IMPROVEMENTS IN MOTIVE-POWER ENGINES
Year: 1874

page_text: LETTERS PATENT to Benjamin Franklin Stevens, of Henrietta Street,
Covent Garden, in the County of Middlesex, for the Invention. of
“IMPROVEMENTS IN MOTIVE-POWER ENGINES."-A communication from
T
T
11
PROVISIONAL SPECIFICATION left by the said Benjamin Franklin
Stevens at the Office of the Commissioners of Patents, with his
Petition, on the 6th July 1874.
I, BENJAMIN FRANKLIN STEVENS, of Henrietta Street, Covent Garden,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN MOTIVE-POWER ENGINES," a communication
to me from abroad by Joseph Laubereau, of Paris, in the Republic of
France, to be as follows:-
-
This Invention relates to motive power engines which are actuated by.
means. of hot and cold air employed in combination, and has for its
object more particularly the production of an engine of a cheap and
compact construction, which shall be applicable to the pumping or

page_text: raising of water in dwelling-houses and other places, the driving of sewing
machines and other light machinery, the propulsion of velocipedes, and
generally to all purposes for which a small amount of an inexpensive and
readily available motive power is required.
According to this Invention it is proposed to employ a vertical cylinder
in which works a piston, which is connected by a rod and crank or
eccentric with the driving shaft of the engine. This cylinder is open at
its upper end to the atmosphere, whilst its lower end is in direct com-
munication with a chamber situate below (the cylinder and chamber
forming in fact one cylinder), in which chamber is a moveable plunger
of the peculiar construction herein-after described, which plunger is also
connected by rods and cranks or eccentrics with the driving shaft before
mentioned. The chamber may be surrounded at its upper portion by a
jacket or casing, through the space between which and the outer sides or
surfaces of the chamber cold water may be caused to circulate by means
of a pump worked by the engine; or the jacket or casing may be
dispensed with, and a covering of linen, or felt, or other suitable non-
conducting material may be employed in lieu thereof. The bottom or
lower portion of the chamber is made of a dome, or concave, or other
suitable form and with double sides, and covers another chamber which
is provided beneath for the reception of a lamp, gas burner, or other
convenient heating apparatus. The piston fits loosely within its cylinder,
and is provided with an annular rim or flange at each end. The body
of the piston is surrounded by a ring of india-rubber or other suitable
material, which by its rolling contact with the external surface of the
piston and the interior of the cylinder during the motion of the piston
maintains a tight joint between such surfaces. The plunger consists of
an inverted, cup fitted loosely within its chamber, so as to leave a slight
annular space for a film of air between the two surfaces, the bottom of
which cup (placed uppermost) is formed of plaster of Paris or other
suitable non-conducting material, encased by preference in sheet iron
covered with cotton, flannel, or other like fabric, with a coating of white
lead or its equivalent, whilst its pendent sides extend down between the
double sides of the plunger chamber. The driving shaft is provided with
a fly wheel for equalizing the motion, and also with pullies or other
means for transmitting the power when the engine is to be employed for
driving machinery.
L

