IMPROVEMENTS IN SAFETY LAMPS
Year: 1854

page_text: LETTERS PATENT to Francis Whitehead and William Whitehead, both
of Crayford, in the County of Kent, Engineers, for the Invention of
"IMPROVEMENTS IN SAFETY LAMPS."
Sealed the 12th January 1855, and dated the 20th July 1854.
PROVISIONAL SPECIFICATION left by the said Francis Whitehead and
William Whitehead, at the Office of the Commissioners of Patents,
with their Petition, on the 20th July 1854..
We, FRANCIS WHITEHEAD and WILLIAM WHITEHEAD, both of Crayford, in
the County of Kent, Engineers, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN SAFETY LAMPS " to be as follows:-
Our Invention consists in so constructing safety lamps that the light cannot
be reached except for the purpose of trimming the wick by the miner or user
of the lamp; and that no dangerous explosion of foul air can take place from
contact with the flame; we also attach a pipe to the lamp, so that a supply of
fresh air may be made to pass to the light and support combustion. The frame
of our lamp is of solid, in contradistinction to perforated, metal. The light is
made to pass through a "bull's-eye" or plate of glass fitted in the frame. Air
enters from the lower part of the outer casing into the body of the lamp, but
the admission is so regulated as only to admit of sufficient air entering to
support combustion. The lamp proper screws into the frame, and on any

page_text: attempt being made to get at the light by unscrewing the lamp, a detent is
acted upon, which frees a spring, causes it to fall upon the wick and extinguish
the light. In working in foul air, or in a mine before it has been properly
ventilated, we attach a pipe to the air inlet orifice and lead it into pure air.
The products of combustion pass out through the sides of the top of the frame,
the apertures being provided with wire gauze. Where desirable, more than
one "bull's-eye" or plate of glass may be fitted into the frame.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Francis Whitehead and William Whitehead in the Great
Seal Patent Office on the 20th January 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, We, FRANCIS
WHITEHEAD and WILLIAM WHITEHEAD, both of Crayford, in the County-of-
Kent, Engineers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of July, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us,
the said Francis Whitehead and William Whitehead, Her special licence that
we, the said Francis Whitehead and William Whitehead, our executors, ad-
ministrators, and assigns, or such others as we, the said Francis Whitehead
and William Whitehead, our 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 "IM-
PROVEMENTS IN SAFETY LAMPS," upon the condition (amongst others) that we,
the said Francis Whitehead and William Whitehead, or one of us, by an
instrument in writing under our hands and seals, or under the hand and
seal of one of us, 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 we, the said Francis Whitehead and William
Whitehead, do hereby declare the nature of our said Invention, and in what
manner the same is to be performed, to be particularly described and ascer-

page_text: tained in and by the following statement thereof, reference being had to the
Drawings hereunto annexed, that is to say :-
Our Invention consists in so constructing safety lamps that the light cannot
be reached except for the purpose of trimming the wick by the miner or user
of the lamp, and that no dangerous explosion of foul air can take place from
contact with the flame. The frame of our lamp is solid, in contradistinction
to its being formed of perforated metal. The light is made to pass through a
bull's-eye" or plate of glass fitted in the frame. Air enters from the lower
part of the outer casing into the body of the lamp, but the admission is so
regulated as only to admit of sufficient air entering to support combustion.
The lamp proper screws into the frame, and on any attempt being made to
get at the light by unscrewing the lamp, a lever is brought over and upon the
wick and extinguishes the light. In working in foul air, or in a mine before
it has been properly ventilated, we attach a pipe to the air inlet orifice and
lead it into pure air. The products of combustion pass out through the side
of the top of the frame, the apertures being provided with wire gauze. Where
desirable, more than one "bull's-eye" or plate of glass may be fitted into the
frame.
In the Drawings hereunto annexed we have shewn the method we adopt in
carrying our Invention into effect. Figure 1 is a side elevation, Figure 2 a
front view, and Figure 3 a section, of a lamp constructed according to our
improvements. A, A, is the body of the lamp, which is made of a piece
of solid sheet metal bent into the required form, the edges being brazed,
rivetted, or otherwise secured to each other; B is the chimney, which is secured
to the upper part of the body of the lamp; C is the "bull's-eye," which is
secured into the frame D, rivetted or otherwise attached to the body A; E is
the lamp or reservoir for containing the oil, the upper part of which is cut
with a thread of a screw, and is fitted into and retained in the bottom of the
body A, which is also provided with a corresponding screw thread; E' is the
wick holder, which is passed through the orifice a, in the top of the reservoir;
F is a conical cap or deflector, which is held in its proper place by means of
the hollow nut b, screwed into the orifice a. The mode of supplying this lamp
with the necessary air for supporting combustion is as follows:-In the front
or other part of the lamp we cut an opening or series of openings G, com-
municating with the inside of the lamp. H is a shield, which is brazed to the
inside of the reservoir, as represented, and bent at the front inwards, so as to
form a channel or space for the admissson of the air to the flame; I is a piece
of wire gauze, or finely-perforated metal, which is placed over the top of the
reservoir, and through which the air has to pass in its passage to the flame, as

