print. etching. David Edward Hughes 1831-1900 / A. Delzers ; avec la permission de Elliott & Fry, Londres. - n.d. [1955-1964] [Men in telecommunications] International Telecommunication Union 23x19cm. -Portrait. HS slightly to L. Hughes, born London, worked in United States, invented carbon microphone, taught music and studied the science of sound, patented type-printing telegraph instrument, invented induction balance and worked with the theory of magnetism.