page_text: beneath the plunger chamber, and a valve or cock forming a com-
munication between the upper part of such chamber and the atmosphere
is closed; the fly wheel is then moved round, so as to bring the plunger
to the bottom of its stroke, when a slight space will remain between the
bottom of the plunger and the bottom of the chamber. In this position
the piston will be nearly at the bottom of its stroke, and the fly wheel
being slightly turned by hand so as to overcome the inertia of the
mechanism the engine is set in motion. The air below the plunger
having been highly heated is expanded, and its elastic force and volume
are increased, and passing in a thin sheet around the plunger such
heated air acts upon the cold air which is situate. in the upper part of
the chamber, and which forms a cushion between the the heated volume
of air and the piston, and raises the piston, which by its ascent also raises
the plunger, the rods of both the piston and the plunger being connected
to the same shaft. The piston having arrived at the top of its stroke
the plunger is at that moment commencing its downward motion.
(having been carried past the dead point by the revolution of the fly
wheel), and the heated air being simultaneously recooled by its contact
with the cold surfaces its volume is reduced, and a partial vacuum is
formed beneath the piston, which being caused to descend by the
pressure of the atmosphere acting upon its upper surface repels the air,
to be again alternately heated or expanded, and cooled or contracted,
and so on in succession. The same air is thus constantly reused, until
by reopening the valve or cock herein-before referred to the upper part
of the plunger chamber is placed in communication with the atmosphere,.
'when the motion of the engine will immediately cease.
When the engine is to be employed for the pumping or raising of
water, the water elevated may be utilized for the cooling of the plunger
chamber, by causing it to pass through the water chamber surrounding
such plunger chamber on its way to the place where it is required for
use.
It is obvious that the cylinder, in lieu of being arranged vertically, may
be placed either horizontally or at an angle, and that the engine may be
made double acting, and the details be otherwise modified without
departing from the principle of this Invention.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Benjamin Franklin Stevens in the Great Seal
Patent Office on the 4th January 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, BENJAMIN.
FRANKLIN STEVENS, of Henrietta Street, Covent Garden, in the County
of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of July, in the year of our Lord
One thousand eight hundred and seventy-four, in the 38th year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Benjamin Franklin Stevens, Her special license that I,
the said Benjamin Franklin Stevens, my executors, administrators, and
assigns, or such others as I, the said Benjamin Franklin Stevens, my
executors, administrators, or assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
MOTIVE-POWER ENGINES," a communication to me from abroad by Joseph
Laubereau, of Paris, in the Republic of France, upon the condition
(amongst others) that I, the said Benjamin Franklin Stevens, my
executors or administrators, by an instrument in writing under my hand
and seal, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Benjamin Franklin Stevens, do
hereby declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Drawings, and to the letters and figures marked thereon, that
is to say :-
The said Invention relates to motive-power engines which are actuated
by means of hot and cold air employed in combination, and has for its
object more particularly the production of an engine of a cheap and

page_text: compact construction, which shall be applicable to the pumping or
raising of water in dwelling-houses and other places, the driving of sewing
machines and other light machinery, the propulsion of velocipedes and
tram cars, and generally to all purposes for which a small amount of an
inexpensive and readily available motive power is required.
And in order that the said Invention may be fully understood, I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed Sheet of Drawings,
the same letters of reference indicating corresponding part in all the
Figures.
Figure 1 is a sectional elevation of an engine constructed in accordance
with the said Invention; Figure 2 is an elevation of same taken at
right angles to Figure 1; Figure 3 is a horizontal section taken along
the line 1, 2, Figure 1; and Figure. 4 is a plan corresponding to
Figure 2.
: A is a vertical cylinder in which works a piston B, which is connected
by a rod a to the crank pin 6 of the driving shaft C, such shaft being
carried in bearings 6¹ in the standards or pedestals C₁ which support the
whole of the apparatus. The cylinder A is opeň at its upper end to the
atmosphere, whilst its lower end is in direct communication with a
chamber D situate below, and which in fact forms with the cylinder A
but one cylinder. In the chamber D is a moveable plunger E of the
peculiar construction herein-after described, to which plunger there aro
attached coupled rods c, c, which slide through the piston B (stuffing
boxes & being formed in such piston for the passage of the rods), and
through guides e, e, in a cross piece f, and are each provided with a
frame in which works one of two cams h carried on the driving
shaft C. The cylinder A with the upper portion of the chamber D is
surrounded by a jacket or casing F, through the space between which
and the outer sides or surfaces of the cylinder and chamber cold water is
caused to circulate by means of a pump (not shewn in my Drawing) to
be worked by the engine, such water entering by the pipe i and escaping
through the pipe k, so as to constantly maintain the cylinder and that.
portion of the chamber in a cool condition. In some cases however the
jacket or casing F may be dispensed with, and any other suitable means
for maintaining the surfaces in a cool condition may be employed in lieu
thereof. The bottom or lower portion of the chamber D is made of a

