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Replica Of Parabolic Receiver For Marconi's Original Beam System, by Marconi Company, London, 1920s/1930s

Inventory Number: 40344

Number of documents: 2

Document Type: Label

Document Heading: Celluloid Plaque


The circular celluloid plaque seems to refer to an early display (late 1920s-1930s) of historic Marconi equipment, and the celludloid company label may also have been made for this purpose. The two instruments that make up Marconi's Original Beam System (Inv. Num.s 59943 & 40344) have long been described as replicas, and were presumably constructed for this display, probably using original components.

Document Type: Label

Document Heading: Museum Label


The beam system is described thus in an associated museum label: "These are replicas of Marconi's first experimental apparatus using parabolic reflectors for the transmission and reception of wireless telegraphy. With such apparatus he demonstrated in Italy the possibilities of 'beam' transmission and reception. He confirmed his results officially before representatives of the British Post Office, the Navy and the Army at Salisbury Plain, in September 1896 when he communicated over 1 miles."

The receiver of the beam system is described thus in an associated museum label: "A Marconi Coherer with small copper wings forming a Hertz resonator is placed in the focal line of a similar parabolic cylindrical copper mirror. The recording apparatus, consisting of an ordinary telegraph relay and Morse recorder and the necessary batteries were connected to the four terminals shown. The two reflectors were placed exactly in line and the wings of the Hertz resonator connected to the coherer were properly adjusted to correspond to the wavelength of the transmitter. When the transmitting key was pressed, sparks were caused to pass between the balls of the Righi oscillator, the metal filings in the sensitive tube cohered and became conductive, thus permitting a weak current to pass through the tube and the telegraph relay. This brought into action the Morse Recorder, which registered a dot or a dash as the case might be, and the tapper tapped the tube, causing filings to decohere, the sensitive tube or coherer becoming non-conductive again; the tapper then ceased to function, leaving the tube ready for the next signal."

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