Mechanical telephone, used for communicating between two places a short distance apart, unknown maker, probably British, 1880-1920.
Mechanical telephones work by using a very taught wire between two points, along which vibrations can travel. As they contained no electrical transmitting or receiving devices, mechanical telephones didn't infringe Bell's telephone patents. Therefore they were popular as an alternative method of short range communication during the early years of the telephone, when sets were expensive. These examples were probably used in a railway office or yard.