An Improved Electric Safety-lamp.
Year: 1892

page_text: Date of Application, 22nd Mar., 1892
Complete Specification Left, 22nd Dec., 1892-Accepted. 11th Feb., 1893
TRUVIDIONAL OF MOTIVATION.
An Improved Electric Safety-lamp.
JOHN PRICE REES, of 234 New Kent Road, Newington, in the County of Surrey,
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention is designed to provide an improved electric lamp for use in powder-
magazines, coal-mines and other places where it is dangerous to employ naked
lights.
My improved electric safety-lamp is constructed in the manner hereinafter
mentioned so that, should the glass globe or bulb be broken, the electric circuit
will at once be automatically interrupted and the lamp thus extinguished.
For this purpose, I arrange an incandescent electric lamp of any suitable
description within a globe or bulb of thick glass attached to the top or cover of an
electric battery. The space between this globe or bulb and the glass bulb of the
incandescent lamp I use as a chamber for compressed air, and I make the bottom of
this chamber of a flexible or elastic diaphragm. Beneath the said diaphragm !
provide a movable contact-piece which is arranged above another contact-piece and
is held away from the latter by a suitable spring. These parts are so arranged that,
when the aforesaid chamber is charged with compressed air, the said diaphragm will
be forced downward and the movable contact-piece thereby pressed against the
contact-piece beneath it. It is evident that when the lamp is in operation, should
the globes or bulbs or even the outer globe or bulb alone be broken, the air therein
will at once expand and the said diaphragm will be forced upward and the movable
contact raised by its spring away from the contact beneath it thus interrupting the
circuit and extinguishing the lamp.
One of the leading-in wires of the lamp is connected with the said diaphragm.
The lower contact-piece and the other leading-in wire are connected with the
battery through the medium of suitable conductors in such a manner that, when the
lid or cover of the battery is closed and the aforesaid chamber is filled with .
compressed air, the circuit will be complete and the lamp will operate. When.
however, the said lid or cover is raised, the circuit will be broken or interrupted and
the lamp extinguished.
I find it advantageous to make the said movable contact of a short rod or pin.
having a suitable head to bear against the said diaphragm, and fitted to slide up and
down in a tubular guide formed on a cross-piece, and to use a spiral spring which
surrounds the said guide and bears at its upper end against the head of the said
rod or pin and at its lower end against the said cross-piece.
I find it advantageous to connect the leading-in wire last above mentioned, with
the battery as follows, that is to say, I connect the corresponding pole of the battery
with a terminal attached to the upper edge of the box, and 1 secure to the lid of the
box a strip of conducting material so arranged that when the box is closed the said
strip will be pressed against the said terminal. I secure in the said strip a screw-
threaded pin or stud which is passed through a hole in the lid or cover of the
battery and is secured therein by means of a nut above the said lid or cover...I
then connect the said pin or stud by means of a flexible wire or conductor with the.
said leading-in wire of the lamp. By this arrangement, I avoid the liability to
destruction of the nut and screw-threaded pin by the acids used in the battery, and
obviate the necessity for disconnecting the conductor to permit the detachment of
the lamp from the lid or cover of the battery in order to obtain access to the
aforesaid contacts.
To provide for the filling of the air-chamber with compressed air, I make my

