Electric lamps on the arc principle are almost as numerous as the trees
in the forest, and it is somewhat fresh to come upon something that is
novel. In these lamps the carbons are consumed as the current flows, and
it is the variation in their consumption which occasions the flickering
and irregularity of the light that is so irritating to the eyes. Special
mechanical contrivances or regulators have to be used to compensate for
this destruction of the carbons, as in the Siemens and Brush type, or
else refractory materials have to be combined with the carbons, as in
the Jablochkoff candle and in the lamp Soleil. The steadiness of the
light depends upon the regularity with which the carbons are moved
toward each other as they are consumed, so as to maintain the electric
resistance between them a constant quantity. Each lamp must have a
certain elasticity of regulation of its own, to prevent irregularities
from the variable material of carbon used, and from variations in the
current itself and in the machinery.

In all electric lamps, except the Brockie, the regulator is in the lamp
itself. In the Brockie system the regulation is automatic, and is made
at certain rapid intervals by the motor engine. This causes a periodic
blinking that is detrimental to this lamp for internal illumination.

[Illustration: FIG. 1. FIG. 2.]

M. Abdank, the inventor of the system which I have the pleasure of
bringing before the Section, separates his regulator from his lamp.
The regulator may be fixed anywhere, within easy inspection and
manipulation, and away from any disturbing influence in the lamp. The
lamp can be fixed in any inaccessible place.