IMPROVE- MENTS IN THE MANUFACTURE OF INCANDESCENT LAMPS
Year: 1884

page_text: I JAMES HENRY GARDINER of 69 Warner Road Camberwell in the County of
Surrey Electrician, do hereby declare the nature of my Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF INCANDESCENT LAMPS" to be as follows:-—
This Invention has for its object improvements in the manufacture of
incandescent lamps.
I wind the fibre or thread to form the filament whilst in a moist and flexible
state upon a cylindrical block to a spiral form with two straight central ends
projecting in opposite directions. The fibre or thread is kept tightly distended by
springs until it sets in the spiral form. The block is made in two parts which
separate to release the spiral.
The filament is carbonised in the usual way. It is then if necessary plated by
igniting it in the presence of hydrocarbon vapour to adjust the resistance and for
this purpose its ends are held in clips supported upon a glass rod.
The ends of the filament are then set into terminals. The terminal consists of a
platinum wire armed at one end with a cup or tubular socket of a size to adinit
the extremity of the filament and the other end of the wire is turned simply into
a loop. The wire is coated spirally with glass and for this purpose it is clamped
in a mandril on which is a screw thread. The mandril can be revolved by a
handle in a bearing which also perunits of longitudinal movement.
A spring
piece bearing on the screw thread limits the longitudinal movement to that due to
the advance of the screw thread except when the spring piece is pressed out of the
way. The platinum terminal having been clamped centrally in the mandril is
advanced by turning the handle between the points of two blow-pipe flames one on
either side. When the platinum is thus heated a thread of glass is wound upon
it so as to cover it completely the even distribution of the glass being ensured by
the forward movement of the platinum wire whilst it rotates, and winds the glass
upon it.
Two terminals thus prepared are then clamped upon a holder with the required
interval between them and the ends of the filainent are inserted into the platinum
cups or sockets. A good junction is made by the application with a brush of a
suitable paste or paint.
The enclosure for the filament is blown to a spherical oval or pear like form
from a small tube of glass a part of which is left projecting from the two opposite

page_text: sides of the glass bulb. Another tube is then sealed into the bulb at the side for
the connection with the air pump. The first mentioned tubes are then cut off
leaving small holes in the globe. Through one of these small holes the filament is
inserted and it is turned round and round to allow it to pass in and until its
further extremity issues again by the hole on the other side. The glass covered
terminals of the filament are then sealed into these holes. The lamp is then
exhausted and sealed off as usual. The lamp in use is suspended by hooks engaging
with the loops in the platinum terminals and fine wires ascend from the hooks to
main conductors provided overhead. Or two fine wires may be led from the
platinum terminals down to a socket or holder in which the lamp is held by the
projection left in sealing off after exhausting.
1 T

