The key component of Louis John Crosley's improved telephone was the microphone invented by David Edward Hughes (1831-1900) in 1878, only two years after Alexander Graham Bell's (1847-1922) invention of the telephone. Crosley's transmitter used the same loosely touching carbon rods as in Hughes' device to translate sound into electrical waves, but it was much better designed. This telephone was made by the Yorkshire partnership of Emmot and Blakey. Walter Emmot was well known to William Preece, Chief Engineer of the Post Office, which bought the Crosley telephone in large numbers.
© Science Museum / Science & Society Picture Library