IMPROVEMENTS TO REDUCE THE CONDENSATION OF STEAM IN SLIDE OR VALVE CHESTS AND CYLINDERS OF STEAM ENGINES OF EVERY DESCRIPTION
Year: 1876

page_text: LETTERS PATENT to Henri Gilles Hautermann, President of the Board of
Directors of the Compagnie Anonyme "Le Progrès "of Brussels, for the
Invention of "IMPROVEMENTS TO REDUCE THE CONDENSATION OF STEAM IN
SLIDE OR VALVE CHESTS AND CYLINDERS OF STEAM ENGINES OF EVERY
DESCRIPTION." A communication from A. A. Emmanuel Lissignol, Civil
Engineer. residing at 260, Rue de Brabant, Brussels.
PROVISIONAL SPECIFICATION left by the said Henri Gilles Hautermann
at the Office of the Commissioners of Patents on the 26th February 1876.
HENRI GILLES HAUTERMANN, President of the Board of Directors of the Com-
"of Brussels. "IMPROVEMENTS TO REDUCE THE
pagnie Anonyme "Le Progrès
CONDENSATION OF STEAM IN SLIDE OR VALVE CHESTS AND CYLINDERS OF STEAM
ENGINES OF EVERY DESCRIPTION."
This Invention has for its object improvements to reduce the condensation of
steam in slide or valve chests and cylinders of steam engines of every description.
The improvements may be employed on any engines, either separately, partly, or
altogether, and consists, first, in making double the metallic sides of the slides or
valves which separate two steams at different temperatures. Between the two
partitions composing each double side there must be a void space filled with air, or
better, stuffed with some material a bad conductor of caloric.
The improvements also consist in keeping the steam cylinder out of all contact
with the exhaust pipe.
Either by double sides enclosing a mattress of air, or of some material a bad
conductor of caloric, and standing between the cylinder and the exhaust pipe.
Or by a covering a bad conductor of caloric laid outside the cylinder and inside
the exhaust; this covering is extended over all the part of the cylinder which forms
one of the sides of said exhaust pipe.
Or by employing together the preceding double sides and covering.
The improvements also consist in keeping the exhaust pipe out of contact with
the pipes running from the steam ports to the cylinder.
Either by double sides enclosing a mattress of air, or of some material a bad
conductor of caloric, and extending over all the surface between these pipes andthe
exhaust.

page_text: Or by a covering a bad conductor of caloric laid inside the exhaust on each of
surfaces forming sides of the above steam pipes.
Or by employing at once both the said double sides and coverings.
The improvements also consist in separating the valve chest or slide chest from
the pipes running from the ports to the cylinder.
Either by giving double sides to these pipes between themselves and the steam of
the above chest, and enclosing between these double sides a mattress of air, or of
some material a bad conductor of caloric.
Or by covering with some kind of mastic or with some solid body (one or the
other a bad conductor of caloric) the sides of the said pipes touching the steam of
the slide or valve chest.
Or by employing both said double sides and covering at the same time.
The improvements also consist,in covering, as far as possible, with a layer of a
body less conductor of heat than cast iron, both upper and under side of the piston,
the inner surfaces of the cylinder, bottom and cover, and the inner surfaces of the
pipes running from the steam ports to the cylinder.
The shape and thickness of the double sides heretofore mentioned and the
thickness of the void space enclosed between these doubles sides are necessarily
variable according to the special requirements of each engine and the means to be
disposed of.
To fill the void space enclosed between the double sides, charcoal, mastic, porcelain,
plaster, or wood may be employed.
Whatever be the material selected it must fulfil the following conditions:-
1st. To be less conductor, of caloric than cast iron and as bad a conductor as
possible.
2nd. To produce no chemical action notable or injurious to the enclosing metal by
contact with cast iron, iron, steam, oil, grease, or any other body which may exist
inside the engine, neither under the influence of cold nor under any of the possible
temperatures inside the cylinders and valve chest.
The coverings laid outside the cylinder, and outside the pipes running from the
steain ports to the cylinder may vary in nature and composition according to the
temperature of the steam to the engine requirements and to the materials at hand,
charcoal, mastics, plaster, porcelain, wood, vulcanized india-rubber, and thick plates
of lead may be employed.
Whatever be the selected material it must fulfil the following conditions :-
1st. To be as bad conductor of heat as possible, and especially much less conductor
than cast iron.
2nd. To produce no chemical action (or combination) notable or injurious by
contact with cast iron, iron, steam, oil, grease, and any other body which may exist
inside the engine, neither under the influence of cold, nor under any of the possible
temperatures inside the cylinder and slide chest.
3rd. To admit of being laid and fitted exactly and kept invariably upon all the
extent of the surfaces to be covered, either by itself or by means of total or
partial envelopes, by metallic plates, screws, or bolts, by welding or any other
means.
These coverings act by their entire thickness, and are exposed on each side during
the normal working of the engine to nearly fixed temperatures, accordingly-
1st. Their thickness must be as large as the engine allows.
2nd. Under the same thickness the covering being the less conductor of heat will
give the better result.
