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His inventive faculties now getting full play, he took out over fifty patents in connection with improvements in telegraphy, including the duplex, quadruplex, and sextuplex system; the carbon telephone transmitter; microtasimeter; aerophone, for amplifying sound; the megaphone, for magnifying sound.

Amongst his numerous inventions are the quadruplex and sextuplex telegraph, the carbon telephone transmitter, the 'Edison system' of lighting, the electric fire-alarm, the 'Edison electric railway', the phonograph, and the megaphone.

Among his principal inventions are his system of duplex telegraphy, which he later developed into quadruplex and sextuplex transmission; his carbon telephone transmitter; the microtasimeter, for the detection of small variations in temperature; the phonograph, which records and reproduces all manner of sounds; the cinematograph, which his improvements made practicable; and his method of preparing carbon filaments for the incandescent electric lamp.

He was still busily engaged on the telephone, on acoustic electrical transmission, sextuplex telegraphs, duplex telegraphs, miscellaneous carbon articles, and other inventions of a minor nature.

Here he continued, moreover, his earlier work on the quadruplex, sextuplex, multiplex, and automatic telegraphs, and did his notable pioneer work in wireless telegraphy.