Improvements in Electric Arc Lamps.
Year: 1891

page_text: Date of Application. 28th Dec., 1891
Complete Specification Left, 28th Oct., 1892-Accepted, 28th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps.
I, WILLIAM BROOKS SAYERS, of Glenwood, Bearsden near Glasgow, in the
County of Dumbarton, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
This invention has reference to a construction of electric arc lamp in which
two or more electrodes preferably of carbon, and hereinafter referred to as
carbons, are arranged side by side with a narrow air space between them, the
arc or arcs formed between their adjacent surfaces, when the circuit is completed,
being driven to and kept at the free ends of the carbons by a current of air.
By suitably proportioning the cross sectional area of the carbons to the strength
of current used, and adjusting the distance between the carbons and also the
strength or velocity of the air current, the free ends of the carbons will be
burnt away evenly so as to leave no unburat portions on their outer sides.
The current of air may be produced by any suitable or well known means as
for example by a fan driven by a spring or other mechanical motor, or by an
electro-motor. Or the lamp may be constructed with a chimney with or without
a gas jet or other means for causing a greater draught than the heat from the
arc alone would produce. Or compressed air may be supplied from a main
through a pipe provided with a suitable reducing valve, or with a nozzle having
a small aperture.
In each arrangement it is advantageous to cause the air to
percolate through suitable material such as cotton wool, asbestos, glass wool, or
fine gauze for the purpose of ensuring a steady and uniform current of air.
An electro mechanical device may be employed to automatically regulate the
velocity of the air current.
When the lamp is to be used in the open air it may be nearly or quite sealed
up and the air made to circulate in the required manner by suitable means such
as hereinbefore described. The oxygen in the enclosed air will then be quickly
burnt up with the result that the carbons will last longer, but the light will be
less intense, than would be the case if fresh air were supplied.
To prevent damage of the carbon holders that might ensue, if from any cause
the air current were insufficient or should fail and the are should travel to the
carbon holders, a fuse may be arranged in the vicinity of the carbon holders so
as to be melted by the heat given off by the arc. This fuse would also serve
as a cut out in the event of the lamp being allowed to burn too long without
renewal of carbons. The fuse may be connected across the terminals of a shunt or
high resistance coil so that on the breaking of the fuse the coil would be put into
circuit and operate a contact making device to short circuit the lamp thereby
obviating the breaking of the main circuit in the case of a series system.
In one arrangement of arc lamp according to this invention the carbons are
suspended parallel with each other within a glass tube or chimney enclosed within
an inverted glass bell or bowl, means being provided to cause a current of air to
flow downward through the tube and around the carbons and to ascend through the
annular space between the tube and bell or bowl. One of the carbon holders is so
mounted and arranged in relation to the other that the ends of the carbons are in
contact when the circuit is open, and are moved apart to strike the arc when the
circuit is closed. For this purpose the one carbon holder may be carried by a lever
that is provided with a spring or is so weighted as to move the carbon carried
thereby into contact with the other or fixed carbon when the circuit is open and
with an armature for an electro-magnet the winding of which is in the main circuit
so that when this circuit is closed the magnet will attract the armature so as to

page_text: move the carbons apart and strike the arc. The same or another magnet may be
arranged to turn on the air supply or to set in action the means employed for
producing the current of air. Or an electro-magnetic trigger may be used to short
circuit the carbons near their fixed ends, the short circuiting piece (preferably of
carbon) being drawn away by the action of the main current, the arc then produced
being driven to the free ends of the carbons by the air blast.
For an alternating current lamp the carbons would be of the same size. For
fifty volts or thereabouts, one pair of carbons may be used. For one hundred volts
or thereabouts, three carbons may be used of which the central one may advan-
tageously be about double the weight of each of the others, and might advantageously
be of oval form in cross section. In this case there would be two arcs in
series, one between each side carbon and the central one which would not be
connected to the circuit except by the arcs at one end thereof. The usual resistance
coils, when running in parallel circuits, would be employed. In a continuous
current lamp the carbons would be of different sizes, the positive being approximately
double the weight of the negative. For one hundred volts, two pairs may be used
connected in series in the same tube. Or three carbons may be used in which case
the central one would require to be about equal in weight to the other two, the
positive side carbon being double the weight of the negative side carbon, and all
being of the same length.
Instead of employing carbon rods in a glass tube I may use a carbon tube as one
electrode, and a central carbon rod as the other, and cause a current of air to pass
between them and so keep the arc at one end. The arc will then have a tendency
to travel around the end of the tube with the central carbon as an axis, the tendency
to rotation being due, when the carbons are held vertically, to the effect of the
vertical component of the earth's magnetic field. An electro or a permanent
magnet may be used to produce lines of force at right angles to the arc for the
purpose of increasing this tendency or of causing or accelerating such rotation and
securing greater uniformity and steadiness in the light.
Dated this 28th day of December 1891.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
I, WILLIAM BROOKS SAYERS, of Glenwood, Bearsden, near Glasgow, in the
County of Dumbarton, Electrical 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 :-
This invention has reference to a construction of electric arc lamp in which two
or more electrodes preferably of carbon, and hereinafter referred to as carbons, are
arranged side by side with a narrow air space between them, the arc or arcs formed
between their adjacent surfaces, when the circuit is completed, being driven to and
kept at the free ends of the carbons by a current of air. By suitably proportioning
the cross sectional area of the carbons to the strength of current used and adjusting
the distance between the carbons and also the strength or velocity of the air
current, the free ends of the carbons will be burnt away evenly so as to leave no
unburnt portions on their outer sides.
The current of air may be produced by any suitable or well known means as for
example by a fan driven by a spring or other mechanical motor, or by an electro-
motor. Or the lamp may be constructed with a chimney, with or without a gas
jet or other means for causing a greater draught than the heat from the arc alone
would produce. Or compressed air may be supplied from a main through a pipe
provided with a suitable reducing valve, or with a nozzle having a small aperture,