3rd. It matters very little for the final result whether the exterior surfaces be the.
surface of the covering itself or the surface of another material used to keep the
covering in its intended place.
The coverings placed inside the cylinder, or inside the pipes running from the
steam ports to the cylinder, can be made with a great variety of materials, according
to the maximum and minimum temperature in the cylinder, to the dispositions of
the engines, and to the materials at hand. Thick stuffs made waterproof, amianthus,

page_text: cloth, vulcanized india-rubber, wood layers, porcelain, lead, and several coatings
which may be welded on cast iron may be used.
Whatever be the selected material it must fulfil the following conditions:-
1st. The material must not sensibly soak with water.
2nd. The product of its density of its specific heat, and of its coefficient of interior
calorific conductibility must be as inferior as possible to the product of the
corresponding three numbers relating to cast iron. The greater the difference
between the two preceding products the greater will be the result.
3rd. The covering must not crack or become sensibly disaggregated, neither under
the pressure of the fastenings nor by the influence of the temperature and atmos-
phere to the action of which the said covering is subjected during the working of
the engine, nor under the influence of the changes of temperature the engine may
suffer inside and outside.
4th The covering must not be productive of any chemical action (solution,
combination) notable or injurious by its contact with cast iron, iron, steam, oil,
grease, and all other bodies which exist inside the engine; nor under cold, nor
under any temperature which may exist inside the cylinders and valve chest.
5th. The covering must admit of being laid and fitted exactly and kept invariably.
upon all the extent of the surfaces to be covered, either by itself or by welding, by
metallic fastenings, or by any other means.
The inside coverings act, nearly exclusively, by a very little thickness beginning
at the surface in contact with the steam. This acting thickness is variable with the
body composing the cover, with the maximum and minimum temperature in the
cylinder, with the time necessary for one revolution of the engine, and the fraction
of stroke corresponding to the period of exhaust. Generally a theoretical thickness
about one-sixteenth of an inch would be enough to make sufficient the covering.
But the minimum thickness to adopt being the thickness necessary to prevent any
deformation or breaking while the engine works it will be necessary with most
materials to give the covering a greater thickness than the theoretical one. The
same principle shows that in order to make efficient the inside coverings they must
be fastened in such a way as to leave uncovered the greatest possible part of the
surface of said coverings in contact with the working steam.
When the difference of the respective dilatations of the covering and of the
covered metal is sufficient to cause eventially the breaking of the covering or the
breaking of the fastenings, the fastenings of the covering must be so disposed as to
allow the slipping which results of the different dilatations of the two superposed
materials.
Even when observing all the above conditions the means of fixing the coverings
upon cast-iron or iron surfaces are extemely numerous, and must vary according to
the requirements of the engine, to the available space, and to the material used for
the covering.
Metallic plates, screws and bolts, welding, or any other known or new process of
fastening may be employed according to circumstances.
The improvements also consist in the regulation of cylinder slides or valves so
that for each cylinder, for each of the sides of the piston upon which the steam is
admitted in the normal working of the engine, the slides or valves shut the exhaust,
and begin the compression at such a point of the return stroke that the compression
of the mixture of rarefied steam and water remaining in the cylinder will produce,
in the dead space at the end of said return stroke a temperature equal to the
temperature of the steam flowing from the slide chest in the cylinder, or a tem-
perature as near to that limit as the system of mechanism will allow. To realize
this end it is necessary to shut behind the piston not only the volume of humid
steam (at the temperature of the exhaust) which compressed by the piston (without
addition or abduction of caloric) would give, in the dead space at the end of return
stroke the final temperature intended to be obtained, but also an additional.
quantity of the same rarefied steam which condenses during the compression, and

page_text: warms up by its condensation the metal of the cylinders, covers, and piston, cooled
during the period of exhaust.
The total volume of steam to be compressed behind the piston (a volume equal
to the volume of dead space at the end of return stroke added to the volume
generated by the piston during the period of compression) evidently depends,―
1st. Of the volume of the dead space.
2nd. Of the temperature of the steam in the cylinder when the exhaust shuts.
3rd. Of the temperature to be reached at the end of return stroke.
4th. Of the degree of cooling undergone by the cylinder and piston during the
exhaust, hence of the time employed for one revolution, and the part of that time
during which the exhaust is open.
5th. Of the weight of water presumed to remain in the cylinder.
The proportion of the stroke corresponding to the period of compression it is
consequently variable with each case.
To determine in each case the total volume of rarefied steam to be compressed,
this volume is calculated at first as approximately as possible by the formula of the
mechanical theory of caloric; the slides or valves and their motions are then
regulated, provisionally, according to the result of these calculations. The final
regulation necessary to reach the intended temperature at the end of compression is
afterwards secured by successive little gropings upon the relative position of the
eccentrics on the shaft and upon the length of the slide faces, or upon the regulation
of the valve motion, if the engine is worked by valves instead of slides. When
adopting such a protracted normal compression it is very useful to limit the
admission of the steam in the cylinder, so as to get at the end of expansion a
pressure as near as possible to the pressure during the exhaust.