page_text: I, JAMES HENRY GARDINER of 69 Warner Road, Camberwell in the County of
Surrey Electrician do hereby declare the nature of my Invention for IMPROVE-
MENTS IN THE MANUFACTURE OF INCANDESCENT LAMPS " and in what manner
the same is to be performed to be particularly described and ascertained in and
by the following statement:-
This Invention has for its object improvements in the manufacture of
incandescent lamps.
I wind the fibre or thread to form the filament whilst in a moist and flexible
state upon a cylindrical block to a spiral form with two straight central ends
projecting in opposite directions. The fibre or thread is kept tightly distended by
springs until it sets in the spiral form. The block is made in two parts which
separate to release the spiral.
The filament is carbonised in the usual way; it is then if necessary plated by
igniting it in the presence of hydro carbon vapour to adjust the resistance and for
this purpose its ends are held in clips supported upon a glass rod.
The ends of the filament are then set into terminals. The terminal consists of a
platinum wire armed at one end with a tubular socket of a size to admit the
extremity of the filament and the other end of the wire is turned simply into a
loop. The wire is coated spirally with glass and for this purpose it is clainped in
a mandril on which is a screw thread. The mandril can be revolved by a handle
in a bearing which also permits of longitudinal movement. A spring piece bearing
on the screw thread limits the longitudinal movement to that due to the advance
of the screw thread except when the spring piece is pressed out of the way.
platinum terminal having been clamped centrally in the mandril is advanced by
turning the handle between the points of two blow pipe flames one on either side.
When the platinum is thus heated a thread of glass is wound upon it so as to
cover it completely the even distribution of the glass being ensured by the forward
movement of the platinum wire whilst it rotates and winds the glass upon it.
The
Two terminals thus prepared are then clamped upon a holder with the required
interval between them and the ends of the filament are inserted into the platinum
sockets. A good junction is made by the application with a brush of a suitable
paste or paint.
The enclosure for the filament is blown to a spherical oval or pear like form from
a small tube of glass a part of which is left projecting from the two opposite sides
of the glass bulb. Another tube is then sealed into the bulb at the side for the
connection with the air pump. The first mentioned tubes are then cut off leaving
small holes in the globe. Through one of these small holes the filament is inserted
and it is turned round and round to allow it to pass in until its further extremity
issues again by the hole on the other side. The glass covered terminals of the
filament are then sealed into these holes. The lamp is then exhausted and sealed
off as usual.
The lamp in use is suspended by hooks engaging with the loops in the platinum
terminals and fine wires ascend from the hooks to main conductors provided over-
head. Or two fine wires may be led from the platinum terminals down to a socket
or holder in which the lamp is held by the projection left in sealing off after
exhausting.
In order that my said Invention may be most fully understood and readily
carried into effect I will proceed to describe the Drawings hereunto annexed.

page_text: Figure
DESCRIPTION
IDE
shews my improved lamp as it appears when in use; it is here repre-
sented as suspended by cords from points over head. The cords contain the electrical
conductors and spring hooks engaging with the eyes of the lamp terminals from a
sufficient connection.
Figure 2 shews a similar lamp as it appears when mounted upon a foot or
bracket; here two curved springs with hooks at their ends engage with the eyes
of the lamp terminals and both support the lamp and supply to it the electric
current.
The other Figures of the Drawings relate to the means employed for producing
this lamp.
Figures 3 show a block to be employed in moulding the filament to the spiral
form.
Figures 4 show another block, a modification of the block represented by
Figures 3.
Figure 5 shews a holder in which the filament is to be held during the operation
of plating or adjusting its resistance.
Figure 6 shews the completed filament.
Figures 7 shew one of the terminals in which the filament is to be mounted and
also the parts from which this terminal is formed.
Figures 8 shew the holder which receives the terminals whilst the filament is
fixed in them.
Figure 9 shews in plan apparatus employed together with the blow pipe for
covering the terminals with glass to adapt them to be sealed into the glass globe
or enclosure.
Figure 10 shews the glass globe or bulb as it is first prepared by blowing from a
small glass tube parts of which are left projecting on either side.
Figure 11 shews the globe or bulb in a state to receive the filament, the original
tube has been cut off leaving two small apertures and another tube has been sealed
in to make the connection with the air pump.
The processes of manufacture are as follows:-
The fibrous cord thread or ribbon from which the filament is to be made having
if necessary been first prepared, either by means of solution of cupro ammonium
or otherwise in the usual manner is wound whilst in a moist state upon a block
represented by Figures 3. This block is in two parts A' A* which are held
together by a screw pin B. At each end of the block there is fixed by one end a
wire spring C which at its other end is bent to a V form such that the end of the
cord being placed in the V and pressed into the angle becomes securely held.
A* A* are small studs on the parts A¹ A².
D is the prepared cord. One end of this cord is made fast in the manner just
described and the cord is then laid along the block to the stud A*. Between the
two studs A* the cord is wound around the block. From the further stud the
cord is taken to the other spring holder C and there again it is made fast.
The prepared cord is allowed to dry upon this block, and in some cases it will
also require to be baked in order to set it to the form in which it is held so that
this form may be retained when the filament is removed from the block. The
filament is removed from the block by cutting it at the two ends close up to the
spring clips and then sliding the two parts of the block A' A² the one on the other
the screw pin B having first been removed.
The filaments thus prepared are carbonised in the usual manner, being packed
in granulated charcoal and enclosed in an air tight case which is then exposed to a
high temperature.
Figures 4 shew a block which does not require to be taken apart for the purpose
of liberating the filament.

