High Quality Content by WIKIPEDIA articles! An atmospheric railway uses air pressure to provide power for propulsion. In one plan a pneumatic tube is laid between the rails, with a piston running in it suspended from the train through a sealable slot in the top of the tube. Alternatively, the whole tunnel may be the pneumatic tube with the car being the piston with a seal to the walls. By means of stationary pumping engines along the route, air is exhausted from the tube leaving a partial vacuum in advance of the piston or car, and air is admitted to the tube behind the piston or car so that atmospheric pressure propels the train. In some plans, air pressure is applied behind the piston/car.