IMPROVEMENTS IN SAFETY AND OTHER LAMPS
Year: 1861

page_text: LETTERS PATENT to William Renwick Bowditch, Clerk, of Saint
Andrew's, Wakefield, in the County of York, for the Invention of
"IMPROVEMENTS IN SAFETY AND OTHER LAMPS."
Sealed the 12th November 1861, and dated the 16th May 1861.
PROVISIONAL SPECIFICATION left by the said William Renwick Bowditch
at the Office of the Commissioners of Patents, with his Petition, on the
16th May 1861.
I, WILLIAM RENWICK BOWDITCH, Clerk, of Saint Andrew's, Wakefield, in
the County of York, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN SAFETY AND OTHER LAMPS," to be as follows:-
To obtain an improved light, I employ two flat burners, so placed that the
flames issuing from them must touch at the edges or narrow sides, and join
and form one flame; a small notch is cut at the top of each narrow side of the
burner. The burners are in all cases better if made tapering, so that the
bottom part within the lamp is larger than the top part next the flame, and
they should also be a little inclined towards each other from bottom to top.
Instead of placing the burners vertically, as in ordinary lamps, I place their
flat sides at an angle with the horizon. I sometimes use but one flat flame
burner, such burner being notched and placed in an inclined position, as is above
described, but I prefer two. To obtain increased safety in miners' lamps I
apply a covering of open metal work, formed by strips placed edgewise, so as
not to intercept the light, and touching the wire gauze at the top and sides, or
part of the sides, so as to abstract heat from the gauze and radiate it into the
surrounding air. When lamps have a second wire gauze or other metallic

page_text: top, such as the perforated metal of Stephenson, I place between the two, and
touching both, an open coil of metal, to conduct heat from the inner to the
outer casing. When using in a miner's lamp an Argand or other burner
supplied with air from below, I still further protect it by placing around the
hole or holes through which the air passes from below to the flame, two wire
gauze or perforated metallic cylinders, similar to those which are used to
surround the flame. I prefer to have the bottom of such wire gauze or per-
forated metallic coverings closed by a flat plate of metal, so that the air may
pass in through them laterally, and not vertically. I also place metallic plates
vertically between and touching the two bottom perforated coverings through
which air passes to the burners in order to convey heat from the inner to the
outer, and such outer covering may have attached to it open metal work to
cool it more rapidly than air alone will do. A glass within the gauze cylinder
which surrounds the flame should be used with my lamps. When double
gauze tops are used, the glass should be long enough to prevent com-
munication between the flame and the air of the mine, except through the
double gauze; and when single gauze is used, the glass should be covered with
a cap of gauze or perforated metal, such as is used in Stephenson's lamps, and
the glass is made of such a height as to properly regulate the draught or air
current, or this regulation may be effected by the greater or less depth of the
metallic covering. I lock my lamps by a metallic peg kept in its place by a
spring, and acting against a stop placed on the ring which fastens the gauze
around the flame. This peġ is pulled down by a contrivance which passes
through the bottom of the lamp, and acts upon the spring, and at the same
time moves a plate which puts out the light. Thus the lamp cannot be opened
until the flame is extinguished. The wick is raised and lowered by a bent wire,
which passes through the bottom and acts from below, and with which the
wick can also be snuffed.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Renwick Bowditch in the Great Seal Patent Office 30
on the 16th November 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, the
Reverend WILLIAM RENWICK BOWDITCH, of Wakefield, in the County of York,
Clerk, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters 35
Patent, bearing date the Sixteenth day of May, in the year of our Lord One

