IMPROVEMENTS IN ELECTRIC LAMPS AND IN APPARATUS USED IN MAKING THEM
Year: 1881

page_text: LETTERS PATENT to Rankin Kennedy, of Glasgow, in the County of Lanark,
North Britain, Electrician and Engineer, for an Invention of "IMPROVEMENTS
LETTERS PATENT to Rankin Kennedy, of Glasgow, in the County of Lanark,
North Britain, Electrician and Engineer, for an Invention of "IMPROVEMENTS
IN ELECTRIC LAMPS AND IN APPARATUS USED IN MAKING THEM."
PROVISIONAL SPECIFICATION left by the said Rankin Kennedy at the
Office of the Commissioners of Patents on the 17th December 1881.
RANKIN KENNEDY of Glasgow in the County of Lanark North Britain
Electrician and Engineer. "IMPROVEMENTS IN ELECTRIC LAMPS AND IN APPARATUS
USED IN MAKING THEM."
This Invention relates to both incandescent and are electric lamps, and its
objects are principally to facilitate the manufacture to render certain parts or
connections more satisfactory and durable than as hitherto made, and to obtain an
improved automatic regulation.
In making an incandescent lamp according to this Invention when the glass
bulb, which may be made and fitted in any known way, is ready for being
exhausted, it is placed with its capillary tube inserted through two plugs of rubber
or other suitable material fixed in the upper part of a glass tube the space between
the plugs having mercury in it. This glass tube which may be termed the movable
tube, is set, when an exhausting operation is to be performed, in a larger stationary
glass tube or vessel formed with a deep cup at its other end and with a contraction
between the bottom of the cup and the top of a bulb or enlargement. The con-
struction at the bottom of the cup serves as a valve seat and rest or support for
the movable tube which has a conical surface formed on it to fit the seat. The
lower end of the movable tube terminates with a capillary tube but between this
and the upper part there is a slight enlargement containing a valve shaped for
closing a contraction above it but made with wings or feathers to keep it central
and to allow of a passage downwards past it. The bulb or enlargement on the
larger glass tube or vessel has a tube extending from its bottom end down to a
piece fitted with a three-way cock or valve and also connected to a second tube
extending upwards and formed with a funnel at the top. The third way of the

page_text: cock communicates with a nozzle or pipe dipping into a vessel containing mercury.
The cock being turned to shut off this third way and put the other two in com-
munication, mercury is poured into the funnel-topped tube (by preference from a
cistern arranged for the purpose) until it rises up into the bulb and cup of the
larger glass tube or vessel. In thus rising the mercury expels the air either by
lifting the movable tube so as to pass at the contracted part or as is preferred
through a separate valve in connection with the bulb, the movable tube being in
that case less liable to be jerked or injured. The next operation is to turn the
three-way cock and let the mercury run out so as to form a torricellian vacuum in
the bulb of the larger glass tube or vessel; and this causes the air in the lamp
bulb to be exhausted to a certain extent. The operations of filling up with
mercury and withdrawing the mercury are repeated until the lamp bulb is con-
sidered to be sufficiently exhausted. The valve in the movable tube prevents the
mercury from rising into the lamp bulb and when the exhaustion is completed the
mercury in the lower part and bottom capillary end of the movable tube prevents
the entrance of air whilst the movable tube with the lamp bulb is being taken to
have the capillary tube of the lamp bulb closed at the blow pipe.