page_text: The block D in this case is cast upon two stems E E which are sheet metal bent
to a trough like form and each stem has a notch at the end for the purpose of
securely holding the prepared cord. The cord F being thus made fast at one
end is led along within the trough as far as the first stop E* beneath which it
is passed. From this stop the cord is led to the stud D* upon the block and
then is wound around the block making about two and a half turns by which the
cord reaches another stud D*; it passes then beneath the second stop E* and so
to the notch at the further end in the stem of the block and in this it is secured.
It will be seen that whichever block be employed the cord is wound to a helical
or spiral form and its two ends are brought out in the axis of the helix.
After the carbonising operation the prepared filaments are taken to the holder
shewn by Figure 5 and which consists of a glass rod F upon which are clamped
at a suitable distance apart two platinum spring clips G G.
G¹ G¹ are the press buttons of these clips when they are pressed the jaws of the
clip open to admit the end of the filament between them as represented in the
Figure.
The filament being thus held it is adjusted to the required resistance by any of
the usual methods; that which I employ is to enclose the whole in an exhausted
reservoir to which a small quantity of hydro carbon vapour is admitted, or in place
of hydro carbon vapour other vapours containing carbon may be employed; chloride
of carbon and chloriform are very suitable.
The filament is ignited whilst in this vapour by an electric current passed
through it by conductors which are attached to the clips by the binding
screws G2 G².
This operation is continued until by measurement the resistance of the filament
is found to have been reduced to the extent desired. The clips are not opened for
the purpose of releasing the filament, but the ends of the filament are cut close to
the clips.
By this means I ensure that the extremities of the filaments which are inserted
into the sockets are as thick and equal in conductivity to the other parts.
Figure 6 shews the filament in this state.
The terminals into which the ends of the filament are to be set are produced in
the following manner:-
A piece of platinum wire H is bent and cut off to the shape represented in
Figures 7. (This piece of wire is here shown twice the actual size.) The end of
the wire H is then inserted within a small platinum tube H¹ also shown in this
Figure of twice the actual size. The portion of the tube having the wire within it,
and which extends to about half the length of the tube, is now pressed between
dies of suitable form, which bring this portion of the tube to a triangular form.
The pressure serves to establish a very good electrical connection between the
parts H and H¹. In place of platinum other metal as nickel may be used.
The terminal thus prepared is taken to the apparatus represented by Figure 9
and the eye or ring of the terminal is inserted into a slit at the end of the axis K;
it is pinched therein so as to hold the terminal securely by means of a small thumb
screw K.
The terminals should be held in this way in an approximately central position as
regards the axis K.
L is a bearing in which the axis K is able to rotate; it can also slide through
the bearing.
The axis K has a screw thread cut upon it and against the threaded part of the
axis a spring piece M having corresponding helical teeth bears; it is capable
however of being lifted off when desired by a connection with a treadle.
axis K is capable of being turned round by means of a handle at its end.
The
The operation of covering the terminal with glass is performed as follows:-
The operator employs a pointed rod of opal glass about as thick as a straw and
when all is ready he slides the axis K. forward until the extremity of the terminal

