IMPROVEMENTS IN ENGINES FOR OBTAINING MOTIVE POWER
Year: 1868

page_text: LETTERS PATENT to Joseph Gill, of Palermo, in the Island of Sicily,
at present residing at Halfway Street, near Eltham, in the County of
Kent, for the Invention of "IMPROVEMENTS IN ENGINES FOR OBTAINING
MOTIVE POWER."
Sealed the 28th October 1868, and dated the 18th July 1868.
PROVISIONAL SPECIFICATION left by the said Joseph Gill at the
Office of the Commissioners of Patents, with his Petition, on the
18th July 1868.
I, JOSEPH GILL, of Palermo, in the Island of Sicily, at present residing
at Halfway Street, near Eltham, in the County of Kent, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN ENGINES POR
OBTAINING MOTIVE POWER," to be as follows:-
My first method of economising heat and consequently fuel in
working heat engines consists in coating the interior surfaces of the
cover and bottom of the cylinder, those of the ports or passages between
the valves and the cylinder, and the face or faces of the piston exposed
to the contact of the working steam or other hot fluid with enamel, glass,

page_text: My third method of economising heat and consequently the fuel or
combustible used in working the engine, consists in shortening the time
during which the hot elastic fluid in the cylinder exerts its pressure in
propelling the piston. In steam engines I effect this by admitting the
steam at a pressure exceeding that of the atmosphere under a light
independent piston by a sudden puff or blast so regulated by the opening
of a valve as to propel this flying piston rapidly from one end of the
cylinder to the opposite end where it meets the piston proper, which is
connected with a crank and appendages for rotary motion, as in a
common single-acting or atmospheric engine, having in its outward
course expelled from the cylinder the atmospheric air through a line of
apertures slightly below the under edge of the piston proper at its upper
dead point, and therefore open during the ascent of the flying piston,
which passes over and so closes the apertures at the top of its stroke, and
at the same time it opens a small valve in the piston proper, which
valve was previously held closed by a spring strong enough to resist. the
atmospheric pressure, and so opens a communication through a sliding
or elastic tube with the condenser, or otherwise with a separate vacuous
space prepared by the working of the engine, so that the thin stratum
of air remaining between the pistons after the closing of the air eduction
orifices rushes into the vacuum, and the pressure of the working steam
in the cylinder, which though expanded to a comparatively low tension
at the end of the up stroke is still higher than that of the condenser or
other vacuous space used presses the flying piston upwards, and thus
holds the pistons temporarily in contact. This result is the better
insured by accurately fitting a slight annular projection round the outer
edge of the flat face of each piston so as to obtain good contact, or a
narrow groove full of slightly projecting elastic packing in one of the
contiguous faces produces a similar effect. The air eduction orifices are
then still more completely closed by the piston proper passing over
them in the beginning of its down stroke; and at this time the outlet
passage from the lower end of the cylinder to the condenser is opened,
so that the external atmospheric pressure greatly predominates and
causes the pistons to descend together until near the bottom of the
stroke. The flying piston is detached from the piston proper by a slight
puff of compressed air or steam sent in between the pistons by the action
of the engine, or it is pushed off mechanically and remains at the bottom
of the cylinder until the passage to the condenser being closed the
piston proper has again reached the top of its stroke, air being freely

page_text: admitted under it during its ascent by the opening of a valve placed near
the bottom of the cylinder. In reaching the upper dead point the piston
proper uncovers the air eduction orifices by passing slightly beyond
them; a fresh puff or flash of steam is then admitted under the flying
piston, and so the working of the engine continues. I apply the same
arrangement of a light independent piston to explosive gas engines; and
to hold the pistons together at the outer dead point a small vacuous
space is kept prepared by the action of the engine itself to furnish the
trifling amount of power required in this operation.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Joseph Gill in the Great Seal Patent Office on the
18th January 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
GILL, of Palermo, in the Island of Sicily, at present residing at Halfway
Street, near Eltham, in the County of Kent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of July, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Joseph Gill, Her special licence that I,
the said Joseph Gill, my executors, administrators, and assigns, or
such others as I, the said Joseph Gill, my executors, administrators,
and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN ENGINES FOR OBTAINING
MOTIVE POWER," upon the condition (amongst others) that I, the said
Joseph Gill, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should par-
ticularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.

