Improvements in Electric Arc Lamps.
Year: 1896

page_text: Date of Application, 10th Jan., 1896
Complete Specification Left 10th Oct. 1898 Accented 2nd Jan
1897
Date of Application, 10th Jan., 1896
Complete Specification Left 10th Oct 1898 Accented 2nd Jan
1897
Improvements in Electric Arc Lamps.
We, JOHN ISAAC THORNY CROFT, of Eyot Villa, The Mall, Chiswick, in the
County of Middlesex, F.R.S. and JOHN EDWARD THORNYCROFT, of the same
address, Engineer, do hereby declare the nature of this invention to be as
follows:-
According to this invention the carbon holder or holders is or are held and
controlled by a gripping device comprising the cores suitably pivoted or mounted
so as to be able to oscillate of a couple of solenoids which are oppositely excited so
that appropriately shaped grippers formed with or carried by the cores attract one
another and grip more or less according to the strength of current for the time
heing a rod, tape or other part located between them and formed with or counected
to the carbon holder or holders. The one carbon holder may be fixed the other
having a rod or stem that passes between the grippers. The arrangement is such
that upon starting the lamp-the carbons being in contact-the cores become
magnetised, so that the grippers attract one another and clamp the rod, tape or
other part between them, and by the sucking action of the solenoids, are raised
thus lifting the upper carbon and striking the arc. When the normal length of
arc is exceeded the consequent reduction in the sucking and magnetising action of
the solenoids will have the effect of allowing the upper carbon to descend, and
when the arc is of less than normal length, the consequent increase in the sucking
and magnetizing action of the solenoids will have the effect of lengthening the
arc. A dash-pot is provided as usual to control the motion of the movable carbon
or carbons.
Where the arc is to be automatically focussed, the part which is attached to the
upper carbon holder may be a rod a wire, a tape or equivalent and if not itself
flexible then may have attached to it a flexible connection passing over a suitable
pulley and connected directly or through a rod and cross piece or carrier to the.
lower carbon holder.
The grippers may be partly lined with suitable material, for example leather, to
increase their hold on the part they have to grip.
Arc lamps in accordance with this invention can be variously constructed.
In one arrangement the solenoids are arranged vertically side by side, their
cores being jointed to the piston of a dash pot arranged below them. This dash
pot may contain a suitable liquid or air and the piston may be provided with lift
valves to allow it to descend rapidly. The gripping portions of the core may be
provided with leather to enable them the better to grip the part they have to hold.
Each core is of approximately L-shape in side view, its lower portion being of
bifurcated form and connected as by a screw to an extension by which it is jointed
to a web on the piston of the dash-pot. The extension may be separate from the
core and be of non-magnetic material, and carry a block of leather, india-rubber or
equivalent material to act as the bearing surface against the red or other part to be
gripped. The extensions of the two cores may be connected together by a springs
that are in compression and tend to move the grippers apart. The top end of the
rod or part that carries the upper carbon holder is connected to the piston (with
inverted cup leather) of an upper dash pot.

page_text: The lower carbon holder . is connected by a ball and socket joint to the lower
portion of the frame of the lamp.
In another arrangement which is self-focussing the solenoids cores are suspended
to a pair of rods of non-magnetic material that are jointed to a carrier arranged to
slide on a suitable guide. The upper part of the guide is adjustable as a nut on a
screw and carried by a plate attached to the top of the solenoid. The grippers are
adapted to grip a wire or tape that is connected at one end to the upper carbon
holder, is led over a pulley, and thence passes down within a hollow side rod of the
lamp frame where it is connected to a guide rod attached to one end of the lower
carbon carrier which works through a slot in the said side rod, and has its other
end suitably formed to be guided by the other side rod. To this carbon carrier
the corresponding carbon holder is attached, it may be by a ball and socket joint.
The solenoid and adjacent parts are enclosed in a casing which may be provided
with insulating binding screws the plain lower ends of which when the casing is
placed in position for use enter slit sockets connected with the terminals of the
solenoids which are in series with the carbons. The lamp is suspended by a
loop-shaped support jointed to the lamp frame.