Iu the Woolf or compound engines it is easy to regulate the valves of the high and
low pressure cylinders in such a way that the pressure of steam at the end of expan-
sion will be equal or nearly equal to the pressure of the exhaust in the high-pressure
cylinders. It will be useful to adopt such a regulation when the slides or valves,
their motion, and the cylinder ports of an engine do not allow the aforesaid pro-
tracted compression without giving inacceptable proportions to other parts of the
diagram; or when the unavoidable use of variable admissions makes it imposible
to realize a sufficiently protracted compression for each grade of expansion, give to
the cylinder and for the exhaust ports, pipes, and slides or valves, distinct from
the ports, pipes, slides, or valves, used for the admission of steam.
The same contrivance may be employed without being compelled by any special
necessity; it is always useful to prevent the contact of the steam flowing in the
cylinder with surfaces cooled by the exhaust.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henri Gilles Hautermann in the Great Seal Patent Office on the 26th
August 1876.
">
66
HENRY GILLES HAUTERMANN, President of the Board of Directors of the Com-
"Le Progrès
pagnie Anonyme
of Brussels. IMPROVEMENTS TO REDUCE THE
CONDENSATION OF STEAM IN SLIDE OR VALVE CHESTS AND CYLINDERS OF STEAM
ENGINES OF EVERY DESCRIPTION." A communication from A. A. Emmanuel
Lissignol, Civil Engineer, residing at 260, Rue de Brabant, Brussels.
This Invention has for its object to reduce the condensation of steam in slide or
valve chests, and cylinders of steam engines of every description.
The improvements may be employed on any engines either separately, partly, or
altogether.
A. The first improvement consists in making double the metallic sides of the
slides or valves which separate two steams at different temperatures. Between the

page_text: two partitions composing each double side there must be a void space filled with
air, or better stuffed with some material a bad conductor of caloric.
B. The next improvement consists in keeping the steam cylinder out of all contact
with the exhaust pipe.
1. Either by double sides enclosing a mattress or layer of air, or of some
material a bad conductor of caloric, and standing between the cylinder and the
exhaust pipe.
2. Or by a covering a bad conductor of caloric laid outside the cylinder and
inside the exhaust. This covering is extended over all the part of the cylinder
which forms one of the sides of said exhaust pipe.
3. Or by employing together the preceding double sides and covering.
C. The next improvement consist in keeping the exhaust pipe out of contact
with the pipes running from the steam ports to the cylinder.
1. Either by double sides enclosing a mattress of air or of some material a bad
conductor of caloric and extending over all the surface between these pipes and the
exhaust.
2. Or by a covering a bad conductor of caloric laid inside the exhaust on each of
the surfaces forming sides of the above steam pipes.
3. Or by employing at once both the said double sides and coverings.
D. The next improvement consists in separating the valve chest or slide chest
from the pipes running from the ports to the cylinder.
1. Eithor by giving double sides to these pipes between themselves and the steam
of the above chest, and enclosing between these double sides a mattress of air, or of
some material a bad conductor of caloric.
2. Or by covering with some kind of mastic or with some solid body (one or the
other a bad conductor of caloric), the sides of the said pipes touching the steam
of the slide or valve chest.
3. Or by employing both said double sides and coverings at the same time.
E. The next improvement consists in covering, as far as possible, with a layer of
a body less conductor of heat than cast iron both upper and under side of the piston,
the inner surfaces of the cylinder bottom and cover, and the inner surfaces of the
pipes running from the steam ports to the cylinder.
The shape and thickness of the double sides heretofore mentioned, and the
thickness of the void space enclosed between these double sides are necessarily
variable according to the special requirements of each engine and the means to be
disposed of.
To fill the void space enclosed between the double sides charcoal, mastic, por-
celain, plaster, wood, &c., may be employed.
Whatever be the material selected it must fulfil the following conditions :-
1. To be less conductor of caloric than cast iron, and as bad a conductor as
possible.
2. To produce no chemical action notable or injurious to the enclosing metal, by
contact with cast iron, iron, steam, oil, grease, or any other body which may exist
inside the engine, neither under the influence of cold, nor under any of the possible
temperatures inside the cylinders and valve chest.
The coverings laid outside the cylinder and outside the pipes running from the
steam ports to the cylinder may vary in nature and composition according to the
temperature of the steam, to the engine requirements, and to the materials at hand,
charcoal, mastics, plaster, porcelain, wood, vulcanized india-rubber, thick plates of
lead, &c., may be employed.
Whatever be the selected material it must fulfil the following conditions:-
1. To be as bad conductor of heat as possible, and especially much less conductor
than cast iron.
2. To produce no chemical action (solution or combination) notable or injurious, by
contact with cast iron, iron, steam, oil, grease, and any other body which may exist
inside the engine, neither under the influence of cold, nor under any of the possible
temperatures inside the cylinder and slide chest.

page_text: 3. To admit being laid and fitted exactly and kept invariably upon all the
extent of the surfaces to be covered, either by itself or by means of total or partial
|_ envelopes, by metallic plates, screws or bolts, by welding or any other means.
These coverings act by their entire thickness and are exposed on each side during
the normal working of the engine to nearly fixed temperatures; accordingly,—
1. Their thickness must be as large as the engine allows.
2. Under the same thickness the covering being the less conductor of heat will
give the better result.
