Year: 1898

page_text: I, GEORGE THOMAS-DAVIES, Engineer, of 53 Primrose Mansions, Battersea Park,
in the County of London, do hereby declare the nature of this invention, to be as
follows:-
This invention for improvements in enclosed arc lamps consists in mounting the
two carbons side by side in an enclosed chamber and in transmitting the power
required to control the are through the walls of the chamber by electric or magnetic
means, instead of mechanically, so that no gland or similar moving joint is required
in the walls of the enclosing chamber. By this means an absolutely air tight
chamber obtained practically enclosing only the carbons and their holders.
In one way of carrying out this invention one carbon holder is pivoted to a
suitable support withing the chamber and an armature rigidly connected to this holder
vibrates within the chamber in the field of an electro-magnet or solenoid situated
outside the chamber.
In another arrangement the pole or poles of the electromagnet regulating the arc
pass through the wall of the enclosing chamber and the resulting field acts on an
armature or armatures attached to the pivoted carbon holder or holders or directly on
the carbon or carbons.
The advantage of this perfectly closed chamber can be also obtained mechanically,
the necessary motion for controlling the are from the controlling mechanism situated
outside the enclose chamber being transmitted to the carbon bolders by a spindle
adapted to oscillate on a hearing in the wall of the enclosing chamber. The oscillating
spindle convers the motion with a minimum of friction and leakage of air.
This invention also consists in providing from the poles of a magnet or iron cored
solenoid having its exciting coils in such position that there is a minimum obstruction
of light, a magnetic field, at right angles to the plane containing the carbons, for
the are to burn in and such that the arc is forced towards the end of the carbons; and
in providing a similar but more intense field near the butts or holders so that the
arc when it reaches this position is so repelled as to die away or burn out. By
providing the magnetic field from an iron mass and placing the exciting coil away,
the iron mass necessary to conduct the field where it is required being of a compara-
tively small bulk does not materially obstruct the light.
Date : 01
1000
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.

page_text: I, GEORGE THOMAS-DAVIES, Engineer, of 53, Primrose Mansions, Battersea Park,
in the County of London, 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 :-
This invention for improvements in enclosed are lamps has for its object to enclose
the carbons and their holders in an air tight chamber and to transmit the power
required to control the arc through the walls of the enclosed chamber either by means
of a trunnion bearing, or by magnetic means, so that practically the carbons and their
holders alone are enclosed in the air tight chamber; and consists in an enclosed
chamber, two carbon holders situated within the chamber side by side, carbons fixed
in the holders, a trunnion connected to one holder, a bearing supporting the trunnion,
and a means for giving the trunnion an oscillatory movement to control the arc
according to the resistance of the are. It will readily be understood that one carbon
may be fixed or that both carbons may be controlled, and that the two side by side
carbons may be parallel or inclined to one another.
This invention also has for its object to provide a uniform magnetic field at right
angles to the common plane of the carbons for the are to burn in to force the arc
towards the end of the carbons remote from their holders and such that that there shall
be a minimum obstruction of the light; and consists in a magnet or solenoid situated
so as not to obstruct the light, and of extended pole pieces of the magnet or
solenoid, arranged side by side with the carbons but having their common plane at
right angles to the common plane of the carbons. This magnetic field may be made
more intense near the butts or holders of the carbons so that the are when it reaches
this position is so repelled as to die away or burn out.
In the accompanying drawings :-
Figs. 1 and 2 are elevations at right angles to one another and Fig. 3 is a plan of
one form of enclosed are lamp constructed according to this invention one carbou
holder only being movable and the motion being conveyed into the enclosed
chamber by an oscillating spindle at right angles to the carbons, the drawings
showing a differentially wound lamp.
Fig. 4 is a plan of the carbon holders.
Figs. 5 and 6 are elevations of a modified form of enclosed arc lamp constructed
according to this invention both carbon holders being movable and the motion being
conveyed into the enclosing chamber by two oscillating spindles at right angles to the
carbons, the drawings showing a shunt wound lamp.
Figs. 7 and 8 are elevation and plan respectively of a further modification of
enclosed arc lamp constructed according to this invention, one carbon holder being
movable and the motion being conveyed into the enclosing chamber by an oscillating
spindle parallel to the carbons, the drawing showing a shunt controlled lamp.
Figs. 9 and 10 are elevations at right angles to one another, and Fig. 11 is a plan
from below of a further modification of enclosed arc lamp constructed according to
this invention, the controlling motion being conveyed into the enclosing casing by
magnetic means.
Referring to Figs. 1, 2 and 3, the lamp frame comprises the crown plate a, the
pillars 6 and the dome or cover ċ insulated from the pillars b. The dome or cover c
is perforated and is protected by a second cover c¹. The leads or conductors pass
in through the centre. The lamp case m is insulated from the crown plate a by the
porcelain discs m¹ that prevent the case coming into contact with the crown plate.
The glass bell d is provided at its upper end with a flange d¹ and is secured to the
coned bush d by a screw cap d³. The coned bush ď² fits on a conical extension a¹ of

