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The aneroid barometer

This type of barometer is much more portable than the mercury barometer and is found in many homes. It uses a partially evacuated metal box with thin corrugated sides that is stopped from collapsing by a strong metal spring that is fixed to one side. The box is connected to a dial by a set of levers and a light chain.

When the atmospheric pressure changes the box is stretched or squashed a little. This movement is magnified by the system of levers and so the pointer moves.

An Aneroid barometer can also be used as an altimeter in an aircraft because the pressure of the atmosphere changes with height. The lower the pressure the higher the plane.

© Keith Gibbs 2011