AN IMPROVED APPARATUS POR DISCOVERING THE LEAKAGE OR ESCAPE OF GAS
Year: 1855

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, and of Glasgow, North Britain, Gentleman,
for the Invention of "AN IMPROVED APPARATUS POR DISCOVERING THE
LEAKAGE OR ESCAPE OF GAS."-A communication from Etienne Abram
Maccaud, of Paris, in the Empire of France, Gentleman.
Sealed the 4th April 1856, and dated the 11th December 1855.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 11th December 1855. ...
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, and of Glasgow, North Britain, Gentleman, do hereby declare the
nature of the said Invention for "AN IMPROVED APPARATUS FOR DISCOVERING THE
LEAKAGE OR, ESCAPE OF GAS," a communication from Etienne Abram Maccaud,
of Paris, in the Empire of France, Gentleman, to be as follows:
This Invention relates to a peculiar arrangement of apparatus for discovering
any leakage or escape of gas in buildings lighted by that medium. The
apparatus consists of a cylinder, formed, with several branches, and in one piece
with a bed plate, for the facility of attachment to a wall or other convenient
object. At the lower extremity of this,cylinder is fitted a bent pipe, connected
to a force pump, which may be worked by hand or by other suitable means.,
Air is then drawn in at one aperture of the pump and forced into the bent

page_text: pipe and cylinder by another aperture; whence it passes to the supply pipes,
and to two side tubes in connection, the one with a dial pressure guage, and
the other with a mercurial guage for indicating the pressure in the gas pipes,
all the cocks at the burners and meter having been previously closed. By
using two guages of different constructions one serves to verify the other. If
desirable, one guage may be used to indicate the pressure of the-air, and the
other the pressure of the gas when burning. A safety valve is fitted to the
apparatus also to prevent any excess of pressure occurring in the pipes. Any
leakage that would occur in the pipes will be readily indicated by the hissing
of the air through the leaks. In place of forcing air into the pipes, a vacuum
may be made therein, the apparatus being worked in a reverse manner to that
herein-before described. In some cases a reservoir of compressed air may be
used, either with or without the force pump, for establishing a pressure in the
pipes and fittings. The force pump will be found particularly applicable for
forcing any suitable liquid. into the pipes, for the purpose of cleaning them,
and will serve, by forcing air through the pipes, to remove or expel the drops
of moisture which sometimes condense in the burners.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Henry Johnson in the Great Seal Patent Office on
the 11th June 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
and of Glasgow, North Britain, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eleventh day of December, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Henry Johnson, Her special license that I, the said John
Henry Johnson, my executors, administrators, and assigns, or such others
as I, the said John Henry Johnson, my executors, administrators; or assigns,
should at any time agree with, and no others, from time to time and at
all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "AN IMPROVED APPARATUS FOR DISCOVERING THE LEAKAGE OR ESCAPE OF GAS,"
a communication from Etienne Abram Maccaud, of Paris, in the Empire of

page_text: France, Gentleman; upon the condition (amongst others) that I, the said
John Henry Johnson, by an instrument in writing under my hand and, seal,
should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same.
to be filed in the Great Seal.Patent Office within six calendar months next:
and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Henry Johnson, do hereby declare:
the nature of the said Invention, and in what manner the same is to be.
performed, to be particularly described and ascertained in and by the following.
statement, reference being had to the accompanying Drawings, and to the
letters and figures marked thereon, that is to say:
The said Invention relates to a peculiar construction and arrangement of
apparatus for giving intimation or notice of any leakage or escape of gas in
buildings lighted by that medium. The apparatus consists of a cylinder with
Ia bed plate, for the facility of attachment to a wall or other convenient object,
to the lower extremity of which cylinder is fitted a pipe, connected to a force
pump, which may be worked by hand or by other suitable means. Air is :
drawn in at one aperture of the pump, and forced into the pipe and cylinder.
by another aperture, whence it passes to the supply pipes and to two side tubes
in connection, the one with a dial pressure guage, and the other with a.
mercurial guage for indicating the pressure in the gas pipes, all the cocks at
the burners and meter having been previously closed. By using two guages.
of different constructions one will serve: to verify the other. If desirable, one,
guage may be used to indicate the pressure. of the air, and the other the.
pressure of the gas during its use. A safety valve may be also fitted to the.
apparatus to. prevent any excess of pressure occurring in the pipes. Any.
leakage that may occur in the pipes will be readily indicated by the hissing of
the air through the leaks. In place of forcing air into the pipes, a vacuum.
may be made therein, the apparatus being worked in a reverse manner to that.
herein-before described. In some cases a reservoir of compressed air or a vacuum.
chamber may be used, either with or without the force pump, for establishing a
pressure in the pipes.and fittings.
4
And in order that the said Invention may be fully understood, I shall now.
proceed more particularly to..describe the same, and for that purpose I shall,
refer to the Figures on the Sheet of Drawings hereunto annexed, the same.
letters of reference indicating corresponding parts throughout both Figures.
Figure 1 of the Drawings represents a side elevation of the apparatus with..
the. force pump attached; and Figure 2 is a front elevation of the apparatus,...
shewing the mercurial guage and manometer, either or both of which may be. +