page_text: the crown plate a and is drawn up against the extension a' by the hooks d' that pass
round the lugs d³ and are drawn upwards by the springs do bearing against the crown
plate a. It will readily he seen that the conical extension a¹, bush d² and spring
hooks d form a valve that will allow any excess pressure with the hell d to escape
but that effectually prevents any ingress of fresh air.
One carbon holder.e is fixed to the crown plate a but is insulated therefrom and
depends into the glass bell d. The other carbon holder f is fixed on a spindle fi
mounted in bearings in the inverted cup a², the holder f being within the cup and
depending through an opening in the crown plate a into the bell d. The cup a² has
a flange at its lower end and is secured in an air tight manner to the crown plate a
hy the screws a³ but is insulated therefrom. The spindle f¹ extends through the
walls of the cup a² to the outside, and has fixed on its ends two levers f f provided
respectively with the adjustable counterbalance weights ff. The weight counter-
balances the system and the weight forms the working weight to adjust the
lamp.
At their other ends the levers f2 f³ carry the cores g¹ h¹ of the series and shunt
solenoids g h. The lever of the shunt solenoid is extended upwards and is pivoted
to but insulated from the cylinder i of the clash pot whose piston i¹ is fixed by means
of the piston rod 22 pivoted in the bracket 62 fixed on the plate b¹ supported by the
pillars b. The weight of the piston and of the cylinder is counterbalanced by the
weight attached to the piston rod 22. The solenoids g h are fixed to the frame
plate supported by the pillars b. The cores g¹ h¹ are provided with extensions or
ears g² h² to cause the magnetic fields to take paths in which they will not unduly
interfere with each other.
The magnet for providing the directing magnetic field for the arc is of horse shoe
shape excited by a coil wound on the bend of the magnet and its two legs 12 passing
tightly through holes in the crown plate a and extending down into the bell beyond
the extreme ends of the carbons. The legs are tapered as shown in Fig. 6, so as to
give an approximately uniform field over the space the arc may occupy. The crown
plate a is formed with a slit or opening at between the legs 12 to prevent eddy
currents, the slit being filled with insulating material. Horns or wings 13 are fixed
to legs shortly below the carbon holders so as to produce by reason of the com-
paratively short air gap at this point an intense magnetic field to prevent the arc
burning higher and so damaging the holders. The adjustable screws as a limit the
motion of the carbon holder, the screw a preventing the carbons again coming into
contact when they have burnt to within the assigned limit so that after the are has
been blown out by the wings 13 the lamp cannot restrike the arc.
The current entering the lamp at + passes into the inverted cup a², the holder f,
the carbons, the carbon holder e through the coil of the deflecting magnet 1, the
series controlling coil g and out of the lamp at The shunt coil is connected in
across the carbons.
The action of the lamp is as follows:
Normally the carbons in a differentially wound lamp may be in contact and on
current being applied to the lamp, the current passes through the series eoil g and
the carbons. The core g¹ of the series coil g is drawn inwards and thus separates the
carbons striking the arc. The dash pot i prevents a violent or too rapid a separation
of the carbons. The shunt solenoid h acts in the well known manner to maintain the
power absorbed by the arc constant.
The current passes through the coils of the deflecting magnet as shown so that
the polarity of the legs 12 corresponds to the direction of the current through the arc,
the field induced between the pairs of carbons being in the same direction as the field
induced by the current through the carbons.
When the carbons have consumed and the arc has reached its safe upper limit, the
strong magnetic field produced by the wings 13 prevents the arc from burning higher
and it blows out, the screw a preventing the carbons from again coming into
contact.
In the modification shown in Figs. 5 and 6 the glass bell d is secured in the cap d³

