Passenger at a drinking fountain at Chester station, Cheshire, 1921.
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The passenger is buying a paper 'Dixie' cup from a machine, for 1/2 d and will fill the cup with water from the fountain. Dixie cups were invented in 1900 in the USA. Prior to this people drank water from a ladle dipped in a barrel, but this was thought to be unhygenic, and disposable paper cups were invented.