AN IMPROVED ELECTRIC ARC LAMP
Year: 1885

page_text: I THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer do hereby declare the nature of my invention for "AN IMPROVED
ELECTRIC ARC LAMP a communication to me from abroad by Oscar Fredrik
Jönsson of Stockholm Sweden Engineer to be as follows:-
"
The object of this invention is an automatically regulating electric arc lamp
having two pairs of carbons intended to burn one after another. The top carbons
with their holders are exactly counterbalanced by weights and chains, in order to
reduce to a minimum the power required for regulating the arc and maintain the;
length of the are constant whereby irregularities in the light are prevented as far
as possible. The lamp is also arranged as a differential lamp.
A case encloses the top part of the lamp this case is attached to a metallic plate
and is provided with a hook for its suspension, the hook is insulated from the
metallic mass of the lamp. Two metallic standards attached to the plate pass
upwards through the case but insulated from it and the plate. Projecting
vertically from the centre of the plate is a tube in which are suspended by a string
running over a pulley two cores of iron of which the lower one bas at its lower.
end a guide bar of non magnetic matter terminating in a cross piece beneath the
plate. It is preferred however to form the upper iron core of a tube and to make
the lower one solid. Beneath the cross piece there is a cataract or dash pot cylinder
containing fluid, and having within it a piston the top end of the piston rod is.
attached to the cross piece. The cylinder is attached to the top of the metallic rod.
which in its turn is attached to a bar which descends from the plate and forms
part of the frame of the lamp. The rod is insulated from the bar. At the lower
extremity of the rod is a cross piece which carries the two lower carbons. The
cross piece has holes at its ends in which the carbons are held each by its spring.
The top carbons are held in the lower ends of their respective tubes and are retained.
there by the springs attached to the tubes. These springs pass through slots in

page_text: the tubes and press against the carbons. The tubes which hold the top carbons
pass upwards through holes in the bar and plate. To the tops of these tubes are
attached chains passing over pulleys. The chains are of such a weight that length
for length their weight equals that of the carbons. The pulleys are attached to a
cross piece projecting from the top of the central tube. In the same cross piece
and directly above the carbon holder tubes are two small pulleys over which wires
are laid-one end of each wire is attached to the top of a hollow counterweight
and the other end is attached to a pin passing through the counterweight and
attached to the lower end of the tube. The weights approximately balance the
tubes the tubes being somewhat the heavier so that they have a tendency to slide
downwards.
There are two solenoids on the central tube the lower one is stationary and
connected with two contact pieces projecting horizontally from the metallic
standards these contact pieces terminate near their respective carbon holder tubes.
The interior wire end of the top solenoid is adjustable on the central tube and is
secured to a metallic piece supported by one of the standards and its exterior end
is secured to a contact pincher pressing on the central tube. The solenoids may be
arranged one within the other.
The lamp is worked in the following manner. The current enters the lamp
through one metallic standard passes from this through the coils of one solenoid
bobbin to the central tube through the contact pincher. When the current has
entered the tube it spreads through the metallic mass of the lamp and enters the
carbon holder tubes. From this it branches down through the upper and lower
carbons and ascends through the rod supporting the lower carbon and then passes
out into the circuit. During the passage of the current through the solenoid both
the iron cores will be pulled in towards one another causing the cross piece attached
to the lower core to rise. Through this cross piece two bars pass one at each side
of the cataract cylinder. Each of these bars is jointed to its respective catch-
these entirely encompass their respective carbon holder tubes. These catches each
consist of two jointed parts between which the tubes pass and the hole formed by
these parts may be adjusted to the diameter of the tube by means of a moveable
metallic piece and spring. Thumb nuts on the bars which carry the catches are
adjusted so that when the cross piece is raised one of the catches will be raised
before the other. When that takes place the catcher seizes the tube assuming an
inclined position and thus lifting the tube and the carbon and breaking the contact.
The current passes then only through the second pair of carbons. During the
continued rise of the iron core these are in turn separated and then the arc is
formed between these carbons. As already indicated a small portion of the current
passes through a derived circuit in which is a second solenoid operating on the
same core. When the arc is prolonged and the resistance consequently increased
the derived current increases whereby the core is drawn downwards until the
catcher comes against the bar which allows the carbon holder tube to slide down
and restores a suitable length of are. Thus the derived current will again be
diminished and the carbon stopped. This arrangement of the solenoids with their
cores has the advantage of preventing shocks in the motion of the cores: In the
mauner described, the descent of the carbon continues until a flange round the top
of the tube comes against a pin projecting vertically from the cross piece the tube
becomes suspended thereon and so the equilibrium within the lamp will not be
deranged In proportion as the tube descends and the carbons are consumed the
chain also is drawn over the pulley to a length equal to that consumed of the
carbon. When the flange of the tube has come against the pin and the carbon
cannot descend further the cross piece is pulled down farther than before owing to
the influence of the second solenoid so that the second catcher bears .against the
bar. The second carbon holder tube with its carbon now descends until the
carbons come into contact. The current will then pass by this pair of carbons
between which the arc is formed in the manner already described. This upper

