Improvements in or relating to Electric Arc Lamps.
Year: 1896

page_text: Date of Application, 18th July, 1896-Accepted, 29th Aug., 1896
Improvements in or relating to Electric Arc Lamps.
I, HENRY LEITNER of 39 Elsasserstrasse, Berlin, in the Empire of Germany,
Philologist, 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 relates to a main circuit are lamp the distinguishing characteristic
of which consists in arranging the core of the solenoid in a special manner whereby
the limits within which the resistance and strength of current and consequently the
length of the electric are and the intensity of the light may be varied are greatly
increased whilst at the same time the mechanism is simplified and the motion is
gradual and steady.
The main features of my improved arc lamp are as follows:-
Two pairs of carbons are arranged at an angle one with the other and are capable
of being fed together; one pair being fixed and the other mounted pivotally.
This pivotally mounted pair of carbons is connected with an irou core or plunger
working in a vertically arranged coil by means of lever mechanism.
The said iron core is relatively a short one and is so located in the lower portion
of the coil that immediately upon passage of an electric current through the coil
(which is inserted in the main circuit) the utmost energy of the current is exerted
upon the plunger which is thereupon gently raised. The resistance or turning of
the rotatable pair of carbons is greatest at the commencement but as the plunger
rises and the said carbons gradually assume a more nearly vertical position this
resistance decreases so that a very small force only is necessary.
The arrangement of the device is such that the force required to raise the iron
plunger and so to separate the ends of the carbons rapidly diminishes after the first
How of current and is maintained constantly proportional.
In order to render the manner of carrying out my invention perfectly clear I
will now describe it with reference to the accompanying drawings, in which :-
Fig. 1 is a front elevation of the lamp partly in section.
Fig. 2 is a side elevation of the same showing the pair of movable carbons.
Fig. 3 is a section taken upon the line - in Fig. 1, and
Fig. 4 is a section taken upon the line y-y in Fig. 1.
The carbons a' and a² are advantageously of half-round section and are supported
at or near their upper extremities in the holders a³ and a¹ which are provided with
rollers travelling along the guide rails 6 and 6' respectively. The lower extremities
of the said carbons are supported and guided by the rollers d d with which the
rods or rails 66 are provided. Upon an arm projecting from the lamp is arranged
the pin e on which a cranked lever fis pivotally mounted one end of such lever
being rigidly connected to the rod 6 whilst the other end engages a pin g¹ upon the
rod h of the solenoid by means of a slot g.
The said solenoid rod is connected to the plunger k by a part h¹ which is non-
magnetic; the said plunger is very short relatively to the solenoid bobbin i and
when the lamp is not in use only its upper extremity is within the said bobbin.
The rod h is prolonged in an upward direction and such prolongation is provided
with a piston m which works in a cylinder l filled with glycerine or the like and
thus ensuring a gentle and uniform adjustment of the carbons.
In order to assist the action of the solenoid and so diminish the amount of
current employed an adjustable spring n is provided for the purpose of separating

page_text: the carbons a' from the carbons a² by means of the cranked leverf which causes
that portion of the frame which is pivoted at b² to rise.
In order that the carbons may be securely held and guided and to prevent them
from slipping past one another and also to provide for the increase of the angles
separating them consequent upon their burning away the carbon holders a³ an a
are connected to the corresponding carbon holders by means of guide rods fl and f³.
Each guide rod is rigidly fixed to one carbon holder but is free to slide in an
opening provided in the other holder. Now as the carbons a' are consumed they
are caused to descend by means of suitable weights or in any convenient manner
the rods fand 2 slide in the said openings and thus provide for the uniform
guidance of the carbons.
The action of the lamp is as follows:-
As has been already stated the solenoid and the pair of carbons are so arranged
upon one circuit that when no current is passing the points of the carbons are
caused to rest one upon the other by their own weight and that of their holders. If
a current is now seut through it will flow through the solenoid with all its energy
and raise the iron plunger k and as a consequence the pair of carbons a¹ will by
means of the lever mechanism fb be caused to turn outwards on its pivot 62 so that
the carbon points will be separated and the electric arc will be formed. Owing to
the peculiar arrangement of the plunger k it will be attracted within the solenoid
bobbin with gradually diminishing force and such diminution will always at all
times be exactly proportional to the position of the carbons; the further the
plunger k is drawn within the bobbin the more nearly the position of the pair of
carbons approaches the vertical and the less will be the force necessary to move
them. As the lower arm of the cranked lever f is adjustable it is easy to regulate
the resistance or turning moment of the pair of carbons a' for any position.
In order that the action of the solenoid may be exactly regulated having regard
to the resistance offered by the pair of carbons a¹ the plunger k is adjustable by
means of a rod h which is screw-threaded.
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. A main-circuit electric are lamp having two pairs of carbons suitably arranged
in combination with means for regulating the length of the electric arc such
means consisting of a plunger or core which is short relatively to the coil and
works within a vertically arranged solenoid such plunger or core being attracted
by the solenoid with a force which is invariably proportional to the resistance
offered to motion by the rotatable pair of carbons for the purpose of permitting the
resistance and strength of current being varied substantially as and for the
purposes described.
2. In an electric arc lamp as claimed above the combination therewith of means
for guiding the carbons said means consisting of rods ff which are caused to
slide by the pressure of the carbons in the weighted carbon holders for the purpose
of ensuring the secure. and accurate holding of the carbons at all times and
preventing them from slipping past one another substantially as and for the
purposes herein before described.
3. The improved electric are lamp constructed and arranged to act substantially
in the manner and for the purposes herein before described and illustrated in the
drawings hereunto annexed.
Duted this 17th dor of Iul 1908
TONGUE & BIRKBECK,
Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.