IMPROVEMENTS IN APPARATUS FOR CONTROLLING OR REGU- TATNA MUT SUDDLY OF GAR TO BURNERS.
Year: 1871

page_text: LETTERS PATENT to Henry Alexander Frederick Duckham, of
Camden Town, in the County of Middlesex, Gas Engineer, for the
Invention of "IMPROVEMENTS IN APPARATUS FOR CONTROLLING OR REGU-
TATNA MUT SUDDLY OF GAR TO BURNERS.
"
Sealed the 31st October 1871, and dated the 4th May 1871.
PROVISIONAL SPECIFICATION left by the said Henry Alexander
Frederick Duckham at the Office of the Commissioners of Patents,
with his Petition, on the 4th May 1871.
I, HENRY ALEXANDER FREDERICK DUCKHAM, of Camden Town, in
the County of Middlesex, Gas Engineer, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN APPARATUS FOR CONTROLLING
OR REGULATING THE SUPPLY OF GAS TO BURNERS," to be as follows:-
My Invention relates to a means of readily economizing or reducing
the consumption of gas at the burners when the illuminating power is
not required, the apparatus of my Invention being peculiarly adapted
for controlling the supply of gas in the carriages comprising a railway

page_text: train, and also in large establishments for lowering the gas when required
without extinguishing it.
The apparatus consists of a closed chamber having inlet and outlet
passages through which the gas is caused to pass on its way to the
burners. The exit of the gas from this chamber is controlled by a valve
connected to a diaphragm of pliant material forming the top of the
chamber, which when fully distended by the pressure of the gas within
said chamber raises or opens the valve for the free passage of the gas.
The valve is closed to cut off or reduce the supply of gas to the burners
by the distension of a second diaphragm acting in opposition to the first,
and also connected to the valve stem and forming part of a second closed
chamber having an inlet passage only, through which air is supplied
under pressure from a reservoir. Thus when the pressure in the air
chamber acting on its diaphragm balances or overcomes the pressure of
gas on the diaphragm of the-gas chamber, the supply of gas for illumi-
nating will be cut off, a small passage, which is permanently open, being
however provided in the valve for the supply of a minimum quantity of
gas to the burners, in order that it may continue to burn but in small
quantity until its illuminating power is again required, as in passing
through a tunnel for instance. The two chambers with their fittings
may be enclosed in an outer metal casing, and the apparatus may be
fitted in any convenient position in the guard's van, the supply being
regulated by adjusting the pressure in the air reservoir.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Alexander Frederick Duckham in the Great 28
Seal Patent Office on the 4th November 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
ALEXANDER FREDERICK DUCKHAM, of Camden Town, in the County of
Middlesex, Gas Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her 30
Letters Patent, bearing date the Fourth day of May, in the year of our
Lord One thousand eight hundred and seventy-one, in the thirty-fourth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Henry Alexander Frederick Duckham, Her
special licence that I, the said Henry Alexander Frederick Duckham, 35

page_text: my executors, administrators, and assigns, or such others as I, the said
Henry Alexander Frederick Duckham, 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, usc, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN APPARATUS FOR
CONTROLLING OR REGULATING THE SUPPLY OF GAS TO BURNERS," upon the con-
dition (amongst others) that I, the said Henry Alexander Frederick
Duckham, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and scals, 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 Henry Alexander Frederick
Duckham, do hereby declare the nature of my 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 Sheet of Drawings hereunto annexed, and to the letters and
figures marked thereon (that is to say)
:-
My Invention relates to a means of readily economizing or reducing
the consumption of gas at the burners when the illuminating power is
not required, the apparatus of my Invention being peculiarly adapted
for controlling the supply of gas in the carriages composing a railway
train, and also in large establishments for lowering the gas when
required without quite extinguishing it, the advantage of this apparatus
being that there are no working joints at which leakage of the gas
could occur.
The apparatus consists of a closed chamber having inlet and outlet
passages through which the gas is caused to pass on its way to the
burners. The exit of the gas from this chamber is controlled by a
valve connected to a diaphragm of pliant material forming the top of
the chamber, which when fully distended by the pressure of the gas
within said chamber raises or opens the valve for the free passage of
the gas. The valve is closed to cut off or reduce the supply of gas to
the burners by the distension of a second diaphragm acting in opposition
to the first and also connected to the valve stem and forming part of a

page_text: second closed chamber having an inlet passage only, through which air
is supplied under pressure from a reservoir. Thus when the pressure
in the air chamber acting on its diaphragm balances or overcomes the
pressure of gas on the diaphragm of the gas chamber the supply of gas
for illuminating will be cut off, a small passage, which is permanently
open, being however provided in the valve for the supply of a minimum
quantity of gas to the burners, in order that it may continue to burn
but in small quantity until its full illuminating power is again required.
The two chambers with their fittings may be enclosed in an outer metal
casing, and the apparatus may be fitted in any convenient position in
the guard's van or to each separate carriage, the supply being regulated
by adjusting the pressure in the air reservoir.
Figure 1 is a central vertical section, and Figure 2 a top plan of the
apparatus; A is the external casing of metal in which the-parts are
enclosed.
a, a, are the sides of the chamber through which the gas-passes-in_the_
direction of the arrows; is the inlet pipe from the gas reservoir to the
chamber a, and c the outlet pipe leading from within chamber a and con-
veying the gas away to the burners. This chamber is made of sheet metal,
(tin plate), and is closed gas tight at top by a diaphragm e of pliant
material consisting of two thicknesses of alpaca joined by a solution
of glue and treacle and coated on each side with an india-rubber solution
as usually employed in my gas regulators; f is the valve rod moving
vertically in guides g at top and bottom and passing through the centre
of diaphragm c, to which it is firmly attached by a clamp h; i is the
valve or rodf to close pipe o, being received in a seat fitted to the
bottom of chamber a; j is a small nick or cut made in the conical side
of the valve i to allow of the passage of a minimum quantity of gas
when the valve is closed; k is the second diaphragm (which is usually
made about half the diameter of diaphragm e) also clamped to rod f, and
serving to close the bottom of a chamber to which it is attached as
shown; m is a pipe by which air is supplied to closed chamber / from
an air bag or other suitable reservoir. The parts are so arranged that
the pressure of the gas in chamber a will distend the diaphragm e and
raise the valve i, thereby opening for itself a free passage to the burners,
no pressure being exerted on diaphragm k, which is collapsed as shown.

page_text: When it is desired to cut off or reduce the supply of gas, air is forced
into chamber by weighting or pressing on the flexible reservoir (not
shown) by means of a hand lever so as to inflate the diaphragm k, as
shown in red lincs, until the pressure thereon overcomes that of the gas on
diaphragm e, thus closing valve i also as shown in red lines (Figure 1.)
The valve may thus be kept closed as long as desired, and when a full
supply of gas is again required it is only necessary to remove the
pressure from the air reservoir.
Having described the nature of my Invention, and the manner of
performing the same, I declare that what I claim as my Invention to be
protected by the herein-before in part recited Letters Patent is, the
combination with a valve i of diaphragms e and k operated by the
pressure of gas and of air respectively, substantially as herein-before
described and shown in the Drawings for controlling or regulating the
supply of gas to burners.
In witness whereof, I, the said Henry Alexander Frederick
Duckham, have hereunto set my hand and scal, this Third
day of November, in the year of our Lord One thousand eight
hundred and seventy-one.