Art Deco World has dated this piece to the 1930s.

Short BIO below.
ATO is short for Hatot (Leon Hatot) Léon Hatot born 22.04.1883 died 11.09.1953.
He patented the Classic form of pendulum which used a magnet and coils to impulse the pendulum. This is done by the current from the first coil switching a transistor which supplies a larger current to the second coil at the right moment. Lalique supplied some of the glass panels for some of his clocks. He used various materials to produce his clocks, marble, onyx, bakelite, wood and glass.
Art Deco World has dated this piece to the 1930s.
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