Cooke and Wheatstone telegraph
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The Cooke and Wheatstone Telegraph was an early telegraph dating from the 1830s.
Overview
It was designed by its namesake inventors, William Fothergill Cooke and Charles Wheatstone.
The receiver had 5 pointers, two of which were energized to point to the selected letter.
Power source
The telegraph was most likely powered by a chemical battery[1] until the invention of the power station in 1882.
Advantages
The main advantages of this telegraph were that it is designed to be used by relatively unskilled operators. The telegraph displayed to the receiver the letter that had been sent.
Disadvantages
The main disadvantage was that is required 5 five wires to connect the sending and receiving stations. A sixth wire might also be desirable for the return current if the earth return were poor, or if there was interference from other circuits.
Another disadvantage was that only 20 letters could be displayed of the 26 letters in the English Alphabet, leaving out C, J, Q, V, X and Z.
Obsolescence
It was later found that telegraph messages could be received by sound alone, which was the basis of the 1-wire and 2-wire Morse Telegraph, which also had no difficulty transmitting the whole alphabet plus symbols as well.
Diagram
Famous Tawell Arrest
The Cooke and Wheatstone Telegraph was famously involved in the arrest of murderer John Tawell. Because this telegraph lacked the letter "Q", while the message contained the word "Quaker", the receiving operator had some trouble understanding that "Kwuaker" was meant to be "Quaker".
It is not clear how the other missing letters would have been transcribed:
- C- K,S?
- J - I ?
- Q - KW
- V - U?
- X - KS (think of sox and socks)
- Z - ?