IMPROVEMENTS IN ELECTRIC LAMPS AND APPARATUS CONNECTED THEREWITH, WHICH
Year: 1881

page_text: LETTERS PATENT to John Hopkinson, of Westminster Chambers, in the
County of Middlesex, F.R.S., for an Invention of "IMPROVEMENTS IN
ELECTRIC LAMPS AND APPARATUS CONNECTED THEREWITH, PART OF WHICH
PROVISIONAL SPECIFICATION left by the said John Hopkinson at the
Office of the Commissioners of Patents on the 3rd August 1881.
"
JOHN HOPKINSON, of Westminster Chambers, in the County of Middlesex,
F.R.S. IMPROVEMENTS IN ELECTRIC LAMPS AND APPARATUS CONNECTED
THEREWITH, PART OR WHICH IMPROVEMENTS IS ALSO APPLICABLE TO OTHER
ELECTRICAL PURPOSES."
My Invention relating to electric lamps has reference partly to the mode of
Pegulating the distance between the carbons.
In carrying out my Invention, one of the carbons is carried from the armature
of an electro-magnet, not rigidly but in part, by means of a catch which can be
liberated when the are becomes too long, either by the action of the aforementioned
armature which also starts the arc, or by the action of a special armature of another
electro-magnet arranged expressly for the purpose. The carbon holder is also
connected to the armature by means of fluid in a suitable receptacle in such wise
that the relative motion of the carbon and armature is controlled and restrained by
the viscosity of the fluid. The electro-magnet or magnets may be wound with
thick wire to carry the whole current, or with thin wire arranged as a shunt, or
they may be wound differentially; or when the electro-magnet is wound with thick
wire a thin shunt wire may be placed on the armature. Various forms of catch
may be used, but I prefer one in the form of a bent weighted lever, the shorter
arm of which presses against the carbon holder, and the longer of which is moved
when the carbon or carbons are to be advanced. The mode of introducing the
fluid friction between the armature and carbon holder may also be varied, but the
simplest is to carry the carbon on a tube on which the catch acts, this tube contains
a fluid and a piston or plunger connected to the armature.

page_text: In some cases the piston or plunger is a fixture instead of being connected to
the armature. I introduce a valve into the piston to enable the carbon holder to
be more rapidly raised. When it is desired to keep the position of the arc fixed,
the carbon holder, operated as above described, is connected by a cord or chain, or
by other suitable connection to the other carbon holder. When an alternate
current is used I control the current by introducing into the circuit self induction
coils, which limit the quantity of current without wasting much energy as a
resistance does. These may be of various forms, but a good form may be made by
winding hoop iron or wire into the form of an annulus, insulating when needful
the layers of iron or the wires from each other, and winding successive coils round
the annulus; the coils may be connected by terminals as in a resistance box at the
pleasure of the user of the instrument. Self induction coils so made may be
usefully employed for other purposes besides electric lighting.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Hopkinson in the Great Seal Patent Office on the 3rd
February 1882.
JOHN HOPKINSON, of Westminster Chambers, in the County of Middlesex,
F.R.S. "IMPROVEMENTS IN ELECTRIC LAMPS AND APPARATUS CONNECTED
THEREWITH, PART OF WHICH IMPROVEMENTS IS ALSO APPLICABLE TO
ELECTRICAL PURPOSES."
OTHER
My said Invention relating to electric lamps has reference to the mode of
regulating the distance between the carbons.
In carrying out my said Invention one of, the carbons is carried from the
armature of an electro magnet or from the framing of the lamp, not rigidly but in
part, by means of a catch which when the arc becomes too long is liberated either
by the action of the before mentioned armature, which also starts the arc, or by
the action of a special armature of another electro magnet arranged expressly for
the purpose. The carbon holder is also connected to the armature or to a part
attached to the framing of the lamp by means of fluid in a suitable receptacle in
such manner that the relative motion of the carbon is controlled and restrained by
the viscosity of the fluid.
According to another part of my Invention when an alternate current is used
I control the current by introducing into the circuit adjustable self induction coils,
which limit the quantity of current without wasting as much energy as is wasted
by a resistance.
And in order that my said Invention may be fully understood, I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 of the accompanying Drawings represents in elevation, partly in section,
an electric lamp constructed or arranged according to my Invention. Figure 2 is
a section (drawn to a larger scale, of the lower part of the tubes and holder
carrying the upper carbon. The framing a of the lamp carries the electro
magnet b, b, the armature 62 of which has fixed to it the tube c closed at top by
the perforated cap c which carries a rod d passing through the said tube, and
carrying at its lower end a fixed piston formed of the disc g and short tube g³.
Within the tube c is another tube e capable of ascending and descending freely in
the said tube c, there being a small annular space e between the interior of the
tube e and the exterior of the piston g and tube g². The tube e contains fluid, its
bottom end being closed and carrying the holder e containing the upper carbon e*.
Hinged or pivotted at f* to the armatures 6 is a bent catch lever f, the end of the
shorter arm of which lever presses against the tube e when the armature b² is
attracted by the magnet b, the longer arm of the said lever being counterweighted
to give this pressure; f³ is an adjustable screw stop on which the longer arm of
the lever rests when the armature 62 is not attracted by the said magnet b. The
lower carbon is or may be supported in the lamp framing in the ordinary
manner; a², a³, are the screws by which the circuit wires are fastened to the lamp
casing, the current entering at a and thence passing through the coils of the
magnet b, and thence through the carbons, as indicated by the arrows.
A light
spring 6 tends to press the armature 6 away from the magnet b. The action is as
follows: When the current passes the cores of the electro magnet b attract the
armature b, which rises rapidly, lifting with it the tube c and piston and tube
9, 9³,
and also the tube e, which is then held in position by the short end of the lever f
bearing there-against. As the carbons burn away and the current is reduced the

