air pressure

the force exerted by air, whether compressed or unconfined, on any surface in contact with it.

Origin of air pressure

First recorded in 1870–75

Its function is probably to keep the air-pressure equal on both sides of the drum.

How it Works |Archibald Williams
We are now getting the air-pressure through the pipe in both ends of the tube alike, and do not move the pellet either way.

Steam Steel and Electricity |James W. Steele
Railway air-brake, use of air-pressure in applying brakes to the wheels of a car.

The Story of Great Inventions |Elmer Ellsworth Burns
A thin place or a hot place will give way under the air-pressure and be sucked into the tube.

Laboratory Manual of Glass-Blowing |Francis C. Frary

By using an air-pump to remove the air-pressure, water may be made to boil when it is still quite cold to the hand.

The Story of Great Inventions |Elmer Ellsworth Burns