Granular microphone in bamboo tube, 1878-1890

Granular microphone in bamboo tube Granular microphone in bamboo tube

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Granular microphone in bamboo tube
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Granular microphone in bamboo tube
Science Museum Group Collection
© The Board of Trustees of the Science Museum

Granular microphone in bamboo tube, probably made by David Edward Hughes, England, 1878-1890.

The development of the microphone owes much to David Edward Hughes (1831-1901). Building on the work of Willoughby Smith and Sir William Thomson, Hughes attempted to detect changes in the resistance of wire with sound. He discovered that these changes occurred only when his stretched test wire broke and when he touched the ends together. He found that light but constant pressure was the only essential and in this experiment tried powdered carbon with means for adjusting contact pressure. Hughes did not patent his discoveries, meaning that subsequent inventors were able to make use of them without giving Hughes the credit.

Details

Category:
Telecommunications
Object Number:
1922-224/4
Materials:
bamboo, wax, metal (unknown) and carbon
Measurements:
overall: 100 mm x 50 mm diameter, .01 kg
type:
microphone
credit:
Executors of the late Anna C. Hughes