page_text: armature b falls a little, and the long arm of the catch lever f coming into contact
with the stop fs, the tube e is released from the retaining pressure of the other end
of the said catch lever f, so that the said tube e begins to descend relatively to the
armature 6, its descent being retarded by the friction of the fluid in the tube e, for
the descent will take place only as rapidly as the said fluid can pass from the one
side of the piston g through the space e to the other side of the said piston.
Through the plunger g an opening or openings is or are made from its lower to
its upper side covered by leather or other valves opening upwards, so that the
upper carbon holder may be readily raised for the purpose of introducing a new
carbon.
The electro magnet may be wound with thick wire, as shewn, to carry the whole
current, or with thin wire arranged as a shunt, or it may be wound differentially,
or when the electro magnet by which the arc is struck is wound with thick wire a
thin shunt wire may be employed to actuate the armature for releasing the upper
carbon holder, and the piston (g) may be a fixture instead of being attached to and
moveable with the armature. Figure 3 is an elevation, partly in section, of a lamp
constructed according to this modification. The tube c, rod d, and piston g, g³, and
the carbon holder es are relatively arranged as herein before described with regard
to Figure 1, but the outer tube c is carried by the framing a instead of by the
armature 62, as in the said arrangement, Figure 1. The lever f carries an
armature which is attracted by the electro magnet i wound as a shunt to the
electric arc, the attraction being opposed by a spring . The holder of the lower
carbon his carried by the armature k of the electro magnet k. The carbon passing
through a tube fixed to the armature and sliding in another tube fixed to the
framing of the lamp. The lower part of the tube is screwed, and upon the screw
runs a screw nut ke by which the distance to which the armature can ascend is
regulated. The collar 7 is adjustable on the tube 5, and can be fixed by the
clamping screw which it carries in order to regulate the tension of the spring k³,
the said spring ³ tending to raise the armature ³ from the magnet k. This
armature and magnet k are for striking the arc by moving the lower carbon,
the controlling of the feed being performed by the electro magnet i and armature f¹.
In some cases I find it advantageous to automatically break the circuit of the
electro magnet i so soon as the armature f' on the lever f rises and releases the
tube e.
In the Drawing the course of the main current is indicated by the full arrows,
and the course through the fine shunt wire is indicated by the dotted arrows.
In Figures 1 and 3, a represent rings and washers of insulating material to
keep the current to its course, and 6', in Figure 1, and is, k³, in Figure 3, represent
studs to prevent the armatures from coming too near these agents.
When it is desired to keep the position of the are fixed, the carbon holder
operated as above described is connected by a cord or chain, or by other suitable
connection to the other carbon holder to cause that carbon also to be moved.
The tube c or e is or may be provided with suitable bearing pieces to preserve
the parallelism of the said tubes to each other.
For the purpose of controlling or varying the current from an alternate current
dynamo electric machine used for obtaining current for electric lighting, when
there are several lamps (either arc lamps or incandescent lamps) worked from the
same machine in divided circuit, then for the purpose of controlling and adjusting
the current in the several divisions of the circuit according to my Invention, I
introduce as part of the circuit (or when the circuit is divided as part of one or
more divisions of the circuit) a coil of wire arranged so as to have a considerable
co-efficient of self induction, and so arranged that this co-efficient may be varied.
By this means I am able to vary the current passing through a lamp without
interfering with the machine, or if it be an arc lamp without altering the length
of the arc, and also without wasting energy by introducing a considerable additional
resistance. I am also able to divide the current and burn arc lamps in parallel
circuit. The adjustable self induction coil employed in carrying my Invention into

