The Irish scientist Robert Boyle investigated the relationship between pressure and volume in the 17th century. He trapped a bubble of air at the sealed end of a J-shaped tube using liquid mercury.

Standard altitude-pressure tables allow mountaineers and aviators to determine their approximate height by measuring atmospheric pressure. This relationship ... per unit of volume, and therefore ...

Charles’ Law states that if a gas is heated up and the pressure does not change, the volume will. So, for a fixed mass of gas at a constant pressure, volume ÷ temperature will remain the same.