Improvements in Electric Arc Lamps.
Year: 1892

page_text: Date of Application, 22nd Feb., 1892
Complete Specification Left, 21st Nov., 1892-Accepted, 22nd Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps.
We CARL ANTON JOHANNES HUGO SCHROEDER and HEINRICH EUGEN
RICHARD SCHROEDER of Whetstone-House, Heslop Road Balham in the County
of Surrey, Electrical Engineers, do hereby declare the nature of this invention to
be as follows:-
This new carbon electrode substitutes the mechanism of an arc lamp and dis-
tributes the electric current automatical.
Our object was to combine in this invention the advantages of arc lighting with
those of incandescent lighting.
Its novelties we describe to be as follows:
Within a tubular carbon a thin carbon rod is fixed in such a manner that the
inner solid carbon is completely insulated throughout its length from the outer
tubular carbon by a layer of a suitable mass such as: plaster of paris, baryta, a
preparation of fossilmcal and allum etc.
One end of this new carbon-electrode is conical in shape and is dipped into a
conductive paste that may consist of finely divided carbon, gum arabic and
water.
This carbon electrode thus constructed rests or presses against an ordinary carbon-
rod or electrode and thereby produces a new and practicable electric arclighting
apparatus.
The adjustment of the arc, the distribution of the current as well as the intro-
It differs however
duction of the arc is effected by the process of combustion.
somewhat according to the methode employed; the most to be recommended is as
follows:
The new carbon is employed as bottom carbon connected to the negativ pole and
the ordinary solid carbon is employed as upper carbon connected to the positiv pole.
The process of combustion that takes place if the carbons are used and connected
in the described manner is as follows:
The current enters the lamp by the upper part and passes through the upper or
ordinary solid carbon than through the pointed end of the center carbon, that forms
the top of the new carbon, thence by the aid of the finely divided carbon over the
space filled with plaster of paris thus reaching the tubular bottom carbon whence
it leaves by the lower part of the lamp.
The arc instantly struck rises from the tubular bottom carbon right to the top
carbon enveloping the projecting part of the center carbon that acts as a kind of
heat reservoir and thus renders the arc less sensitive. The arc produced is of
globular shape and burns perfect centrical. The crater formed on the upper or
solid carbon and the projecting part of the center bottom carbon produce a very
intense light to which the upper edge of the tubular carbon contributes.
As the carbons are consumed the arrangement, that keeps the points in contact,
is brought into action.
The regulation of the arc is based upon the fact that the center carbon and the
layer of plaster of paris are consumed with the tubular carbon.
The center carbon, that formes the pointed end of the bottom carbon, is kept in
continual contact with the upper carbon thus leaving a space between the upper
edge of the tubular bottom carbon and the solid top carbon which determines the
length of the arc the size depending on the angle of the conical pointed end of the
bottom carbon that is to say it increases if it assumes a more slanting shape or
decreases if it assumes a more acute angle.

page_text: 10
Toner burns more slanting and increases the length of the arc if a more
powerfull current is used or burns more at an acute angle and decreases the length
of the arc if less current is employed.
The distribution of the current takes place automatical; for if several lights are
burnt from one source of electricity and by some cause more current passes through
one lamp than the others, its arc increases; however as the resistance increases
with the arc the excess of current distributes itself amongst the other lamps that
offer less resistance and so restores the proper length of the arcs in all lamps, whilst
if the current and electromotive force are constant the length of the arc remains
the same.
To press the upper and lower carbon together any suitable device may be
employed such as: A simple frame that is provided with a carbon holder at the
bottom and four rollers at the top, a pair of which slightly presses against the upper
carbon and thus produces the contact with the positive pole of the current. A
small weight may be attached to the upper end of the top carbon that helps to
press it down. By the aid of this arrangement long carbons may be employed
whereby a long time of burning is procured.
This arrangement however can be varied as follows:
1. By using the positive pole at the bottom.
2. By reversing carbons.
3. By reversing carbons and poles.
In comparing the various arrangements the first remains the best viz. in which an
ordinary solid carbon is situated at the top and formes the positive pole whilst the
new carbon electrode is placed at the bottom and forms the negative pole.
