Its use in offices 293 Its use in telegraphic service 294 Its application to military purposes 297 Its application to industry 302 Its application to scientific research 303 _THE PHONOGRAPH._ Edison’s patent 309 Description of phonograph 313 Several systems 322 Theory of phonograph 327 _USES OF PHONOGRAPH._ Account by Edison 333 Lainbrigot’s system 339 _FABER’S SPEAKING MACHINE_ 341 _APPENDIX._ Perrodon’s system of telephonic alarum 351 Varey’s microphone speaker 352 Fitch’s microphone speaker 353 Theory of telephone 353 Pollard’s microphone 356 Ader’s electrophone 357 Gower’s new telephone 358 Transmission of speech by telephones without diaphragm 360 THE TELEPHONE, _&c._ _HISTORY OF THE TELEPHONE._