Improvements in Portable Electric Lamps.
Year: 1890

page_text: Date of Application, 6th Nov., 1890
Complete Specification Left, 7th Sept., 1891-Accepted, 6th Nov., 1891
PROVISIONAL SPECIFICATION.
Improvements in Portable Electric Lamps.
I, MADS PETER HARDT, Electrical Engineer, of Metropolitan Buildings, Queen
Victoria Street, in the City of London, do hereby declare the nature of my
invention to be as follows :-
My invention relates to miner's safety lamps and other portable electric lamps
which contain an electric battery for supplying the current.
The lamp embodying the above improvements chiefly comprises a wooden box
containing a primary or secondary electric battery composed of flat rectangular
cells, a lid which is hinged to the box and carries an incande.cent lamp together
with its circuit connections and guard and a reversible holder attached to the sides
of the box.
The rectangular cells are placed side by side and the box is made higher than
the cells, so as to project over the upper edge of the same. Two opposite sides
of the box are provided in the centre with narrow slots extending from the upper
edge of the box down to the upper edge of the battery, each slot serving to
receive one of the short terminal wires which project from the side of the battery.
Each slot is bridged over by a metal plate which is laid into the upper edge of
the box and perforated for the reception of a metallic plug extending downward
from the lid of the box. Or instead of a perforation the said metallic plate may
have a pair of electric contact blades, while the underside of the lid is provided
with a metallic wedge adapted to separate the said blades and establish contact
with the same. One of the said contact plugs or wedges may extend through the
lid and have at the top a head for moving the said plug by hand, while the other
plug is fixed to the underside of the lid. The lid is preferably secured to the box
by a hinge-joint, and provided on the opposite side with a lock, arranged so that
the key hole affords an escape for the gases developed by the battery. The two
sides at right angles to the hinge contain the plugs which connect the lamp wires
with the terminals of the battery.
Each cell of the battery is hermetically closed at the top with the exception of
a small circular hole which may be lined with a short glass tube which is preferably
conical or funnel shaped, and can be closed by a specially arranged plug.
This plug is preferably a hemispherical piece of indiarubber or other suitable
material attached to the underside of a leaf spring fixed at the opposite end to the
underside of the lid, so as to press the said plug against the glass tube and prevent
the escape of liquid when the lid is closed, in whatever position the box is held.
The pressure of the spring, and the distance of its free end from the underside
of the lid are so arranged, that the plug will be lifted and act as a safety valve by
allowing the gases to escape from the battery, when the pressure of the said gases
exceeds a given limit.
A small incandescent lamp is mounted in an upright position on the centre of the
lid and secured to a pair of conducting wires which pass through the lid and project
a short distance above the same. In order to keep the lamp steady and maintain a
good contact with the said conducting wires, a split ring of indiarubber is inserted
tightly between the lid and the lamp, and the said ring may support a small circular
reflector placed between the lamp and the ring, so as to reflect the rays, which pass
from the filament downward towards the lid.
The bulb of the lamp is surrounded by a glass globe or flanged hood which rests
on the lid, with an outside flange held down by a metallic ring, the latter being
placed on the top of the flange and fixed to the lid by screws.

page_text: This ring also supports the metallic guard or open frame for protecting the glass
globe.
The guard is preferably cut out from a circular piece of sheet metal, or is cast
so as to form arms radiating from the centre, which arms are then bent at right
angles so as to form a kind of hood adapted to enclose the glass globe, and the end
of each arm is then provided with a foot, either by splitting the end and turning
the extension sideways, or by bending the extremity forward or backward or by
attaching a separate piece. The feet are then placed underneath the edge of the
circular metal ring mentioned above, which may be provided with a slot for each
foot, and serves to hold the said feet to the lid, or the feet may be secured to the
top of the ring. The said guard serves to protect the lamp against blows and other
accidents.
The vertical edges of the box may also be armed with angle irons to increase its
durability.
The holder chiefly consists of a hoop of thick round wire pivoted at its extremities
to the sides of the box in the middle thereof, while the centre of the hoop projects
over the top of the box sufficiently for being held easily by the hand. Each side
of the box is provided with a pair of catches, adapted to retain the hoop in position,
one catch being placed near the top and the other near the bottom edge. Each
catch may consist of an angular piece of metal, the horizontal part of which has
in the centre a semicircular recess for holding the hoop in its position of rest, while
the sides are sloped symmetrically from the surface of the box up to the centre or
the edges of the notch.
For reversing the position of the holder, it is pressed sideways sufficiently, to
cause the round wire to slide over the edge of the notch, on to one of the sloping
sides, after which the box can be easily pivoted on the ends of the hoop, until the
latter arrives at the sloping side of the opposite angle piece or catch, after which
increased pressure is applied, which causes the hoop to bend slightly and slide
into the notch of the angle-piece. Instead of having on each side of the box
only one pair of catches, adapted to secure the holder either in the upright or
in the reversed position (that is when the lamp is at the bottom of the box)
there may be two pairs of catches for each side, one pair being placed in a line at
right angles to the line of the first pair, so that the hoop can also be secured after
it has been turned 90 degrees to the right or to the left, the lamp thus being on
one side of the box, while the hoop is at the top. Instead of angle-pieces as
described, which require a slight bending of the hoop, I may employ spring-
catches, adapted to secure the hoop in the desired position.
Dated this 5th day of November 1890.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Portable Electric Lamps.
I, MADS PETER HARDT, Electrical Engineer, of Metropolitan Buildings, Queen
Victoria Street, in the City of London, do hereby declare the nature of my
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 relates to miner's safety lamps and other portable electric lamps
which contain an electric battery for supplying the current.
The lamp embodying the above improvements chiefly comprises a wooden box
containing any suitable primary or secondary electric battery composed of flat
rectangular cells, a lid which is hinged to the box and carries an incandescent lamp
together with its circuit connections and guard, and a reversible holder attached to
the sides of the box.

