Experimental microphone in sound box, consisting of two small blocks of wood-charcoal pressed upon each other by a spring, probably made by David Hughes, England, 1878-1890 Experimental microphone in sound box, 1878-1890 1878-1890
One of a pair of home made Bell telephone receivers, probably made by David Edward Hughes, England, 1875-1890. one of a pair of home made Bell telephone receivers, 1875-1890 1875-1890
One of a pair of home made Bell telephone receivers, probably made by David Edward Hughes, England, 1875-1890. one of a pair of home made Bell telephone receivers, 1875-1890 1875-1890
Four granular microphones, three in glass tubes, one in bamboo tube, probably made by David Edward Hughes, 1878-1890 four granular microphones, 1878-1890 1878-1890
One experimental microphone in sound box, consisting of two small blocks of wood-charcoal pressed upon each other by a spring, probably made by David Edward Hughes, England, 1878-1890 One experimental microphone in sound box, 1878-1890 1878-1890
Experimental microphone consisting of carbon pencil in carbon cups, probably made by David Edward Hughes, England, 1878-1890 Experimental carbon pencil microphone, 1878-1890 1878-1890