AN IMPROVED LAMP
Year: 1868

page_text: LETTERS PATENT to James Allison Hogg, the younger, of the City
of Edinburgh, in Scotland, Gas Engineer, for the Invention of
"AN IMPROVED LAMP."
Sealed the 22nd January 1869, and dated the 27th July 1868.
PROVISIONAL SPECIFICATION left by the said James Allison Hogg
at the Office of the Commissioners of Patents, with his Petition, on
the 27th July 1868.
I, JAMES ALLISON HOGG, the younger, of the City of Edinburgh, in
Scotland, Gas Engineer, do hereby declare the nature of the said
Invention for "AN IMPROVED LAMP," to be as follows:-
The object of this Invention is an improved lamp or apparatus for
producing light. This apparatus is constructed as follows:-Two
tubes are employed on the Bunsen lamp principle, one of which is of
smaller diameter than the other, and the said smaller tube is placed
within the larger tube. One tube is placed in communication with
condensed gas or air, or both, compressed by a pump or other suitable
apparatus for compressing or condensing air or gas or aeriform or
gaseous fluid. This pump or apparatus may be of ordinary construction

page_text: and worked by hand, steam, or other power. The other tube is placed
in communication with ordinary arrangements for the supply of
atmospheric air or gas thereto. The gas, or the air, or hoth, may be
supplied at any determined pressure, or it may be condensed or
compressed before reaching the tube or tubes in a pump or apparatus
(for the purpose) of ordinary construction. The mixture of gas and
air is passed through a perforated plate of platina or other suitable
material or tissue of platina, wire gauze, or other suitable wire gauze,
by which it is divided into numerous small jets. The mixture of gas
and air is obtained thus:-The tube conducting one of those agents is
conducted through the smaller tube and discharged through the opening
thereof into the larger tube, into which also the other agent is admitted.
The tubes thus act as a sort of blow pipe. The aeriform or gaseous
mixture passes through the larger tube to a piece or surface of fine
platina. Pierced plate, gauze, or woven platina wire or other suitable
metal may be substituted for the platina. The minute jets pass through
the interstices of the plating or other metal and are ignited. The metal
soon becomes incandescent, the supply of air being duly regulated
combustion is made perfect, flame disappears, and the platina or metal
becomes a disc or surface of intense light.
Sometimes instead of using a mixture of gas and air, I use com-
pressed or condensed gas by itself and air at the ordinary pressure.
Sometimes the gas and air may be heated before burning to obtain a
maximum effect.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said James Allison Hogg in the Great Seal Patent Office
on the 27th January 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
ALLISON HOGG, the younger, of the City of Edinburgh, in Scotland,
Gas Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of July, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said James Allison Hogg, the

page_text: younger, Her special licence that I, the said James Allison Hogg, the
younger, my executors, administrators, and assigns, or such others as I,
the said James Allison Hogg, the younger, my executors, adminis-
trators, 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, 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 LAMP," upon
the condition (amongst others) that I, the said James Allison Hogg,
the younger, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, 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 James Allison Hogg, the younger,
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 thereof, reference being had to the
accompanying Drawings, and to the letters and figures marked thereon,
that is to say :-
The object of this Invention is an improved lamp or apparatus for
producing light. This apparatus is constructed as follows:-Two tubes
are employed on the Bunsen lamp principle, one of which is of smaller
diameter than the other, and the said smaller tube is placed within the
larger tube. One tube is placed in communication with condensed gas,
or air, or with both, such gas or air being compressed by a pump or other
suitable apparatus for compressing or condensing air or gas or aeriform
or gaseous fluid.
This pump or apparatus may be of ordinary con.
struction and may be worked by hand, steam, or other power. The other
tube is placed in communication with ordinary arrangements for the
supply of atmospheric air or gas thereto. The gas, or the air, or both, may
be supplied at any determined pressure, or it or they may be condensed
or compressed (before reaching the tube or tubes) in a pump or apparatus
for the purpose of ordinary construction. The mixture of gas and air is
passed through a perforated plate of platina or other suitable material, or
a tissue of platina wire gauze, or other suitable wire gauze, by which it
is divided into numerous small jets. The mixture of gas and air is