page_text: 5
In the following description reference will be made to the accompanying drawings,
in which
Fig. 1 is a vertical section of a lamp embodying my invention,
Fig. 2 is a side view of the same in a different position, and
Figs. 3 to 5 represent details of construction.
A is a wooden box which contains and supports the principal parts of the
apparatus.
B are 3 accumulator cells hermetically closed on all sides, except at the top,
where they are covered with a plate made of a suitable plastic compound and con-
taining three circular openings b, b, b, one for each cell.
C is the lid of the wooden box. It is attached to the box on one side by means
of an ordinary hinge joint (not shown) and on the opposite side by means of a lock,
or by a screw the head of which is sunk into the lid, so that it can only be turned
by a special key.
D is the bulb of an electric glow lamp mounted on the lid C.
E is the reversible holder.
The said openings b, b, b, are closed by means of hemispherical plugs f, f
made of indiarubber or other suitable material which should be compressible and
acid proof. The said plugs are fixed to the underside of a metal plate F which is
attached to the underside of the lid C by means of springs f1f, made of such a
length and strength, that on the lid C being closed, the said plugs f close their
respective openings 6 and are held down with the desired pressure. This pressure
must be sufficient, to prevent the escape of liquid from the cells, in whatever
position the lamp may be held, and to provide that in case the pressure of the gases
developed in the cells should exceed an allowable limit the springs would yield and
allow the plugs to open, so as to act as safety valves, which allow the gases to
escape until the pressure of the gases has fallen to its normal limit. The springs
are coiled around a pair of bolts or pins which are attached to the lid C and guide
the plate F in a straight line.
Instead of attaching the plugs to the same metal plate, each plug may be con-
nected with the lid C by an independent spring.
As shown on a larger scale by Fig. 3, the glow lamp D is placed a short distance
above the centre of the lid C, and connected by a pair of springs d with 2 conducting
wires di which pass through two perforations of the lid C into a pair of grooves c
formed in the underside of the lid, and thence to a pair of contact devices which
serve to lead the current from the box into the lid, when required, as hereinafter
more fully described.
In order to keep the lamp steady and maintain a good contact with the conducting
wires, a split ring G of indiarubber is inserted tightly between the lid C and the
lamp, or, as shown by the drawing, between the lid and a conical reflector H which
surrounds the lower part of the lamp. The ring G fits over the lower part of the
glass bulb D, as shown. A similar reflector H¹ is placed at the top of the glass
bulb, and has a small central opening, to receive and hold the apex of the bulb.
The bulb of the lamp is surrounded by a cylindrical or tapered glass shield I,
which rests on the cover of the box and is held in a metallic frame or guard J which
protects the glass. The said guard has an annular base, into which fits the glass
hield I and the base of the reflector H, while the top or roof is formed by a circular
late to which is secured the upper conical reflector H' mentioned above. The
uter edges of the reflectors are bent outward, so as to fit over the edges of the
lass shields I, as shown.
The holder E chiefly consists of a hoop of thick round wire pivoted at its
xtremities to the sides of the box at or near the middle thereof, while the centre
f the hoop projects over the top of the box sufficiently for being held easily by
e hand. Each side of the box is provided with a metal plate K carrying a pivot
ad with a pair of catches L, L', adapted to retain the hoop in position, one catch
eing placed near the top and the other near the bottom edge. Each catch may

