and in so doing the heavy liquid presses against every part of the
innermost surface of the interior hollow of the wheel, so that the said surface
must sustain a strong columnar pressure of the heavy liquid which is descend-
ing from Y through the hollow axis Q', R, and pressing at every part of such
interior surface, excepting at the area of the open end of the curled pipe, which
area or part of the said interior surface is not subjected to that pressure which
every other part of the interior surface is subjected to, and the absence or
deficiency of such pressure at that said part gives the wheel p, q, r, s, (also
Figure 7) a tendency to turn round in the direction of the arrow, Figure 7,
from the same cause as already explained in reference to that Figure, when it
was considered as part of the rotary engine, Sheet II.; for although the wheel
was in that instance disposed in a vertical position, and was combined with
another wheel, and was also subjected to the combined pressure of clastic fluid
acting together with the pressure of the heavy liquid, nevertheless the tendency
to produce rotary motion of the wheel in Sheet III. is the same, videlicit, by
virtue of the counter pressure of the heavy liquid against that part of the
interior surface of the hollow wheel which is is opposite to the open end of the
curled pipe. The revolving motion and power thus given to the wheel is trans-
mitted to the machinery which the engine is appointed to work by means of
any suitable wheel-work, such as Z, Z, fastened on the upper end of the axis
P, where the same is solid, above the hollow part Q', R, and above the reser-
voir Y. These particulars being understood, it only remains to shew how the
heavy liquid is forced by application of the pressure of an elastic fluid to mount
up into the upper reservoir Y, in order that it may keep the same filled, and
so maintain a continuance of the aforesaid columnar pressure within the
hollow axis R and wheel p, q, r, 8. The boiler A, B, C, D, is divided by a
horizontal partition F, E, into two compartments, an upper and a lower one;
the latter may serve as the steam boiler G¹, G', being the water therein, which
must be kept replenished as it boils away, and it rests above the heavy liquid

page_text: that occupies the bottom C, D, of the boiler, and beneath which bottom the
fire is applied; M, M, being the fire grate; and G, H, K, L, the brick work,
and the flue of the fire-place surrounds the vertical sides D, F, C, E.
The upper compartment A, B, F, E, or dome of the boiler communicates
with the lower compartment F, E, D, C, nearly at the bottom thereof, by means
of a cylindrical pipe or tube d, d, c, c, which descends from the horizontal
partition E, F, around the hollow axis Q', R, and leaves a vacant space or.
passage around that axis. The lower end c, c, is open; and that open end is
immersed beneath the surface of the heavy liquid which is at the. bottom of the
boiler, and by which liquid the wheel p, q, r, s, is surrounded. The steam which.
arises from the water G, G¹, and which occupies the space below the partition:
F, E, passes through openings e, m, into the space H, H', within another
larger tube e, l, f, m, which latter surrounds the former tube d, d, c, c, and like
that tube is joined to the partition E, F, and is also open at its lower end 1, f,
but that open end descends somewhat lower than the aforesaid end c, c, of the.
other tube d, d, c, c. There is also another smaller tube g, h, joined at its.
upper end to the partition E, F, and its lower end 9, which is open, does not:
descend so low as the aforesaid open end c, c. The upper end h of the tube g, h,
rises up through and above the partition E, F, with a small vertical jet pipe h,
which is situated immediately beneath the centre of the lower orifice V of the
large upright pipe V, S, which ascends through the dome cover A, B, of the.
boiler, and joins laterally at S to the reservoir Y. The said lower, orifice V is
not shut up by the jet pipe h, but is left open into the upper compartment
A, B, F, E, and the orifice so left open at V is immersed beneath the surface
of the heavy liquid, which is always contained in the bottom E, F, of, that upper
compartment, in consequence of heavy liquid being forced up into the said
upper compartment from out of the lower compartment through the upright
tube g, h, and also through the larger central tube c, c, d, d, by pressure of the
steam in the space above the water G', G', and beneath the partition E, F,
acting downwards upon the surface of the heavy liquid which is at the bottom
D, C, of the boiler. When the steam, by so acting and pressing downwards,
has accumulated in the boiler until it has depressed the said surface of the
heavy liquid below the orifice g of the upright tube g, h, then, as no more
heavy liquid can be forced up, steam will follow up the tube g, h, with great
rapidity of ascent, and will be emitted upwards in a vertical jet of steam through.
the jet pipe h into the central line of the large upright pipe V, S, so as to ascend.
in the midst of the column of heavy liquid contained in that upright pipe,
whereby the said vertical jet. of steam will operate to. raise.up the column of:
that heavy liquid, and cause the same, to ascend in the upright pipe V, S; fors
up

