Unsigned but likely Pericaud or Radiguet
In 1878, the carbon microphone was invented by David
Edward Hughes. Hughes's microphone was the early model for the
various carbon microphones now in use. This apparatus was manufactured
to be used as an instrument of physics experiments for schools and
The Blake transmitter was
the first successful telephone transmitter (microphone). It was invented by
Francis Blake in 1878 and used a carbon and platinum resistance element.
It was later improved by Berliner and remained the standard for many years.