page_text: by a hollow nut d and the cap d³ screws on to the crown plate a. A projection a on
the crown plate fits in a recess d³ in the nut d and secures the alignment of the parts.
An elastic washer do is fitted in the recess d³.
The carbon holders fare fixed on spindles f¹ mounted in bearings in the inverted
cups a², the holders being within the cup and depending through openings in the
crown plate a into the bell. The top of each cup is perforated and covered by a valve
plate a pressed down on the top by the helical springs a. The spindles fl extend
outside the cups a² and arms fe on the outer ends of the spindles are connected by
insulating adjustable links with the inverted cylinder i of a dash pot having a
piston fixed by the cross bar 63 to the pillars b. The core h¹ of the regulating
solenoid h is provided with brass extensions h² that rest on the top of the cylinder i.
Adjustable springs p secured to the top plate 64 counterbalance the weight of the
core h¹ and cylinder i.
1
The current enters the lamp at + and passes to the terminal v through the carbons,
the coils of the deflecting magnet 1, to the terminal v¹ and out at The sole-
noid his connected in across the terminals v v¹.
The action of the lamp is as follows: On the passage of the current the shut coil h
sucks in its core h¹ and forces down the cylinder and liks 7 and brings the two
carbons into contact, when in consequence of the lessening of the current through
the shunt the springs p draw up the cylinder i and links fi and strike the arc
In the modification shown in Figs. 7 and 8 the fixed carhon holder e is bored
slightly out of line so as to cause the two carbons to be slightly inclined to one
another. The movable carbon holder f is fixed eccentrically on a spindle fl parallel to
the axis of the lamp and working in bearings in the bracket fixed on the crown
plate a. The spindle is connected by the armn to the core h¹ of the shunt sole-
noid h. A spring attached to an arm 3 on the spindle fl and adjustably to a
pillar 3 on the crown plate a normally keeps the carbons apart.
On the current passing to the lamp, the core h¹ of the shunt solenoid rotates the
spindle to bring the carbons into contact at their points. The main current then
passes through the carbons and the are is struck and regulated as above described.
In the modifications shown in Figs. 9, 10 and 11 the whole of the movable
mechanism is contained within the enclosure. The crown a¹0 of the lamp is hollow
and the carbon holders f10 f15 are parallel and are mounted loosely on an axle fll
fixed in brackets 12 inside the crown and are attached to the sector shaped armatures
13 and 14. The poles s¹ of the core 82 of the regulating magnets bear against a
brass, porcelain or mica diaphragm a¹ and influence the armatures f13 and 14 on the
other side of the diaphragm all. The lamp as shown is a shunt lamp and the carbons
are normally kept apart by the tension of springs p fitting into the spring boxes pl
and attached to the armatures. The armature 13 is rigidly attached to but insulated
from the carbon holder f10 and similarly is attached to the carbon holder f15.
Under the influence of the shunt magnet acting through the wall all on the
armatures f¹s and f14, the carbons are drawn together preliminary to striking the arc,
the springs p p afterwards acting to separate the carbons inversely according to
the resistance of the arc.
In Figs. 1 to 4 each carbon electrode t is shown consisting of two separate carbons
that are mounted side by side in an elongated hole in the carbon holders f and e and
tightened up by a screw t¹.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. In an enclosed are lamp the means substantially as described with reference to
Figs. 1, 2, 3, 4, or to Figs. 5 and 6 or to Figs. 7 and 8, or to Figs. 9, 10, and 11,
for transmitting the power to control the are from the outside of the enclosing
chamber to the carbon holders within the enclosing chamber.
2. In an enclosed arc lamp in which the arc is displaced as the carbons burn away
providing an approximately uniform magnetic field over the space which the arc

page_text: occupies to force the are to the points of the carbons by means of extended pole
pieces of a magnet or solenoid, the said pole pieces passing through hermetically
tight joints in the cap of the enclosing chamber, the whole substantially as described
with reference to the drawings.
3. In an arc lamp having two carbons side by side, a magnet or solenoid situated
so as not to obstruct the light, extended pole pieces of the magnet or solenoid
arranged side by side with the carbons and so as to provide a magnetic field at right
angles to the plane of the carbons, and wings on the poles near the carbon holders
to prevent the arc reaching the carbon holders.
4. The improved enclosed arc lamp, substantially as described with reference to
Figures 1, 2, 3, 4, or to Figures 5 and 6, or to Figures 7 and 8, or to Figures 9, 10,
and 11, of the drawings.
Dated this 9th day of February 1899.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.