page_text: used in practice. A is a copper or other metal cylinder, made in one piece
with the plate B, which can be fixed: by nails or screws against a column.or.
wall, or in any other convenient situation. At: the lower extremity of .this-
cylinder a junction is formed with the extremity of the pipe.D;. which. is firmly
united with the force pump. E.....The piston of this pump may be worked by!
hand or by any other means.. In rising, the piston draws in the air by the.
aperture a, and in descending it forces the air out by the pipe D .into the
cylinder A; from whence it..passes to the branch pipes b, c, placed in commu-
nication with the pressure guages G and H respectively, by opening the cocks
d and e, with which the branches are furnished. G is a manometer or metallic-
pressure guage, and H is the ordinary mercurial guage: . These two, guages:
will. thus verify each other. If thought desirable, one: might be. arrangedito
indicate the pressure of the compressed air, and the other that of the gas used
for lighting..
"
At the top of the cylinder is fitted a pipe I, in communication with the gas
pipes; hence it is clear that the compressed air will exercise an equal pressure
on all the pipes; care having been previously taken to close all the cocks.both
of the burners and meter.. Should. there be any escape of gas a hissing noise
will be immediately audible, which can be heard at a great distance, and an
immédiate diminution of the pressure on the manometer will be made apparent.
If, on the contrary, however, no escape exists, no hissing noise will be perceived;
and no diminution of the pressure on the guages will be indicated.. The
dimensions of course can be varied to any extent, and it can be used.in
magazines, public and private buildings, and, in short, in any place. illuminated
or heated with gas. Either an exhaust or force pump may be used for
operating upon the gas pipes. As although the first-described arrangement is
preferable, yet by exhausting the air from the tubes a similar effect will. be
obtained, the external air by rushing into the. pipes through. any leakages
therein producing a hissing noise, similar to that, arising from the escape of
the gas in the former case. If desired, a reservoir of compressed air or a
vacuum chamber may be used, either. conjointly or without the
establishing a pressure or vacuum in the pipes.and fittings. The arrangement
of.apparatus herein-before described is also, applicable: to the cleansing of the
pipes and tubes of gas.fittings. After having stopped the, places where an
escape has been discovered, I introduce through the pipes and fittings by the
aid of the force pump any. suitable cleansing. liquid capable of dissolving the
deposits left by the gas in its passage through the pipes. The force will
pump.
serve also for removing any drops of water which condense in the pipes, and
produce, as is well known, a flickering or jumping of the lights.
.pumps;
for

page_text: Having now described and particularly ascertained the nature of the said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe, in conclusion, that what I consider to be novel and
original, and therefore claim as the Invention secured to me by the herein-
before in part recited Letters Patent is,-
First, the general construction and arrangement of apparatus for discovering
the leakage or escape of gas from gas pipes and fittings by the aid of com-
pressed air or vacuum, as herein-before described.
Second, the peculiar construction and arrangement of apparatus for cleansing
gas pipes and fittings, and for expelling or. removing any drops of moisture or
condensed vapour therefrom, as herein-before described.
In witness whereof, I, the said John Henry Johnson, have hereunto
set my hand and seal, the Eleventh day of June, One thousand eight
hundred and fifty-six.
J. HENRY JOHNSON.. (L.S.)
J. HENRY JOHNSON.. (L.S.)