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

There's a little BIO below for those interested.
About ATO
ATO is short for Hatot (Leon Hatot) Léon Hatot born 22.04.1883 died 11.09.1953. He was a French clock maker and is famous for producing one of the first battery operated clocks in the 1920s. He patented the classic form of pendulum which used a magnet and coils to impulse the pendulum.
Art Deco World has dated this piece to the 1930s.
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