page_text: consist of an angular piece of metal (Fig. 4) the horizontal part of which has in
the centre a semicircular recess for holding the loop in its position of rest, while
the sides slope symmetrically from the surface of the box A up to the edges of the
notch 1.
For reversing the position of the holder, or changing it from that shown in Fig. 1
to that shown in Fig. 2, it is pressed sideways sufficiently, to cause the round wire
to slide over the edge of the notch 1, on to one of the sloping sides, after which the
box can be easily pivoted on the ends of the hoop or the studs k until the hoop
arrives at the sloping side of the opposite angle piece or catch; then the pressure
is increased, which causes the hoop to bend slightly and slide into the notch 7 of
the angle piece L. Instead of having on each side of the box only one pair of
catches, adapted to secure the lamp on the box either in the upright or in the
downward position, there may be two pairs of catches for each side, one pair being
placed in a line at right angles to the line of the first pair, so that the hoop can
also be secured, after it has been turned 90 degrees to the right or to the left, the
lamp thus being on one side of the box, while the hoop is at the top. Instead of
angle pieces as described, which require a slight bending of the hoop, I may employ
spring catches, adapted to secure the hoop in the desired position.
The terminals of the battery are connected by wires to, w, with a pair of contact
devices, situated at the upper edge of the box A. on the opposite sides thereof.
These contact devices are also connected with the lamp wires d' d¹, as described
above and serve to close the electric circuit by the closing of the lid C.
One of these contact devices chiefly consists of a pin O which is situated in a
cylindrical recess of the box and surrounded by a helical spring o. This spring
rests at the bottom on a metallic plate, to which is attached one of the battery
wires w, while the top abuts against a collar of the pin O and presses the latter
upward against the head of a screw P' fixed in the lid C and connected with one of
the lamp wires.
The other contact device chiefly consists of a pin Q passing through a metallic
sleeve R screwed into the lid, and connected with one of the lamp wires. The
lower end of the pin Q forms a cylindrical plug fitting into the sleeve R and
projecting over the face of the lid C. The upper part of the pin Q is surrounded
with a helical spring r which abuts at the upper end against the base of the sleeve R,
while the lower end rests on the plug of the pin Q and presses the latter downward
against the screw S, which is sunk into the edge of the box A and connected with
one of the battery wires w.
The upper end of the pin Q has a radial extension or nose q, which fits into a
recess formed in the base of the sleeve R, as shown by Fig. 5. If the pin Qis
drawn upward by means of the button y', until the nose is clear of the sleeve R,
the pin will no longer touch the screw S, and the circuit is therefore broken.
If now the pin Q is turned on its axis, and then left to itself, its radial nose will
no longer fit into the recess of the sleeve R, but will rest on the top of the latter,
and the current cannot be closed, uatil the pin Q is turned back into its former
position, when the radial nose will enter the recess of the sleeve R and allow the
pin Q to descend.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is
-
1. In a portable electric lamp, the combination of a box containing a herme-
tically closed battery cell or cells having at the top a small circular opening or
openings, with a lil or cover hinged to the box and carrying on its underside one
or more plugs adapted to close the openings of the cells, the said plug or plugs
being connected with the lid by springs adapted to press the plugs upon the said
openings in the act of closing the lid, substantially as described and for the
purposes specified.

page_text: 2. In a portable electric lamp, the means for supporting and holding the glass
bulb, consisting of a split elastic ring interposed between the bulb and the base
plate, so as to surround the connecting wires, substantially as described.
3. In a portable electric lamp, the combination of the lid for the box containing
the electric battery, with an electric glow lamp and connecting wires, a conical
reflector surrounding the lower part of the glass bulb, and a split india-rubber
ring interposed between the lid and the said reflector so as to support the reflector
and receive the lower end of the glass bulb, substantially as described.
4. In a portable electric lamp, the combination of a closed box containing the
accumulator or battery and supporting an electric glow lamp, with a reversible
holder pivoted to two opposite sides thereof, and means for securing the holder to
the box in two or four different positions, substantially as described.
5. In a portable electric lamp, the combination of a box containing the battery
or accumulator, with a lid carrying an electric glow lamp and connecting wires,
and two spring contact devices adapted to connect the battery with the lamp wires
by the closing of the lid, one of the said contact devices containing a spring bolt
which extends through the lid of the box and is provided with means for setting
the contact device out of action, substantially as described.
6. A. portable electric lamp comprising in its construction a battery or accumulator
enclosed in a wooden box carrying a hinged lid, a spring plug or plugs secured to
the underside of the lid, an electric glow lamp, together with reflectors glass shield,
metal guard and connecting wires secured to the lid of the box, a pair of spring
contact devices connected with the battery terminals and with the lamp wires and
adapted to close the lamp circuit by the closing of the lid, a reversible holder, and
means for securing it in different positions, the whole substantially as described
and illustrated.
Dated this 5th day of September 1891.
M. P. HARDT,
By Fairfax & Wetter,
Agents.