page_text: carbon will descend in due course until it is consumed and the flange of the tube
rests against another pin projecting from the cross piece. When this tube is
suspended on its pin the bar is still pulled down until the flanges of both the tubes.
touch contact rails' provided for the purpose. The contact rails are thus put into
direct contact with the metallic mass of the lamp-the consequence is that no
current passes through the solenoid and it is not exposed to destruction by the
current. In this manner an automatic cutting out of the lamp from the circuit
takes place when both pairs of carbons are consumed but the current is not
interrupted for the other lamps on the circuit.
In order as far as possible to steady the motions of the iron cores they are
controlled partly by the cataract cylinder and partly by a spiral spring which is
compressed when the lower core has been drawn up to a certain height.
It is finally obvious that the lamp may also be used if the chains and the
counterbalances are removed, but then the position of the solenoids in relation to
each other and to the iron cores must be adapted to correspond.

page_text: An improved Electric Arc Lamp.
I THORSTEN NORDENFELT of 53 Parliament Street in the City of Westminster
Civil Engineer, do hereby declare the nature of this invention (a communication
from abroad by Oscar Fredrik Jönsson of Stockholm Sweden Engineer) and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
The object of this invention is an automatically regulating electric arc lamp
having two pairs of carbons intended to burn one after another. The top carbons
with their holders are exactly counterbalanced by weights and chains, in order to
reduce to a minimum the power required for regulating the arc and maintain the
length of the arc constant, whereby irregularities in the light are prevented as far
as possible. The lamp is also arranged as a differential lamp.
On the annexed Drawing. Figure 1 represents an arc lamp in longitudinal
section through the two carbons, and Figure 2 a section at right angles to it.
Figure 3 is a horizontal section of the lamp on the line 1. 2 (fig. 1) Figure 4 a
section on the line 3. 4. Figure 5 a section on the line 5. 6 and Figure 6 a section
on the line 7. 8 Figure 7 is a plan view and Figures 8 and 9 are details of the
bottom part of the top carbon holder.
A is a case enclosing the top part of the lamp this case is attached to a metallic
plate B and is provided with a hook C for its suspension, the hook is insulated
from the metallic mass of the lamp-D and E are two metallic standards attached
to the plate B and passing upwards through the case A but insulated from it and
the plate-F is a tube projecting vertically from the centre of the plate B in which
are suspended by a string running over a pulley I two tubes G and H or cores
of iron of which the lower one H has at its lower end a guide bar of non
magnetic matter terminating in a cross piece K beneath the plate B It is preferred
however to form the upper iron core G of a tube and to make the lower one H
solid. Beneath the cross piece K there is a cataract or dash pot cylinder L con-
taining fluid, and having within it a piston the top end of the piston rod is attached
to the cross piece K. The cylinder L is attached to the top of the metallic rod N
which in its turn is attached to a bar M which descends from the plate B and
forms part of the frame of the lamp. The rod N is insulated from the bar M, at
the lower extremity of the rod N is a cross piece O which carries the lower
carbons P and Q. The cross piece has holes at its ends in which the carbons
are held each by its spring R (see figures 1 and 6) The top carbons S and T are
held in the lower ends of their respective tubes U and V and are retained there by
the springs X attached to the tubes. These springs pass through slots in the tubes
and press against the carbons (see figures 1. 8 and 9) The tubes U and V pass
upwards through holes in the bar M and the plate B. To the tops of the tubes
are attached chains Y Y passing over pulleys Z Z the other ends of the chains
being fastened to the bottom of their respective chain boxes i. The chains Y are
of such a weight that length for length their weight equals that of the carbons.
The pulleys Z are attached to a cross piece k projecting from the top of the tube F.