page_text: effect may be of various forms. The following I find well suited to the purpose:-
Figure 4 is a perspective view of one form of coil. A ribbon of thin sheet iron is
coiled into the form of an annulus 1, there being preferably a layer of insulating
material between the overlapping portions or layers of the said annulus. Round
the said annulus coils of covered copper wire m, m, are wound. These several
adjacent coils m are connected at their adjacent ends with plates, into which
contact plugs connected with the main wires can be inserted for throwing one or
more of the said coils into or out of the electric circuit. As these appliances are
well known and used in ordinary resistance boxes, I do not consider it necessary
to describe or illustrate them.
The co-efficient of self induction will approximately vary as the square of the
number of convolutions of copper wire through which the current is caused to pass.
In order to facilitate the placing of the coils of copper wire upon the annulus a, it
is convenient, after well securing the layers of the said annulus, to cut it in halves,
as at 1, After the copper coils m, m, have been put in place upon the said
annulus it is only necessary to bring the two halves of the said annulus into
contact, in the position in which they were before division. Instead of an annulus
of sheet iron, iron wire may be used, wound after the manner employed in the
construction of the armature of the "Gramme machine." If it is desired that the
co-efficients of self induction should approximately increase by equal steps, as
1, 2, 3, 4, and so on, as successive coils are thrown into circuit, the number of
convolutions in these coils should not be equal, but should be in the ratios
1, 21, 3-2, and so on.
This form or construction of self induction coil is applicable for use for con-
trolling or varying alternate currents for purposes other than for electric lighting.
Another form of adjustable self induction coil is shewn in Figure 5.
n is the
horse shoe core of an electro magnet formed of layers of sheet iron preferably
insulated from each other; p, p, are the coils of copper wire, through which the
alternating current passes; q is an armature for the electro magnet, also formed of
layers of sheet iron preferably insulated from each other. The electro magnet n
can be thrust into or withdrawn from the coils p, and clamped or otherwise fixed
in any desired position by the clamp r. When the electro magnet n is drawn
from the coils p and is at a distance from its armature q, the co-efficient of self
induction is small, and as it is thrust in and approaches the armature the said
co-efficient increases. If the instrument be introduced into the circuit of an
electric lamp the current through that lamp is diminished as the electro magnet n
is thrust into the coils p. Figure 6 is a diagram shewing a dynamo electric
machine S arranged to give a current for lighting a number of incandescent lamps t.
Into the circuit of the current of the said machine I introduce the adjustable self
induction coil X. When all the lights are required the co-efficient of self induction
is reduced to a minimum either by short circuiting the coils, if the form of coil,
Figure 4, be used, or by drawing out the magnet, if the arrangement, Figure 5, be
used. When it is desired to burn fewer lamps it is only necessary to increase to
co-efficient of self induction by causing the current to pass through a greater
number of the coils if the arrangement, Figure 4, be used, or by thrusting inwards
the magnet if the arrangement, Figure 5, be used.
Figure 7 is a diagram representing a number of arc lamps burning in parallel or
divided circuit. S represents the dynamo machine, and t the lamps. In the
branch circuit of each lamp is introduced a self induction coil X, which coils,
firstly, by their presence enable the lamps to burn in parallel circuit; and, secondly,
by adjustment enable a variable division of current to be made between the
lamps.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that I lay no claim to the bent catch lever f
illustrated in Figures 1, 2, and 3 for holding the upper carbon in position, nor to
the use of fluid friction for retarding the descent of the upper carbon holder, nor

page_text: to the other parts of the apparatus herein before described and illustrated alone,
and in themselves otherwise than as hereinafter stated, neither do I limit myself
to the precise details herein described and illustrated, as the same may be varied
without departing from the nature of my Invention, but what I consider to be
novel and original, and therefore claim as the Invention secured to me by the
herein before in part recited Letters Patent is,-
First. The combination of parts constituting the electric lamps hereinbefore
described and illustrated in Figures 1, 2, and 3 of the accompanying Drawings, the
essential feature of which is the combination of the means for utilizing fluid
friction for retarding the feeding of the carbon or carbons without retarding the
motion of the armature which parts the carbons in striking the arc with the bent
catch lever farranged and operating as hereinbefore described.
Second. The use in electric lighting for controlling or varying the current or
division or divisions of the current of an adjustable self induction coil or coils in
combination with an alternate current dynamo electric machine, substantially as
herein before described with reference to Figures 4 to 7 of the accompanying
Drawings.
Third. The adjustable self induction coil constructed or arranged substantially
as hereinbefore described with reference to Figures 4 and 5 of the accompanying
Drawings for use in controlling or varying alternate electric currents for electric
lighting or other purposes.
In witness whereof, I, the said John Hopkinson, have to this my Specification
set my hand and seal, this First day of February, One thousand eight
hundred and eighty two.