ument regardless of the original state, a requirement usually met by mod- ern equipment. 1. Ease of operation. The initial invention was by Alexander Bain in 1843 using a 2. Adequate quality, convenient size and compatibility with the pendulum scanner which made contact with characters of raised working environment. metal type. The current flowing was passed, by the pendulum in 3. Ability to transmit the documents already available in the office. synchronisation at the receiver, through damp chemically impreg- nated paper which then discoloured. This invention operated on 4. Reasonable operating costs, both line and consumables. telegraph wires complementary to Morse and predating the tele- 5. Reliable operation. phone. 6. Growing business base. One of the early uses of facsimile commercially was for the transmission of photographs for newspapers. In this case it was not G3 equipment is stand alone and easy to connect to telephone line just to mark the paper or not, but to mark with a density similar to and to the power source. Its growth in use has been due to the the original photograph. These were dedicated users with skilled application of practical CCITT recommendations which reflect the operators, at a time when almost any effort was justified to obtain technological and manufacturing possibilities. Coupled with this pictures, not to be compared with today's operation. was the development and availability of high sensitivity thermal paper, which ensured the realistic equipment purchase price and Technical problems such as synchronisation, detection of the operating costs. image at the transmitter and exposure at the recorder, amplification and the transmission by radio and telephone line, were solved step by step. In parallel with these solutions the search continued for an ideal 60.2 Facsimile types recording medium with the advantages/disadvantages of photo- graphic, electrolytic, carbon, wax coated, electrostatic, thermal and Excluding the document facsimile equipment, all other types per- now plain pape