Improvements in Electric Glow Lamps.
Year: 1895

page_text: Date of Application, 3rd Oct., 1895
Complete Specification Left, 1st June, 1896-Accepted, 4th July, 1896
BUY DIVNAT DE PUITIVATION.
Improvements in Electric Glow Lamps.
GEORGE DAVIS Electrical Engineer 246 Vauxhall Bridge Road London S.W.
I do hereby declare the nature of this invention to be as follows:-
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My invention relates to improvements in a type of electric lamps, commonly
called "high voltage" lamps which some electric supply companies have recently
found advisable to adopt or recommend for use on their mains. The voltage in
general use among these companies has been 100 volts but to facilitate their supply
this voltage has been doubled and a demand has therefor sprung up for 200 volt
lamps or "high voltage" lamps. Owing to the difficulty experienced by lamp
makers in producing lamps of this description with a single filament as in the lower
voltage lamps, the "high voltage" lamp is at present generally made with an oval
or pear shaped bulb with two filaments therein which are connected in series. The
high voltage" lamp so constructed however has the disadvantage that if one of
the filaments breaks the lamp is of no further use as a "high voltage" lamp
although it still has one good filament. To obviate this disadvantage, my invention
provides, instead of one oval or pear shaped bulb with two filaments therein as
above stated, two bulbs of the tubular pattern containing one filament each.
These two tubular lamps are placed close against & parallel to each other so as to
occupy the same (or little more) space as the oval shaped bulb. They have only
one common cap of the bayonet or screw type as in the case of the single bulb
high voltage lamp above described. This cap, instead of being cemented or
permanently attached to them as in the case of the above mentioned single bulb
high voltage lamp, is detacheable & being made with a broader & deeper base than
the ordinary cap, contains therein the necessary connections, loop or spring, for
receiving the tops of the two tubular bulbs which are also furnished with platinum
loops or connecting lugs. These connections in the cap are made so as to put the
two single filament lamps in series when they are attached thereto. In the event
of one of the two lamps giving out, through whatever cause, before the other, it is
only necessary to disconnect it and put another in its place, thus obtaining the full
life & value out of each filament and lamp.
Dated this 3rd day of October 1895
GEORGE DAVIS.
GEORGE DAVIS Electrical Engineer late of 246 Vauxhall Bridge Road but
now of 38 Margravine Gardens West Kensington London 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 relates to improvements in and connected with electric lamps and
refers primarily to certain improvements in that class of lamp commonly known as
"high voltage" and which some electric supply companies have recently found
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page_text: advisable to adopt or recommend for use on their mains. The voltage in general
use among these companies has been 100 v. but to facilitate their supply the voltage
has been doubled and a demand has therefore sprung up for 200 volt or "high
voltage" lamps. Owing to the difficulty experienced by lamp makers in producing
lamps of this description with a single filament as in the lower voltage lamps, the
high voltage lamp is at present generally made with two filaments in one bulb
which are connected in series. The "high voltage" lamp so constructed however
has the disadvantage that if one of the filaments breaks the lamp is of no further
use as a "high voltage" lamp although it still has one good filament. To obviate
this disadvantage my invention provides instead of one bulb with two filaments
therein as above stated, two bulbs containing one filament each. These two bulbs
are placed close against each other so as to be as compact as possible, and are
arranged under one common cap of the bayonet (double contact or centre contact)
screw or other suitable type, as in the case of the single bulb "high voltage" lamp
above described. The said cap instead of being permanently cemented or attached
to the bulbs is provided in this case with a broad and deep base containing or
carrying the necessary connections to receive the tops of the two bulbs which are
furnished with caps fitted with or carrying connecting lugs. The aforesaid
connections in the base of the common cap are arranged in such a manner as to
put the two bulbs or lamps in series when attached or connected thereto. It
will thus be seen that in the event of one of the two lamps or bulbs giving out,
through whatever cause, before the other, it is only necessary to disconnect it
and put another in its place thus obtaining the full life and value out of each
lamp.
In order that my invention may be more fully understood, I will now proceed to
describe same with reference to the accompanying drawings in which
Fig. 1 is a view in side elevation illustrating my improved arrangement of lamps
and the common cap used in connection therewith.
Fig. 2 being an underside view of the base of the common cap showing the
attachments for supporting or holding the lamps.
Fig. 3 is a side elevation of the base of the common cap, Fig. 4 being a plan
view of same with the cap proper removed showing the connections.
Fig. 5 is a sectional elevation of the common cap still further illustrating the
connections, Fig. 6 being a plan of same with the cap proper in position.
Fig. 7 is an end elevation of the common cap.
Fig. 8 is a central section through the cap proper showing the method of
construction preferably adopted.
Fig. 9 is a side elevation of the cap with which each of the lamps or bulbs
referred to is furnished showing the form and arrangement of the connecting lugs
and Fig. 10 is a plan of one of the lamps or bulbs with cap further illustrating the
connecting lugs.
Fig. 11 is a detailed perspective view drawn to an enlarged scale of one of the
end plates which is formed with a loop for receiving one of the connecting lugs,
and illustrates the method of construction which I prefer to adopt.
In carrying my invention into practical effect, the two lamps or bulbs b, b, are
arranged under one common cap c said cap being furnished with an enlarged base s
which is made of porcelain or other suitable material, and furnished with a common
supporting plate p having perforations or slots pl, pl, designed to receive the inner
connecting lug 1,, of each lamp or bulb, the base s being also provided with end
plates p, p, one upon either side, said end plates heing furnished with a looped
portion d (Fig. 11) designed to receive the outer connecting lug of each lamp
or bulb b, b.
Referring now more particularly to Figs. 9 and 10 each lamp or bulb b is fitted
or furnished with a separate and distinct cap c', the connecting lugs 1, 1, being
partially embedded in vitrite v or other suitable material contained in the upper
portion of the cap c' as indicated in dotted lines (Fig. 9) the tops of the said luga
projecting for the purpose of attachment to the receiving or connecting plates of

