The first English edition of a work originally published in Paris in 1878, this book is an important early contemporary account of the gestation of three important and interrelated inventions. Heavily documented and supported by valuable engraved illustrations, most of Count Du Moncels work is devoted to telephones. He discusses telephone development and competing systems as well as describing the experimentation taking place during the period of Bell's 1876 patent application. Briefer attention is given to the initial stages of microphone technology and information is included about Edison's phonograph.