Improvements in Air-gas Mechanism for Lighting Railway Carriages and the like.
Year: 1896

page_text: Date of Application, 30th May, 1896-Accepted, 22nd Aug., 1896
[Communicated from abroad by ANDREW DEMPSTER, of 266 Post Office Place,
Melbourne, in the Colony of Victoria, Gas Engineer.]
Improvements in Air-gas Mechanism for Lighting Railway Carriages
and the like.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for Foreign
Patent Solicitors, 322 High Holborn, in the County of Middlesex, 6, Lord Street,
Liverpool, and 6, Bank Street, Manchester, both in the County of Lancaster, and
Lower Temple Street, Birmingham, in the County of Warwick, Civil Engineer, do
hereby declare the nature of this invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:
Various attempts have been made to construct satisfactory mechanism for the use
of air gas for lighting purposes prepared by admixture of air and some liquid volatile
hydrocarbon such for instance as light petroleum spirit. These mechanisms have
displayed certain disadvantages in working which tend to restrict their usefulness
in various ways both in respect to freedom from danger and cost of working in
relation to the efficiency as a lighting apparatus.
The present invention as communicated to me by my foreign correspondent relates
to certain improvements in this system of lighting. The apparatus is divisible into
the following main elements:-
I. A source of compressed air. In railway carriage installations this may be from
the Westinghouse pump which actuates the vacuum brake or a special pump of the
same or similar pattern exclusively for the lighting apparatus, preferably also placed
on the locomotive. In other installations a pump driven by suitable mechanism must
be provided, or a supply of compressed air from an outside source arranged.
Il. An air filter for intercepting impurities.
III. A storage cylinder of sufficient capacity to keep the lights going for at least
30 minutes in the event of interruption to the action of the air compressor.
IV. A pressure regulating mechanism.
V. A carburetting mechanism.
VI. A mixing valve for regulating the proportions of carburetted air and unmixed
air passing to the burners.
VII. A burner of special design.
Referring to the accompanying drawings
:―
Fig. 1 represents a diagram of the carburetting and storing mechanism with its
connections.
Fig. 2 shows the carbu. ettor in horizontal section.
Fig. 3 the same apparatus in vertical section.
Fig. 4 the controlling and regulating mechanism for the supply to the burners.
Fig. 5 shows further details of the connecting tubes leading to the burners.
Fig. 6 shows a vertical section of the lamp adapted for railway carriages, with
the burner and connections in place.
Fig. 7 shows a vertical section of the burner.
Fig. 8 shows a vertical section on an enlarged scale of the regulator.
The air main A conveys atmospheric air compressed usually at about 50 lbs. per.
square inch from the Westinghouse or other pump actuated by any suitable source of
power. In the case of railway carriage lighting the pump may be that fixed for the

page_text: supply of air to the air brakes, but it will in practice be found better to fix a separate
pump for the purpose.
B is a tap for shutting off the supply of air from the main if necessary.
C indicates the air filter for intercepting dust or other impurities, it is preferably
formed of a casing containing a screen of woollen cloth supported on each side by wire
gauze or other suitable filtering medium which will strain off impurities from the air.
D indicates an intercepting valve of the Westinghouse type provided with a spiral
spring and compressing screw which can be operated from the outside. The spring
is preferably so adjusted that the retaining valve will not open under 50 lbs. pressure
per square inch. In the case where this inechanism is combined with a brake
mechanism this valve is important to prevent the efficiency of the brake being
interfered with by the lighting apparatus, and it also prevents the back pressure of
the contents of the storage cylinder from passing into the main whenever the pressure
therein falls short of that in the storage cylinder.
E represents the storage cylinder or reservoir the dimensions of which are
proportionate to the size of the installation. It has been found that a cylinder
9 ft. long by 1 ft. 6 inches in diameter is sufficient to maintain seven lights for
30 minutes without fresh supply of air where the pressure has been over 50 lbs.
F is a stop cock on the branch pipe leading from the storage reservoir to the
regulator G Fig. 1, illustrated on an increased scale in Figure 8 and hereinafter
described.
H represents the carburettor, this may be constructed in very many forms, but
in the form I prefer, it consists of a shallow vessel insulated from the outer air
by means of a packing of sawdust or other non-conducting material and provided
internally with partitions extending from top to bottom as shown in Figure 3 and
from one side to the other alternately as shown in Figure 2 so that the air entering
at the inlet I travels backwards and forwards along the passages until it escapes
at the outlet J. These passages are loosely packed with hemp, wool, asbestos or
other absorbent material saturated with gasoline by capillary attraction there being
a small quantity of gasoline in the apparatus maintained at a constant level from
an outside reservoir-not shown in the drawing. When the air is passed through this
apparatus it has become a combustible gas of high illuminating power. Only a small
portion of the air from the main A is passed through the carburettor, the remaining
air passes through the pipe K and tap O (Figure 4) to be subsequently mixed with
the carburetted air for combustion at the burner. The normal proportion of the
mixture is about one part of carburetted air to eight parts of ordinary air. The
pipe marked L also passes the carburettor to the pressure gauge marked M and the
pressure gauge shows the pressure of air in the storage cylinder. The outlet pipe J
is also carried forward to the tap Q (Figure 4). This tap Q has a slotted opening
one-eighth wide through it in place of the usual round hole. The pipe K is united
to Q below the tap O as shown in Figure 4. The taps O and Q are each provided
with indexes P. The tap O is used for lowering the lights or shutting them off and
the slotted tap for regulating the exact amount of gas admitted into the pipe R
leading to the burners so as to form the above named mixture of air gas, normally
about one part of carburetted air to eight parts of ordinary air. The mixed air then
passes through the tap O and is conveyed through pipe R to the lamps T each lamp
having a regulating tap marked S.
The pipe N (Figure 4) is carried up to a suitable height and provided with a stop
cock and screw cap or funnel or other ineans for conveniently charging the carburettor
with the liquid combustible.
Figure 6 shows the form of lamp preferred for roof illumination as for instance
in lighting railway carriages. It consists of a cup with a flat reflector enamelled on
the under side, a two inch round opening through the centre in which the chimney X
is fitted and a suitable cover to protect the apparatus from the weather and afford the
requisite ventilation and a globe or glass shade of ordinary shape enclosing burner U.
The burner may however be used without such a protection as it is not in the least
affected in its operation by even a strong draught.