page_text: NOW KNOW YE, that I, the said Joseph Gill, do hereby declare
the nature of the said Invention, and in what manner the same iş
to be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say :-
In heat-motive engines generally the hot gas or vapor acting in the
cylinder undergoes considerable changes of pressure, and therefore of
temperature, during each stroke, and the metallic surfaces in contact
with the hot fluids during these changes must also in some degree
undergo corresponding changes of thermic condition, the amount of
which depends chiefly on the nature of the solid material and the time
it is in contact with the fluid during each fluctuation of temperature.
Under ordinary circumstances in the working of steam engines the
interior surfaces of the cylinder are at the end of each stroke colder than
the steam which enters for the next stroke, and with saturated steam
some condensation must take place from the contact of the hotter fluid
with the colder solid surfaces which become rapidly coated with a film
of dew. In cases of great expansion part or perhaps the whole
of this moisture may be re-evaporated during the working stroke, and
thus the loss of heat from this source may become less, but generally
the greater part of the film of moisture flashes off into vapor the
moment the opening of the exhaust passage allows a fall of pressure, and
this amount of heat of vaporization taken from the hot metals is lost.
This loss may be diminished or entirely prevented by the use of steam
less or more superheated, but the destructive action of dry steam on the
rubbing metallic surfaces renders its indiscriminate use very objec-
tionable. A steam jacket round the cylinder is not so effective in
preventing internal condensation as might be expected from a superficial
view of the circumstances, as the heat current from without travels
inwards through the walls of the cylinder at a rate very much slower
than that of the smaller heat wave, which suddenly ebbs out with the
evaporation of moisture from the inner surfaces on the relief of pressure
resulting from the exhaust, thus leaving the inner skin of the oylinder
for the moment at a temperature much lower than that of the steam
from the boiler which enters for the next stroke, and consequently a
rapid condensation of some of this fresh steam takes place on the
surfaces, until by the joint action of the inflowing thermic current from
the jacket through the metal, and of the re-entering heat wave directly
from within their temperature becomes again nearly equalized with that

page_text: of the mass of steam with which they are in contact. In most cases the
loss of heat from this source is considerable, sometimes so great that the
water resulting from condensation in the cylinder has been mistaken for
'priming" from the boiler.
66
My Invention consists in improvements in the construction and
arr ngements of certain parts of the mechanism of heat-motive engines
for avoiding as much as possible the above-mentioned evils, which
improvements are founded on the following general bases :-
First. To employ for the non-rubbing surfaces of the cylinder and
piston which come in contact with the working steam or other hot fluid
some resistant substance, which as compared with iron has a smaller
specific heat and a lower rate of thermal conductivity, so that in a given
time a smaller amount of heat will be absorbed and given out by an
equal surface.
Secondly. To apply in steam engines the heating action of a steam
bath as much as possible to the interior rubbing surfaces of the cylinder
by direct contact instead of indirectly from the outside, as with the
common steam jacket, or rather in combination with the jacket.
And, thirdly. To shorten the period during which the steam may
produce its dynamical effect in the cylinder by allowing it to act by
sudden impulse against the elastic resistance of some medium possessing
but little inertia, as, for example, the common atmosphere, a method
which has hitherto been attempted only with the explosive action of
gases, &c. in motive engines.
My Invention is practically performed as follows:-
First. In steam engines, and also in engines working by the expansive
energy of other hot elastic fluids, I coat the inner surfaces of the cover
and bottom of the cylinder and of the passages between the valve or
valves and the cylinder, and the face or faces of the piston or pistons
exposed to the contact of the working steam or other hot fluids with a
enamel or glass fused directly on to the metallic surfaces, which are pre-
ferably prepared with shallow undercut grooving or otherwise roughened
or furnished with indentations or projections to hold the vitrified coating
more firmly in place. Or I protect the surfaces from contact with the
working steam by covering them with metallic enamelled plates, or
plates of glass, baked earth, or natural stone laid in cement impervious
to steam, and held in place by screws, clamps, or equivalent con-