page_text: In the same cross piece and directly above the tubes U and V are two small
pulleys over which threads or fine cords are laid-one end of each is attached to
the top of a hollow counterweight m and the other end is attached to a pin m¹
passing through the counterweight and attached by the cross pin m² to the lower
end of the tube. The weights m approximately balance the tubes the tubes being.
somewhat the heavier so that they have a tendency to slide downwards.
nand o are two solenoids on the tube F-the lower one o is stationary and con-
nected with two contact pieces p and q projecting horizontally from the metallic
standards or contact pieces D and E (see figure 4) these contact pieces terminate near
their respective tubes U and V. The top solenoid n is adjustable on the tube F
The interior wire end of this solenoid is secured to the metallic piece El supported
by the standard E and its exterior end is secured to the contact pincher The
piece D¹ corresponding with the piece El is insulated. The solenoid o may (instead
of being as shown in the drawing, placed beneath the solenoid n) be arranged
either on the exterior or the interior of the solenoid n that is to say the coils of
the solenoid o may be wound either outside or inside of the solenoid n. When
arranged in this way, the current in the coils of the solenoid o will counteract the
current in the solenoid n.
The lamp is worked in the following manner. The current enters the lamp
through the metallic standard E passes from this through the coils of the bobbin n
to the tube F through the contact pincher r. When the current has entered the
tube F it spreads through the metallic mass of the lamp and enters the tubes U
.and V. From this it branches down through the carbons S and T and the
carbons P and Q which are in contact with the cross piece O, it ascends through
the rod N the connecting wire 8, the standard D and then passes out into the
circuit During the passage of the current through the solenoid n both the iron
cores G and H will be pulled in towards one another-causing the cross piece K to
rise. Through this cross piece two bars T and T¹ pass one at each side of the
cataract cylinder L Each of these bars is jointed to its respective catch u and u¹-
these entirely encompass their respective tubes U and V. These catches are
represented in detail in figure 10, and each consist of two jointed parts u² and u³
between which the tubes U and V pass and the hole formed by these parts may be
adjusted to the diameter of the tube by means of a moveable metallic piece u and
a spring . Thumb nuts v and v¹ on the barst and t¹ are adjusted so that when
the cross piece K is raised the nut with its bar t and the catcher u for instance
will be raised first. When that takes place, the catcher seizes the tube U
causing the catcher to assume an inclined position thus lifting the tube U and
: the carbon S and breaking the contact. The current passes then only through
the carbons T and Q. During the continued rise of the iron core H the cross
piece K comes against the nut v¹ so that the bar t¹ and the catcher u¹ in their
turn lift the tube V causing the carbons T and Q to separate, then the arc is
formed. between these carbons. As already indicated, a small portion of the
current passes through a derived circuit from the standard E the contact plate
the bobbin o the contact plate p and the standard D. When the arc is prolonged,
and the resistance consequently increased the derived current increases, whereby
the core H is drawn downwards until the catcher u¹ comes against the bar M
which allows the tube V to slide down and restores a suitable length of arc.
Thus the derived current will again be diminished, and the carbon stopped. This
arrangement of the solenoids n and o with their cores G and H has the advantage of
preventing shocks in the motion of the cores when the derived current increases and
the traction of the solenoid o is in consequence augmented-this solenoid has to
overcome not only the tendency of the solenoid n to draw the lower iron core H
upwards, but also to overcome the tendency of the same solenoid to draw the iron
core G downwards. In the manner described, the descent of the carbon continues
until a flange round the top of the tube V comes against a pin x¹ projecting
.vertically from the cross piece K and passing through a hole in the plate B the
tube V becomes suspended thercon and so the equilibrium within the lamp will not