3. It matters very little for the final result whether the exterior surfaces be
the surface of the covering itself or the surface of another material used to keep the
covering in its intended place.
The coverings placed inside the cylinder or inside the pipes running from the
steam ports to the cylinder can be made with a great variety of materials,
according to the maxiinum and minimum temperature in the cylinder, to the dis-
positions of the engine, and to the materials at hand. Thick stuffs made water-
proof, amianthus cloth, vulcanized india-rubber, wood layers, porcelein, lead coatings,
&c., &c., may be used.
Whatever be the selected material it inust fulfil the following conditions:
1. The material must not sensibly soak with water.
2. The product of its density, of its specific heat, and of its co-efficient of interior
calorific conductibility, must be as inferior as possible to the product of the corre-
sponding three numbers relating to cast iron; the greater the difference between
the two preceding products the greater will be the result.
3. The covering must not crack or become sensibly disaggregated either under
the pressure of the fastenings nor by the influence of the temperature and atmo-
sphere, to the action of which the said covering is subjected during the working of
the engine, nor under the influence of the changes of temperature the engine may
suffer inside and outside.
4. The covering must not be productive of any chemical action (solution or
combination) notable or injurious by its contact with cast iron, iron, steam, oil,
grease, and all other bodies which exist inside the engine, nor under cold, nor under
any temperature which may exist inside the cylinder and valve chest.
5. The covering must admit of being laid and fitted exactly and kept invariably
upon all the extent of the surfaces to be covered, either by itself or by welding by
metallic fastenings or by any other means.
The inside coverings act nearly as exclusively by a very little thickness, begin-
ning at the surface in contact with the steam. This acting thickness is variable,
with the body composing the cover, with the maximum and minimum tempera-
ture in the cylinder, with the time necessary for one revolution of the engine, and
with the fraction of stroke corresponding to the period of exhaust. Generally a
theoretical thickness about one-sixteenth of an inch would be enough to make
sufficient the covering, but the minimum thickness to adopt, being the thickness
necessary to prevent any deformation or breaking while the engine works, it will be
necessary with most materials to give the covering a greater thickness than the
theoretical one. The same principle shows that in order to make efficient the inside
coverings they must be fastened in such a way as to leave uncovered the greatest
possible part of the surface of said coverings in contact with the working steam.
When the difference of the respective dilatations of the covering and of the
covered metal is sufficient to cause eventually the cracking of the covering or the
breaking of the fastenings the fastenings of the covering must be so disposed as to
allow the slipping which results of the different dilatations of the two superimposed
materials.
Even when observing all the above conditions the means of fixing the coverings
upon cast-iron or iron surfaces are extremely numerous, and must vary according
to the requirements of the engine to the available space and to the material used
for the covering.

page_text: Metallic plates, screws, and bolts, welding, or any otlier known or new process of
fastening may be employed according to circumstances.
F. The next improvement consists in the regulation of the cylinder slides or
valves, so that for each cylinder and for each of the sides of the piston upon which
the steam acts in the normal working of the engine the slides or valves shut the
exhaust and begin the compression at such a point of the return stroke that the
compression of the mixture of rarefied steam and water remaining in the cylinder
will produce in the dead space at the end of said return stroke a temperature equal
to the temperature of the steam flowing from the slide chest in the cylinder, or a
temperature as near to that limit as the system of mechanism will allow. To
realize this end it is necessary to shut behind the piston not only the volume of
humid steam (at the temperature of the exhaust), which compressed by the piston
(without addition or abduction of caloric) would give in the dead space at the end
of return stroke the final temperature intended to be obtained, but also an
additional quantity of same rarefied steam, which condenses during the compression
and warms up by its condensation the metal of the cylinders, covers, and pistons,
cooled during the period of exhaust.
The total volume of steam to be compressed behind the piston (a volume equal
to the volume of dead space at the end of return stroke added to the volume.
generated by the piston during the period of compression) evidently depends,-
1. On the volume of the dead space.
2. On the temperature of the steam in the cylinder when the exhaust shuts.
3. On the temperature to be reached at the end of return stroke.
4. On the degree of cooling undergone by the cylinder and piston during the
exhaust, hence on the time employed for one revolution, and the part of that time.
during which the exhaust is open.
5. On the weight of water remaining in the cylinder when the exhaust shuts.
The proportion of the stroke corresponding to the period of compression is con-
sequently variable with each case.
To determine in each case the total volume of rarefied steam to be compressed
this volume is calculated at first as approximately as possible by the formulas of
the mechanical theory of caloric. The slides or valves and their motions are
then regulated provisionally according to the result of these calculations. The final
regulation necessary to reach the intended temperature at the end of compression
is afterwards secured by successive little gropings upon the relative position of the
eccentrics on the shaft and upon the length of the slide faces, or upon the
regulation of the valve motion if the engine is worked by valves instead of slides.
When adopting such a protracted normal compression it is very useful to limit the
admission of the steam in the cylinder, so as to get at the end of expansion a
pressure as near as possible to the pressure during the exhaust.
