perform, and that at the beginning, but this once done the apparatus
operates with certainty, and for a long time. With a Meritens machine of
the first model it has been found possible to light five lamps of this
kind placed in the same circuit.

[Illustration: Fig. 2]

According to the inventor, this lamp will give a light of 100 carcels
per one horse-power, and with a three horse-power six lamps may be
lighted; but we have made no experiments to ascertain the correctness of
these figures.

As for the cost of the glass rods, that amounts to one franc per
two hundred meters length. They can, then, be considered only as an
insignificant expense in the cost of the carbons. We consequently
believe that it will be possible to employ this system advantageously in
practice.--_Th. du Moncel_.

[Illustration: Fig. 3]

* * * * *




MONDOS'S ELECTRIC LAMP.


Since the month of May last, the concert at the Champs Elysees has been
lighted by sixteen voltaic arc lamps on a new and very simple system,