IMPROVEMENTS IN MINERS' SAFETY LAMPS
Year: 1874

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN MINERS' SAFETY LAMPS."-A communication from
abroad by Benjamin Tappan, of Steubenville, in the County of
Jefferson, and State of Ohio, United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville
Clark at the Office of the Commissioners of Patents, with his
Petition, on the 23rd July 1874.
I, ALEXANDER MELVILLE CLARK, of 58, Chancery Lane, in the County
5 of Middlesex, Patent Agent, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN MINERS' SAFETY LAMPS," to be as
follows:
The object of this Invention is to provide a lamp or lantern for the use
of miners, which shall be strong, easily made, of good lighting capacity,

page_text: and quite safe in use in mines whatever may be the state of the air
therein, and to this end it consists in a lamp or lantern provided with a
mica chimney or casing, at the upper and lower ends whereof are sections
of wire gauze or finely perforated metal of corresponding shape, and in so
uniting or connecting the said sections and casing to each other and to
the lamp that the union shall be very tight and secure. It consists also
in the general detail of construction of this safety lamp or lantern for
miners' use, whereby a safe and effective lighting device is produced.
Tho oil cup has an extended neck, on the insido of which is a flange,
on which rests a disc carrying the wick tube secured in place by a ring
screwed down upon it. A small tube passes through the oil cup for the
passage of the clearing wiro and pick. The oil cup has a screw thread
on its exterior surface, by means of which it is screwed into a ring or
flange at the bottom of the chimney, in which it can be locked by
means of a screw bolt. The wire gauze or finely perforated metal is
placed both at the top and bottom of the mica portion of the cylinder
which surrounds the wick, and constitutes the flame chamber, thus
making provision for the escape of the products of combustion at the
upper part and for the admission of sufficient quantity of air to support
combustion of the lamp wick, and at the same time preventing any
flame or fire escaping beyond the inner periphery of said chamber or
gauze as well as the entrance of any of the explosive or dangerous
gases. The piccc of gauze at the lower end of the chimney is secured to
the flange or ring before mentioned by bending its ends outward so that
they will catch or engage upon the shoulder in the inner side of the
flange, or in any fast or safe manner that workmanlike skill shall
suggest. It projects upward, surrounding the neck of the oil cup, and
terminates about on a line with its top, so that its upper edge is very
near even with the top of the wick tube. The mica portion of the
casing is made in any ordinary or well-known manner, and may be
of any suitable size or shape; that is, triangular, square, polygonal, or
cylindrical, and may be made in one or many pieces. Its lower and
upper ends may be made of such shape and size as to fit tight and firmly
upon and over or inside the ends of the wire gauze. I may make one
or both of these connections in this way, and one or both by flaring the
end of the wire gauze so that it shall fit into a ring or annulus, and upon
the shoulder thereof. The end of the mica portion of the casing will
also fit into or upon this ring and be held firmly in place.

page_text: The like method of connection could be used at the upper end of the
mica portion of the casing, so that when the mica portion and the
supplemental upper and lower wire gauze sections are set in position,
the entire chimney thus formed can be fastened and clamped in proper
position by means of the hinged and locked cap, as will be explained
hereafter; but these are simply details of the construction that may be
used in carrying out the Invention, and in and of themselves aro not
unlike what is now well known; and while these and yet other means
may be used for carrying out the Invention none of them will modify
or change the same in any essential degree.
The upper piece of gauze should have a head or cover. This may be
made a part of the said piece by shaping it out in a press or by stamping,
or a flat piece or disk of gauze or finely perforated metal may be secured
on and over the upper end in any well known manner.
The mica portion of the casing and the upper and lower cylinders or
sections of wire gauze are protected and supported by means of
standards or wire rods, which are usually fitted into or secured upon
the lower ring or flange. Their upper ends are in like manner fitted
into or secured to an upper ring to which the top or cap is hinged. By
means of the hinge it can be turned back, and thus leave the top of the
lamp or lantern open. In this way the several parts can be removed
when there is occasion for cleaning or repairs.
The top, when shut down, may be fixed in place by a lock or spring,
and when thus fastened in place the mica and perforated sections, with
their bands, connecting rings, or pieces, are bound or clamped into
position, so that no opening or crevice is allowed of sufficient size for
the admission of dangerous and explosive gas. In and upon its upper
side is a ring or handle, by means of which it can be hung up or carried
about.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-third day of July, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Alexander Melville Olark, Her special licence
that I, the said Alexander Melville Clark, my executors, administrators,
and assigns, or such others as I, the said Alexander Melville Clark,
my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times there-
after 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 MINERS' SAFETY LAMPS," a communication to me
from abroad by Benjamin Tappan, of Steubenville, in the County of
Jefferson, and State of Ohio, United States of America, upon the
condition (amongst others) that I, the said Alexander Melville Clark,
my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, should particularly describo
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 Alexander Melville Clark, do hereby
declare the nature of the 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
Drawing, and to the letters and figures marked thercon (that is to
say) :-
The object of this Invention is to provide a lamp or lantern for the
use of miners, which shall be strong, easily made, of good lighting
capacity, and quite safe in use in mines whatever may be the state of
the air therein, and to this end it consists in a lamp or lantern provided
with a mica chimney or casing, at the upper and lower ends whereof
are sections of wire gauze or finely perforated metal of corresponding
shape, and in so uniting or connecting the said sections and casing to
each other and to the lamp that the union shall be very tight and
secure. It consists also in the general detail of construction of this

