The only absolute pressure gauge is the manometer, but, because it is liquid filled, it is difficult to transport, and must always be kept vertical.
A solution is the aneroid barometer, in which a sealed bellows expands and contracts as the outside pressure changes.
In 1849 the Bourdon tube pressure gauge was invented in France by Eugene Bourdon. In this design the gas whose pressure is to be measured is introduced into a flattened tube coiled into a full circle. As the pressure increases the tube straightens out, and the motion of the free end of the tube is amplified by a mechanical lever device.
The apparatus at the left is at Cornell University, and is large enough to be viewed by a class of several hundred students.