The BT Museum Memorial Pages

Telegraphy Items - 1

Wheatstone's ABC Telegraph

Wheatstone ABC Telegraph An example of de-skilling. Unlike Morse telegraphs, no knowledge of a code was needed. The button next to the desired letter was held down and the handle cranked. The needles of the instruments at both ends moved until they pointed to the chosen letter. The foreground part of the instrument is the transmitter, and the part at the back is the receiver.



Wheatstone Stick Punch

Stick punch Wheatstone's first means of producing punched paper tape for high speed Morse transmission. Paper tape feeds from the reel at the back through the punch head. The operator supplies all the power by striking the buttons at the front using the sticks whose tips are just visible in the foreground.



Pneumatic Punch

Pneumatic punch Wheatstone's original method of preparing punched Morse tape required the operator to thump the keys very hard with a stick. This later development used a pneumatic action to make only a light pressure on the keys necessary to punch the tape. The three keys would produce a dot, a dash, or a space.



Morse Transmitter

Morse Transmitter Messages prepared in advance on paper tape could be sent to line at much greater speed than possible with a human operator. The tape was advanced by a series of sprocket holes in the centre with larger holes either side signifying a dot or a dash. A pair of "peckers" underneath felt at the holes and translated them into the dots and dashes to line.



Morse Sounder

Morse Sounder The black coils of the electromagnet attracted the steel pole piece, across the top, pulling the pivotted brass lever down giving the characteristic click. The sound was amplified by placing the sounder in a wooden case (in background)



The Baudot Distributor

Baudot Distributor An early system of time-division multiplex. The operators' keyboards were connected to a single telegraph circuit via the distributor. At the receving end the receivers were connected through a similar distributor. By keeping the commutators at both ends in synchronism the signal from one keyboard was routed to its correspnding receiver. This Baudot distributor (now believed to be at Amberley) is more complete than the one in the Science Museum.



Baudot Keyboard

Baudot Keyboard The operator had to memorise the five-unit code and press the keys at the precise moment the commutator was connected. The operation is described in the Short History of Telegraphy




 

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Exhibits: British Telecom Collection
Photos: copyright Sam Hallas 1992-1997

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