page_text: In each arrangement it may be advantageous in some cases to cause the air to
percolate through suitable material such as cotton wool, asbestos, glass wool or fine
gauze for the purpose of ensuring a steady and uniform current of air.
When the lamp is to be used in the open air it may be nearly or quite sealed up
and the air made to circulate in the required manner by suitable means such as a
fan. The oxygen in the enclosed air will then be quickly burnt up with the result
that the carbons will last longer, but the light will be less intense, than would be
the case if fresh air were supplied.
In the accompanying drawings,
Figs. 1 and 2 are sectional elevations at right angles to each other; and
Fig. 3 a plan view of an electric arc lamp constructed according to this
invention.
1,1 are two carbons suspended parallel with each other and at a short distance
apart, within a glass tube 2 supported by a holder 3 and enclosed within an inverted
glass bell or bowl 4. This bell or bowl is secured to a metal cover or closure 5
and may be provided with external wire netting 4. Connected to the cover 5 and
above the tube 2 is an inlet pipe 6 that is connected, when the lamp is in use, with
means such as a fan, or with a pipe containing air under pressure, so that a current
of air can be caused to descend the tube 2 for the purpose hereinbefore mentioned.
77 are perforations in the cover 5 for exit of air and products of combustion from
the top of the lamp. The carbon is fixed in a holder 8 that is fixed to, but
insulated from the cover 5, and is in connection with a terminal 9. The carbon 1*
is fixed in a carbon holder 10 that formis one arm of a lever pivoted at 11 and the
other arm 12 of which is provided with an adjustable weight 13, and carries an
armature 14 for an electro magnet 14ª. 14 14 are stops or distance pieces of non-
magnetic material for example brass. The winding of the electro-magnet 14ª is in
series with the carbons, one of its ends being for this purpose connected with the
insulated terminal 15 and the other with the metal cover 5 with which the carbon
holder 10 is in connection. The arrangement is such that when the circuit of the
lamp is open the movable carbon 1 will, under the action of the weight 13, rest
against the fixed carbon 1, and when the circuit of the lamp is completed the
electro magnet 14" will be energized and attract the armature 14 so as to auto-
matically move the carbon 1 from the carbon 1" aud into the position shown in full
lines, thereby striking the arc. A current of air is at the same time or previously,
caused to descend the tube 2 for the purpose of keeping the arc at the free cods of
the carbons and prevent it travelling upward through the air space between the
carbons.
I have obtained satisfactory results with an air current having approximately the
same or a little less velocity as that commonly used for gas blow pipes for brazing
light brass work the carbons 1, 1 being about 9 mm and 11 mm in diameter
respectively and at a distance apart of th of an inch. Or the cover 5 may be fitted
with a metal cap formed with an opening at the top to which a funnel or chimney
can be connected, the tube 2 being connected by a bend 2 passing to the external
air through the side of the cap as indicated by dotted lines in Fig. 1.
In this case
a gas jet or other flame may be placed in the upper part of the cap or chimney to
increase the draught through the tube 2 to the desired degree.
Instead of employing carbon rods arranged in a glass tube as in the arrangement
described, I may use a carbon tube as one electrode, and a central carbon rod as
the other, and cause a current of air to pass between them and so keep the arc at
one end.
Fig. 4 is a sectional elevation of an electric arc lamp thus constructed, 1 being
the fixed positive carbon in the form of a cylindrical tube within which the other
or negative carbon 1 which is solid, is suspended by the pivoted carbon holder 10
so as to be concentric with 1 when the lamp is in action. In this arrangement the
arc will have a tendency to travel around the end of the tube with the central
carbon as an axis, the tendency to rotation being due, when the carbons are held
vertically, to the effect of the vertical component of the earth's magnetic field.
An

