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SOLIGNAC'S NEW ELECTRIC LAMP.


When it becomes a question of practical lighting, it is very certain
that the best electric lamp will be the one that is most simple and
requires the fewest mechanical parts. It is to such simplicity that is
due all the success of the Jablochkoff candle and the Reynier-Werdermann
lamp. Yet, in the former of these lamps, it is to be regretted that the
somewhat great and variable resistance opposed to the current in its
passage through two carbons that keep diminishing in length, in measure
as they burn, proves a cause of loss of light and of variation in it.
And it is also to be regretted that the duration of combustion of the
carbons is not longer; and, finally, it is allowable to believe that the
power employed in volatilizing the insulator placed between the carbons
is prejudicial to the economical use of this system. In order to obviate
this latter inconvenience, an endeavor has been made in the Wilde candle
to do away with the insulator, but the results obtained have scarcely
been encouraging. An endeavor has also been made to render the duration
of the carbons greater by employing quite long ones, and causing these
to move forward successively through the intermedium of a species
of rollers, or of counterpoises, as in the lamps of Mersanne and
Werdermann; but then the system becomes more complicated. Finally, in
order to keep the resistance of the carbons at a minimum and constant,
their contact with the rheophores of the circuit has been established