page_text: indicated by the arrows in Figure 3. By means of this wire gauze the flame
from the the wick is prevented from igniting any of the explosive gases by
which the lamp may be surrounded when using it in foul places; and also by
admitting the air from below the flame, a small quantity only of gas can be
collected in the lamp, as it becomes consumed as fast as supplied; any danger
which might otherwise ensue, should the body of the lamp become at any time
filled with gas or other explosive mixtures, is thus obviated. J is a wire, which
is passed up through the short tube J', and is used for the purpose of trimming
the wick; J2 is a fixed deflector, which passes partly round the interior of the
lamp and above the oil reservoir for directing the air to the flame; K is a
dise of perforated metal, secured in the chimney B, for the purpose of inter-
cepting the flame, and thereby preventing its communicating and exploding
the surrounding gases. This is further prevented by the sheet of fine wire
gauze K', secured over the top of the chimney. L is an outer casing or
guard of sheet metal, bent into the desired form and rivetted or otherwise
secured at its edges. This outer casing is rivetted to the body of the lamp, and
openings are formed in the lower part of it, as represented at c, c, whereby a
stream of air is admitted, and caused to circulate between the casing and the
chimney, whereby the casing is kept cool and capable of being handled. M is
a cap or cover, which is placed above the top of the chimney and casing; it is
supported upon the wires d, d; a space is thus provided for the escape of the
smoke and other products of combustion. N is a ring or loop for suspending
the lamp. Where the lamp is required to be used in new workings or parts
of the mine not ventilated, we attach to the opening G, by means of the screw
cap G, a pipe or tube of vulcanised india-rubber or other elastic material,
and carry the end of it to a purer air. O is a reflector, placed at the back
of the lamp and opposite to the "bull's-eye;" and P is a lock, for preventing
the oil reservoir and lamp from becoming detached from the body of the
lamp A.
Figure 4 represents a modification of the above arrangement, in which the
air is admitted to the flame through holes a, cut in the casing A of the lamp,
and immediately above the oil reservoir. The wick-holder and orifice into
the interior of the reservoir are also placed eccentrically and nearer to the
"bull's-eye," whereby a broader extent or sheet of light is thrown. We havo
also in this lamp dispensed with the outer casing L. In this lamp we have
shewn an arrangement, whereby, upon the miner or user of the lamp attempting
to remove the oil reservoir, so as to expose the flame and thereby render the
lamp dangerous, the act of unscrewing the reservoir brings a bent lever in
contact with a detent, and causes the said lever to pass over the wick and

page_text: immediately extinguish the light. P is a bent lever, which is secured to the
oil reservoir by the pin a', and upon which the lever turns as a centre; Qis
the detent, suspended upon a short bar Q. This detent is capable of being
lifted only in one direction, namely, that in which the oil reservoir is turned
when screwing it into its place. Q2 is a spring, which bears upon the detent
and restores it to its proper place after the passing of the lever when screwing
in the oil reservoir; R is a projecting piu, against which the lever bears, and
is kept thereby in its proper place. It will be seen, that immediately upon
unscrewing the oil reservoir the lever comes in contact with the detent, which
being prevented from giving way in that direction, the lever is caused to turn
upon its centre, and thereby to bring the opposite and bent end thereof across
the wick and extinguish the light.
Figure 5 represents a further modification of lamp, and consists in adapting
the old and ordinary "bottoms" or reservoirs for oil and wick-holder to our
improved construction of the outer casing or body of the lamp. A is the
outer casing; B, the "bull's-eye;" and C, its frame; D is the oil reservoir;
and E, the wick-holder. This reservoir for oil may be either inserted into
the body or casing A from the top; or it may be screwed into the casing,
as represented in Figures 1, 2, and 3. F is an orifice in the casing, for
admitting air for the support of combustion. This orifice is covered with
wire gauze or finely-perforated metal. A similar sheet of perforated metal
or wire gauze is placed over the top of the casing. G is the cover; and II,
the ring for suspending it by; G' is a shield, which is placed over the air
orifices, in order to prevent any water that may trickle down the side of
the lamp from entering therein. Although we have only shewn our
arrangements applied to a lamp or reservoir for oil of the ordinary con-
struction, we do not limit ourselves to reservoirs so constructed, as a
moderator or other form of lamp may be readily employed. Our outer
casings may also be applied to the stationary gas burners now used in
some pits.
And having now described the nature of our said Invention, and in what
manner the same is to be performed, we declare that what we claim as our
improvements in safety lamps is,
First, the general arrangement and construction of the parts of which the
same consists, all as herein-before described and represented in Figures 1, 2,
and 3 of the Drawings hereunto annexed.
Second, we claim the constructing the frame or body of safety lamps of solid
sheet metal, in contradistinction to perforated metal, as herein-before described
and represented in the Drawings hereunto annexed.

page_text: Third, we claim the surrounding the upper portion of safety lamps with an
extra and outer casing, in the manner and for the purpose herein-before
described and represented in Figures 1, 2, and 3 of the Drawings hereunto
annexed.
Fourth, we claim the placing a fixed deflector on the inside of safety lamps
for the purpose of directing the air to the flame, as herein-before described
and represented in Figure 3 of the Drawings hereunto annexed.
Fifth, we claim the modification in the construction of safety lamps as
represented in Figures 4 and 5 of the Drawings hereunto annexed and
herein-before described.
And sixth, we claim the arrangement for extinguishing the flame consequent
upon the removal of the oil reservoir, as herein-before described and
represented in Figure 4 of the Drawings hereunto annexed.
In witness whereof, I, the said Francis Whitehead, for myself and on
-behalf of the said William Whitehead, have hereunto set my hand
and seal, this Twentieth day of January, One thousand eight hundred
and fifty-five.
FRANCIS WHITEHEAD. (L.S.)