page_text: owing to the admixture of the heavy liquid with the steam, which is in the act
of making its way upwards through the heavy liquid contained within the pipe
V, S, the compound which is formed of heavy liquid and elastic steam within
that upright pipe V, S, will become much less lighter or of less specific gravity
than the heavy liquid by itself would be, and consequently the columnar
pressure of the contents of the upright pipe V, S, will be lessened so much as
that the continuance of the upward rush of the jet of steam acting at h will
carry up the contents of the pipe V, S, and cause the same to overflow at the
upper end S into the upper reservoir Y, where the steam which has ascended
in mixture with the heavy liquid will then extricate itself therefrom, and pass
away through the eduction pipe X, which may either lead to the open air, if
steam or smoke, gas or heated air, is used to work the engine, or to a condenser,
if steam is used; and as fast as the heavy liquid is so caused to mount up the
pipe V, S, more of the same liquid will be drawn in at the lower orifice V, at
the space thereof which is left open around the jet h, so as (by the liquid so
drawn in) to replenish the column of heavy liquid in the upright pipe V, S, and
supply the place of that which has been raised upwards therein and discharged
at S. The action whereby the ascending jet of steam at h causes the ascent of
the heavy liquid in the upright pipe V, S, is somewhat similar to that action
whereby the jet or blast of waste steam which is admitted into the lower part
of the upright chimney of a locomotive steam engine causes a rapid ascending
current of the contents of such chimney to pass up through the same; but the
lightening of the heavy liquid which is caused in manner aforesaid by the
admixture of the steam therewith greatly facilitates the aforesaid action of
the jet of steam h, whereby it occasions the upward motion of the contents of
the upright pipe V, S, as above explained. And in order to regulate the action
of the jet of steam at h, the same may have a regulating cock to diminish or
enlarge the passage through it; or instead of a cock a valve may be applied
beneath the jet pipe h, as at i, and which valve is suspended by a small rod
from a regulating screw 2, which can be turned at the outside in order to raise
or lower the valve, and thereby give more or less passage for the steam which
is to form the jet at h. A high temperature is produced by the combustion of
coal within a close furnace, which (as herein-before explained) is supplied con-
tinually with compressed atmospheric air forced into the close ash-pit beneath
the fire grate by a blowing machine worked by the rotary engine, that mode
of operating with a close furnace being for the purpose of supplying compressed
smoke, gas, or heated air to serve as the compressed elastic fluid for working
the rotary engine. The said high temperature causes a rapid destruction of

page_text: the iron bars of the fire grate, and to obviate that inconvenience the said bars
are to be covered at their upper surfaces whereon the fire rests with a substance
which will resist fire, and which is a slow conductor of heat. For that purpose
each iron bar is formed with an open groove along its uppermost edge, as is
shewn in section at W and R, Figure 6, Sheet II., and also at M, in Sheet III.,
and that groove is rammed full with earthy matter, which will stand fire, and
which may be fire clay, such as is used for making crucibles, or melting pots
mixed with a proportion of like clay, which has been strongly burnt and
pounded, that is, old crucibles broken up and pounded, the object of such
mixture being to diminish the shrinkage that the fire clay would undergo by
action of the fire if fire clay alone were to be used. The groove in each bar
being thus filled, the bar is subjected to fire, in order to burn the earthy mixture
into pottery, which will be held in place in the groove by roughness of the
metal of the bar, which metal is left rough for that purpose within the groove;
but as the said pottery will crack across, owing to the shrinking of the clay in
burning, all such cracks are afterwards to be filled up with fine fire clay, and
the upper surface of the pottery then covered over with a layer of suitable
pottery glaze of a hard quality, which will strongly resist fire, and form a sort
of enamel by burning. The fire grate, which is composed of a row of fire bars
of the above kind, has every other bar, W, W, W, Figure 6, Sheet II., alter-
nately, in the row of bars fixed immoveably, as in ordinary fire grates, but the
intermediate bars R, R, between those fixed ones are moveable upwards and
downwards at one end R, Figure 5, of each bar, about a centre of motion R7,
at the other end of the same bar. The rising and falling motion of the move-
able end R of the bar is guided by an upright pin 7, fixed into the strong cross
bearer bar 9, which sustains the grate, and such pin, passing through a hole in
the moveable end Rs of the fire bar, retains that end from lateral deviation.
Beneath the said fixed bearer bar 9 a horizontal axis 10 is is situated, being
sustained in bearings at each end, and it has short levers or fingers projecting
out from it to reach beneath the moveable end Rs of each moveable bar R, R,
and one end of the axis 10 comes out through the side wall of the close ash-
pit 16 to the outside, and by means of a lever handle on the end of the axis
10, motion can be given to the moveable ends RS of the bars R, R, so as to
lift them up, as shewn by dotted lines in Figure 5, and let them down
suddenly, in order to agitate the grate, and break the continuity of the
masses of burning fuel upon it, and also to clear the air spaces between the
bars from obstructions that might arise from pieces of coal lodging therein,
the motion of the bars causing such pieces to be broken, so that they

