IMPROVEMENTS IN ELECTRIC LIGHTING AND
Year: 1882

page_text: LETTERS PATENT to Otway Edward Woodhouse and Frederick Lawrence
Rawson both of 11 Queen Victoria Street in the City of London Electrical
Engineers for an invention of IMPROVEMENTS IN ELECTRIC LIGHTING AND
PROVISIONAL SPECIFICATION left by the said Otway Edward Woodhouse
and Frederick Lawrence Rawson at the Office of the Commissioners of
Patents on the 23rd March 1882.
OTWAY EDWARD WOODHOUSE, and FREDERICK LAWRENCE RAWSON, both of
11 Queen Victoria Street, in the City of London, Electrical Engineers;
"IMPROVEMENTS IN ELECTRIC LIGHTING AND APPARATUS CONNECTED THEREWITH
"
Our invention relates to improvements in electric lamps deriving their luminosity
from an incandescent conductor in vacuo, and is designed to effect more perfect
reflection of the light from the globes of such electric lamps than has hitherto
been effected, and to obtain a simple method of constant resistance in them and
other electrical appliances.
Our improvements are as follows:-
FirstWe render one half of the enclosing globe opaque, or make it of such
surface or material as will produce the like effect, and be suitable for the reflection
of light. The other half of the globe is of more or less transparent material, to
allow both the direct and reflected light to pass through it.
The reflecting surface may consist of silver, tin, or other substance, applied
either inside the globe before exhaustion, or preferably outside after exhaustion.
This may be applied in the form of foil, by chemical deposit, or other known
means; and in most cases a protective covering of metal, varnish or other suitable
material, should be added. We prefer, after depositing the silver on the glass, to
deposit a coating of copper on the silver, and then paint this second coating over
with a protective covering of varnish.
Alternatively, the reflecting surface may be formed of opal or other reflecting
glass; and the reflecting and transparent halves are in such case fused or joined

page_text: .
together at their edges, in such a way as may be found most convenient to form a
complete globe.
Secondly-The reflecting surface may be either flattened or curved, to cause
divergence or parallelism of the reflected rays. The transparent half may be also
flattened, to allow of the more ready passage of the direct and reflected rays, and
either or both may be lenticulated for the same purposes of parallelisin or
divergence. The additional thickness thus obtained will add to the strength of
the glass.
Where it is desirable to break up and distribute the light, the reflecting surface
or the transparent face is corrugated, lobed, or otherwise varied;
:-
Thirdly We construct the incandescing conductor partially of carbon and
partially of metal, the two connected so as to be in series, in suitable form for
reflection, and with the face next the luminous carbon polished or brightened.
We form the junction between the filament and external copper wires by leading
the ends of the filament into a hole bored in a copper or other metallic wire, the
other end of which is entered by the platinum wire, which. passes through the
glass and is joined to the external copper wire. We form the copper wire with a
slight undulatory curve at the end, so that the mere pressing of the filament into
the hole in the wire secures it in place and makes good contact. The junction may
be electroplated preferably with nickel if required.
The compound construction of filament as before described may be made to give
a continuous conductor of constant resistance, the resistance of carbon decreasing
inversely with the temperature, whilst that of the metal increases.
This construction of incandescent conductor may be advantageously employed
for the purpose of an incandescent lamp filament of constant resistance, inde-
pendently of the purpose of reflection, the metal and the carbon being suitably
proportioned; and such a compound conductor is applicable in other electrical
appliances where constant resistance may be desirable, such as in ordinary
resistance coils,

