Telegraphone for recording on disc.
© Science Museum / Science & Society Picture Library
This clock-work-driven disc-type telegraphone was used for magnetic recording and replay of sound, and was a forerunner of the modern dictaphone. The Telegraphone was patented in 1898 by the Danish electrical engineer and inventor Valdemar Poulsen (1869-1942). Poulsen discovered that he could record sound by speaking into a microphone attached to a magnet that was moved slowly acros a thin wire. As the wire became magnetised, a trail of sound patterns was recorded.