page_text: dome or concave form (by preference of roughened sheet iron) at k¹, and
with double sides 1, 1, and covers and encloses a chamber G which is
provided beneath for the reception of a gas burner H, or a lamp, or other
convenient heating apparatus, a pipe H¹ being fitted to such chamber
for carrying off the products of combustion. The piston B fits loosely
within its cylinder, and is provided with an annular rim or flange m at
each end; the body of the piston is surrounded by a ring m. (composed
of tubular or solid india-rubber or other suitable material), which by its
rolling contact with the external surface of the piston and the interior
of the cylinder during the motion of the piston maintains a tight joint
between such surfaces; or in lieu of a ring the usual piston packing may
be employed. The plunger E consists of an inverted cup fitted loosely
within its chamber D, so as to leave a slight annular space o for a film
of air between the two surfaces, the bottom E' of which cup placed
uppermost is formed of plaster of Paris mixed with cork powder and
rough cork in alternate layers, or other, suitable non-conducting material,
encased by preference in sheet iron covered with a layer p of cotton,
flannel, or other like fabric, with a coating of whitelead or its equivalent,
whilst it's pendent sides q, q, extend down between the double sides 1, ª,
of the plunger chamber D. The driving shaft C carries a fly wheel I for
equalizing the motion, and may also be provided with pullies or other
means for transmitting the power when the engine is to be employed for
driving machinery.
When it is desired to start the engine the burner H is lighted beneath
the plunger chamber D, and a cock r forming a communication between
such chamber and the atmosphere is closed; the fly wheel I is then
moved round so as to bring the plunger E to the bottom of its stroke,
when a slight space will remain between the bottom E¹ of the plunger
and the bottom of the chamber. In this position the piston B will be
nearly at the bottom of its stroke, and the fly wheel I being slightly
turned by hand so as to overcome the inertia of the mechanism the
engine is set in motion. The air below the plunger E having been
highly heated is expanded; and its elastic force and volume are increased
and passing in a thin sheet around the annular sides q of the plunger
first down the space comprised between the wall of the chamber D and
the sides q of the plunger; and then up through the space contained
between the sides q and the wall ; such heated air acts upon the cold
air which is situate in the upper part of the chamber D or in th

page_text: cylinder A, (and which forms a cushion between the heated volume of
air and the piston B) and raises the piston, which by its ascent also raises
the plunger E, the rod a of the piston and those c, c, of the plunger
both working in connection with the shaft C. The piston B having
arrived at the top of its stroke (to the position shewn in the Drawing)
the plunger E is at that moment commencing its downward motion
(having been carried past the dead point by the revolution of the fly
wheel I), and the heated air being simultaneously recooled by its
contact with the cold surfaces its volume is reduced, and a partial
vacuum is formed beneath the piston, which being caused to descend
by the pressure of the atmosphere acting upon its upper surface repels
the air, to be again alternately heated or expanded, and cooled or
contracted, and so on in succession. The same air is thus constantly
reused, until by reopening the cock the plunger chamber is placed in
communication with the atmosphere, when the motion of the engine will
cease.
jo
When the engine is to be employed for the pumping or raising of
water, the water elevated may be utilized for the cooling of the
cylinder A and plunger chamber D by causing it to pass through the
water chamber F on its way to the place where it is required for use.
It is obvious that although I have described the improved engine as
being actuated by means of atmospheric air, any suitable expansive gas
or vapour may be employed in substitution therefor.
It is also obvious that the cylinder in lieu of being arranged vertically
may be placed either horizontally or at an angle, and that it may be
caused to oscillate; also that the cylinder may be closed at the top,
sufficient space being allowed to prevent undue compression of the air
above the piston, and that the engine may be made double acting, if
required.
Any other suitable arrangement of mechanism may also be substituted
for the crank for working the shaft, and for the cams for operating the
plunger, and the details may be otherwise modified in various ways
without departing from the principles of the said Invention.
Having now described and particularly ascertained the nature of the
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider

page_text: 'to be novel and original, and therefore claim as the Invention secured to
me by the herein-before in part recited Letters Patent is,-
.
First. The peculiar arrangement and combination of motive-power
engine having a cylinder in which works a piston and a plunger actuated
by means of heated air in conjunction with cold air, and operating
together substantially in the manner herein-before described and illus-
trated by the accompanying Drawings.
Second. Passing the water to be elevated when the engine is
employed for raising water through a chamber surrounding the cylinder,
substantially in the manner and for the purposes herein-before
described.
In witness whereof, I, the said Benjamin Franklin Stevens, have to
this my Specification set my hand and seal, the Second day of
January, One thousand eight hundred and seventy-five.