Improvements in Electric Arc Lamps.
Year: 1896

page_text: Date of Application, 22nd June, 1896-Accepted, 15th May, 1897
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
I, MORIZ BAUMER, of Feuerweg No. 8, Nuremburg, in the Kingdom of
Bavaria, German Empire, Manufacturer, do hereby declare the nature of, my
invention and in what manner the same is performed to be particularly described:
and ascertained in and by the following statement :-
The present invention relates to electric arc lamps and consists of means for
adjusting the length of the arc by means of a solenoid.
As is well known the core of a solenoid is attracted with varying strength at
different parts and consequently the adjustment of the length of the arc in electric
lamps provided with solenoids is irregular. This disadvantage is obviated according
to the present invention by employing a double solenoid composed of two single
solenoids arranged side by side parallel to each other, instead of the single solenoid
hitherto used for the purpose. The spools of the two single solenoids are so
wound that one shall have a power of attraction gradually increasing from the
bottom to the top whilst the other gradually increases in attractive power in the
opposite direction, viz. from the top to the bottom. This is attained by winding
the coils conically, i.e. by increasing the number of coils towards the top of the
one solenoid and towards the bottom of the other, so that the spools will have a
conical exterior. Thus the point of minimum attraction of one solenoid will
correspond to that of maximum attraction of the other. By this means the effect.
of both members of the double solenoid will be so compensated that the adjustment
of the carbons will take place uniformly.
And in order to render the present specification more easily intelligible reference
is had to the accompanying drawing in which similar letters of reference denote
similar parts throughout the several views:
Fig. 1 is a vertical section through a main circuit lamp in which the carbon
holders are suspended on the ends of a cord or chain conducted over a guide.
roll and
Fig. 2 is a diagrammatical representation showing the electric connections of the
lamp.
o is the upper and the lower carbon holder, s is the cord or chain to which the
same are attached and r the guide roll for the same.
The upper carbon holder o is attached to the lower ends of two parallel and.
vertical solenoid cores k, k, (the upper parts k', k³, being of brass tubing and attached
to the iron cores by welding). These cores are adapted to slide in corresponding
orifices of the plates t¹ t2. sand s3 are the two solenoid coils. As will be seen.
from the drawings the same are wound conically, so that the number of coils of s
gradually decreases from the bottom to the top, whilst the coils of s3 gradually
increase in the same direction. Towards the thinner end of the spools the coils
may be arranged cylindrically. By means of this arrangement of the spools, the
two members of the double solenoid will so compensate each other that the
attractive power of the cores will be uniform throughout their lengths, each weaker
point of one solenoid being close to a stronger point of the other, and vice versa.
The device operates in the following manner :-When the current is not passing
through the spools the top carbon rests on the under one. On the current passing
through the spools the cores will be raised thus lifting the upper carbon off the
lower one and striking the arc. If the top carbon has been lifted too far off the

page_text: under one, the current will be weakened owing to the distance between the carbons,
and the cores will fall a corresponding distance. Thus it will be clear that the
lamp will regulate itself. The object of winding the spools conically in the opposite
directions is to maintain the attractive force constant, irrespective of the position
of the cylindrically shaped cores. This action results from the fact that the two
points of the cores at which the attractive force of the solenoids may be considered
as being concentrated are kept at such relative vertical position in the solenoids
that the sum of the efficiency of the latter remains constant.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
An electric arc lamp having solenoids for adjusting the length of the arc,
characterised by the arrangement of pairs of solenoids having spools wound
conically along a part or the whole of their length, the conicity of said spools
lying in opposite directions substantially as described.
Dated this 22nd day of June 1896.
BOULT & WADE,
Agents for the Applicant.