In the Woolf or compound engine it is easy to regulate the valves of the high
and low pressure cylinders in such a way that the pressure of steam at the end of
expansion will be equal or nearly equal to the pressure of the exhaust in the high-
pressure cylinders. It will be useful to adopt such a regulation.
When the slides or valves, their motion, and the cylinder ports of an engine,
do not allow the aforesaid protracted compression without giving inacceptable
proportions to other ports of the diagram, or when the unavoidable use of variable
admissions makes it impossible to realize a sufficiently protracted compression for
each grade of expansion, I give to the cylinder, and for the exhaust ports, pipes,
and slides, or valves, totally or partly distinct, according to circumstances, from the-
ports, pipes, slides, or valves used for the admission of steam.
The same contrivance may be employed without being compelled by any special
necessity. It is always useful to prevent the contact of the steam flowing in tho
cylinder with surfaces cooled by the exhaust.
In order that the several improvemonts above described may be fully under-
stood, and readily carried into effect, I will give an example of their application to
the old engines of a screw steamer.

page_text: The engine was an ordinary inverted engine having two similar_steam
cylinders," diameter 1·05, stroke 8; one of the cylinders is shown at Figures
7 and 8. Each of the cylinders had an ordinary slide valve, shown at Figure 1,
with a cut-off valve at the back, Figures 1, 2, 7, and 8. The load on the safety
valve of the steam boilers was 110 C. M. of mercury. above the atmospheric
pressure. The problem to be resolved was to apply the new arrangements to this
apparatus without changing either the cylinders or the mechanism:
Old System of Supplying Steam before the Application of the New Arrange-
ments. The distribution given by the old slide valve, Figure 1, was set out and a
diagram drawn of this distribution, Figure 3, in the manner practiced in the French
Navy. To set out this diagram the positions of the crank are determined for every
tenth part of the forward and backward stroke of the piston, as shown at Figure 4.
The angles described for each of these positions from the commencement of the
forward stroke o (Figure 4), are taken as abscissæ of the curves, Figure 3. The scale
adopted for these abscissæ is one millimetre for a degree, that is 360 millimetres
for the entire circumference. At each of the 20 points marked on the line of the
abscissæ and corresponding to the ten successive positions of the piston in its
forward and backward stroke, ordinates are erected of a length equal to the
fraction of stroke made by the piston at the time when the crank has passed
through an angle corresponding to that indicated by. the abscissæ. A continuous
curve shewn in red at Figure 3 is drawn through the points so obtained, and
represents geometrically the positions of the piston. A scale of 1/6th the natural
size has been taken for the ordinates of this curve in order that the Figure may
occupy a sufficiently restricted space. To set out the travel of the piston and slide
valve a line is marked upon one of the side blocks of the piston rod crosshead, then
the engine is turned by hand, and opposite to this line two marks are made on the
crosshead guide, each corresponding to the position of the parts when the crank is
at one of its dead points. The distance between these marks equal to the stroke of
the piston is then divided into 10 equal parts. Evidently when the mark on the
slide block coincides with the lines marked successively on the crosshead guide the
piston will have made 0 1/10th 2/10 19 &c. of its course. Having done this the slide
valve is replaced by a board of hard fine grained wood representing exactly the
vertical section of the slide valve (Figure 1), and this board is fixed on the rod of
the slide valve in the exact position that the slide valve occupied. A wooden rule
is held immovably on to the valve surface of the cylinder against the wooden valve
and parallel with its movement; the engine is then turned by hand, and upon the
rule marks are made corresponding to the successive positions occupied by any one
point of the valve for each¹/10 part of the stroke of the piston, and also for the two
extremes of the stroke of the valve.
th
The distance of each of the points marked upon the rule from the end of the
stroke of the valve gives an ordinate corresponding to one of the abscissæ of the
curve for the piston (Figure 3). These ordinates are set out on the diagram to a
scale of 1/2 natural size.
By joining the ends of the preceding ordinates with a continuous curve, the
curve shewn in black is obtained, and this curve represents the positions occupied
by any one point of the slide valve.
The ordinates of the red and black curves corresponding to any one of the
abscisse give the corresponding positions of the slide valve and piston for the angle
described by the crank, the number of the degrees of which angle is represented by
the number of millimetres measuring that abscissæ.
In the engine in question the stroke of the slide valve is 270 millimetres, and
the radius of eccentricity of the eccentric is 135 millimetres, whilst the length of
the eccentric rod is 2 metres, 200 millimetres, that is about sixteen times the
aforesaid radius. Accordingly the parts of the curve of the slide valves above and
below the horizontal line a, b, (Figure 3), middle of the eccentric stroke are very
sensibly similar to one another.

page_text: When the preceding curves have been set out it is easy to obtain all the details
of the steam distribution with the old slide valve (Figure 1).
When the piston rod was at 0, the steam port for the top of the cylinder or back
of the piston was open 5 millimetres. Take c, d, (Figure 3), equal to 5 millimetres
on the same scale as the ordinates of the curve of the slide valve. It is evident
that if a horizontal line be drawn from the point d this horizontal will cut the
curve of the slide valve at a point g which will correspond with the closing of
steam admission, and at a point m. corresponding with the opening of the same
admission. The ordinate of the curve of the piston passing through g will be the
space travelled through by the piston during the steam admission.