page_text: safety lamp or lantern for miners' use, whereby a safe and offective
lighting device is produced.
Figure 1 of the Drawing is a side elevation; and Figure 2 is a
vertical central section of the improved lamps, similar letters of reference
indicating corresponding parts in the two Figures.
A represents the oil cup, which has an extended neck A', and the
wick tube a, which is attached to a disc a' placed upon a flange on the
inside of-the-neck-A', and-is-secured-in-place by a ring which is screwed
down upon it. A.small tube a passes from the base of the oil cup to and
just above the said disc, and in it is placed a clearing wire and pick a³.
The lower end of said wire is bent so as to serve as a handle on the
under side of the cup to move the pick, while the end near the wick is
so bent that it can be turned horizontally to clean the wick, or moved
up and down in the wick tube slot to raise the wick. The oil cup has
a screw thread on its exterior surface at a*, by means of which it is
fitted into the ring or flange B on the screw thread on the inner face of
said flange. When the oil cup is screwed into this flange in this
manner it can be locked in by means of a screw bolt, which can be
made to project from the said ring or flange through a socket. The
said outer end is flat, and can be readily grasped by the bifurcated end
of key, and easily turned in and upon the screw thread on the oil cup,
and will thus hold these said parts rigidily together; so that in ordinary
use or moderate shaking or concussion will detach them or separate them
from each other. Thus the lamp will seldom, indeed almost never, fall
out or be skaken from its seat. D is the wire gauze. This gauze or
finely perforated metal is placed both at the top and bottom of the mica
portion E, thus making provision for the escape of the products of com-
bustion at the upper part of the cylinder which surrounds the wick and
constitutes the flame chamber, and for the admission of a sufficient
quantity of air to support combustion of the lamp wick, and at the same
time preventing any flame or fire escaping beyond the inner periphery of
said chamber or gauze as well as the entrance of any of the explosive
or dangerous gases. The piece of gauze at the lower end of the chimney
is secured to the flange or ring B by bending its ends outward so that
they will catch or engage upon the shoulder in the inner side of the
flange, or in any fast and safe manner that workmanlike skill shall
suggest. It projects upwards, surrounding the neck of the oil cup, and
terminates about on a line with its top, so that its upper edge is very