The above described arrangement of casing, binding screws and sockets may be
used in other forms of lamps. In lamps according to this invention the solenoi Is
may be differentially wound so that the lamp may be adapted for series as well as
parallel working.
We, JOHN ISAAC THORNYCROFT, of Eyot Villa, The Mall, Chiswick, in the
County of Middlesex, F.R.S., and JOHN EDWARD THORNYCROFT, of the same
address, Engineer, 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 :-
In an arc lamp according to this invention, the carbon holder or holders is or are
held and controlled by a gripping device comprising the cores, suitably pivoted or
mounted so as to be able to oscillate, of a couple of solenoids which are oppositely
excited so that appropriately shaped grippers formed with or carried by the cores
will attract one another and grip more or less, according to the strength of current
for the time being, a rod, tape or other part located between them and formed with
or connected to the carbon holder or holders. The one carbon holder may be
fixed, the other having a rod or stem that passes between the grippers. The
arrangement is such that upon starting the lamp-the carbons being in contact-
the cores become magnetized, so that the grippers attraet one another and clamp
the rod, tape or other part between them, and by the sucking action of the
solenoids, are raised, thus lifting the upper carbon and striking the arc. When
the normal length of arc is exceeded, the consequent reduction in the sucking and
magnetizing action of the solenoids will have the effect of allowing the upper
carbon to descend, and when the arc is of less than normal length, the consequent
increase in the sucking and magnetizing action of the solenoids will have the effect
of lengthening the arc. A dash-ot is provided as usual to control the motion of
the movable carbon or carbons.

page_text: Where the arc to be automatically focussed, the part which is attached to the
upper carbon holder may be a rod, a wire, a tape or equivalent, and if not itself
flexible, then may have attached to it a flexible connection passing over a suitable
pulley and connected directly or through a rod and cross piece or carrier to the
lower carbon holder.
The grippers may be partly lined with suitable material, for example leather,
to increase thier hold on the part they have to grip.
Arc lamps in accordance with this invention can be variously constructed.
Fig. 1 of the accompanying drawings, is a side elevation, partly in section,.
illustrating one construction of arc lamp according to this invention, the upper
casing being removed.
Fig. 2 is a vertical section of the upper portion of the lamp, the section being.
in a plane at right angles to Fig. 1.
Figs. 3 and 4 are horizontal sections on the lines x x and y y respectively of
Fig. 2.
and
Fig. 5 is a plan of the piston of the lower dash-pot shown in Figs. 1 and 2 ;:
Fig. 6 is a vertical section thereof on the line 2, z of Fig. 5.
1, 1 are two solenoids arranged vertically side by side, and provided with loosely
fitting cores 2. Each core, which is of iron, is of approximately L-shape in side
view, its lower portion or gripper 2ª being of bifurcated form and connected, as by
screws 3, to an extension 4 of non-magnetic material by which it is jointed to a
web 5 on the piston 6 of a dash-pot 7. This dash-pot may contain a suitable
liquid, such as glycerine, or merely air, and the piston 6 may be provided with lift
valves 6 (Figs. 5 and 6) to allow it to descend rapidly. Each gripper 2 may, as
shown, have a block 8 of leather, india-rubber, or equivalent material clamped.
between it and the corresponding extension to enable it the better to engage the
rod 9 which forms an extension of the upper carbon holder 10. This rod works.
through a central guide tube 7 carried by the dash-pot 7. The extensions 4 of the
two cores may, as shown, be connected together by springs 11 that are in
compression and tend to move the grippers 2ª apart against the force of magnetic:
attraction, which draws them together. The top end of the rod 9 is connected by.
a rod 9" to the piston 12 (with inverted cup leather 12") of an upper dash pot 13.
which is carried by the top part 14 of the lamp frame 14. The lower carbon.
holder 15 is connected by a ball and socket joint 15 too the lower portion of the
lamp frame.
