Improvements in Arc Lamps.
Year: 1898

page_text: COMPLETE SPECIFICATION.
Improvements in Arc Lamps.
I, PAUL MERSCH, of No. 4, Avenue Hoche, Paris, in the Republic of France,
Doctor-at-Law, 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 arc lamps and has for its object the provision of means
for effecting the regulation of the carbons by magnetic effect within narrower limits
and with greater efficiency than has hitherto been obtainable it has been found in arc
lamps which have two solenoids in series and cores operated magnetically that the
action of the bobbins upon the cores is very irregular, because each coil is provided
with a core having a free external pole, which as the carbons are consumed would
draw nearer and nearer to the coil. As the attractive force of the coils constantly
increases, the action of this free external pole would be evidenced by irregular
working as the constant diminution of the weight to be attracted owing to the
consumption of the carbons, corresponds to the progressive increase of the attractive
force of the solenoids.
This effect is largely prevented by my invention and is essentially an improvement
on the arc lamp as described in the complete specification of my application for
Letters Patent No. 25244 97.
My invention consists in providing a magnetic yoke connecting the magnetic
cores so as to form a horse shoe arrangement in combination with a magnetic shield
placed about the solenoids as hereinafter described.
In order that my invention may be the better understood I will now proceed to
describe the same in relation to the accompanying drawing, reference being had
to the letters and figures marked thereon. Like letters refer to like parts in the
figures.
Figure 1 is a front elevation of a lamp having a magnetic yoke to the cores.
In Fig. 1 it will be seen that the coils A of the solenoids are encased by magnetic
shields of iron B which are attached to washers Cat top and bottom. The cores D
which work within the solenoids are connected at their lower ends by a yoke E of
magnetic material so as to form a horse shoe magnet and at the same time carry the
lower carbon holder.
The cores are supported by cords F passing over pulleys G and attached to the
upper carbon holder H, the pulleys having retaining pawls J.
In this way the presence of a free external pole drawing nearer to the coils during
the working of the lamp is absolutely avoided and the yoke in combination with the
magnetic shields on the solenoid reduces the magnetic resistance in the system as
far as possible.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1st. In an arc lamp having two regulating solenoids, the combination of coils

page_text: with a horse shoe core of magnetic material adapted to work within the coils,
substantially as described.
2nd. In an arc lamp having two regulating solenoids the combination of two coils
provided with magnetic shields, with a horse shoe core of magnetic material adapted
to work within the coils substantially as described.
Dated this 12th day of September 1898.
FELL & JAMES,
1, Queen Victoria Street, London, E.C., Agents for the Applicant.