On looking at Figure 1, which represents the old slide valve, it will be seen that
when the valve is at the centre of its stroke the inner edge of each bar coincides
with the edge of the corresponding steam port on the exhaust side, it is accordingly
at the point h of the curve of the slide valve, a point marked on the line a, b,
(centre of the stroke of the slide valve), that the exhaust is opened for the back of
the piston. The ordinate of the red curve passing through the point gives the
space travelled by the piston at the time when the exhaust is opened for the back
of the piston. Similarly it is at the point also on the line a, b, that the exhaust
closes for the back of the piston, and it is at the point m on the horizontal line d, g,
that steam is again admitted at the back of the piston. The steam port for
admitting steam to the front of the piston was open about 5 millimetres at the time
when the crank was at the dead point. Now take c¹, d', = 5 millimetres on the
same scale as the ordinates, and draw the horizontal d¹, g¹, the diagram shews for
the front of the piston that the steam admission opens at m¹, closes at g¹, and that
the exhaust opens at , closes at h.
The distribution set out in this way on the diagram, and which corresponds
exactly with the distribution in the engine itself, gives the following results :-
Height in millimetres of the steam port which is
opened at the time when the piston commences
its stroke
Back of Piston. Front of Piston. Mean.
5 m/m
5 m/m
5m/m
Duration of admission in fractions of the stroke -
Fraction of stroke at the end of which exhaust
0.75
0.60
0.705
0.93
0.90.
0.915
opens
-
Fraction of return stroke during which com-
0.10
0.07
0.085
04m/m
04m/m 64m/m
whole
} 416 m²
2
585 €/m²
pression takes place
Maximum height of steam port open for steam
admission (in millimetres)
Maximum height of port open to exhaust.
Surface open for steam admission in square centi-
metres.
-
Surface open for exhaust
2
whole whole
416416/³
2
585 m² 585/m³
It will be seen that the space which the piston has still to travel (to complete its
stroke) at the time when the steam port opens is practically nothing. The cut-off
valve closes the steam admission at 0.25 of the stroke on cach side of the piston.
If the nominal horse-power is valued by the formula used in the French Navy
DC N equivalent to the old formula of Watt, then D (diameter) = 1.050 C (course),
0-800, and N, the number of revolutions being from 62 to 63 a minute, the result is
94 horse nominal. The old distribution gives then for each horse-power
0.59
DC N
0.59
-
nominal,-
416
94
=
4 square centimetres of open steam port.
385
6
94
1
"
of open exhaust port.
This distribution as it existed in the engine before the application of the improve-

page_text: ments would be considered a good distribution according to the principles here-
tofore admitted.
The diagram (A, Figure 5) is a copy of one of the diagrams given by the engine
with this old distribution. The temperature of steam in the valve box was 126°
centigrade, corresponding to a pressure of 104 centimetres of mercury above the at-
mospheric pressure. The vacuum in the cylinders was 50 centimetres, corresponding
to a temperature of 72° (centigrade). The total fall in temperature in the cylinder
was thus 53° (centigrade). The piston at each end of its course had a clearance
of 19 millimetres between itself and the end of the cylinder. The volume of such
dead space was thus,——
New Distribution after the Application of the Arrangement F and other of the
Improvements.-The coverings of lead of a thickness of 4 millimetres applied to the
piston, as herein-after explained, reduces the spaces between the piston and cylinder
end to 11 millimetres =
19™/m 8/m
The volume of dead space is thus
reduced to 40 litres. The effect of the improvements being to reduce the con-
densation in the cylinders, the quantity of water in the liquid state in the cylinders
should be diminished, and the vacuum thereby notably increased. A vacuum of
about 60 centimetres mercury in the cylinders (corresponding temperature 611/2
centigrade) was reckoned on. The rarefied vapour remaining in the cylinder on the
closing of the exhaust should therefore have as is estimated a tension of 26 centi-
metres mercury.
To restore this vapour by compression to the temperature of the
steam in the valve box (126° centigrade) it was necessary, even supposing the
compression effected at a constant heat and no excess of water mixed with the
vapour in the cylinder, to reduce this vapour to about 1/10th of its original volume.
The total dead space (40 litres) represents the volume of compressed vapour. The
exhaust should then be closed soon enough to retain in the cylinder and dead space
400 litres of rarefied vapour. The portion of the stroke of the piston representing the
period of compression will thus in this case be
m³
0:400
m³
0:040
Volume generated by the
piston at each stroke.
=
"
0-360
in³ = 0.52.
0.69272
Since the cylinder is not impermeable to heat it is necessary in order that the
temperature at the end of the compression shall be 126°, to close the exhaust even
sooner. Not only should the above volume of steam be compressed, but also an
additional quantity equal to that which in condensing will restore the sides of the
cylinder to or as near as possible to a temperature of 126° at the end of the com-
pression. A compression to this extent could not be obtained without entirely
changing the parts by which the distribution was effected. As it was required not
to change the movement of the mechanism nor the system of distribution, the
amount of compression only which could be obtained with these existing parts
could be arrived at.