Figs. 7 and 8 are similar views to Figs. 1 and 2 respectively, showing a modified
construction of arc lamp according to this invention, and Fig. 9 is a plan thereof,
the casing being removed.
In this arrangement, which is of self-focussing type, the solenoid cores 2 are
suspended from a pair of rods 16 that may be of non-magnetic material and are
jointed to a carrier 17, 17 arranged to slide on a fixed guide 18". This guide,.
which is in the form of a stem, extends upward centrally from the bottom of a dash
pot 18, that is attached to the top of the solenoids 1 and in which works a
piston 17 carried by the lower end of the part 17 of the carrier. The piston may
be provided with lift valves 17 and the dash pot be charged with liquid or air as
in Figs. 5 and 6. The upper part 17. of the carrier is adjustable as a nut on the
lower part 17 to enable the position of the cores 2 relatively to the solenoids 1 to
be adjusted, the said parts 17, 17" being adapted to be locked in their adjusted
positions by a nut 17. The grippers 2 are adapted to grip a wire or tape 10*
that is connected at one end to the upper carbon holder 10, is led over a pulley 20,
and thence passes down within a hollow side rod 14+ of the lamp frame 14, where-
it is connected to a guide rod 21 attached to one end of the lower carbon
carrier 22 which works through a vertical slot in the said side rod and has its other
end slotted or otherwise suitably formed to be guided by the opposite side rod..
To this carbon carrier the corresponding carbon holder 15 is attached, it may be
by a ball and socket joint 15° as shown.

page_text: The solenoid and adjacent parts can conveniently be enclosed in a casing 14
which may, as shown, be provided with insulated binding screws 23 having plain.
lower ends 23 which, when the casing is placed in position for use, enter and
tightly fit slit sockets 24 connected with the terminals of the solenoids 1 which are.
in series with the carbons. The lamp is suspended by a loop-shaped support 25
jointed at 25 to the lamp frame 14.
In lamps according to this invention the solenoids 1 may be differentially wound
so that the lamp may be adapted for series as well as parallel working, as well
understood.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we'
claim is :-
1. An electric are lamp in which the carbon holder or holders is or are held and
controlled by a magnetic gripping device comprising the cores, suitably pivoted or
mounted so as to be able to oscillate and reciprocate, of a couple of solenoids
which are oppositely excited, so that appropriately shaped grippers formed with or
carried by the cores will, upon starting the lamp (the carbons being in contact)
attract one another and clamp between them a rod, tape, or other part connected
to the carbon holder or holders, and by the sucking action of the solenoids will be
raised, thus striking the arc, and variation in the length of the arc above or below
the normal length will respectively reduce or increase the sucking and magnetizing
action of the solenoids, and consequently the magnetic attraction between the
grippers, whereby the carbons will be either allowed to move towards each other
by gravity, or be moved apart by the grippers, so that an arc of practically
constant length will be maintained substantially as described.
2. An electric arc lamp of the kind referred to in Claim 1, in which the grippers
are carried by approximately L shaped cores having non-magnetic extensions
jointed to the piston of a dash pot, and springs are arranged in compression between
the grippers, the arrangement being such that the grippers can move in a direction
towards or from each other and so vary their hold on the part connected with the
carbon holder or holders in accordance with variations in the magnetizing action
of the solenoids due to variations in the length of the arc, substantially as
described.
3. An electric arc lamp of the kind referred to in Claim I in which both carbon
holders are movable and are connected by a flexible connection that passes over a
guide pulley and is engaged by a pair of magnetic cores and grippers carried by
rods jointed to a vertically sliding carrier, substantially as described.
4. The improved electric arc lamps constructed, arranged and operating sub-
stantially as hereinabove described with reference respectively to and shown in
Figs. 1 to 4 inclusive and in Figs. 7 and 8 of the drawings annexed.
Dated this 10th day of October 1896.
Dated this 10th day of October 1896.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.