page_text: is between the two blow pipe flames N N. At the same time whilst turning the
handle the operator releases the treadle and allows the spring piece M to engage.
The terminal is thus made to travel gradually forward through the flames, and
being thus highly heated it is cleansed from any adhering grease or other impurity.
When the terminal bas been thus traversed through the flames nearly up to the
end by which it is held, the terminal is touched at the point where most highly
heated with the glass rod and the glass being softened by the heat adheres to the
metal. The end of the rod is then drawn slightly back producing a glass thread of
suitable thickness, which, is then wound up upon the terminal towards the
tube H. The other end of the tube H is left uncovered for about half the length
of the tube.
The terminals thus prepared are then taken to the holder Figures 8 and two of
them are set in the holder facing each other at the proper distance apart to receive
the filament between them. They are laid in grooves and held in their places by
the spring flaps O. O. which close upon them with a movement like that of the
blade of a pocket knife.
A small quantity of the carbonaceous cement usually employed has been placed
within the tubes H. H¹ with a small camel hair brush, and the ends of the filament
are now sprung into the tubes as indicated in the Figure. To hasten the drying of
the cement a piece of hot metal may be placed beneath the tubes H¹. H¹. I do not
apply any cement after the filament is placed in the terminals for I find that
cement so applied is liable to liberate gas after the lamp has been sealed off which
after a time destroys the filament. The distance at which the terminals are set is
such that the filament when sprung in between them butts upon the ends of the
wires H. H. and is held in slight compression between them so that these parts
may be directly in contact. A clip hook of aluminium wire resembling a safety
pin is at this stage inserted through the ring of one of the terminals and the parts
are theu released from the apparatus Figures 8 by opening the spring clip.
The filament is now in a condition to be inserted into the enclosure of the lamp
represented at Figure 11. It is held suspended by the clip hook whilst one of its
terminals is dropped through one of the small apertures left at P. P in the side of
the glass globe or bulb.
By turning the clip hook the filament is introduced into the globe. The screw
like form of the filament admits of its entering the enclosure notwithstanding the
small size of the hole at P which indeed is only just sufficiently large to allow the
terminal to pass.
The terminal so dropped into the globe or bulb is made to pass out again by the
corresponding second aperture P on the further side of the globe. The globe or
bulb with the filament so arranged within it is then taken to the blow pipe and
the lips of the hole P are softened by heat around the terminal which has just been
passed through the globe.
The softened glass closes upon the glass covering of the terminal and the two
become fused together making a secure joint.
The terminal whilst it is being thus sealed in is kept in its proper position by
the clip hook at the other end resting upon the exterior of the globe. One terminal
having thus been sealed the clip hook is removed and another joint sealing in the
terminal at the other end is then similarly made.
Care should be taken in this final sealing in that the helical filament is left under
slight compression, this is effected by sealing in whilst the free terminal is
uppermost and the filament is consequently slightly compressed by its weight; the
object is to ensure that the terminals when they become heated shall not allow the
filament to draw out of contact with the wires H. H.
The lamp is now taken to the air pump and is exhausted until a high vacuum is
obtained; it is then sealed off in the usual way.

page_text: Having now particularly described and ascertained the nature of my said
Invention and in what manner the saine is to be performed I declare that what
I claim is:-
First. An incandescent lamp substantially as described consisting of a blown
glass globe or bulb having two metal terminals fused into it on its opposite sides
and a helical or curved filament of carbon connecting the said terminals.
Second. The method of producing an incandescent lamp substantially as described
and especially providing a carbon filament with metal terminals, then passing it
into a glass globe or bulb by holes in the opposite sides so that one terminal
entering by the hole on one side appears through the hole on the opposite side and
finally closing the holes by heat around the terininals.
Third. A filament having a helical body and axial ends as represented at
Figure 6.
Fourth. The method of and apparatus for covering terminals with glass sub-
tantially as described.
Fifth. The method of setting the filament into its terminals consisting in
clamping the said terminals in position face to face and then springing and securing
the ends of the filament substantially as described.
Sixth. Sealing the filament into the lamp in a state of slight compression
between two opposite terminals so as to ensure good electrical contact.
Seventh. Plating up the filament in greater length than required and cutting off
the parts held in the temporary terminals used whilst plating so as to ensure good
conductivity in the parts of the filament which enter into the permanent terminals
in which it is held in the lamp.
Dated this 16th day of September 1884