page_text: obtained thus, that is to say, one of those agents is conducted through
the smaller tube and discharged through the opening thereof into the
larger tube, into which also the other agent is admitted. The tubes thus
act as a sort of blow pipe. The aeriform or gaseous mixture passes
through the larger tube to a piece or surface of fine platina. Pierced
plate, or wire gauze, or woven platina wire, or other suitable metal may
be substituted for the platina. The minute jets pass through the
interstices of the platina or other material and are ignited. The metal
soon becomes incandescent, the supply of air being duly regulated com-
bustion is made perfect, flame disappears, and the platina or metal becomes
a surface of intense light.
Sometimes instead of using a mixture of gas and air I use compressed
or condensed gas by itself and air at the ordinary pressure.
Sometimes the gas and air may be heated before burning to obtain a
maximum effect.
What I understand by the expression "suitable" above used is a
substance having the property of becoming incandescent like platina.
In order that the mode of carrying the Invention into effect may
be well understood I proceed to describe the same with reference to
the Drawings, which represent lamps constructed according to my
Invention.
Figure 1 is a vertical elevation in section of a lamp in which are used
compressed gas and air at ordinary pressure. Figure 2 shews the lamp
constructed for using slightly compressed air and gas at ordinary pressure,
or both agents at the same pressure; this is also a vertical elevation in
section.
M is a tube forming the external tube of the lamp. It is screwed at
bottom to the gas fitting or gas supply pipe G* which terminates
at top in a small pipe G which projects into the interior of the tube M
and forms an inner tube concentric therewith but extending only for a
small portion of the length of the tube M. This inner tube G is nearly
closed at its upper end, but it has in this end a small hole made by a
needle drill for the passage of the gas, and the gas under pressure of
about 7 to 10 lbs. on the square inch rushes through this small orifice
into the tube M. The air is admitted into the tube M through two
holes A, A. The tube M thus forms a mixing chamber, whence the
mixture of gas and air passes through a metal or other plate P

page_text: pieced with a large number of small holes; or this plate may be
a diaphragm of metal gauze. This plate or gauze is fastened to the
top of the tube M, whence it can be removed when actinic light is
required for photographic or other purposes. C is a chamber or cap
fitted on the top of the tube M. It constitutes the combustion chamber,
and is formed of a tissue of iridio-platina wire, platina wire, or other
metal or substance capable of becoming incandescent like platina. The
mixed gas and air or gaseous mixture passes through the plate P into
the chamber C, and issues through the interstices or meshes of the tissue
of the chamber in small jets, which are lighted, and the result is an
intense white light produced without flame.
The lamp, Figure 2, is similar to that in Figure 1 except as regards
the under portion, that is to say, the air enters through the pipe
and orifice A and passes through a diaphragm of fine gauze, lining
the interior of the ball-shaped chamber B, and then meets and mixes
with the gas in B, whence the mixture passes into the tube M as
before.
I usually adopt the following method for lamp Figure 1-I place
a small pump near the meter, and I attach the gas pipes thereto.
This pump can be worked by hand, turbine, water wheel, revolving
shaft, or otherwise. The gas on leaving the pump enters a holder or
reservoir provided with a pressure gauge indicating pounds. When the
pointer shews 7 lbs., for instance, the lamp can be lighted. Sometimes
in place of a holder and pressure gauge I use a cast-iron tube bored out
and a piston fitted with concentric rubber rings, which become air-tight
when placed in the tube. The top of the piston is loaded to give the
required pressure. When the pump is working the piston will not rise
until the necessary pressure is on, and while the gas is being consumed
it is delivered at the same pressure until all is exhausted. For this cast-
iron tube two inches inside diameter and three feet high are good
dimensions.
I use the following arrangements with advantage for lamp Figure 2:-
An ordinary air holder sealed with water as used in gasworks is filled
with air, and a tube communicates with and is joined to the lamp at the
side or sides. The air may conveniently have a pressure of two inches
to one and a half inches of gas. The holder can be filled with air by
reversing the counterpoise weights or by pump or other ordinary means.
The air holder having been duly adjusted to weight like a gas holder the

page_text: light will be maintained in efficiency so long as the supply of air and
gas is kept up in abundance.
Sometimes the due influx of air for compounding the igniting
mixture of air and gas may be obtained by rarefying a column of air by
heat, whereby an adequate supply of air may be forced into or drawn
through the burner.
Having now described the nature of the said Invention, and in what
manner the same may be performed, I declare that I claim, the
improved lamp in which two tubes placed one within the other, and a
perforated or a wire gauze surface, tissue, or chamber which is capable
of becoming incandescent and of emitting intense light are constructed,
arranged, and combined substantially in the manner and for the purpose
herein-before described.
In witness whereof, I, the said James Allison Hogg, the younger,
have hereunto set my hand and seal, this Twenty-third day of
January, in the year of our Lord One thousand eight hundred
and sixty-nine.
JAMES ALLISON HOGG, JN". (L.S.)
Witnesses,
JOHN REID, witness.
PETER W. GREIVE, witness.