page_text: thousand eight hundred and sixty-one, in the twenty-fourth year of Her reign,
did, for Herself, Her heirs, and successors, give and grant unto me, the
said. William Renwick Bowditch, Her special licence that I, the said William
Renwick Bowditch, my executors, administrators, and assigns, or such others
as I, the said William Renwick Bowditch, 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 AND OTHER LAMPS," upon the condition (amongst
others) that I, the said William Renwick Bowditch, my executors or admi-
nistrators, 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 William Renwick Bowditch, 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, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say :—
My said Invention relates to improvements in safety and. other. lamps, and
to obtain an improved light, I employ two flat burners so placed that the
flames issuing from them must touch at the edges or narrow sides, and join
and form one flame. I prefer to place these burners a quarter of an inch
apart, and at an inclination towards each other of about seventy-two degrees.
A sinall notch about an eighth of an inch deep is cut at the top of each narrow
side of the burner. The burners are in all cases better. if made tapering so
that the bottom part within the lamp is rather larger than the top part next
the flame, this allows the oil to ascend easily. Instead of placing the
burners vertically, as in ordinary lamps, I place their flat sides inclined both
in the same direction at an angle of twenty degrees from the vertical line.
I sometimes use but one flat flame burner, such burner being notched and
placed with its flat side in an inclined position, as is above described, but
I prefer to use two burners. To obtain increased safety in miners' lamps
I apply a covering of open metal work (shewn in the Drawings at X, Y, and Z,
formed by strips brazed, riveted, or otherwise united together, placed edgewise
to the wire gauze, so as scarcely to intercept the light, and touching the wire

page_text: gauze at the top and sides or part of the sides, so as to abstract heat from the
gauze, and radiate it into the surrounding air. I prefer to place these strips
three-quarters of an inch apart where they touch the wire gauze at the sides,
as they then cool the gauze sufficiently, without obstructing the light injuriously.
At the top they may be half an inch or less apart, but must not be near
enough together to impede the exit of the hot air and products of combustion.
The best size for the strips I have found to be about an eighth of an inch in
thickness, and three-eighths of an inch in width, and extending along the
whole of the wire gauze not covered by a glass. When lamps have a second
wire gauze or other metallic top, such as the perforated metal of Stephenson's
lamps, I place between the two, and touching both, an open coil of metal to
conduct heat from the inner to the outer; this coil is shewn on the
Drawings at 2, 2, and may be formed of a piece of sheet copper, or iron, or
other suitable metal, bent loosely into a spiral or serpentine form, so as to
allow the products of combustion to pass away between the parts of the coil.
The metal of which it is made need not be thicker than the twentieth of an
inch. When using in a miner's lamp an Argand or other burner, supplied
with air from below, I still further protect it by placing around the hole or
holes through which the air passes from below to the flame, two wire gauze or
perforated metallic cylinders, similar to those which are used to surround the
flame, the apertures in which should not be larger than those in wire gauze
of thirty meshes to the lineal inch, shewn in the Drawings at A, A. Gauze or
perforated metal cylinders are fastened to the bottom of the lamp by screws,
in. the same way as the cylinder which surrounds the flame is fastened to the
upper part of the lamp. These lower gauze or perforated metal cylinders may
be about an inch and a quarter in depth, and one of them should be from
half to three-quarters of an inch greater in diameter than the other, so as to
leave a space of not less than a quarter of an inch between them. I prefer to
have the bottom of such wire gauze or perforated metallic cylinders closed by
a flat plate of metal, so that the air may pass through them laterally and not
vertically, as the lamp is not so liable to be extinguished by a strong current of
air as when the air passes through vertically. I also place strips of metal
vertically between and touching the two lower gauze or perforated metallic
cylinders, through which air passes to the burners, in order to convey heat
from the inner to the outer, and such outer covering may have attached to it
open metal work, similar to the strips already described, to abstract heat
from it, and cool it more rapidly than the air would do without such external
metal work. A glass within the gauze cylinder which surrounds the flame
should be used with my lamps, as it greatly increases the safety by preventing

