A PORTABLE GAS LAMP
Year: 1819

page_text: I TO ALL TO WHOM THESE PRESENTS SHALL COME, we, DAVID
GORDON, of the City of Edinburgh, in the County of Edinburgh, Esquire, and
EDWARD HEARD, of Brighton, in the County of Sussex, Chemist, send greeting.
WHEREAS.. His most Excellent Majesty King George the Third, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Nineteenth day of June, in the fifty-ninth year of His reign,
did, give and grant unto us, the said David Gordon and Edward Heard, His
especial licence that we, the said David Gordon and Edward Heard, our
exors, adiňors, and assigns, or such others as we, the said David Gordon
and Edward Heard, our exors, admors, or assigns, should at any time agree
with, and no others, from time to time and at all times during the term of
years therein. expressed, should and lawfully might make, use, exercise, and
vend, within England, Wales, and the Town of Berwick-upon-Tweed, our
Invention of "A PORTABLE GAS LAMP;" in which said Letters Patent there
is contained a proviso obliging us, the said David Gordon and Edward Heard,
cr one of us, by an instrument in writing under the hands and seals of us or
one of us, particularly to describe and ascertain the nature of our said Inven-
tion, and in what manner the same is to be performed, and to cause the same
10 be inrolled in His Majesty's High Court of Chancery within two calendar
months next and immediately after the date of the said recited Letters Patent,
as in and by the same, reference being thereunto had, will more fully and at
large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
David Gordon, do hereby declare that the nature of our said Invention, and the
manner in which the same is to be performed, is described and ascertained
in the Plan drawn on the margin of these Presents, and the following explana-
tion thereof, that is to say:-
The Invention for making a gas lamp portable consists in condensing the
inflammable gass by forcing it into a strong vessel by means of a pump, which
vessel forms the body or reservoir of the lamp, and when it is desired to light the
lamp, permitting the gas to issue out in a sufficiently moderate manner to supply
the burner or burners of the lamp by means of a valve or a stopcock of a par-
ticular construction. The reservoir or body of the lamp may be made of any
substance that is sufficiently strong and close in its texture to contain the con-
densed gas.
I prefer and employ metals. This body or reservoir of the lamp
may be made of almost any form that may be wished, provided the strength to
resist the expansive force of the gas be encreased to compensate for any loss of
strength arising from unequal resistance. I, however, recommend that this
body or reservoir should be made in the form of a sphere or a cylinder with
hemisperical ends, as these are the strongest forms. When it is desired to
have the lamp of gold or silver, or any expensive material, it may be best to
have a copper cylinder or sphere put into the more expensive case.
The body
or reservoir may either form part of the lamp exhibited to view, or it
may
be
concealed under a table, desk, &c., &c., &c., put into a statue, or the pedestal
of a statue, or even put into a different room or closet from that where it is
wished the light should be exhibited, and then uniting it with the burner or
burners. It will also be a most useful appendage to carriages, mail or stage
coaches, &c., as the reservoir may be placed under the seat, so that the road
may be illuminated in the darkest night at a trifling expence; it will also
be a most useful lamp on board of ships.
The following is a more particular description of one of the portable gas
lamps, the figure of which is drawn upon the margin. A is the cylinder of
copper, six inches diameter, and nine inches high, exclusive of the hemispherical
ends, and one twentieth of an inch thick. B is the stopcock, constructed in
the following manner:-After the cock has been drilled through in the usual
manner, the circular hole in the key is contracted at one side by soldering
into it two pieces of brass which join at one side of the hole, and are about
one twentieth of an inch distant at the other side, forming an acute angle
thus V By this means the issue of gas can be regulated to the smallest
possible stream by bringing the acute angle of the opening in the key to

