IMPROVEMENTS APPLICABLE TO MINERS' SAFETY LAMPS
Year: 1876

page_text: LETTERS PATENT to John Clayton Mewburn, of 169, Fleet Street, in the
City of London, Patent Agent and Consulting Engineer, for the Invention of
"IMPROVEMENTS APPLICABLE TO MINERS' SAFETY LAMPS." A communication
from abroad by Achille Dinant, of the Mines of Anzin, Nord, France.
Sealed the 7th July 1876, and dated the 25th January 1876.
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn at
the Office of the Commissioners of Patents on the 25th January 1876.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS APPLICABLE TO MINERS' SAFETY
LAMPS."
The object of this Invention is to prevent the possibility of safety lamps being
opened by the miners, and thus to avoid the accidents which are produced by such
misconduct. Many attempts have already been made to meet this difficulty; most
of them have, however, necessitated the employment of a key which remains in
charge of the lamp man, and it has been found that the miners soon procure false
keys. Now, according to this Invention, the closing of the lamp is effected by
means of solder. This solder is applied by the lamp man to the bottom of the
lamp and as it can only be removed under the action of a cherry red heat, the
opening of the lamp at the bottom of the mine where there is no fire becomes
impossible, while any attempt to open it by mechanical means leaves ineffaccable
marks which lead to discovery.
When the lamp is closed a stop pin entering a notch on the lower edge of the
lamp cover guarantees the closing when the cover is screwed home. The stop pin
is retained in its position by a small helical spring enclosed in a tube, which
serves as a guide to the pin and its spring. If the lamp cover be removed and it
is wished to screw it again on the body of the lamp, the spring will permit the stop
pin to descend under the pressure of the cover until the notch comes opposite the
pin; the pin then at once enters the notch and effects the closing of the lamp
provided the soldering, as herein-after described, has been effected.
Below the tube above mentioned is a piston, to the lower part of which is
rivetted an elongated plate, while a transverse pin passes through the piston and
through the base of the tube. Around the said tube is a second helical spring
which bears against the base of the tube and is enclosed within an outer tube or
[Price Gd.]

page_text: guide. Before the soldering, is effected this second spring overcoming the action of
the first named spring, keeps the stop pin down clear of the notch in the lamp
cover, so that there is nothing to interfere with the removal and replacing of the
cover at will.
'
To solder and seal the mechanism a brush impregnated with spirit of decom-
posed salt is applied to the elongated plate before named; the lamp without its
cover is then placed inverted on the platform of a soldering apparatus, the base
of the piston before described being under a vertical spring rod of such apparatus.
A piece of tin is then placed under the elongated part of the plate, and melted by
means of an iron heated to cherry red; the rod of the soldering apparatus which
has been kept up by pressing on a hand lever is now allowed by the action of its
spring to come down upon the piston, and hold it with the elongated plate against
the bottom of the lamp until the tin in cooling becomes fixed to the said bottom.
The outer or larger spring is thus prevented overcoming the power of the smaller
spring. The lamp is thus ready to be given to the miner, who after lighting it
screws on the cover; the stop pin will enter the notch in the cover from which it
now cannot possibly be released so long as the solder unites the elongated plate to
the lamp bottom. The lamp. man can open the lamp when returned to him by
melting the solder, so that the outer spring being free to act withdraws the
stop pin.
'ו'
'
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Clayton Mewburn in the Great. Seal Patent Office on the 20th
July 1876.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS APPLICABLE TO MINERS' SAFETY
LAMPS." (A communication to me from abroad by Achille Dinant; of the Mines of
Anzin, Nord, France:)
"
The object of this Invention is to prevent the possibility of safety lamps being
opened by the miners, and thus to avoid the accidents which are produced by such
misconduct. Many attemps have already been made to meet this difficulty; most of
them have however necessitated the employment of a key which remains in charge
of the lamp man, and it has been found that the miners soon procure false keys.
Now according to this Invention the closing of the lamp is effected by means of
solder. This solder is applied by the lamp man to the bottom of the lamp, and as
it can only be removed under the action of a cherry red heat the opening of the
lamp at the bottom of the mine where there is no fire becomes impossible, while
any attempt to open it by mechanical means leaves ineffaceable marks which lead
to discovery.
The manner in which the closing of the lamp may be effected by means of solder
will be understood by the annexed Drawings and the following description:-
Figures 1 and 2 being vertical sections of a lamp through the line A, B, of
Figure 1, and shewing the lamp in the unclosed and closed positions respectively;
Figures 3 and 4, horizontal sections through the lines E, F, and G, H, respectively;
and Figure 5 representing various parts detached.
When the lamp is closed, as scen in Figure 2, a stop. pin F entering a notch on
the lower edge of the lamp cover guarantees the closing when the cover is screwed
home. The stop pin is retained in this position by a small helical spring I, enclosed
in a tube H, which serves as a guide to the pin and its spring. If the lamp cover
be removed and it is wished to screw it again on the body of the lamp; the spring I
will permit the stop pin to descend under the pressure of the cover until the notch
comes opposite the pin, the pin then at once enters the notch and effects the closing
of the lamp, provided the soldering as herein-after described has been effected.
Below the tube H is a piston J, to the lower part of which is rivetted, an

page_text: elongated plate C, while a pin E passes through the piston J'and through the base of
the tube H. Around the tube H is a second helical spring D, which bears against
the base of the tube and is enclosed within an outer fixed tube or guide A. Before
the soldering is effected this spring D, overcoming the action of the spring I, keeps
the stop pin F down clear of the notch in the lamp cover (see Figure 1), so that
there is nothing to interfere with the removal and replacing of the cover at will.
To solder and seal the mechanisin a brush impregnated with spirit of decom-
posed salt is applied to the elongated plate C, the lamp without its cover is then
placed inverted on the platform M, N, of a soldering apparatus, Figure 6, the base
of the piston J being under a vertical spring rod G, H, of such apparatus.
A piece of tin is then placed under the elongated part of the plate C, and melted by
means of an iron heated to cherry red, the rod of the soldering apparatus which has
been kept up by pressing on a hand lever A, B, is now allowed by the action of its
spring to come down upon the piston J, and holds it so that the elongated plate
U is kept against the bottom of the lamp until the tin in cooling becomes fixed to
the said bottom. The outer or larger spring D of the lamp is thus prevented over-
coming the power of the smaller spring I. The lamp is now ready to be given to
the miner, who after lighting it screws on the cover; the stop pin F will enter the
notch in the cover from which it cannot possibly be released so long as the solder
unites the elongated plate C to the lamp bottom. The lamp man can open the lamp
when returned to him by melting the solder, so that the outer spring D being free
to act withdraws the stop pin F.
And having now described the nature of the said Invention, and in what manner
the same is to be performed, I declare that I claim,―
First. The employment of solder for the purpose of securing or closing safety
lamps, substantially as herein-before described with reference to the annexed
Drawings.
Second. Constructing safety lamps, substantially as herein-before described and
represented in the annexed Drawings.
In witness whereof, I, the said John Clayton Mewburn, have hereunto set
my hand and seal, this Fifteenth day of July, One thousand eight hundred
and seventy-six.
J. C. MEWBURN. (L.S.)