Other arrangements for keeping the two ends of the carbons in continual
contact than that where the weight of the top carbon is employed may be
deviced as:
'
1. Where the bottom carbon is moved upwards by a pulley and counter weight.
2. By the propelling force of its own when placed into a tube with mercury.
3. By a float in a tube with mercury.
4. By a float in a tube with glycerin, oil or any other liquid.
5. By a spring or springs that serve for pressing the positive and negative carbon.
together.
By all arrangements just mentioned it is not always necessary that the carbon-.
rods or electrodes assume a vertical position.
The great advantages achieved by our new carbon electrode for electric arc
lighting, are:
First. Reliable division of the current without the aid of resistance coils,
magnets, selenoids or any other hindrance.
Second. Great steadiness of light; for if these new carbon electrodes are once
burnt at the right angle of inclination, effected in half a minute, it is found that
the angle of inclination of the conical points of all lamps put in the circuit are
identical and remain so until the carbon electrodes are consumed, which takes from
18 to 24 hours, provided no alteration takes place with regard to the current or
electromotive force, small or sudden variations of either are eliminated; for as the
time of altering the angle of inclination of the conical point of the new carbon-
electrodes takes longer than the variation lasts, besides variations of any kind may
increase or decrease the total lighting effect of all lamps, but will not cause
flickering. The light is kept remarkably steady by the center carbon which forms
a kind of heat reservoir for the arc.
Third. Simplicity in all respects.
Fourth. Great reliability in its action.
Fifth. Great economy as regards installation as well as use.
The great economy obtained as regards installation is, owing to:
a. Saving the great purchase and fixing expenses of regulator arc lamps.
b. Avoiding resistant coils and appliances of any kind for distributing the

page_text: The great economy as regards use is achieved by :
1. The economy of current that is effected by :
a. The employment of the center carbon an additional source of light not
present in any other arc light.
b. Having the two carbons right opposite each other.
c. Not passing the current through resistant coils or selenoids as is the case by
all other arc-light regulators.
d. Decreasing the resistance of the carbon by enabling the current to enter
the top carbon, near the place of combustion, by means of rollers.
2. Reduction of expense in carbon as well as attendant's wages, which is
obtained by:
a. Being able to employ in this system a comparatively stout carbon with out
decreasing the efficiency of the current.
b. Employing carbons three or four times longer than in other systems thus
requiring little attention.
c. Abolishing all complicated arrangements thus avoiding the labour necessarily
attached to them.
In having now substantially described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is:
1. The invention of new electric lighting carbon electrodes that consist of a
carbon-tube into which is fixed a thin solid carbon-rcd or pencil by means of
suitable material such as: plaster of paris, baryta, a preparation of fossil-meal
and allum etc. whereby the thin carbon rod insulated from the outer carbon-tube
and thus forms one rod. One of its ends is conical in shape and is coated with a
conductive paste such as made of carbon or charcoal which serves for starting the
arc substantially as described.
2. The application of this new carbon electrode for electric arc lighting either in
combination with or without another ordinary solid electric lighting carbon, or
cored carbon, or charcoal electrode, or prepared carbon Patent No. 6191.
(26 April 1888) or the combination of two of such new carbon electrodes.
3. The combination of this new carbon electrode with a new electric lamp
specially adapted for the use of this carbon electrode and that is composed of two
parts insulated from each other and to which either part or both is fitted a suitable
appliance for keeping the carbons in continual contact; which may consist in:
a. One or several springs.
b. Rollers through which the carbon passes by means of its own or an addi-
tional weight.
c. A pulley and counterweight.
d. A tube by which the propelling force of mercury or a liquid is employed.
CARL ANTON JOHANNES HUGO SCHROEDER.
HEINRICH EUGEN RICHARD SCHROEDER.
