Science | 1940 | Silent | B/W
Telephones and how they work 1940's
'Sound is carried over long distances by the telephone'. Lines of telegraph poles. 'A model telephone can be made with pill boxes and string'. Young boys with cups and string telephone over a hedge. 'Sound normally travels through the air'. 'Air is composed of millions of particulars called molecules so small that they are invisible'. Wind through trees. Ping-pong balls. Hammer hits a drum. Diagram of waves through the air. Waves through billiard balls hitting each other. Diagram of waves hitting an ear drum. Waves hitting a diagram to send waves down a line and receiving at the other end. Old dial phone. Receiver is unscrewed and dismantled. Diagram shown. Carbon granules which form the electrical connection. A magnet in the receiver. A man on the telephone, man at the other end.
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