page_text: electro or a permanent magnet may be used to produce lines of force at right angles
to the arc for the purpose of increasing this tendency or of causing or accelerating
such rotation and securing greater uniformity and steadiness in the light. An
electro magnet for this purpose is indicated in dotted lines at 15, its winding being
connected with the insulated terminal 9 and with the carbon 1 as shown.
Fig. 5 is a diagrammatic view illustrating a modified construction of lamp in
which the carbons are so arranged that the are burns at their upper free ends. In
this arrangement 15 is a funnel or chimney arranged above the tube 2 in order to
produce the necessary air draught which in this case enters the lower end of the
tube. The carbons 1, 1ª are formed each with a lateral extension by which they
are fixed to the carbon holders 8 and 10 respectively of which the former is secured
to a fixed rod 8, whilst the other is pivoted and connected by a rod 16 to the
pivoted armature 14 of the electro-magnet 14" by which the carbon 1 is moved and
the arc struck when the circuit of the lamp is completed. 17 is a reflector at the
top of the lamp. The chimney 15 may be provided with a damper 18 having an
external arm 19 connected to a cord 20 by operating which the position of the
damper can be varied to control the draught through the tube 2.
To prevent damage of the carbon holders that might ensue, if from any cause the
air current were insufficient or should fail and the arc should travel to the carbon
holders, a fuse may be arranged in the vicinity of the carbon holders so as to be
melted by the heat given off by the arc.
This fuse would also serve as a cut out in
the event of the lamp being allowed to burn too long without renewal of carbons.
The fuse may be connected across the terminals of a series-coil so that on the
breaking of the fuse the coil would be put into circuit and operate a contact making
device to short circuit the lamp thereby obviating the breaking of the main circuit
in the case of a series system.
Fig. 6 is a diagrammatic view illustrating an arrangement of fuse for this
purpose suitable for a lamp in a series circuit. 21 is a fuse wire of U shape so
fixed that its lower part extends a short distance down the space between the
carbons against the positive of which it may rest without detriment. One end of
this fuse is connected to the positive lamp terminal 9 so that the current normally
passes through it to the positive carbon and then to the negative carbon 1".
22 is an electromagnet having a low resistance winding connected to the circuit
of which the fuse forms part, at the point 23 and 24. 25 is the armature of
the electro-magnet 22; it is connected to the said circuit at the point 24 and
carries a contact 26 adapted when raised to bear against a contact 27 in
connection with the negative carbon or metal frame of the lamp. Thus with the
arrangement described it will be seen that should the carbon be allowed to burn
away too far the fuse wire 21 will be melted, by reason of the arc reaching it.
The current will then pass wholly through the electro-magnet 22 which by
attracting the armature 25 will cause the circuit of the lamp to be completed
through the contacts 26 and 27, thus short circuiting the carbons and preventing
the breaking of the circuit and the destruction of the carbon holders.
When the lamp is used on a parallel circuit the electro-magnet 22, the
armature 25 and contacts 26 and 27 are omitted, the melting of the fuse in this
case simply breaking the circuit and preventing destruction of the carbon
bolders.
For an alternating current lamp the carbons would be of the same size. For
fifty volts or thereabouts, one pair of carbons may be used. For one hundred
volts or thereabouts, three carbons may be used of which the central one may
advantageously be about double the weight of each of the others, and might
advantageously be of oval form in cross section. In this case there would be two
arcs in series, one between each side carbon and the central one which would not
be connected to the circuit except by the arcs at one end thereof. The usual
resistance coils, when running in parallel circuits, would be employed.
In a coutinuous current lamp the carbons would be of different sizes, the positive
being approximately double the weight of the negative as is the case in the

page_text: example shown in Figs. 1, 2 and 3 where 1 and 1ª are respectively the positive
and negative carbons. For one hundred volts, two pairs of carbons may be used,
Or three carbons may be used in which
connected in series, in the same tube 2.
case the central one would require to be about equal in weight to the other two,
the positive side carbon being double the weight of the negative side carbon, and
all being of the same length.
I have found it advantageous to use a higher voltage than is usual, the arc in my
lamp being generally longer than in other forms of arc lamps. It is practicable to
use a voltage of from 70 to 100 volts on a single pair of carbons. As in lamps
constructed with inverted carbons as shown in Figs. 1 to 4 inclusive the light from
the crater of the positive carbon is not obstructed either by the negative carbon or
any parts of the lamp the useful light obtained is much greater for the same energy
consumed than in the forms of lamps generally in use.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is:
--
1. An electric arc lamp in which two or more carbons are arranged side by side
with a narrow air space between them, and provision is made for causing a current
of air to flow along the carbons for the purpose of keeping the arc at the free ends
thereof substantially as herein described.
2. An electric arc lamp of the kind referred to in the preceding claim comprising
a glass bell or bowl having a cover or closure provided with an inlet and with
outlets for air and within which the carbons can be arranged side by side with a
narrow air space between them, carbon holders one of which is movable and holds
its carbon in contact with the other when the circuit of the lamp is open, and an
electro-magnetic device arranged in the lamp circuit and adapted when such circuit
is completed to operate the movable carbon holder and carbon to strike the arc
substantially as herein described.
3. My improved electric arc lamp constructed substantially as hereinbefore
described with reference to and shown in Figs. 1, 2 and 3 of the drawings annexed
or modified according to Fig. 4, and whether with or without a fuse arranged to act
in the manner set forth.
4. An electric arc lamp constructed substantially as herein before described with
reference to and shown in Fig. 5 of the drawings annexed.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.