Adevice for measuring atmospheric pressure is a

Barometer

The device used in meteorology to measure atmospheric pressure is called a barometer. It consists of a long glass tube filled with mercury and turned upside down into a container of mercury. The tube is closed at one end and open at the other which works by balancing the mercury in the glass tube against the outside air pressure. As air pressure increases, the air becomes heavier and it pushes more of the mercury up into the tube. As air pressure decreases, mercury drains from the tube. 

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.