page_text: Figure 7 shows the incandescent burner of my invention. I prefer to form the
same of a small cylinder of platina foil about the 300 part of an inch in thickness
perforated as closely as possible by means of a punch formed of a number of needles
of 6 or 7 size and closed at its lower end with a cap formed by rounding the foil on a
mandril and folding the end over until the points meet in the centre and close the end.
This burner U is fastened on to a brass nipple Y. screwed into the tube V (Figure 7).
Inside the tube V at the dotted lines of the drawing I press in a small square piece of
fine brass wire gauze for the purpose of preventing any scale or dust falling into the
burner and also to prevent any possibility of the light from the burner flashing
back into the supply pipes. This incandescent burner gives a brilliant illumination
without visible flame and is not affected by draughts nor does it require a supply of
outside air having sufficient oxygen provided by the current of air blown through the
supply tube.
The combustion of the gas when the burner is working properly is
almost entirely within the tube which it should bring to a brilliant white incandescence.
When the tube is in place and lighted for the first time the edge of the tube of
platina should be pressed down gently and firmly by means of a suitable knife blade
when the same will weld together and prevent jets of flame which may cause a fracture
of the lamp globe. The adjustment of the proper supply of air and gas to this
burner is as follows:-
The main tap is opened full then the slotted tap Q is gradually turned on whilst a
light is being held to the burner. When the gas ignites at the burner it will show a
blue flame outside, but this will disappear and the burner become incandescent in a
few seconds, if this does not result the gas supply should be slowly decreased until
the right quantity passes. No flame whatever should show outside the burner when
incandescent, this may be easily ascertained by holding some opaque object between
the eye and the burner to cut off the brilliancy of the same and observe the outer
edge of the burner beyond which no flame should show. When the lights commence
to burn dull a little more gas should be supplied until the supply of gasoline in the
reservoir exhausted and the same has to be recharged.
The regulator shown on a larger scale in section in
follows:-
Figure 8 is constructed as
It consists of an elastic diaphragm e within a casing d. The diaphragm is arranged
so as to force down a lever k by means of the rod ; which opens the inlet valve and
keeps it open until the pressure upon the diaphragm is sufficient to raise it and the
lever and close the said valve. It is provided with a spring and screw ng for
regulating it so that the pressure upon the diaphragm can be altered at will without
removing the cover of the regulator.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In apparatus for lighting railway carriages and similar vehicles the combination
of parts consisting essentially of an air compressor, an air filter, a storage cylinder,
a pressure regulating mechanism, a carburetting mechanism placed beneath the
carriage, a mixing valve for regulating the proportions of carburetted air, a slotted
adjusting tap for regulating the exact amount of combustible admitted to the burner
and a platinum burner substantially as herein before set forth and illustrated in the
accompanying drawings.
2. In apparatus for lighting railway carriages with a mixture of air and liquid
volatile hydro-carbon, a carburetting mechanism adapted to contain a supply of liquid
benzoline placed at a convenient point below the level of and at a distance from the
lamps at which the gas is burned substantially as described.
3. In apparatus for lighting railway carriages and the like by a mixture of air and
liquid volatile hydro-carbon, the arrangement of a regulating tap Q having a slotted
opening, substantially as described.
4. In apparatus for lighting railway carriages and the like by a mixture of air and
liquid volatile hydro-carbon, the platinum incandescent burner adapted to consume

page_text: the combustible within its surface constructed in the manner described and shown in
"the accompanying drawings.
5. In apparatus for lighting railway carriages and the like by a mixture of air and
liquid volatile hydro-carbon, the regulating device substantially as described and
shown in Figure 8 of the accompanying drawing.
Dated this 29th day of May 1896.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.