page_text: be deranged. In proportion as the tube V descends, and the carbons T and Q are
consumed the chain Y also is drawn over the pulley to a length equal to that
consumed of the carbon T When the flange of the tube V has come against the
pin and the carbon T cannot descend further, the cross piece K is pulled down
farther than before owing to the influence of the solenoid o so that the catcher u¹
bears against the bar M. The tube U with its carbon S now descends, until the
carbons S and P come into contact. The current will then pass by this pair of
carbons between which the arc is formed in the manner already described. The
carbon S will descend in due course until it is consumed and the flange of the
'tube U rests against a pin x projecting from the cross piece K. When this tube is
.suspended on its pin, the bar H is still pulled down until the flanges of both the
tubes U and V touch the contact rails p and q-the contact rails are thus put into
.direct contact with the metallic mass of the lamp-the consequence is that the
current passes from the standard E through the rail g over into the tube V and
into the metallic mass of the lamp and from this through the tube U the rail p
and away through the standard D. When this takes place, no current passes
through the solenoid o and it is not exposed to destruction by the current. In this
manner an automatic cutting out of the lamp from the circuit takes place when
both pairs of carbons are consumed but the current is not interrupted for the other
lamps on the circuit,
In order as far as possible to steady the motions of the iron cores H and G they
are controlled partly by the cataract cylinder L and partly by a spiral spring y
which is compressed when the iron core H has been drawn up to a certain. 'height.
The barst and inay also be made in the shape of spiral springs to prevent too
rapid motions.
It is finally obvious that the lamp may also be used if the chains and the
counterbalances are removed but then the position of the solenoids n and in
relation to each other and to the iron cores G and H must be adapted to corre-
spond because the solenoid n must then be made to work more powerfully that
it may counteract the weight of the tubes and the carbons which are then not
counterbalanced.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The application in an electric arc lamp of two solenoids n and o mounted on
a central tube F of which the upper and larger is moveable and has the whole
current passing through it whilst the lower o is fixed and forms a shunt circuit;
these solenoids acting on two iron cores G and H hung on the same thread inside
the tube F, of which the upper G is tubular and is situate at the upper end of the
solenoid n whilst the lower H is solid and so placed that its upper end enters the
lower part of the solenoid n and its lower end into the upper part of the solenoid o;
such core H being connected with a cross piece K intended with the assistance of
.the bars t, t¹ and the friction catches u u¹ to regulate the distance of the carbons
from each other substantially as described.
2. The combination with the mechanism set forth in the above claiming clause
of pins x x¹ standing up from the cross piece K. on which pins the tubes Ū and V
hang by their flanges partly in order to maintain equilibrium within the lamp and
partly to prevent the tubes falling down on the contact bars p and q before the
carbons have entirely burnt out, substantially as described.
3. The mode of employing in an electric arc lamp two solenoids n and o of which
solenoids one is moveable and traversed by the whole current while the other is
stationary and forms a derived circuit both solenoids acting upon two iron cores G
and H suspended within them on a common wire one of the said cores carrying a
cross piece K. with clips embracing the carbon holders, substantially as described.
4. The combination in an electric arc lamp of tubes or carbon holders U and V
with flanges or projections upon them with pins x and x¹ projecting vertically from

page_text: the cross piece K on which the tubes U and V become suspended by their flanges
partly in order to maintain equilibrium within the lamp and partly with the view
of impeding the tubes from falling down on the contact rails p and q before the
carbons are completely consumed, substantially as described.
5. The combination in an electric arc lamp of the two tubes U and V supporting
at their lower ends the top carbons S and T such tubes having attached to them
chains y laid over the pulleys Z, these chains baving the same weight, length for
length, as the carbons, and the tubes also being counterbalanced by the weights m
contained within the tubes, and attached to wires laid over the pulleys sub-
stantially as described.
6. The combination in an electric are lamp of two standards or terminals D and E
insulated from the metallic mass of the lamp and two tubes or carbon holders U
and V and a solenoid or solenoids controlling the tubes or carbon holders and
flanges or projections on the tubes or carbon-holders which when the carbons have
been in succession consumed descend on to metallic pieces in electrical connection
with such standards or terminals thus short circuiting the solenoid or solenoids
substantially as described.
7. The improved carbon holder for the lower carbons P and Q consisting of a
cross piece attached to the rod N and provided with two holes through which the
carbons are introduced and where the carbons are retained by means of the springs R
substantially as described.
8. The means for carrying the upper carbons S and T in tubes U and V by
introducing them in the lower ends of the tubes and there retaining them by means
of springs X which pass through openings in the tubes, and press against the carbons
substantially as described.
9. The improved and automatically regulating electric arc lamp in its entirety
substantially as described.