The carbon thread or fibre of the incandescent lamp is by this Invention made
to consist of a carbonized fibre or filament of the aloe plant; it is however con-
nected to the platinum or other conducting wires of the lamp in an improved
manner which is advantageously applicable to any carbon threads or fibres used
in incandescent lamps. On the end of each platinum wire a tube or a helical coil
of very fine platinum wire is placed and the ends of the carbon thread are entered
down into these tubes or coils. By means of a pair of temporary connecting wires
an electric current is made to pass through each joint tube or coil whilst the bulb
or vessel containing the parts is filled with coal gas or other carbonaceous gas or
vapor. The current passed through in this way is made sufficiently intense to
produce a white heat, and this causes carbon from the gas or vapor to be deposited
about the joint and so as to fill up all pores, or interstices. In this way con-
nections or joints are formed of a very durable and satisfactory character,
When with the view of obtaining a single powerful and very white light the
electric arc is substituted for a number of incandescent lamps, the length of the arc
and the movements of the carbons are by this Invention regulated in the following
manner. The carbons being vertical with the negative one which consumes more
slowly the lower, the upper one is attached to the core of a vertical solenoid
through the coil of which the lamp current passes and which is arranged to have
the greater lifting power with the stronger current. The lower carbon is held by
a cross bar held up by cords passing over pulleys to counterweights proportioned
to give the lower carbon a tendency to move upwards. On the pulleys are fixed
ratchet or friction wheels, and in connection with these wheels there are catches or
brake pieces which are movable by the holder of the upper carbon. When the
current passing through the solenoid coil is of less than the proper strength the
upper carbon descends and at the same time releases the pulleys so that the lower
carbon rises to meet the upper carbon. This allowing a greater strength of current
to pass the solenoid draws up the upper carbon and at the same time checks or
stops the pulleys. An adjustable stop is fitted in connection with the upper carbon
or solenoid so that the raising action of the solenoid is limited to give the precise
length of arc which is desiderated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent and
of an Order of the Lord Chancellor filed by the said Rankin Kennedy in the
Great Seal Patent Office on the 5th July 1882.
RANKIN KENNEDY of Glasgow, in the County of Lanark, North Britain,
Electrician and Engineer. "IMPROVEMENTS IN ELECTRIC LAMPS AND IN APPARATUS
USED IN MAKING THEM."
This Invention relates to both incandescent and are electric lamps, and its objects
are principally to facilitate the manufacture, to render certain parts or connections
more satisfactory and durable than as hitherto made and to obtain an improved
automatic regulation.
In making un incandescent lamp according to this Invention and when the glass
bulb which may be made and fitted in any known way is ready for being
exhausted, it is placed with its capillary tube inserted through two plugs of rubber
or other suitable material fixed in the upper part of a glass tube, the space between
these plugs having mercury in it. The glass tube which may be termed the
moveable tube, is set (when an exhausting operation is to be performed) in a larger
stationary glass tube or vessel forned with a deep cup at its other end and with a
contraction between the bottom of the cup and the top of the bulb or enlargement.
The construction at the bottom of the cup serves as a rest or support for the
moveable tube which has a conical or flat surface formed on it to fit the seat.
The lower end of the moveable tube terminates with a capillary tube but between
this and the upper part there is a slight enlargement containing a valve, shaped for
closing a contraction above it but made with wings or feathers to keep it central
and to allow a passage downwards around it. The bulb or enlargement on the
larger glass tube or vessel has a tube extending from its bottom end down to a
piece fitted with a three-way cock or valve and also connected to a second tube
extending upwards and formed with a funnel at its top. The third way of the
cock communicates with a nozzle or. pipe dipping into a vessel containing the
mercury discharged from the pump. The cock being turned to shut off this third
way and put the other two in communication, mercury is poured into the funnel
topped tubed (by preference from a cistern arranged for the purpose) until it rises
up into the bulb and cup of the larger glass tube or vessel. In thus rising the
mercury expels the air through a valve in connection with the bulb.
The next operation is to turn the three-way cock and let the mercury run out so.
as to form a toricellian vacuum in the bulb of the larger glass tube or vessel, and
this causes the air in the lamp bulb to be exhausted to a certain extent. The
operations of filling up with mercury and withdrawing the mercury are repeated
until the lamp bulb is considered to be sufficiently exhausted. The valve in the
moveable tube prevents the mercury from rising into the lamp bulb.