page_text: will drop through. When tar or coal tar from gas works is to be burned
as fuel in a close furnace of the kind above mentioned, or when other
liquid fuel is to be used therein, for the purpose of working a rotary
engine, by the smoke, gas, or heated air resulting from the combustion,
then the apparatus represented in perspective by Figure 9, Sheet II., is to be
applied. A, B, is a flat shallow vessel, occupying the place of a fire grate, and
being enclosed within the lower part 16, Figure 5, of the close furnace, the
other part whereof is not shewn. There is no fire grate, but a number of
parallel air pipes a, a, Figure 9, are disposed at the bottom of the shallow
vessel A, B, nearly in the same position as the bars of a fire grate would
occupy. All those air pipes extend out through one side of the shallow vessel
A, B, and through the side of the close furnace, and are joined together by a
large cross pipe b, b, which, by means of two forked branches of a larger pipe D,
receives a continual supply of compressed air from the blowing machine F,
which may be a cylinder, or forcing pump, or other suitable blowing machine,
worked by the rotary engine. The tar or other liquid fuel is forced into the
lower part of the shallow vessel A, B, through a small pipe e, by action of a
small feeding pump C, which may be worked by the rotary engine, and which
introduces so much tar or liquid fuel into the fire-place as to keep the surface
of the liquid always standing a little above the level of the row of air pipes
a, a, which pipes are therefore just immersed beneath the said surface of the
tar or liquid fuel. All the said air pipes are pierced with rows of small
holes, which inject streams of compressed air into the close fire-place, and by
blowing of that air up through the tar or liquid fuel, the same is caused to
burn in jets of flame over each such small hole, which supplies a stream of
compressed air for animating the combustion. And there is also another
branched air pipe E, proceeding from the blowing machine F, to introduce a
full supply of compressed air into the close fire-place above the level of the tar
or liquid fuel, and thus give full effect to the combustion, and so much of that
air as is not consumed becomes strongly heated, and, together with the com-
pressed smoke and gas resulting from the combustion, forms the elastic fluid to
work a rotary engine of either of the kinds represented in Sheets I. or II.
or III. The fire must be lighted before the furnace is shut up, by introducing
flaming pieces of wood into the fire-place, and beneath the bottom of the flat
vessel A, B, to give heat thereto, and when the jets of flame are well lighted,
then the furnace doors may be closed, and the blowing being continued will
cause a strong combustion within the close furnace.
Having now described the said improvements, I, the said Colin Macrae, do

