Granular microphone in glass tube, 1878-1890

PART OF:
four granular microphones, 1878-1890
Made:
1878-1890 in England
maker:
David Edward Hughes
Granular microphone in glass tube Granular microphone in glass tube

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

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

Granular microphone in glass 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:
1922-224/3
Materials:
glass, metal (unknown), wax and carbon
Measurements:
overall: 23 mm x 75 mm x 25 mm, .009 kg
type:
microphone
credit:
Executors of the late Anna C. Hughes