The Brillié is one of the few master clocks which have a sweep seconds
Interestingly,the French terminology for a "Master" clock is
a "Mother" clock and a "Slave dial" is called a
"Daughter clock". The French always seem to do things
differently but in this politically correct day and age, "daughter
clock" may have a better sound than "slave"
The clock shown here is a typical Brillié master clock in a metal case
intended for industrial or office use.
Mahogany cased versions can also be found but are less common. One for
domestic use (the slave drive contacts are not fitted) is shown here
A four glass version designed just as a clock is especially collectable
Brillié clocks are not often found in England (where I live) but were
very popular in France, where they developed from a clock invented by
Charles Féry in 1908. The Brillié Bros, with Charles Le Roy developed a
system based on Féry's clock for the Paris Observatory in 1910. The shape
of the magnet was modified to give a more uniform magnetic field, this
modification was due to Marius Lavet who later designed the first
transistor switched clock for ATO.
The small bars of soft iron near the coil act as regulators. Contacts
in the master clock version provide a pulse every 30 seconds but these are
of alternating polarity.