I will first explain what was done to attain this end, and then explain why the
compression could not be carried further. The lead of the eccentric, which was 34°
for the old slide valve (No. 1), was increased to 49°, or by 15°. The mechanism
(eccentrics, rods, &c.,) not being changed, it is evident that the curve corresponding
to the movement of the slide valve after the increase in angular advance will be
obtained by shifting the old curve horizontally from right to left a distance repre-
senting the 15° of advance. This distance will be 15 millimetres on the Drawing,
as one millimetre represents a degree. We thus obtain the blue curve (Figure 3),
which gives the movement of the new slide valve.

page_text: The lead for steam admission has been carried to 18 / at the two ends of the
cylinder; consequently, at the time when the steam admission opens the piston is
still at a distance from the end of stroke of 5 m/ for the front of the cylinder,
and 8 m/m for the back.
The advance in the admission can even be so regulated that the piston shall
have 1/10th of its return stroke to make when the admission of steam opens. No
inconvenience would attend such a limit. Let us take K. and K¹¹ each equal to
18 m/ on the scale, draw the horizontals 8 8 8¹, and on each side of Figure 3
draw the steam ports tinted blue. The cylinders not being changed the dimensions
of these orifices remain the same as before.
The points and ¹ on the blue curve are the points at which the steam ports
close, the respective ordinates of the curve of the piston passing through and ✗1
give the fraction of the stroke at which the steam admission closes for each of the
sides of the piston.
If the old slide valve was retained with this new position of the eccentric the
exhausts would open at two points where the blue curve cuts the line a, b, that is,
at 85 hundredths of the stroke for the back of the piston, and 80 for the front of
the piston. These leads of the exhaust would be inadmissible; but if 35 millimetres
of interior lap be added to one bar of the slide valve, and 45 to the other bar, the
new orifices of emission must be placed as indicated at Figure 3. The leads of the
exhaust would then remain nearly the same as before, and the compression would
be considerably increased. The bars of the new slide valve, Figure 2, are thus
obtained, and give the following distribution :-
Width of steam port open at the time when the
piston commences its stroke -
Duration of admission in fractions of the
Back of Piston. Front of Piston. Mean.
stroke
?} 18 m/m
} 0.575
18 m/m
18 m/m
•
0.468
0.520
Fraction of the stroke at the end
of
which
0.935
0.915
0.925
exhaust opens
Fraction of return stroke, during which com-
0.325
0.267
0.296
pression takes place -
Maximum opening in millimetres of admission
50 m/m
50/
50 m/m
steam port. -
Maximuni opening of exhaust
whole
whole
whole
-
Surface open for adinission in square centimetres
Surface open for exhaust in square centimetres
325 (/) 325 (c/m)² 325 (c/m)²
585 (/m) 585 (/m)² 585 (c/m)²
new distribution gives then for
The mean number of revolutions being from 64 to 65 with the new distribution,
the nominal horse-power will be 96 to 97. The
cach horse-power nominal,-
325
97
585
97
=
-
3310 square centimetres of surface open for steam admission,
6 square centimetres open for exhaust.
The ports at the back of the slide valve, Figure 2, are the same as in the old
slide valve, Figure 1. In adopting this arrangement the aim was to utilize without
change the old expansion valve. The angle of advance of the eccentric which works
this valve has been slightly modified to obtain the same cut-off with the valve,
Figure 2, as with the valve, Figure 1.
I will now describe why the amount of compression obtained is the maximum
that could be obtained with the engine in question without changing the mechanism
and system of distribution.
In the first place the increase of the angle of advance which can be given to the
eccentric is limited. It was necessary, first, not to reduce the surface of the ports
opened for steam admission below the minimum usually allowed, which is 3(c/m) for
cach horse-power nominal calculated by the formula above given. It was also
necessary not to close the admission too soon in order that the engine might be readily
started when in any position.

page_text: In order that the following reasoning may be readily comprehended it is necessary
to observe that the engine had two cylinders with the cranks at right angles:
When one of the slide valves is is at any point on the blue curve the slide valve of
the other cylinder is in a corresponding position on the same curve at a point distant
from the first by 90° (that is, 90 millimetres), the distance being measured parallel to
the axis of the abscissa.
No difficulty can be experienced in starting the engine, except when one of the
cranks is close up to its dead point.
If a crank is at the dead point at the time when the engine is started the slide
valve of the second cylinder must still allow sufficient steam to pass to obtain a
pressure in the second cylinder which shall be capable of turning the crank shaft.
This quantity is very small on account of the great lever arm on which acts the
connecting rod belonging to this last cylinder.
If the admission has already been closed in this second cylinder it is indis-
pensible that the crank, of the first cylinder shall have passed its dead point a
sufficient number of degrees in order that the action of its connecting rod shall alone
be sufficient to turn the crank shaft. An angle of 2012 degrees from the dead
point would with the engine in question give at least a lever arm of 20 millimetres
for the connecting rod to act with, that is, 0.05 of the radius p of the circle described
by the crank. As the lead for steam admission is considerable (18 m/m) the steam
port will be already well open, and one might reckon on a pressure of 150 centimetres
of mercury (including vacuum) upon the piston. The moment which tends to
turn the crank will then be 150 cm x 0.05 = p × 7c/m 50.
