Double-plate sounder (1860) : a Bright idea

The needle telegraph moved fairly quickly from five needles to one and it was simple enough to understand a message with a little practice. One swing to the left could mean one letter, while two to the right might indicate another. The problem was trying to write it out at the same time as reading it.

The solution was to match the movement of the needle to sound. There were several attempts at workable machines, but this elegant piece of machinery, crafted by an engineer named Sir Charles Tilson Bright was one of the first to succeed.

He linked the movement of the needle to sounders on either side of the dials. If it flicked to the left it rang 'ting' and to the right 'tong'. This way the operator could listen to the message ringing out of the telegraph without needing to look at the dials and could concentrate on writing it down correctly.