page_text: communicate with the circular opening in the cock, and as the expansibility
diminishes as the gas is consumed the aperture can be increased in the same
proportion; but to secure the above ebject more completely, and to prevent
the possibility of turning the cock suddenly, so as to admit too great a
discharge of gas, a ratchet wheel is fixed on the end of the key of the cock,
in which an endless screw works. By turning this screw the flame may be
enlarged or diminished in any degree, however great the condensation of the
gas in the body of the lamp may be. Any of the variety of burners may be
united to the stopcock at C where it screws upon the pump when it is to be
charged with gas. Another contrivance which I employ to produce the same
effect is a conical leather valve (similar to that in the reservoir of an air gun)
placed in the opening of the reservoir of the lamp where it screws on to the con-
densing pump. When the reservoir has been charged with gas and removed
from the pump, a set of brass, as drawn on the margin, is screwed in above
the valve. Through this piece of brass a finger screw passes, the point of
which, when made to press upon the valve, forces it back and allows the gas to
issue in any quantity that may be required. This screw may also be turned by
an endless screw working in edge of the circular head, as before described
for opening the cock. A bridge of brass in the form of a gothic arch passes
over the head of this regulating screw. The use of this arch, which is a
hollow tube, is to give freedom to the fingere in turning the screw to regulate
the flame, and to conduct the gas to the burner, which, in a standing lamp, is
screwed on at the center of the arch. In those that are suspended this screw
will be attached to the center of their arms that communicate with the
burners, but this must vary with the variety of patterns in the lamps. By
either of the above contrivances the command of the flame is so complete
that it may be reduced to an almost imperceptible quantity; this must render
the portable gas lamp valuable for a sick chamber, as by touching the screw
the light may be increased in an instant. For the reservoir of large lustres,
or where it is desireable not to have occasion to turn the screw of the valve to
increase the aperture from whence the gas issues, a small spiral spring may,
when required, be added, which must act with a certain force on the valve so
as nearly to counteract the internal force of the condensed gas. As this is
diminished by 'the burning of the gas the power of the spring will prepon-
derate and force back the. valve, which will increase the aperture, and in this
way compensate for the diminished expansibility of the gas. From experience
I prefer the valve as being the most easily constructed. When the body or
reservoir of the lamp is not in use a cap of brass is screwed on above the
valve instead of the set of brass to prevent dust or anything from deranging

page_text: the valve. It also keeps all tight in case the valve should any way get injured.
A similar cap is fitted to the stopcock. The forcing pump has a solid piston
worked by a lever with shears, and a guide to produce a perpendicular motion:
There is a valve in the centre of the bottom of the cylinder opening inward;
and the connection being made between this and the gasometer, when the
piston ascends the gass passes through the communication from the gasometer;
and is prevented from returning by the valve. The gas is forced through a
channel at one side of the bottom, terminating in a male screw, furnished with
a valve to open outwards. To this screw the reservoirs are attached when
they are to be charged with gas. The above valve is only necessary when a
reservoir with a stopcock is used.. When the pump is moveable the.con-
nection between it the gasometer is formed by a flexible pipe; when the
pump is fixed the connection may be metal, and made with an elbow :thus
to give it some flexibility, and to unite it by means of
As con
swivel nuts, sometimes called connecting screws or coupling boxes.
densing the gas causes considerable heat, it is proper to have a means of
keeping the pump cool, which may be conveniently done by having a case
round it filled with water, and changing the water as it gets heated.
Method of filling the lamp.-When the reservoir or body of the lamp is to
be filled for the first time it is proper, although not absolutely necessary, to
nearly discharge the common air from the reservoir. This can be done suffi-
ciently by forcing into a few volumes of inflammable gas, and then permitting
the mixture to escape. When the body or reservoir of the lamp is ready to
be filled, screw it on the male screw, where the gas is forced from the cylinder
of the syringe or pump, and the connection between the gasometer which con-
tains the inflammable gas and the pump being made as has already been
described, then open the stopcock (if one is used) of the reservoir of the gas
lamp, and work the pump or syringe until a sufficient quantity of gass is forced
into the reservoir or body of the lamp. If the reservoir has a valve it may
be at once screwed off; if it has a stopcock, first close it, and then screw off
the reservoir; this reservoir is then to be attached to the burner or burners,
and the lamp is ready for use. Twenty-five volumes or upwards of inflam
mable gas condensed into one volume will be sufficient. This, however, may
be managed as circumstances require. For supplying portable gas lamps with
facility, and which will be found to possess great advantages when many of
these lamps require to be filled, I recommend using the power of steam,
water, wind, or horses to work the syringe or pump, and also to condense the
inflammable gas into very large reservoirs, from whence the lamps may be