page_text: the common cap c as hereinbefore described, but as this form of lug cap c¹ is
distinctly new I do not wish to restrict myself merely to the use of same in
connection with the arrangement of lamps herein described, but reserve to myself
the right to use it in connection with incandescent electric lamps of all kinds when
and where it can be employed with advantage.
For the purpose of illustration, the common cap proper is shown of the double
contact bayonet type (Figs. 6 and 8) and according to the method I adopt of
constructing same said cap consists of a short cylindrical body r furnished with
two screws f, f, the ends f¹, f¹, of which are bent at right angles to protrude
through the body r so as to form the pins for completing the bayonet connection
as shown in Fig. 8, said screws being held or retained in position by means of
vitrite v or other suitable material arranged in the top of body .
The projecting portions of the screws f, pass through the holes or perforations h, h,.
formed in the bases their projecting ends being then furnished with nuts or the
like n, n, for the purpose of firmly securing the cap c to the base s, while one of the
said screwef projects a sufficient distance to form a support for the hold fast g, which
consists of a plate of metal preferably of the shape shown in the drawings (Fig. 7).
and which is furnished with a flat spring k projecting on either side and designed
to bear against the cap c¹, c', of the lamps or bulbs b, for the purpose of retaining
them firmly in position and ensuring good contact. This holdfast g when adjusted
on the free end of the screw fis prevented from falling or jerking off by the spiral
spring m one end of which is secured to the said holdfast g, the other end being
drawn out and made fast under the base s to one of the screws f, a wire m¹ being
passed through the centre of spiral spring, having its ends bent over at right angles
so as to prevent the said spring m from being overstretched when removing the
holdfast g from the support.
I may provide if advisable suitable projections such as indicated at 9 (Figs. 2
and 3) on the porcelain base s as a safeguard against short circuits between the
contact pieces or connecting lugs, caused through accident or negligence.
I will now proceed to describe the connections and the course of the current
through my improved arrangement of lamps and referring more particularly to
Figs. 1, 4 and 5, the current enters at the wire a passing to the end plate p' through
the connecting staple to which the said wire is attached. The current then
passes from the plate p' to the outer connecting lug and from thence through one
lamp to the common connecting plate p (secured in position by the staple y) by
means of the inner connecting lug P. The current then passes through the second
lamp in a similar manner, to the outer connecting lug 1 of same and then is
conveyed through the second plate p³ and its connecting staple ¹ to the return
wire a¹.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The new
or improved arrangement of two lamps in series under one
common cap, substantially as herein described and shown and for the purposes
specified.
2. In an arrangement of two lamps in series as above claimed, the common cap
consisting essentially of the cap proper c, enlarged bases, common plate p with
perforations p¹, p', end plates p², p³ and holdfast g, the whole arranged and
constructed substantially as herein described and shown and for the purposes
specified.
3. In combination with an arrangement of two lamps in series such as above
claimed, the special construction of cap proper c, substantially as herein described
0
ins

page_text: particularly with reference to Figs. 9 and 10 of the accompanying drawings and
for the purposes specified.
5. In combination with incandescent electric lamps of all kinds, the use of a
lug cap such as c¹, substantially as herein described and shown with reference to
Figs. 9 and 10 of the accompanying drawings.
Dated this 1st day of June 1896
GEORGE DAVIS.