An Improved Electric Arc Lamp.
Year: 1891

page_text: Date of Application, 21st Nov., 1891-Accepted, 24th Dec., 1891
An Improved Electric Arc Lamp.
A communication by LA COMPAGNIE DE L'INDUSTRIE ELECTRIQUE, SUCCESSOR
AND REPRESENTATIVE OF LA SOCIÉTÉ D'APPAREILLAGE ELECTRIQUE,
of Geneva, Switzerland, Electrical Engineers.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, and 323, High Holborn, in the County
of Middlesex, Civil Engineer, 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 :-
The improved construction of electric arc lamp has for its object to effect the
following―
1. That when the lamp is lighted, should the electric current be intercepted
for any cause, the carbons shall not be liable to approach one another.
2. That the space between the carbons determining the length of the arc shall
be produced and regulated exclusively by a shunt current, thus allowing several of
these lamps to be easily arranged in series.
3. That the mechanism shall be simple, possess as few parts as possible, and
only occupy a very little part of the total length of the lamp. Such is of importance
when it is a question of lighting a room having a low ceiling, and when the lamp is
to be lit for a long time.
4. That the pattern shall be uniform, allowing of lamps being constructed so
that they will burn for any length of time without necessitating a change in the
gearing, or the altering of the height (y) of the lamp.
The annexed sheet of drawings illustrates a lamp constructed according to this
invention,
Figures and 2 being vertical side elevations at right angles to one another
(parts of Figure 1 being broken away for the purposes of illustration) and
Figure 3 a plan view showing the arrangement of magnets and regulating
mechanism.
The lamp as will be seen is composed of two movable parts A and B carrying
the carbon holders and moving in an inverse direction between the guides CD.
They are connected together by a metallic chain passing over the toothed
wheel E and tend to constantly approach one another under the influence of the
excess of the weight of A over that of B. This movement cannot however take
place without causing the wheel E to revolve being itself placed under the
influence of a regulating electro magnet by means of the following arrangement-
The wheel E has a toothed crown F engaging a pinion G. This pinion G is
mounted loosely on the shaft of the wheel H, and is provided with a ratchet in such
manner that the wheel H is actuated when the ratchet is turning in the direction of
the automatic approach of the carbons but, on the contrary, the ratchet slips over
the lateral teeth of this wheel when pressure is applied to B for separating or
renewing the carbons.
The wheel H then actuates the wheel M by the pinion L and the latter
actuates N.
The whole device is mounted on a frame O pivoted at O' on screw points and
supported at Q by the spiral spring R. This spring fixed to the column K raises
the armature by means of a curved support S allowing the whole height of the box
to be utilised for this spring. The frame O is raised by the pull of this spring and
assumes the position in which an arm of the mover N strikes against the screw
point T.

page_text: All the gearing is then fixed and it is impossible for the carbons to approach one
another..
An electro magnet mounted in shunt at U draws on the one hand the armature V
fixed in the oscillating frame O and tends to counterbalance the effect of the
spring.
The electric current is brought to the two insulated terminals X X' and from
there is conducted respectively by flexible wires to the two carbon holders Y Y'
insulated with mica on the parts A and B.
At the moment when the lamp is put in circuit, the carbons being no longer in
contact, the total electro motive force of the supply makes itself felt at the
terminals XX, and the magnet, strongly magnetised, pulls the armature sharply.
The drawing shows clearly how the mechanism works; the carbons approach one
'another and come in contact, the electro motive force at the terminals immediately
diminishes, reducing proportionately the attractive force of the magnet and the
opposing spring raising the armature produces the separation of the carbons between
which the arc arises.
In proportion as the carbons are consumed, the arc lengthens, the resistance
increases simultaneously with the intensity of the shunt current.
The magnet again commences to act and little by little, the armature, with the
frame supporting it, causing the carbons to approach together slowly until the
arm N releasing itself from the catch T, the gearing commences to revolve under
the influence of the weight A. The carbons approach one another, the electro
motive force at the terminals diminishes, and the spring again coming into play, brings
back the whole apparatus to its former position. An equilibrium
very quickly
established between the spring R and the magnet U, and the apparatus becomes
sensitive to the slightest variations in the electro motive force, that is to say, in the
length of the arc.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is-
1. The construction of, or combination of parts forming the electric arc lamp,
substantially as hereinbetore described and shown' and more especially the arrange-
ment by which the carbons are prevented from approaching one another when the
electric current is interrupted.
Dated this 20th day of November 1891.
WM. P. THOMPSON & Co.,
Agents for the Applicant.