at a short distance from the arc, and this is one of the principal
advantages possessed by the Reynier-Werdermann system. At a certain
epoch it was thought that the problem might be simply solved by
arranging in front of each other two carbons actuated by a spiral
spring, as in car lamps, and kept at a proper distance apart for forming
the electric arc by two funnel-shaped pieces of calcined magnesia, into
which they entered like a wedge in measure as their conical point were
away through combustion. This was the system of Mr. De Baillehache,
and the trials that were made therewith were very satisfactory. But,
unfortunately, the magnesia was not able to resist very long the
temperature to which it was submitted. The problem found a better
solution in the sun-lamp but has been solved in another manner, and just
as simply, by Mr. Solignac, and the results obtained by him have been
very satisfactory as regarded from the standpoint of steadiness of the
luminous point.

In this system, a general view of which is given in Fig. 1, and the
arrangement in Figs. 2 and 3, the carbons, F F, which are horizontal and
about fifty centimeters in length, are thrust toward each other by
two barrels, K, K, which wind up two chains, E, E, passing around the
pulleys, D, D, fitted to the extremities of the carbons. These latter
are provided beneath with small glass rods, G, G, whose extremities
toward the arc abut at a short distance from the latter against a nickel
stop, L (Fig. 3), which supports them, moreover, at M, by means of
a tappet whose position is regulated by a screw. The current is
transmitted to the carbons by two friction rollers, I, I, which serve at
the same time as a guide for them, and which give the electric flux a
passage of only one or two centimeters over the front of the carbon
to form the arc. Finally, the whole is held by a support, A, and two
pieces, CB, CB, which at the same time lead the current to the friction