page_text: trivance. Instead of mineral covering, as above mentioned, I sometimes
coat the inner surfaces with a metal or alloy of lower specific heat and
smaller thermal conductivity than iron, preferably an alloy of bismuth
and lead for steam of moderate pressure and temperature, soldered on
or fixed in place mechanically.
Secondly. In steam engines I keep up the temperature of the interior
rubbing surfaces of the cylinder by keeping in direct contact with these
surfaces as much as possible a moveable mass of steam constantly at or
near the full boiler pressure on one side of the piston or pistons while
the working steam is undergoing various stages of expansion from full
pressure to the vacuum in the condenser on the other side. This is
effected by making the cylinder longer than what is usually required
for a given length of stroke, preferably about double that length, and
using a long double-headed piston or two pistons firmly connected
together, as shewn by a, a', Figure 1. The space d being in free com-
munication with the boiler, and preferably forming a passage for the
whole working steam on its way to the inlet valves b, b', is constantly
occupied by steam of full pressure and temperature, which moving alter-
nately from end to end of the cylinder by the action of the engine
communicates heat to the solid surfaces in contact with it, while at the
same time the other portions of the cylinder walls at c, c', are undergoing
a fall of temperature from the expansive working of the steam on the
one hand and its exhaust into the condenser on the other. Thus the
unavoidable fall of temperature in the cylinder from expansion and
exhaust is in a great measure made up by the direct contact of this
steam bath with the inner skin of the cylinder at each stroke just before
the fresh steam is admitted for the succeeding stroke. Any water
resulting from condensation in the space d drains off through a steam
trap or equivalent arrangement. I sometimes use in the space d steam
from another source hotter than the working steam, which in this case
passes from the boiler directly to the inlet valves. I apply the same
principle of heating by an internal steam bath to single-acting engines
by keeping one side of the piston in constant free communication with
the full-pressure steam, while on the other side of the piston steam is
alternately admitted to the cylinder and exhausted therefrom.
Thirdly. To shorten the time during which the hot fluid may exert
its energy in propelling a piston against some given resistance in steam
engines I admit the steam at a pressure exceeding that of the atmosphere

page_text: under a light independent piston e, Figure 2, in a sudden puff or blast
Bo regulated by the action of the inlet valve f (to be explained presently)
as to propel this flying piston rapidly to the other end of the cylinder,
where it meets the piston proper g connected with a crank and appen-
dages for rotary motion, as in a common single-acting or atmospheric
engine, having in its outward course expelled from the cylinder the
atmospheric air through a line of apertures h, h¹ parallel with and a
little lower than the under edge of the piston proper at its upper dead
point, and therefore open during the ascent of the flying piston, which
passes over and so closes the apertures at the top of its stroke. In the
piston g is the valve i, held down by a spring adjustable from the outside
stronger than the atmospheric pressure on the valve against a vacuum
and communicating through a sliding (telescopic) or flexible tubej with
the condenser, or otherwise with a separate small vessel or space made
vacuous by the working of the engine, so that the thin stratum of air
remaining between the pistons after the apertures h, h¹, are closed acts
as a momentary "cushion" to the flying piston, preventing injurious
concussion, but still allowing this piston to strike the tail of the valve i
projecting slightly below the bottom of the piston proper, and thus open
a passage to the condenser or other vacuous space through which the air
rushes out, and the pressure of the working steam in the cylinder, which
though expanded to a low tension at the end of the flying piston's stroke
is still higher than that of the vacuum on the other side, urges the flying
piston still upwards, and thus brings the pistons together and keeps them
in temporary contact. The contiguous faces of the pistons should fit
well together round the outer edge, which condition in large engines is
more easily ensured by a ring of elastic packing laid in a groove in one
of the faces and projecting a little beyond the surface or some analogous
arrangement. The apertures h, h', are still more completely closed by
the piston proper passing over them in the beginning of the down stroke,
at which time the outlet passage to the condenser is opened through the
eduction valve k, and the external atmospheric pressure being now
almost unbalanced forces down the piston proper and with it the flying
piston until near the bottom of the stroke. The latter is detached from its
fellow by a regulated puff of compressed air or steam sent in between
the pistons, or the flying piston is pushed off by mechanical action of the
engine, and it remains at the bottom of the cylinder until the passage to
the condenser being closed the piston proper has again reached the top
of its stroke, air being freely admitted under it during its ascent by the