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
CARL ANTON JOHANNES HUGO SCHROEDER and HEINRICH EUGEN RICHARD
SCHROEDER, Electrical Engineers residing at Whetstone House, Heslop Road,
Balham in the County of Surrey, 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:-
A thin carbon rod is fixed in such a manner within a tubular carbon, that the
carbon rod is completely insulated throughout its length from the tubular carbon
by a layer of a suitable substance such as plaster of paris, baryta, or a preparation

page_text: of fossil meal and alum, made as follows:-fossil meal is mixed with a concentrated
solution of alum to a thick paste; this is dried and heated to redness; when cool
it is ground to powder and mixed with gum arabic and water, or shellac solution :
it is then ready to be introduced into the electrode.
One end of this new carbon electrode is conical in shape, and is dipped in a
conductive paste, which may consist of finely divided carbon, gum arabic, and
water.
The carbon electrode thus constructed rests or presses against an ordinary carbon
rod or electrode, and thereby produces a new and practicable electric arc-lighting
apparatus.
The introduction and adjustment of the arc, and the distribution of the current,
are effected by the process of combustion.
The best way to apply the new electrode is as lower carbon, connected with the
negative pole an ordinary solid carbon being used as upper carbon connected with
the positive pole.
The process of combustion which takes place when the new electrode is used and
connected in the manner described is as follows :
The current enters the lamp at the upper part; passes through the upper or
ordinary solid carbon, then through the pointed end of the center rod which forms
the top of the new electrode, and thence by the aid of the finely divided carbon
over the space filled with plaster of paris etc., thus reaching the tubular carbon,
whence it leaves by the lower part of the lamp.
The arc, which is instantly struck, rises from the tubular carbon to the upper
carbon, enveloping the projecting part of the center rod, which acts as a kind of
heat reservoir, and thus renders the arc less sensitive. The arc produced is of
globular shape and burns perfect centrical. The crater formed on the upper or
solid carbon, and the projecting part of the center lower rod produce a very intense
light, to which the upper edge of the tubular carbon contributes.
As the carbons are consumed the arrangement for keeping the points in contact
is brought into action.
The regulation of the arc is based upon the fact that the center rod and the
layer of plaster of paris or other material are consumed with the tubular carbon.
The center rod, that formes the pointed end of the lower or new electrode, is kept
in continual contact with the upper carbon in the lamp, whereby a space is left
between the upper edge of the tubular carbon and the upper solid carbon, which
determines the length of the arc, the size of the space depends on the angle of
the conical pointed end of the lower carbon that is to say it increases if it assumes
a more slanting shape or decreases if it assumes a more obtuse angle.
The new electrode burns more slanting and increases the length of the arc if
a more powerfull current is used or burns more at an obtuse angle and decreases the
length of the arc if less current is employed.
The distribution of the current takes place automatical; for when several lights
are burnt from one source of electricity and by some cause more current passes
through one lamp than the others, its arc increases; however as the resistance
increases with the arc the excess of current distributes itself amongst the other
lamps that offer less resistance and thus restores the proper length of the arcs in all
lamps; whilst if the current and electromotive force are constant the length of the
arcs remain the same.
If a non conductive rod is employed as center rod the insulating layer of plaster
of paris etc. may be dispensed with.
Such non conductive center rod may consist of graphite and fire clay, or graphite
alone, or carbon and zinc oxide and zinc chloride, or slate, pipe-clay, or other
suitable substance; it may be made separately, and introduced into the tubular
carbon, or the latter may be filled with any of the above mentioned substances in
the form of a paste.
To
press the upper and lower carbons together any suitable construction of lamp
may be employed;

page_text: The general arrangement of the lamp may be varied as follows:-
1. By employing the positive pole below.
2. By reversing the electrodes.
3. By reversing electrodes and poles.
The arrangement first described is, however, the best, viz.
that in which an
rdinary solid carbon is used as upper electrode, and forms the positive pole, and .
he new electrode as lower electrode, forming the negative pole.
The advantages obtained by our new carbon electrode are:
"
1. Reliable division of current without the aid of resistance coils, magnets,.
elenoids, or other hindrances.
