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Picture Telegraphy

    Naturevolume 134page732 (1934) | Download Citation



    METHODS of transmitting pictures by telegraphy have been known for the last ten years. In a suitably constructed photoelectric cell, the electric current through it can be made proportional to the light falling on it. If a picture in the form of a film negative be moved between a constant source of light and a cell in such a way that the light beam passes suc cessively, line after line, through each minute area of the picture, the current transmitted will vary in intensity. The receiver is complicated, but the amount of light from a local source varies with the current received and falls on a photographic film which moves in step with the original film. A photoelectric cell can only distinguish light from darkness. Unlike the eye, it cannot distinguish form and colour. Photographs can be transmitted in this way by both wired and radio telegraphy. A recent remarkable achievement was the photograph of the Duke of Gloucester sent from Australia by the Marconi facsimile system of radio picture telegraphy. A still greater achievement was the transmission of the pictures on ten feet of cinematograph film showing the arrival of Scott and Campbell Black at Melbourne. An example of a news picture sent by the ordinary telegraph services between London and various Continental towns was the funeral of King Alexander at Belgrade. For ordinary commercial purposes, we think that picture telegraphy might be more widely used with advantage. Possibly the facilities it gives have not been sufficiently advertised.

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