Microphone, after Hughes

In 1878 the English professor David Edward Hughes (1831-1900) invented the carbon-rod microphone. Its working is based on the characteristic feature that the electric resistance of carbon varies lightly when a carbon rod is set in vibration (for example by sound). Contemporary microphones are in fact still based on this discovery. Hughes’ microphone was so sensitive, that a demonstration model was usually provided with a ticking pocket watch. The version in the Teylers Museum, however, has a fly cage and the buzzing sound of the caught flies was meant to be transmitted to elsewhere via this electric microphone. During his work on the microphone, Hughes stumbled accidentally across the phenomenon of radio waves, which made him one of the fathers of wireless communication by way of electromagnetic waves.