Antique  instrument measuring atmospheric pressure, used especially in forecasting the  weather and determining altitude.This aneroid barometer is an instrument used  for measuring pressure as a method that does not involve liquid. Invented in  1844 by French scientist Lucien Vidi, the aneroid barometer uses a small,  flexible metal box called an aneroid cell (capsule), which is made from an alloy  of beryllium and copper. It includes a mercury barometer has a vertical glass  tube closed at the top sitting in an open mercury-filled basin at the bottom to  gage temperature .This one is art deco in style so it was produced around 1920.   
Size H.18 x W.8  x D.3 , wood base , good antique condition