The carbon thread or fibre of the incandescent lamp is by this Invention made to
consist of a carbonised fibre or filament of the aloe plant; it is however connected
to the platinum or other conducting wires of the lamp in an improved manner
which is advantageously applicable to any carbon threads or fibres used in
incandescent lamps. On the end of each platinum wire a tube or helical coil of
very fine platinum wire is placed and the ends of the carbon thread are entered
down into these tubes or coils.-By means of a pair of temporary connecting wires
an electric current is made to pass through each joint tube or coil whilst the bulb
or vessel containing the parts is filled with coal gas or other carbonaceous gas or
vapour. The current passed through in this way is made sufficiently intense to
produce a white heat, and this causes carbon from the gas or vapour to be deposited

page_text: about the joint, so as to fill up all pores, or interstices. In this way connections
or joints are formed of a very durable and satisfactory character.
When with the view of obtaining a single powerful and very white light, the
electric arc is substituted for a number of incandescent lamps, the length of the arc
and the movements of the carbons are by this Invention regulated in the following
manner. The carbons being vertical with the negative one which consumes more
slowly the lower: the upper one is attached to the core of a vertical solenoid
through the coil of which the lanp current passes and which is arranged to have
the greater lifting power with the stronger current. The lower carbon is held by
a cross-bar held up by cords passing over pulleys to counterweights proportioned
to give the lower carbon a tendency to move upwards. On the pulleys are fixed
ratchet or friction wheels and in connection with these wheels there are catches or
brake pieces which are moveable by the holder of the upper carbon. When the
current passing through the solenoid coil is of less than the proper strength the
upper carbon descends and at the same time releases the pulleys so that the lower
carbon rises to meet the upper carbon. This allowing a greater strength of current
to pass, the solenoid draws up the upper carbon and at the same time checks or
stops the pulleys.
An adjustable stop is fitted in connection with the upper carbon or solenoid so
that the raising action of the solenoid is limited to give the precise length of are
which is desiderated.
Under a modification of this lamp the upper carbon, instead of being attached
to the core of the solenoid, is attached to a cross-bar which forms the counterweight
of the lower carbon, and thus both the upper and lower carbons are moved by-
means of the motion of the core which works the pawl levers as in the arrangement
hereinbefore described, and instead of a single solenoid two solenoids may be
employed consisting one of thick and the other of thin wire.-The currents passing
through the thick wire solenoid acts on the core as described before drawing it up
and separating the carbons and allowing them also to come together when the
current becomes too feeble.-The thin wire solenoid is arranged as a shunt on the
outer solenoid and arc, and it receives a greater proportion of current in proportion
to the length of the are which separates the carbon points.-The current passes in
such a way in the thin wire solenoid as to partially neutralize the attractive power
of the thick wire solenoid and allows the weights to draw the upper and lower
carbons closer together. Thus when the are becomes too long the core of the
solenoid is allowed to fall.The pawls are drawn back and the pulleys allowed to
turn and the weights draw the carbons, together.-When the are becomes too short
the core is lifted. The pawls are caused to catch in the teeth of the ratchet wheel
and turning it backward a little, draw out the arc to be of the proper length.
The adjustable stop at top of the core prevents core from rising so high by
inertia or otherwise as to break the arc.
And in order that my said Invention may be properly understood I now proceed
more particularly to set forth the system, mode, or manner in or under which the
same is or may be used or practically carried into effect reference being had to
the accompanying Drawings and to the letters and figures marked thereon that
is to say:
Figure 1, Sheet 1, represents (in part section) a vacuum pump constructed
according to my Invention.
Figure 2, represents a view of an incandescent lamp in a preliminary stage of
construction.
Figure 3, represents a view of same in a more advanced stage.
Figure 4, represents (in part section) an arc lamp constructed according to my
Invention.
Figure 5, represents the same in side elevation.
Figures 6, and 7, represent a modified arrangement of the arc lamp.
