_The Lamp_ (Figs. 1, 2, and 3.)--The bottom or negative carbon is fixed,
but the top or positive carbon is movable, in a vertical line. It is
screwed at the point, C, to a brass rod, T (Fig. 2), which moves freely
inside the tubular iron core of an electromagnet, K. This rod is
clutched and lifted by the soft iron armature, A B, when a current
passes through the coil, M M. The mass of the iron in the armature is
distributed so that the greater portion is at one end, B, much nearer
the pole than the other end. Hence this portion is attracted first, the
armature assumes an inclined position, maintained by a brass button, t,
which prevents any adhesion between the armature and the core of the
electromagnet. The electric connection between the carbon and the coil
of the electromagnet is maintained by the flexible wire, S.

[Illustration: FIG. 3.]

The electromagnet, A (Fig. 1), is fixed to a long and heavy rack, C,
which falls by its own weight and by the weight of the electromagnet and
the carbon fixed to it. The length of the rack is equal to the length of
the two carbons. The fall of the rack is controlled by a friction break,
B (Fig. 3), which acts upon the last of a train of three wheels put
in motion by the above weight. The break, B, is fixed at one end of
a lever, B A, the other end carrying a soft iron armature, F,
easily adjusted by three screws. This armature is attracted by the
electromagnet, E E (whose resistance is 1,200 ohms), whenever a current
circulates through it. The length of the play is regulated by the screw,
V. The spring, L, applies tension to the break.

_The Regulator_.--This consists of a balance and a cut-off.