An aneroid barometer is an instrument used to measure atmospheric pressure. The name “ANEROID” itself means ‘without water’ , that gives clear indication that there is no involvement of liquid.
A metal box partially exhausted of air (vaccum) will undergo changes of shape as the outside pressure varies. These small movements of the box are transmitted to a pointer displayed on the face of the aneroid barometer by a system of levers.
Construction & Working:
Its construction includes a thin metal chamber which is sealed but having partial vacuum inside. This chamber is fitted with certain levers and spring mechanism to which a needle is connected , which shows the barometer readings in milibars or hectopascals projected on a graduated circular card. The thin metal chamber has elastic properties , when atmospheric pressure increases this chamber gets compressed , when atmospheric pressure decreases , the chamber gets expanded , this inward and out ward movement of the chamber acts on the needle mechanically and the needle then registers a reading on the graduated card. The accuracy of the reading depends upon the size of the metal chamber , if the chamber is large , accuracy will be better.