page_text: speedily filled. To each of these large reservoirs (made in the same form for
strength as the reservoir of the lamp,) a mercurial gage (of the common con-
struction for ascertaining the force of condensed air) should be fixed to enable
any one to ascertain the degree of condensation of the gas in the large reser-
voir. The large reservoir ought to be fitted with a stopcock or stopcocks,
valve: or valves, one or more, as the 'number of lamps to be speedily filled 'may
require, to which the body of the lamp can be screwed; and then by 'opening
the communication between the two the lamp will be immediately filled;
then close the communication; unscrew the lamp, and after being united to.
the burner or burners, the lamp is ready for use. It shall be proper to put
a collar of oiled or greased leather on the shoulders of each of the male
screws of the lamp, pump, and reservoir, &c., &c., &c. The large reservoir,
from whence the lamps can be so speedily filled I consider as a very important
facility to the general use of the lamps. By means of it a great number of
lamps may be filled in a few minutes. For example, if it is required to be
able to fill quickly ten lamps, each to contain about thirteen cubic feet of gas
(which will be about the contents of a sphere of one foot diameter condensed
twenty-five times), prepare: a reservoir with a mercurial gage, as before
described) of twenty-six feet of cubic contents, sufficiently strong to bear with-
out-danger gas
condensed thirty times. Fit to this a valve as directed for the
reservoir of the lanp, and unite it to the pump at the part from whence the
gas is forced, and, making the communication pipe as short as possible, then
work the pump, having previously connected it with the gasometer until the
gas is condensed thirty times in the large reservoir. It will then 'contain
seven hundred and eighty feet of, gas. To this large reservoir fit also one or
more valves similar to those already described, but with. the addition of a male
screw, as drawn and described on the margin, to which the body of the lamp
to be. filled is to be screwed; and then with the finger screw, which presses
up the valve, open the communication, and the lamp will be immediately
filled; then close the communication, and unscrew the lamp. By this means
ten lamps, each containing about thirteen feet of gas, will be speedily filled;
& which will have reduced the condensation in the twenty-six feet reservoir
to about twenty-five times. The pump may then again be set to work, and,
in fact, the process of condensing of the gas may be going on at the same
time that it is drawn off to fill lamps, taking care never to force the
condensation too far, or allowing it to be drawn too low by filling too many
lamps. The mercurial gage will at all times enable this to be easily ascer-
tained. I recommend for filling the lamps in towns, villages, &c., that one of
these large reservoirs, filled with condensed inflammable gas, should be placed

page_text: upon a wheeled carriage, having a smaller reservoir attached thereto, and a
syringe or pump, as before described, fitted between them, and having the
whole communicating together, as before described. By working this pump,
.when required, either by manual labour, or by connecting it with the rotatory
motion of the wheels of the carriage, the smaller reservoir may always be
kept full of gas of the required density, to be ascertained by the gage; and
from this smaller reservoir, fitted with valves as before described, the lamps
along the streets. and at houses may be filled. Probably it may be found the
most expeditious and easy way to carry the condensation of gas to a high
.degree to pump it from one condensed reservoir to another, even when not
sent on a wheeled carriage. By fitting the wire gauze of Sir Humphry
Davy's lamp to the top of the portable gas lamp the most complete safety
lamp is formed, as it never can be required to take off the safeguard when in
a coal mine; and as much greater light can be given by means of gas than is
usually given by Sir Humphry Davy's lamp, the darkening effect of the gauze
may be overcome..
In witness whereof, I, the said David Gordon, have hereunto set my
hand and seal, the Tenth day of August, in the year of our Lord One