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Otway Edward Woodhouse and Frederick Lawrence Rawson
in the Great Seal Patent Office on the 23rd September 1882.
.OTWAY EDWARD WOODHOUSE, and FREDERICK LAWRENCE RAWSON, both of
11 Queen Victoria Street, in the City of London, Electrical Engineers
IMPROVEMENTS IN ELECTRIC LIGHTING AND APPARATUS CONNECTED THEREWITH.
Our invention relates to improvements in electric lamps deriving their luminosity
from an incandescent conductor in vacuo, and is designed to effect more perfect
reflection of the light from the globes of such electric lamps than has hitherto been
effected, to obtain a simple method of relatively constant resistance in them and
other electrical appliances, and to produce improved methods of clip attachments
for securely holding the filaments, wires, and lamps
And in order that our invention may be the better understood we now proceed
to describe the same with reference to the drawings annexed, reference being had
to the figures and letters marked thereon.
Figs 1 to 5 show the arrangement of reflecting surfaces in our improved incan-
descent lamps
Fig 6 shows the compound filament as applied to an incandescent lamp
Figs 7 to 17 show the various modifications and applications of our improved
undulatory connecting grip to the filaments, to incandescent lamps, and to wires
connected therewith
Figs 18, 19 and 20 show adaptations of our undulatory clip joint, applied to
insulators for filaments or wires, and to a spring clip holder for an incandescent
lamp.
Figs 1 shows our improved reflecting globe for incandescent lights, in which one
part A is of glass, to allow both the direct and reflected light to pass through it.
The other part B of the globe is rendered reflecting by the application of silver or
tin in the form of foil, either inside the globe before exhaustion, or preferably
outside, after exhaustion. The reflecting surface may be alternatively fixed by
chemical deposit. When externally applied we prefer to protect the silver with a
coating of copper, and that again by a plate or coat of thin metal or exterior coat
of varnish or other substance.
Fig 2 shows a modification of the arrangement in which the light is placed
within an inner globe to protect the reflecting surface from the heat.
Fig 3 shows another alternative in which the reflecting coating is applied to an
independent shell or shield of glass or other material fused in places or otherwise
fixed to the globe containing the incandescent light, but with an air space left
between
Fig 4 shows a further modification, in which a reflecting material such as chalk
unaffected by heat, is packed between the exterior surface of one half of the globe
and an exterior shield, conveniently fastened or fused to the globe
We may make the reflecting surface specially curved to produce parallelism of
the reflected rays, and the transparent surface is flattened to allow of the more
ready passage of the direct and reflected rays,
On the other hand, when desired, the reflecting surface may be alternatively

page_text: flattened for divergence and the front portion of the globe lenticulated to increase
that divergence.
Or again we may make the reflecting surface corrugated, and the transparent
surface lobed, for the diffusion of the light. These reflecting and refracting
modifications, though we may employ them in combination with our improvements,
we do not claim as novel.
Secondly-Fig 5 shows a lamp in which the incandescing conductor is formed
partially of carbon and partially of metal, such as platinum or copper, the metal
being extended, and with its face toward the carbon polished, so as to form a
reflector of the light from the latter, and which is possessed of properties herein-
after more particularly specified.
Fig 6 shows the same form of compound metal and carbon filament without the
former being extended so as to form a reflecting surface...
-
Thirdly Fig 7 shows in enlarged detail one form of junction we may employ
between the filament and external copper wires by leading the ends of the filament
into a sleeve, which may be a tube or be formed by a bored hole in a copper or
other suitable wire, which is connected through the glass with the main circuit or
the hole may be formed in the filament itself. We form the sleeve, hole, or wire
with a slight undulatory curve at the end, so that the filainent is securely gripped
when passed into the hole. The filament may be dipped into cement before being
inserted, or may be cemented afterwards if desired. The junction may be electro-
plated if desired. Alternatively we take a piece of thin copper or platinum plate
and cut notches in the side, which we turn up so as to be a little out of the direct
line, the carbon being put in between them is slightly bent and so firmly held as
shewn in Fig 8, or we stamp or drill out 2 or more holes in the plate and thread
the filament through as shewn in Fig 9. We obtain a specially large contact
surface by stainping back tongues cut three sides of a square and pressed back on
alternate sides, the filament being threaded through, as shown in Fig 10, the metal
being slightly bent or undulated to prevent the filament being bent excessively.
The broad portion or plate of the contact wire may be soldered on to the end of
the wire, or may be hammered round and rivetted to it, or the end of the wire
itself may be hammered out and flattened to form the broad part.
By another method we take a spiral wire and bend it out of the straight into an
undulatory line. By closing the spring together, the filament may be inserted,
and on springing out again the filament is securely held. This is shown at Fig 11.
Again another method is to flatten out the end of metal wire, as.in Fig 12, bend
it into a tube (Fig 13) conveniently by a pair of needle nosed pliers, and then
bent, so that the tube forms a part of a circle with its axis in the line of the
supporting wire. If required a sliding block may be fitted to the wire stem, so as
to press out the lower part of the filament, and make its grip more secure in the
bent tube. If desired the filament may be further cemented into place above and
below the tube.
As an alternative to the undulatory spiral wire connections at Fig 11, we may
use a double undulatory spiral connected together at the bottom by a loop, as in
Fig 14, and the ends of these spirals may be simply flattened out or brought
together as two semicircular troughs to hold the filament (Fig 15)
Fig 18 shows an undulatory gripping clip to surround the troughs aforesaid and
make all firm. This clip is in the forin of a tube longitudinally split and with a
recess in one half corresponding with a projection on its fellow forming an
undulation in the gripping surface A collar is slid over the outer side, which may
be slightly coned. This clip is adaptable as an insulator as shown in Fig 19, the
insulator being partially split when made, in order to secure a good fit when the
split is completed just before use, and the grip is made by the staple being driven
home in the annular recess
Again as another method the flattened end. of the wire may be bent down
and upwards again in the form of a crook to receive the end of the filament,