The vacuum pump as represented in Figure 1, I construct with the moveable
tube A, provided at its upper end with a deep cup B, for a purpose hereinafter

page_text: more fully explained, and below this cup but not adjacent thereto and on the
outside of the tube A, I form the stop or check C. At the lower end of the
moveable tube A, is formed the bulb or enlargement D, within which is the valve E,
which is free to move vertically, and thereby to close at the proper times the upper
part of the bulb or enlargement D, (which forms a seat for the valve, E,) whose
upper end is ground to fit the same. Upon the sides of the valve E, are formed
the wings or feathers a, which keep the said valve E, in position, and allow of a
passage round its sides.-The moveable tube A, is fitted into a larger tube F, (which
I prefer to refer to hereinafter as the "body of the pump") which at its upper end
is formed with a deep cup G, the bottom of which is reduced to form a rest for the
hereinbefore-mentioned stop or check C.-Just below this stop or check C, and
opening into the body of the pump F, is attached the branch tube I, which is fitted
at its upper end with the valve and seating b.-At the lower end of the tube F, is
the tube c, of reduced diameter, communicating with a three-way cock d―This
cock d, also connects with the tube e, which is furnished at its upper end with a
funnel for affording greater convenience for pouring in the mercury. The third
way of the cock d is provided with a nozzle or pipe dipping into a vessel J, for
containing the mercury when it is run out of the pump.
When it is desired to produce a vacuum within a lamp bulb I insert the
capillary tube into the cup B, and through a washer at its lower part, having
previously slipped on to the capillary tube a similar washer.-I then fill the space
around this capillary tube with mercury and then press the upper washer into its
place, by these means making an air-tight joint. Then with the tube e, placed in
communication with the body of the pump F, by means of the three-way cock d,
the mercury is poured into the funnel-topped tube e, (by preference from a cistern
arranged for the purpose) until it rises up into the body of the pump F, thus
expelling the air through the branch tube 1, and around the valve b, at its upper
end. The cock d, is then turned, putting the body of the pump F, into communi-
cation with the vessel J, whereinto the mercury thus liberated flows, and so
forming by its fall a torricellian vacuum in the body of the pump F, and at the
same time exhausting to a certain extent the air in the lamp bulb. This operation
of filling and discharging the mercury may be repeated until the air in the lamp
bulb is considered sufficiently exhausted. The valve E, in the bulb D, of the
moveable tube A, by rising to its seat as the mercury rises in the pump, prevents
the mercury from passing up into the tube A, or into the lamp bulb.
In Figures 2, and 3, are shewn my improvements consisting in connecting the
platinum or other conducting wires a, a, of the lamp A', to the carbon filament b',
of the same. Over the ends of these conducting wires a', a', 1 slip tubes or helical
coils c', c', of very fine platinum wire and into these coils c', c', I pass the ends of
the carbon filaments b¹. By means of temporary connections represented by the
wires n', I then pass electric currents through the coils c', c', while the whole is
placed in an atmosphere of hydro-carbon gas, the current so passed through is
made sufficiently intense to bring the coils c', c', up to a white heat, which causes
carbon from the gas to be deposited on these coils cl, cl, and so to fill up all the
crevices or interstices between their several turns. In finishing off the lamp A', I
take the stem preferably down to the shoulder d', d', Figure 3, leaving the con-
ductors a, a, protruding and then sea! this stem into the bulb A', by a joint
around d, after which the bulb is exhausted and sealed.
In Figures 4, and 5, are shewn my improvements in are lamps in which the
length of the are and the movements of the carbons are regulated by means of the
lamp current passing through the solenoid a, as shewn, thereby acting magnetically
as is well understood upon the core c, which is connected to the cross-bar d.
This cross-bar d, carries at its ends the pawls c, e, and is at the same place
coupled to the pawl levers f, f, by pins n, n, which pass through holes in the cross-
bar d, pawls e, e, and pawl levers f, f, the latter being mounted at their outer ends
upon the axes g. g, which also carry the ratchet pulleys h, h. The upper carbon is
attached to the core c of the solenoid a; and the lower carbon D, is attached to the

page_text: carbon holder B, which is suspended by cords i, i, passing over the ratchet
pulleys h, h, and is kept in proper working position by the antifriction rollers k, l,
bearing against the upright bars of the framing j.