page_text: corresponding opening of a valve in the lower part of the cylinder or in
the piston itself. In reaching the upper dead point (by the momentum
of the fly wheel in a single cylinder engine or by a counterweight in a
simple pumping engine) the piston proper again uncovers the apertures
h, h', by passing a little beyond them; a fresh puff or flash of steam
admitted under the flying piston projects it to the top of its stroke as
before, and so the working of the engine continues. The puff or flash
of steam may be admitted to the cylinder in various ways. One method
which answers well for small powers is as follows:-The spring or elastic
hammer is pressed down at each stroke of the engine a little below the
maximum point of working tension by a cam, not shewn in the Figure,
which leaves it locked on the adjustable catch o of the locking piece m
some time before the piston proper reaches the top of its stroke. At the
moment when it reaches this position the trigger n is suddenly depressed
by a suitable escapement in the mechanism of the engine and liberates
the hammer, which striking the tail of the valve f effects a momentary
opening through which the steam flashes and the valve shuts again.
Though the inlet is here shown at the side the steam should preferably
act on the flying piston as centrally as possible. For large engines the
steam is preferably admitted by the rapid motion of a flat or cylindrical
valve actuated by a spring wound up and suddenly let off (as in the
Corliss engine) uncovering the inlet port and closing it again during its
motion in one direction. With steam of high pressures the quantity or
charge for each stroke is conveniently measured by an intermediate
vessel which fills from the steam pipe during a portion of each stroke
and is closed before the piston proper reaches the upper dead point, at
which instant a passage is suddenly opened between the charging vessel
and the cylinder and the flying piston is projected to the top of its stroke,
the inlet passage to the cylinder closing again more slowly during the
down stroke. Besides the valve or cock connecting the charging vessel
with the steam pipe there is a valve just inside of it in the neck of the
vessel opening inwards and held down by a spring or weight adjustable
from the outside, and as the tension of the charge of steam in the vessel
corresponds to the difference between the pressure of the spring or weight
above the valve and the full steam pressure below it the action is regu-
lated accordingly.

page_text: all circumstances the flying piston should have power enough to propel
it to the top of the cylinder at each stroke, but to prevent a waste of
steam and to avoid injury from too much momentum a small indicator p
shows the intensity with which the "cushion" air between the pistons
is compressed and the steam admission is regulated accordingly by hand,
or the indicator is made larger and so connected with the steam admis-
sion gear as to act automatically on the mechanism which regulates the
inlet, for instance, the adjustable catch o of the locking piece m or
equivalent arrangement. Instead of having the cylinder open at the
top I sometimes close it in and apply for the downward pressure on the
piston the isolated atmosphere of a sufficiently large air vessel at common
atmospheric pressure or regulated to any convenient artificial pressure.
I apply the method of a light independent piston with its pneumatic
arrangement and mode of regulation also to engines worked by the
explosive action of gases, &c., a small space being made vacuous by the
action of the engine to furnish the slight amount of pneumatic power
required for temporarily attaching the pistons at each stroke.
It will appear evident that the above-described improvements may be
used singly or in combination as may best suit different circumstances.
Having now described the nature and particulars of my Invention,
and the manner in which the same is to be performed, I desire it to be
understood that I claim,-
First. Enamelling the non-rubbing surfaces of the cylinder and piston
in direct contact with the working steam or other hot fluid, or otherwise
coating them with a mineral or metallic substance of lower specific heat
and smaller thermal conductivity than the iron or other metal of which
the cylinder and piston may be made.
Second. Keeping up the temperature of the interior rubbing surfaces
of steam cylinders by direct contact with them of heating steam on one
side of the piston or pistons whilst the working steam is losing tem-
perature by expanding and exhausting on the other side.
Third. The employment in motive-power engines of a light indepen-
dent piston free from mechanical attachments in combination with an
ordinary attached piston, substantially as herein described.
Fourth. Combining with such an arrangement of independent piston
apparatus for admitting steam to the cylinder in regulated puffs or
flashes.

page_text: Fifth. The pneumatic mode of bringing the flying or independent
piston into contact with the piston proper at the outer dead point and
holding them temporarily together, as described.
In witness whereof, I, the said Joseph Gill, have hereunto set my
hand and seal, this Fifteenth day of January, in the year of
our Lord One thousand eight hundred and sixty-nine.