IMPROVEMENTS IN SAFETY LAMPS
Year: 1868

page_text: LETTERS PATENT to Thomas Gray, of Taibach, in the County of
Glamorgan, Mining Engineer, for the Invention of "IMPROVEMENTS
IN SAFETY LAMPS."
Sealed the 13th April 1869, and dated the 15th October 1868.
PROVISIONAL SPECIFICATION left by the said Thomas Gray at the
Office of the Commissioners of Patents, with his Petition, on the
15th October 1868.
I, THOMAS GRAY, of Taibach, in the County of Glamorgan, Mining
Eugineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN SAFETY LAMPS," to be as follows:-
According to this Iuvention the "poles," which as in other safety
lamps support and keep together the different parts, are hollow for the
purpose of supplying the flame with the necessary oxygen to support
combustion. These hollow or tubular poles connect the extreme top and
bottom of the lamp; at the bottom the poles are screwed or let into

page_text: chamber in which the air after passing down the poles circulates, and in
which there is a ring or washer of perforated metal or gauze through
which the air passes to the flame. From the flame the heated air and
products of combustion ascend the ordinary glass cylinder and a metal
chimney placed in the wire gauze cylinder. The ring or washer of gauze
or perforated metal prevents the return up the hollow poles of the ignited
gas while the lamp is surrounded by or is being used to detect the
presence of inflammable gas. A cap prevents dust entering the top of
the hollow poles. Instead of a wire gauze cylinder a close metallic
cylinder may be employed having in the top a piece of gauze or
perforated metal to allow the heated air and products of combustion
to issue.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Gray in the Great Seal Patent Office on
the 15th April 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
GRAY, of Taibach, in the County of Glamorgan, Mining Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of October, 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 Thomas Gray, Her special licence that I,
the said Thomas Gray, my executors, administrators, and assigns, or
such others as I, the said Thomas Gray, 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, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands, and
Isle of Man, an Invention for "IMPROVEMENTS IN SAFETY LAMPS," upon the
condition (amongst others) that I, the said Thomas Gray, 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

page_text: Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, tho said Thomas Gray, do heroby 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 figures and letters marked thereon, that is
to say:-
According to this Invention the " poles," which as in other safety
lamps support and keep together the different parts, are hollow for the
purpose of supplying the flame with the necessary oxygen to support
combustion. These hollow or tubular poles connect the extreme top and
bottom of the lamp; at the bottom the poles are screwed or let into a
chamber in which the air after passing down the poles circulates, and in
which there is a ring or washer of perforated metal or gauze through
which the air passes to the flame. From the flame the heated air and
products of combustion ascend the ordinary glass cylinder and a metal
chimney placed in the wire gauze cylinder. The ring or washer of gauze
or perforated metal prevents the return up the hollow poles of the ignited
gas while the lamp is surrounded by or is being used to detect the
presence of inflammable gas. A cap prevents dust entering the top of
the hollow poles. Instead of a wire gauze cylinder a close metallic
cylinder may be employed having in the top a piece of gauze or
perforated metal to allow the heated air and products of combustion
to issue.
Figure 1 of the accompanying Drawings is an elevation of a safety
lamp fitted with my improvements applied thereto, and Figure 2 is a
sectional elevation of the same. A, A, are the hollow poles or pillars
of tubular form; they are brazed or otherwise secured at the bottom
to the upper part of the gallery A', A, of the lamp, as shown in the
Figures; this portion of the gallery forms an air distributing chamber
by which the air which passes down the hollow poles becomes equally
distributed over the whole area of the chamber. D is a vertical ring of
wire gauze or perforated metal through which the air passes to the flame,
as indicated by the arrows, and which prevents any ignited mixture of
gas from communicating with the explosive atmosphere in which the

page_text: lamp may be. This ring D of wire gauze is sustained in position by a
washer E, part of which is vertical and part bears on its outside edge a
screw thread by which it is screwed to the chamber; the vertical
part has apertures for the passage of air at intervals. A part of this
washer E and marked C, C, screws up into a projecting flange of the
chamber or gallery and retains the glass cylinder B, B, in its place;
this part of the washer C, C, has on its under side a projection which
Serves as a guide for the washer E when being screwed and keeps the
wire gauze ring in its place; these two washers therefore when screwed
into place are combined and support the vertical ring of wire gauze, and
all the air which the flame requires must pass through it. The body or
oil reservoir of the lamp is screwed up into the lower portion of the
gallery and is firmly held in place by a tightening screw a. The
flange C, C, supports the glass cylinder B, B, as shown; the glass is held
in place by a ring b, b, which forms part of a metal chimney F, F; this
flange is provided with apertures through which the hollow poles pass
and by which they are held in place and steadied. The upper end of the
chimney is spread out and carries a perforated metal plate or wire gauze
disc H through which the products of combustion pass. Over this disc
of gauze I place a cap made in such a way, and with apertures for the
passage of the heated air and smoke, that when the lamp is in any
current of air the flame burns uniformly and is not affected thereby.
The tops of the hollow poles are attached to a flange d, d, to which the
handle or loop e by which the lamp is carried is fastened. Sometimes I
fit into the neck of the chimney F a cone or tapered tube G by which the
draft of air supplied to the flame is governed. A cap can be placed over
the tops of the poles when necessary to prevent dust entering them.
Lamps constructed in the above manner have been proved to be practically
safe in all circumstances under which the miner works.
And having now described the nature of my said Invention and in
what manner the same is to be performed, I declare, that I claim as my
improvements in safety lamps,-
First. Constructing them with hollow poles in the manner and for
the purpose herein-before described and shown in the Drawings.
Secondly. Forming a chamber, and fitting a ring or washer of
perforated metal or gauze therein, in the manner and for the

page_text: purpose herein-before described and represented in the accompanying
Drawings.
In witness whereof, I, the said Thomas Gray, have hereunto set
my hand and seal, this Thirteenth day of April, in the year of
our Lord One thousand eight hundred and sixty-nino.
THOMAS GRAY. (L.S.)