It is known from the experiments of Bourgois and Moll that the product of p by
5 or 6cm is the mean moment of effort upon the pistons below which the cranks
cease to turn. For these several reasons it was therefore thought that by arranging
that the crank of the piston nearest to the dead point should have passed beyond
this point by at least an angle of 21 degrees at the time when steam is cut off
from the other cylinder that the engine could readily be started even if one of its
pistons should be at the dead point. Experience has justified these expectations.
To attain this end we determined the positions of the horizontals 8 6 (88) and
81, 8¹ (8, ¹), which determine the natural cut off of the new slide valve by the
condition that the lengths à (8 d) and 8¹¹ (8¹¹), should be at least equal
to 92, millimetres, that is, 921/2 degrees. Then when the steam admission closes
for one of the pistons the crank of the other has already passed at 21 degrees
beyond the dead point.
3
If it were, thought that the starting of the engine would be too difficult for
certain positions of the cranks by reason of the duration of steam admission being
too abridged, the inconvenience could casily be remedied. It would only be
necessary to give to the eccentric for a stern motion and angle of advance 6° to 7°
less than the angle of advance of the eccentric for moving forward. If, when
starting, the engine is not in a good position for moving forward, it can readily be
brought to a convenient position by making a portion of a turn with the backward
motion which will always start the engine in whatever position the cranks may be.
This precaution was taken in the engine herein spoken of, but it was found not at
all necessary.
The condition that the engine shall be easily and at once started being indis-
pensible for a marine engine therefore redered it impossible to increase the angle
at which the eccentric is set in advance beyond that which was adopted.
The position of the blue curve corresponding to the new slide valve being thus
fixed, the possible duration of compression was limited by the condition that the
interior overlaps necessary with this valve should open the exhaust sufficiently
soon before the end of the stroke.
It was considered that the lead of the exhaust could not be reduced beyond what
is shown on the diagram (about 71/2 per cent. of the stroke.

page_text: The line X, Y, which is the geometrical axis of the boss should be in the
direction in which the metal will expand. For example, if the surface to be
covered is a circle the line X, Y, should be directed to the centre of the circle, and
the clearance B, C, between the boss and the slot in the lead should be placed on
the side of same centre.
For a covering of lead 4 millimetres thick the above fastenings have been placed
at 200m from centre to centre. The fastenings have been put somewhat closer at
places where the form of the parts to be covered seemed to require it.
in
The leaden covering of the screw nut of the piston has been soldered at its edges
(mu), (Figure 7), to the part placed over the piston.
The leaden covering of the recess at the centre of the cylinder cover has likewise
been soldered to the leaden coating of the cover.
The diagram B (Figure 5), was obtained with the engine after the above-
mentioned improvements had been made in it.
In place of the leaden coating being secured in the manner just described, it is
better that the coating of lead should be secured to the cast and wrought iron
surfaces to be covered by soldering. This is an easy and ready way of covering
with lead not only the covers and bottoms of the cylinders and the two faces of
the piston, but also the whole of the distribution passages. To solder lead on to
wrought or cast iron it is necessary first to give a coating of tin by any ordinary
process to the surface of iron to be covered. The covering of tin should be well
done, and should be somewhat thick. When tinning cast iron the cast-iron surface
must be made white with the file and afterwards well washed with acids and
water. When the tinning has been effected the iron, whilst protected from air, is
heated up to the fusing point of lead. When the piece has been heated and the
tin well softened the tinned surface is quickly cleaned by rubbing it with a little
borax and rosin. The melted lead is then poured on to the desired thickness
without loss of time. The workman must then take a very hot soldering iron and
rub with its point the whole surface of the cast iron under side the melted lead.
The union thus effected is very tenacious. The lead cannot be separated from the
metal below it without cutting. Sheets thus coated with lead have remained for
15 days immersed in the water and steam of a steam boiler heated to 160°
centigrade; on being taken out of the steam boiler in winter they have been
exposed for several days to a temperature of from 10 to 17 degrees below zero
(centigrade).
If pure lead appears too soft the lead coating may be hardened by mixing with
the melted lead a little antimonium, a metal which has very nearly the same
specific heat and conductibility as the lead. After these tests the leaden covering
has shown no sign of change neither in the soldering or in the lead itself. If the
surface coated with lead is of large area, and fears are entertained of the coating
becoming unsoldered or splitting from the effect of unequal contraction and
expansion of the superimposed metals, the following means may be employed :-
When the lead coating has been welded and cooled it is divided in as many parts
as seems necessary by slits perpendicular to its surface. These slits will be from 1
to 2 millimetres in width. They are made in the coating with a sharp cutting tool,
and are carried through the whole thickness of the lead to the metal below. This
means, which in no way effects the adhesion of the lead, will prevent the evils
anticipated.
In witness whereof, I, the said Henry Gilles Hautermann, have hereunto set
my hand and seal, this Twenty-second day of August, in the year of our
Lord One thousand eight hundred and seventy six