page_text: improved safety-lamp with a nozzle which is connected with the said chamber by a
pipe provided with a stop-valve, and which is adapted to receive an india-rubber
tube connected with a hollow. india-rubber. ball or pear, so that by squeezing the
latter in the, hand, the air may be easily compressed to the desired extent in the
said chamber. Or I provide other suitable means whereby the said chamber may
be charged with air under pressure.
Dated 100-11
11002-
COMPLETE SPECIFICATION.
An Improved Electric Safety-lamp.
I, JOHN PRICE REES, of 234 New Kent Road, Newington, in the County of
Surrey, Electrical Engineer, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and.
ascertained in and by the following statement :-
My invention is designed to provide an improved electric safety-lamp for use in
powder-magazines, coal-mines and other places where it is dangerous to employ
naked lights.
My improved electric safety-lamp is constructed in the manner hereinafter
described so that, should the glass globe or bulb be broken, the electric circuit will
at once be automatically interrupted and the lamp thus extinguished, thereby
avoiding any risk of explosion through the ignition of fire-damp or other gases by
the incandescent filament.
For this purpose, I arrange an incandescent electric lamp of any suitable
description within an additional or supplementary globe or bulb of thick glass
attached to the top or cover of an electric battery. The space between this globe
or bulb and the glass bulb of the incandescent lamp, I use as a chamber for
compressed air; and make the bottom of this chamber of a flexible or elastic
diaphragm. Beneath the said diaphragm, I provide a movable contact-piece which
is arranged above another contact-piece and is held away from the latter by'a
suitable spring. These parts are so arranged that, when the aforesaid chamber is
charged with compressed air, the said diaphragm will be forced downward!and the
movable contact-piece thereby pressed against the contact-piece beneath it. It is
evident, therefore, that, when the lamp is in operation, should the globes or bulbs
or even the outer globe or bulb alone be broken, the compressed air therein will at
once expand, the said diaphragm will return to its original position, and the movable
contact' will rise under the action of its spring away from the contact beneath it,
thus interrupting the circuit and extinguishing the lamp.
In the accompanying drawing; I have shown, partly in front elevation and partly
in vertical central section, one form of my improved safety-lamp.
a is a box or vessel for containing the battery elements, and provided with
a hinged lid or cover b
c is the electric incandescent lamp which is attached in any convenient manner to
the lid or cover band is electrically connected with the poles of the battery as
hereinafter described. d is the additional or supplementary globe or bulb, which is
secured in a metal socket e so as to form a fluid-tight joint. The said socket'e is,
moreover, secured to the lid or cover b in such a manner as to form at fluid-tight!
joint. A pipe fis secured in one side of the socket e, and is provided with a branch
or nozzle for connection with a flexible tube through which air under pressuretist
introduced into the space between the two globes or bulbs.. The pipe is also
provided with a screw-down valve g for retaining the compressed air in the said
Брасе. A flexible or elastic diaphragmh is stretched across the lower end of the
socket e, and beneath this diaphragm is arranged a vertically movable stud or
contact-piece which is pressed upward against the said diaphragm by means of at
spring. Another spring contact-piece is secured to the lid or cover b in suchta

page_text: manner that it extends beneath the lower end of the contact-piece). The leading-in
wire m of the lamp is connected with the said diaphragm h. The lower contact-
piece and the other leading-in wire m' are connected respectively with the poles of
the battery through the medium of conductors n, n' attached to the said lid or cover
and arranged to bear against conducting strips p, p, which are connected one to the
positive pole and the other to the negative pole of the battery, and which project
over the upper edges of the sides of the box a in such a manner that, when the lid
or cover of the battery is closed, the conductors n, n¹ are in contact with the
strips p, p, and, when the aforesaid space or chamber is filled with compressed air,
the circuit will be complete and the lamp will operate. When, however, the said
lid or cover is raised, the circuit will be broken or interrupted and the lamp
extinguished.
I find it advantageous to secure in each of the said conductors n, n¹, a screw-
threaded pin or bolt 7 which is passed through a hole in the lid or cover band
secured therein by means of a nut above the said lid or cover, and to connect one of
the said pins or bolts 7 directly with the contact-piece and the other pin or bolt q'
by means of a flexible wire or conductor with the leading-in wire m' of the lamp.
By this arrangement, I avoid the liability to destruction of the nuts and screw-
threaded pins by the acids used in the battery; and I obviate the necessity for
disconnecting the conductors to permit the detachment of the lamp from the lid or
cover of the battery in order to obtain access to the aforesaid contacts.
an
For filling the air-chamber with compressed air, I apply to the nozzle
india-rubber tube connected with a hollow india-rubber ball or pear, so that, by
squeezing the latter in the hand, the air may be easily forced into the said chamber
and compressed to the desired extent. Or I provide other suitable means whereby
the said chamber may be charged with air under a suitable pressure.
Having now particularly described and ascertained the nature of my said inveu-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
The improved electric safety-lamp constructed substantially as described with
reference to the accompanying drawing for the purposes above specified.
Dated the 22nd day of December 1892.