the motorman emerged from his compartment with a hose, lifted an iron cover plate from a hole in the station platform and connected the hose to an underground air-supply line. Incredible though it may seem, there was no compressor on the train, but reliance was placed on periodic charging of a reservoir which fed air to the Westinghouse brakes and also to the Westinghouse electro-pneumatic controllers for the traction motors. When a satisfactory charge had been obtained, the motorman turned off the cocks on supply-pipe and reservoir, and pulled up the hose with a loud "sssh—ack" as the air in the hose escaped.