page_text: nearly even with the top of the wick tube. The mica portion E of the
casing is made in any ordinary or well known manner, and may be of
any suitable size or shape; that is, triangular, square, polygonal, or
cylindrical, and may be made in one or many pieces. Its lower and
upper ends may be made of such shape and size as to fit tight and
firmly upon and over or inside the ends of the wire gauze. I may make
one or both of these connections in this way, and one or both by flaring
the end of the wire gauze so that it shall fit into a ring or annulus and
upon the shoulder thereof. The end of the mica portion of the casing
will also fit into or upon this ring and be held firmly in place.
The like method of connection could be used at the upper end of the
mica portion of the casing, so that when the mica portion and the
supplemental upper and lower wire gauze sections are set in position the
entire chimney thus formed can be fastened and clamped in proper
position by means of the hinged and locked cap, as will be explained
hereafter; but these are simply details of the construction that may be
used in carrying out the Invention, and in and of themselves are not
unlike what is now well known, and while these and yet other means
may be used for carrying out the Invention none of them will modify or
change the same in any essential degree.
The upper piece of gauze should have a head or cover as at d. This
may be made a part of the said piece by shaping it out in a press or by
stamping, or a flat piece or disc of gauze or finely perforated metal may
be secured on and over the upper end in any well known manner.
The mica portion of the casing and the upper and lower cylinders or
sections of wire gauze are protected and supported by means of standards
or wire rods G, which are usually fitted into or secured upon the lower
ring or flange B. Their upper ends are in like manner fitted into or
secured to the ring H. The top or cap I is hinged to this. By means
of the hinge it can be turned back, and thus leave the top of the lamp
or lantern open. In this way the several parts can be removed when
thero is occasion for cleaning or repairs.
The top when shut down may be fixed in place by a lock or spring;
and when thus fastened in place the mica and perforated sections with
ther bands, connecting rings, or pieces, are bound and clamped into
position, so that no opening or crevice is allowed of sufficient size for
the admission of dangerous and explosivo gas. In and upon its upper

page_text: side is a ring or handle K, by means of which it can be hung up or
carried about.
For excellence in use this device prosents many rare and most
valuable advantages. It is so strong that it cannot easily be broken
under any ordinary circumstances of use. The chimney being made of
mica will not be broken by the varying effects of heat and cold, while
at the same time it will allow nearly or fully the same amount of
lighting rays from the lamp flame to pass through it as glass will. The
casing thus constructed with the mica and the sections of wire gauze
cannot be easily broken by the pieces of coal, slate, or stone, which
are occasionally sent forth from the blows of the pick when the miner
is at work; nor will the mica when heated bo broken by the spattering
of water on its exterior surface. It constantly happens in mines that
the trickling water, or the water from the opening of an unexpected
spring, falls upon the outside case of the lantern. This renders the
ordinary glass chimney, globe, or lens, entirely impracticable in a
minor's lamp. By placing the gauze or finely perforated metal both at
the lower and upper end of the chimney a sure and perfect combustion
of the oil is obtained, and also almost every opportunity or chance for
explosion prevented.
"
The ordinary miners' safety lamp is made on the principle of the
Davy" lamp, and has wire gauze continuously from the lamp up to
the cap. This cap is held in place and the gauze also protected by wire
bars or rods extending from the ring or annulus about the lamp to that
at the top and secured at both ends, while the gauze makes the lamp
safe. There is sent out from the wick flame but a small percentage of
its illuminating power. To remedy this defect-miners have used various
expedients. Sometimes a reflector has been placed opposite the flame
and inside the surrounding or incasing wire gauze. At other times a
reflector has been placed outside the wire gauze. Again a glass lens has
been placed in the wire gauze on a line with the flame; and yet again or-
dinary gas has been used. But it will be readily seen that the device
as above described is very different from each and all these. The several
sections composing the lantern case or chimney are easily made and
securely adjusted in relative position, and the lighting power of the
flame to a large extent secured, and thus the lantern presents a simpler
and better device than any other of the kind I am aware of. It is
sufficiently strong to safely withstand almost any exposure or usage.

page_text: Having described the nature of the Invention, and the manner of
performing the same, I declare that what I claim as the Invention to bo
protected by the herein-before in part recited Letter Patent is,-
1st. In a miners' safoty lamp or lantern, substantially as described,
a casing composed of a central section of mica, and an upper and a lower
section of wire gauze or finely perforated metal, tho said section entirely
surrounding the upper part of the lamp, the wick or flame chamber, and
the space above, and fitted in, upon, or over cach other, and held in
position in manner set forth.
2ndly. Tho mica portion of the casing E having wire gauze sections
D, D, fitted to its edges at top and bottom, as described, and combined
with the lamp a, a', rods G, flange B, ring H, and hinged and lock cap I,
substantially as and for the purposes set forth.
In witness whereof, I, the said Alexander Melville Clark, have
hercunto set my hand and seal, this Twenty-second day of
January, in the year of our Lord One thousand eight hundred
and seventy-fivc.
Witness,
HY. SWALES,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)