Improvements in or relating to Electric Lamps.
Year: 1897

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 18 of the Patents, &c. Act, 1883) as allowed by the
decision of the Chief Examiner of the 2nd day of February, 1899.
Date of Application, 23rd Aug., 1897-Accepted, 20th Aug., 1898
COMPLETE SPECIFICATION (AMENDED).
Improvements in or relating to Electric Lamps.
I, FREDERICK GEORGE WILLIAM JAMES ADAMS, of 24, Newman Street, Oxford
Street, in the County of Middlesex, 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 :-
This invention relates to improvements in the construction of electric lamps.
The improved lamp is especially suitable for use in coal mines or other places liable
to be invaded by explosive gas, its construction being such that the electric circuit is
made or broken by the action of a difference of gas pressure upon either side of a
movable conductor. This conductor or circuit breaker is arranged so as to close an
opening leading into a chamber which encloses the lamp, the difference in the fluid
pressure upon the opposite sides of this circuit breaker being so regulated that the
fracture of the enclosing envelope of the lamp will cause the circuit to be broken and
the lamp consequently to be extinguished, thus obviating the risk of any spark or
heated portion of the wire of the lamp igniting the explosive gas near which the lamp
may be situated.
In the accompanying drawings
Figure 1 is a sectional elevation showing one arrangement of the improved lamp.
Figure 2 is a similar view showing a modification.
Figure 3 is a perspective view showing a further modification.
Like letters indicate like parts throughout the drawings.
The lamp A is mounted upon a hollow glass receptacle B which is secured to the
wall of a glass envelope C which encloses the whole lamp. Within the receptacle B is
arranged a flexible conductor in the form of two diaphragms D, which enclose between
them a space E which is in communication through an opening E' in the wall of the
receptacle B with the space around the lamp enclosed by the envelope C. The
diaphragms D divide the receptacle B into two parts B1 B2 which contain air
at atmospheric pressure. One conductor F leading from the filament G is
brought out from the lamp bulb directly through the wall of the envelope C,
the other conductor H is brought into the chamber B where it is
formed into a hook with which engages a hook H¹ formed upon the end
of a conducting wire which passes through the diaphragms D through the chamber B
and out through the wall of the latter. The wire H2 is preferably coiled at the part
which passes between the diaphragms D and between the lower diaphragm and the
wall of the enclosing envelope. As long as the envelope C contains air at atmospheric

page_text: pressure the hooks on the ends of the wires Hand H do not actually touch and there.
fore the circuit of the lamp is broken, but if the air be exhausted from the envelope C
the diaphragms D are caused to approach each other and the hook on the end of the
wire H makes contact with the end of the conductor H.
:
By a suitable arrangement of the conductors H and H¹ and the diaphragms D,
the contact between the wires H and H¹ may be caused to be made by keeping the
air within the envelope C under pressure, the chambers B1 and B2 in this case being
preferably exhausted."
In the arrangement illustrated in Fig. 2 the flexible conductor instead of having
the form of the diaphragms D is made as a short preferably platinum tube J,
projecting into the receptacle B. The tube is curved round and so arranged that
when air is exhausted from its interior, that is to say from the interior of the
envelope C, the free end of the tube curls round and makes contact with the end of
the conducting wire H, the tube itself being in communication with the conductor H.
This lamp may also be arranged so that the circuit is made by introducing air
under pressure within the envelope C, by so arranging and coiling the tube J
that the pressure of air within its interior will cause it to uncoil, and make contact
with the conductor H¹.
The modification shown in Fig. 3 differs from those previously described,
inasmuch as the movable circuit breaker consists of mercury or like conducting
Anid. The receptacle B here acts purely as a support for the lamp bulb A,
the conductor F passing straight through and terminating on the outside of the
envelope C. The end of the other conductor H is sealed into the closed end of a
glass tube K which is coiled round behind the lamp bulb A, the end of the
conducting wire H¹ being introduced into this tube K about half way along its
length. Into this tube is placed a small amount of mercury L forming a circuit
breaker which upon the pressure of the air in the envelope C being increased, is
forced down the tube K until it establishes communication between the ends of the
conductors H and H¹.
.
It is obvious that in all these constructions directly the envelope C is broken
the lamp is extinguished by the breaking of the circuit.
A convenient means of closing the opening C¹ in the envelope C is to introduce
into the latter a small bead of wax, shellac or other suitable substance. After the
air has been compressed through the capillary tube communicating with the
opening C, the wax bead is shaken down into the hole and by the application of a
gentle heat is caused to melt and occupy it, temporarily closing its entrance and
enabling the capillary tube to be broken off The hole C¹ may now be sealed off
and the envelope hermetically closed. It is obvious that when the air in the
envelope C is exhausted instead of setting up a pressure within it, the natural
contraction that takes place will of itself automatically close the opening C¹ directly
heat is applied to the capillary tube.
It must be understood that some other fluid than air may be employed to fill the
envelope C and chambers B' and B².
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an electric lamp the combination with a chamber enclosing the lamp bulb
of a movable circuit breaker so disposed as to close an aperture in the chamber and
become operative by variation of the fluid pressure upon its opposite sides
substantially as described.
2. In an electric lamp the combination with a lamp bulb mounted upon a support
such as B of a chamber enclosing the bulb and support and a movable circuit
breaker such as D or J substantially as described with reference to Figs. 1 and 2.
3. In an electric lamp the combination with a lamp bulb mounted upon a support
of a carrier such as K for a movable circuit breaker L and a chamber enclosing the
lamp its support and the carrier, substantially as described,

page_text: 4. The complete electric lamp arranged and operating substantially as described
and illustrated in Figure 1 or Figure 2 or Figure 3 of the accompanying
drawings.
ALL
t
FREDERICK G. W. J. ADAMS.
Boult & Wade,
Agents for the Applicant.