2. Great steadiness of light.
For as soon as the pointed end of the new electrode is burnt to the required angle.
f acuteness, the angle of the conical points in all the lamps in the circuit is the
ame, and remains so till the carbons are consumed, (which takes place in 18 to
4 hours) provided no considerable alteration takes place in the current or electro-
notive force.
Small or sudden variations are eliminated, since the time required for altering
he angle of the conical point is greater than that during which the variation lasts;
esides variations of any kind may increase or decrease the total lighting effect of
Il lamps, but will not cause flickering.
The light is kept further remarkably steady by the center rod, which forms a
kind of heat reservoir for the arc.
3. Simplicity in all respects.
4. Great reliability of action.
5. Great economy both in-installation and use.
The economy in installation is obtained by:
a. Saving the great expense of regulator arc lamps both in prime cost and
in fixing.
b. Avoiding resistance coils and appliances of any kind for distributing the
current.
The economy in use is obtained by:
a. The employment of a center carbon as an additional source of light, not
present in any other arc light.
b. Placing the two carbons exactly opposite each other.
c. Not passing the current through resistance coils, coils of magnets, shunt
coils, or selenoids, as by all regulator arc lamps.
d. Being able to employ a comparatively stout carbon without decreasing the
efficiency of the current.
e. Employing carbons three or four times longer than in other sytems, thus
requiring but little attention.
f. Abolishing all complicated arrangements, and thus avoiding the labour
necessarily attending them.
EXPLANATION OF THE FIGURES IN THE ANNEXED DRAWING.
Figure 1 represents the new electrode in connection with an ordinary solid
electric lighting carbon, (a) is the ordinary solid carbon, (b) the tubular carbon
nd (c) the insulating material.
Figure 2 represents the new electrode in connection with an ordinary electric
ighting carbon, (d) is the ordinary solid carbon, (E) the tubular carbon, (F) the
nsulating layer or free space, (G) the center carbon or rod of any other suitable
naterial.
Having now substantially described and ascertained the nature of our said inven-
ion and in what manner the same is to be performed we declare that what we
laim is :
1. The invention of a new electric lighting carbon electrode consisting of a

page_text: carbon tube into which is fixed a thin solid carbon rod or pencil, by means of
plaster of paris, baryta, fire-clay, lime, chalk, pipe clay, porcelain clay, or a
mixture of any of these materials mentioned, or a preparation of fossil meal and
alum (described in this Specification) or any other suitable material whereby the
thin carbon rod is insulated from the outer carbon tube thus forming one rod; in
connection with a third carbon facing and touching this electrode, such as:
An ordinary solid electric lighting carbon, or cored carbon, or charcoal electrode,
or prepared carbon Patent No. 6191 (26th April 1888), or the new carbon electrode
(as described in this Specification).
2. The application of a non conductive material such as a mixture of non con-
ductive carbon or graphite and fire clay or lime or chalk or pipe clay, as substitute
for a thin carbon rod and an insulating layer within a tubular carbon (as mentioned
in Claim 1).
3. The application of a non conductive rod made of slate, pipe clay, hardwood
or any other suitable material, as substitute for a thin carbon rod and an insulating
layer within a tubular carbon.
4. The application of a non conductive rod of smaller diameter than the inside of
a tubular carbon fixed with one end to and within the center of such tubular
carbon, as substitute for a thin carbon rod and an insulating layer within a tubular
carbon.
5. The application of a non conductive rod of smaller diameter than the inside
of a carbon tube put within the center of such carbon tube and both fixed to one
and the same contrivance of any suitable device, as substitute for a thin carbon rod
and an insulating layer within a tubular carbon.
6. The application of the various constructions of the new carbon electrode as
mentioned in Claim 1, 2, 3, 4 and 5 of this Specification in combination with any
suitable construction of electric lamp.
7. That one pole of the current is connected with the tubular carbon of the new
electrode of various construction (described in this Specification), and the other
pole with the carbon facing and touching it.
Dated 22nd day of February 1893.
CARL ANTON JOHANNES HUGO SCHROEDER.
HEINRICH EUGEN RICHARD SCHROEDER.