Ansonia crystal regulator mantel clock. Circa 1914.

This is an Ansonia crystal regulator mantel clock, an antique timepiece produced around the year 1914, by the Ansonia Clock Company, which was active from 1844 until just before the 1929 market crash.
These clocks are characterized by four beveled glass panels that allow visibility of the inner mechanism.
They typically feature ornate brass or gilt metal cases with onyx or marble accents.
The movements are often eight-day, time-and-strike mechanisms with an open escapement and a porcelain dial.
American crystal regulators, like this one, typically used a pendulum with nickel slugs in the vials, in contrast to the mercury pendulums found in many French versions, making them a more economical alternative.