page_text: communication between the flame and the air of the mine except through a
double metallic covering. When double gauze tops are used the glass should
be long enough to prevent cominunication between the flame and the air of
the mine, except through the double gauze; and when single gauze tops are
used the glass should be covered with a well-fitted cap of gauze or perforated
metal, such as is used in Stephenson's lamps, and the glass made of such a
height as to properly regulate the draft or air current; or this regulation may
be effected by the greater or less depth of the metallic covering. I obtain an
excellent result with a glass of an inch and a half in diameter, when the
perforated metallic cap which fits the glass has three-quarters of an inch of
side above the glass. When flat flames are used the wick is raised, and
snuffed by a bent wire in the usual way, shewn on the Drawings at B. In
the case of two burners being used, as I recommend, the small holes in the
sides, through which the wire acts to push up the cotton, should be made on
opposite sides of the burners, to enable the same wire to raise the wick in
both. The bent wire marked D upon the Drawings raises, lowers, and snuffs
the wick of an Argand lamp. It passes through the centre and bottom of the
lamp in a small gas-tight tube, as does the snuffer of ordinary safety lamps:
It should be made long enough to be put up out of the way of the flame, and
may be kept in its place by having a thread on the lower portion, which will
screw into a corresponding thread in the bottom of the lamp, as shewn.
The bottom of the wire outside the lamp screws into a nut or milled head, so
that the wire can be removed when it is necessary to put a new cotton into
the lamp. The horizontal part of the wire is used to snuff the wick, and the
short portion turned down at right angles to this is used to raise and lower
the wick by acting upon the pegs marked S, S, on the Drawing, fixed to the
top of the notched cylinder which surrounds the wick, and by the turning of
which the wick is raised and lowered. The short portion which acts upon the
pegs and turns up the wick must not be longer than will allow the horizontal
part to touch and snuff the wick. I lock my lamps by a metallic peg p, kept
in its place by a spring, marked F in the Drawings), to which it is fixed:
The spring is fastened to the lamp, so that the metallic stop (marked E on the
Drawings), upon the ring which fastens the wire gauze slides up and over the
spring at each turn of the screw, which attaches the wire gauze to the body
of the lamp. When the stop has passed over the spring the spring is released,
and if an attempt be made to unscrew the top of the lamp, the stop presses
against the spring. To depress this spring and set the cover of the lamp free,
a rod is used, which passes upwards through the bottom of the lamp, and of
which, when drawn down, the part L acts upon the spring, and at the same

page_text: time brings. down a metallic plate or extinguisher K, which puts out the light;
the bent wire D, if an Argand lamp, having been. previously drawn down.
Thus the lamp cannot be opened without extinguishing the flame. The con-
trivance which passes through the bottom of the lamp and holds down the
spring is shewn at G on the Drawings; it is made of metal sufficiently strong
to press down the spring, and long enough to be put up. out of the way of the
flame. When not in use, it is kept in its place by screwing the thread upon
its lower portion into the corresponding thread in the bottom of the lamp, as
shewn. When raised up it should not be so near the gauze or perforated
metallic top as to obstruct the air current. The wire of this extinguisher may
be put through the centre of the lamp, and is made to act similarly. In this
case it may have a small contrivance (shewn at N on the Drawings) to raise,
lower, and snuff the wick of Argand lamps, and the bent wire marked D may
be dispensed with. The bottom of the wire outside the lamp should be
screwed into a nut or milled head, to allow of the removal of the wire when a
new cotton is put into the lamp.
1. I claim as my Invention the two flat burners notched at the narrow sides
and inclined to the horizon and to each other, as described, and also one flat
burner, notched and inclined, as described.
2. I also claim, the method of locking safety lamps by means of a self-
acting spring against a stop, and of opening the same by a contrivance, as
described, which puts out the light when it draws down the spring, and allows
the lamp to be opened.
3. I also claim the double separated vertical metallic gauze or perforated
metal cylinders placed below the lamp, as described.
4. I also claim the use of a metallic heat conductor in the various parts of
safety lamps, as described.
5. I also claim the mode of raising and lowering of the wick of Argand
lamps by a bent wire acting from below upon projecting arms, as described.
The claims numbered 2, 3, and 4, apply to lamps fed with gas, as well as to
those fed with oil.
In witness whereof, I, the said William Renwick Bowditch, have here-
unto set my hand and seal, this Sixteenth day of November, in the year
of our Lord One thousand eight hundred and sixty-one.
W. R. BOWDITCH. (L.S.)