page_text: the pocket of the crook being undulated to cause a grip upon the filament.
(Fig 16)
i ୮
It will be seen that in all the preceeding modifications of gripping joint between
the filament and connecting wire the same feature of gripping the filament by the
undulation of the holding wire or clip is maintained.
We may alternatively use the converse of this method, that is, we may employ a
hollow filament and insert into it the end of the wire, undulated to ensure a good
grip (Fig 17)
In this latter and in other cases the filament may be advantageously fixed
in the gripping wires before being reduced to carbon, and may be afterwards
charred.
When a straight filament is required we may use any pair of joints as
herein before described, the wires being bent so as to bring the axis of the joints
in a line with each other. The filament may be slightly undulated to better secure
the ends in the undulated metal clips
Fourthly We also apply our improved undulatory joint to the attachment of
the incandescent globe to a stand, fig 20, so as to make a secure joint and
immediate contact to the filament wires. This we effect by constructing the stand
in the shape of a split metallic cylinder, each half insulated from the other and
connected each to a line wire. These semi-cylindrical clips are also undulated in
their length and fit similar undulations in the interior neck or leg of the
incandescent globe. These undulations in the neck of the globe may be formed
in the material of the globe itself, or from any convenient material inserted as a
plug into the neck of the globe. The ends of the filament holders are brought
through the upper part of the neck or leg of the globe as described, and bent or
fixed along the interior of the described undulatory neck or plug.
The lamp may be then pressed on to the cylindrical spring joint, the joint
opening by its elasticity, and making electrical contact against the ends of the
wires aforesaid, at the same time that the clip securely holds the lamp
The compound carbon and metallic conductor, when suitably proportioned, so
that the decrease of resistance of the carbon with a rise of temperature may
balance the increase of resistance of the metal, is applicable in other electrical
contrivances where constant resistance may be desirable, such as in resistance
coils
Where our conductor is employed as the incandescing conductor of electric
lamps, it will possess the property of automatically keeping the lamps in a circuit
at a constant resistance when in operation, notwithstanding any variety there may
have been in their construction, inasmuch as where any lamp is deficient in
resistance the increased current passing through it raises the temperature of the
metal, and therefore increases its resistance
And having now described and ascertained the manner in which our said
invention may be carried out, be it known that what we consider novel, and desire
to protect by letters patent is :—
1st The construction of a partially reflecting and partially transparent globe for
incandescent electric lights, substantially as and for the purposes specified in
reference to Figs 1. to 5
2nd The construction in series in incandescent lights or electric appliances of a
compound conductor of carbon and metal, such as platinum or copper, whether the
metal be extended as a reflector or not, substantially as and for the purposes
specified in reference to Figs 5 and 6
3rd The construction in incandescent electric lights of improved junctions
between the filaments and main wires, substantially as and for the purposes specified
in reference to Figs 7 to 18
4th The construction in incandescent electric lights of an improved undulatory
junction spring clip, either conducting or insulating for firmly holding filaments or

page_text: wires, or for holding the lamps and making electrical contact therewith, substan-
tially as and for the purposes specified in reference to Figs 18 to 20
In witness whereof I the said Frederick Lawrence Rawson on behalf of
myself and the said Otway Edward Woodhouse have hereunto set my hand
and seal this twenty second day of September in the year of our Lord
one thousand eight hundred and eighty two.
Witness
FREDERICK LAWRENCE KAWSON (L.S.)
S. P. WILDING
23 Rood Lane, Fenchurch St
London, E.C.
Patent Agent.