When the lamp is put into circuit the current passes through the solenoid a,
thence through the wire m, to the upper carbon C, and from this the current
passes across a space occupied by the are to the lower carbon D, which is not
insulated from its carrier, thence to the return wire E, through the metallic con-
nections formed by the rollers k, k; and the framingj. When the current passing
through the solenoid a is of less than the proper strength the solenoid core c,
descends and at the same time releases the pulleys h, k, so that the carrier B, and
the lower carbon D, rise while at the same time the upper carbon descends. This
shortens the arc and allows a greater quantity of current to pass; the solenoid
then draws up the core c, and thus checks the pulleys h, h. An adjustable screw
stop, is fitted at the upper end of the solenoid a, so that the raising action of the
core is limited to give the precise length of the are described.
Figures G, and 7, shew in detail a modification of the arrangement herein last
described by means of which the objects herein before described are accomplished
The parts of the lamp shewn in Figures 6, and 7, correspond with those shewn in
Figures 4, and 5, and corresponding letters are used in both cases but affixes are
attached to the letters in Figures 6, and 7. The modification consists in attaching
the upper carbon C³, to the cross bar A instead of attaching it to the core of the
solenoid. The cross-bar A2, with the upper carbon C, forms a counterweight to
the cross-bar B2, and the lower carbon D²; _and_both_carbons.tend_to_move-towards-
each other by the superior weight of the bar A2, and the upper carbon. When
the current passes the solenoid a², draws back the solenoid core c, which is
attached to the cross-bar d³, and the pawl levers f; and the cross-bar ², being
drawn upward, the ratchet wheels are worked in such a manner as to separate
the carbon points and form an arc. When the arc becomes too long the strength
of the current passing in the solenoid coil a² becomes too feeble and the core c³ is
allowed to fall a little. This liberates the ratchet wheels 2, and permits the
carbons to approach each other; and by this action the proper length of arc is
maintained. And in order to make the action of the solenoid coil more sure a
second solenoid 62, is used and placed within the solenoid a² and it is so arranged
as to be opposite to the solenoid a², in its action on the core c²; and it is connected
so as to form a shunt on the solenoid a², and on the arc. As the arc becomes larger
the resistance in the arc circuit becomes greater and the proportion of current
passing through the solenoid 62, is correspondingly increased. The solenoid b²,
acting against the solenoid a², neutralises more or less the attractive power of the
solenoid a³, and the core c², is the more readily allowed to fall so as to shorten the
are to the proper extent.
Having now described and particularly ascertained the nature of my said
Invention, and the system, mode, or manner, in or under which the same is or
may be carried into effect, I wish it to be understood that I do not claim as new
all the parts of the improved vacuum pump herein before described and shewn on
the annexed Drawings, but what I consider to be novel and original and
therefore claim as the Invention secured to me by the hereinbefore in part recited
Letters Patent is :-
First In the vacuum pump herein before described the branch I, with its
valve b, the cup G, for the mercury seal, the three-way cock d, and the fixed
mercury supply tube e, all as, and for the purposes hereinbefore described with
reference to Figure 1, of the accompanying Drawings.
Second-The means of making the connection between the platinum conducting
wires and carbon filament of an incandescent lamp and the filling up of the
interstices of the said joint by depositing carbon therein from a hydro-carbon gas
when the said joints are heated by a temporary current of electricity being passed
therethrough substantially as herein before described with reference to Figures 2,
and 3, of the accompanying Drawings.

page_text: Third The arc lamps herein before described and shewn at Figures 4, 5, 6, and 7
of the accompanying Drawings wherein the distance apart of the carbons is
regulated by the action of a solenoid or solenoids upon a core operating through
pawls and pawl levers, ratchet pulleys over which the carbon holders are suspended
by cords, substantially as herein before described.
In witness whereof, I the said Rankin Kennedy have hereunto set my hand
and seal this First day of July in the year of our Lord, One thousand
eight hundred and eighty two.
RANKIN KENNEDY. (L.S.)