Easy Working Model of a MONOMETER used to measure Liquid & Gas Pressure Learn Science with Neha 

Manometer - A device used to measure pressure of Liquids based on the difference in water level in both the columns which have water
As you go deeper pressure of water increases & as you move up , it decreases. Pressure is measured in atm ( Atmospheres) .
P= hmg
H is Height or depth as you move down.
m is mass of water
g is acceleration due to gravity
Liquid used in manometer is coloured water