Experimental microphone using steel needles and gas carbon, 1878-1890

One experimental microphone consisting of steel needles suspended in contact with blocks of gas carbon, 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 steel needles in contact with blocks of carbon. Hughes did not patent his discoveries, meaning that subsequent inventors were able to make use of them without giving Hughes the credit.