page_text: hereby declare that the new Invention which I claim to have been granted to
me by the said Letters Patent consists in the following particulars of improve-
ment, namely,
First, the improvement herein-before described, and represented in Sheet I.
of the Drawings hereunto annexed, being improvements upon the rotary
engine which formed part of Monsieur Degrand's Patent of the Twelfth
day of December, One thousand eight hundred and thirty-eight, and which
engine, as herein-before explained, although it had two revolving wheels
formed of curled pipes, yet they were both curled in the same direction of
spiral convolution, and were both enclosed within the same box or case, and
wherein a plenum of elastic fluid was kept up. To such rotary engine no
claim is now made, but I only claim the improvement thereof, which consists
in giving to the curled pipes of the two wheels contrary directions of spiral
convolution, each wheel being enclosed within a distinct compartment of the
box or case, and one of those compartments being kept in a state of plenum
of elastic fluid, whilst the other is kept in a state of exhaustion (or relative
exhaustion) of that elastic fluid, and the engine being capable of being worked
either way round, that is, either backwards or forwards, at pleasure, the rotary
engine with such improvement being used either with or without a condenser,
and being worked by steam (either high pressure or low pressure) or by
compressed smoke, gases, or heated air resulting from combustion of fuel, or
by steam mixed with compressed smoke, gases, or heated air.
Secondly, the improvement of combining together in manner herein-before
described two or more such rotary engines of the kind represented in Sheet J.
for forming a series of such engines to be worked by the same elastic fluid
passing in succession from one of those engines to another.
Thirdly, the improvement herein-before described and represented in
Sheet II., whereby a rotary engine, which is for the most part similar in
construction to the rotary engine represented in Sheet I., is (by virtue of the
improvement constituting this third claim) rendered capable of operating with
the full effect due to an elastic fluid of much stronger elastic force that can be
done in an engine, such as Sheet I., having its wheels of only the same
diameter as the engine in Sheet II., because (by virtue of the improvement
constituting this third claim) the barometric columns of the heavy liquid used
in the machine Sheet II. are much higher than the diameter of the wheels of
the rotary engine, as herein-before explained.
Fourthly, the improvement herein-before described and represented in
Sheet III., whereby one revolving wheel, formed of one curled pipe, and

page_text: being very similar in its construction to one of the two wheels of the rotary
engine, Sheet I., is placed in a horizontal position, with its hollow axis in a
vertical position, the said wheel being at the lower end of that axis, and
immersed. in the heavy liquid contained in the box or case wherein the wheel
is enclosed, and by a suitable action of steam or of compressed smoke, gases,
or heated air, when the same is applied in the manner herein-before described
in reference to Sheet III., so as to act within the compartments and pipes of
the box or case, a portion of the heavy liquid is caused to mount up into an
upper reservoir or compartment, from whence it enters into the upper end of
the hollow axis of the wheel, and by descending therein to the interior central
hollow of the wheel, it acts with a continual columnar pressure within the curled
pipe of the wheel, so as to cause a continuous rotative motion thereof, and of its
axis; and the heavy liquid which has passed through the said curved pipe, and
has escaped from the open end thereof into the box or case wherein the wheel
is contained, is then forced by suitable action of steam, smoke, gas, or heated
air to mount up again, as aforesaid, into the said upper reservoir, in order to
repeat its said action over and over again by a continual circulation of the
same heavy liquid.
Fifthly, the improvement herein-before described of applying two or more
rotary engines when combined together in a series (in the manner above
stated as the second particular of improvement) to the purpose of locomotive
engines, either on railways and roads, or for impelling vessels on water, or to
other useful purposes.
Sixthly, the improvement herein-before described and represented at
Figure 6, Sheet II., of protecting the upper surface of the metal bars of
the fire grate with earthy matter which will resist fire and conduct heat
slowly.
Seventhly, the improvement herein-before described and represented at
Figures 5 and 6, Sheet II., for giving an agitating motion to every alternate
fire bar of the fire grate, in order to stir the fire which is burning therein.
Eighthly, the improvement herein-before described, and represented at
Figure 9, Sheet II., for applying tar or coal tar or other liquid as fuel to
produce combustion within a close furnace.
In witness whereof, I, the said Colin Macrae, have hereunto set my
hand and seal, this Thirtieth day of January, in the year of our Lord
One thousand eight hundred and forty-one.
COLIN (L.s.) MACRAE.

page_text: AND BE IT REMEMBERED, that on the Thirtieth day of January, in
the year of our Lord 1841, the aforesaid Colin Macrae, Esquire, came before
our said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and everything therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Inrolled the Fifth day of February, in the year of our Lord One thousand
eight hundred and forty-one.