4.8 Has the telephone led to any related or spin-off products?
There have been a number of branches of the telegraph and the telephone family tree where research and experiment into one technology have contributed to the development of another.
An early example was Edison inventing the phonograph. He'd been working on a telegraph repeater to record telegraph signals using a stylus to vibrate onto and indent a sheet of paper. The idea was that when the indented paper passed across the stylus again the indentations would cause identical vibrations and the telegraph message would be repeated exactly. Edison was also experimenting to improve the telephone.
When feeling the vibrations caused when sound passed through the diaphragm in a telephone mouthpiece, Edison realised that the repeater idea could be applied to the human voice being transmitted by the telephone. His first working prototype of the phonograph was hand-cranked and used tinfoil as the recording medium. Though there was something almost miraculous about hearing the human voice reproduced by this simple mechanical device there was no obvious use for it, particularly when the quality of recording was so poor. One of Edison's first ideas was to use it to record telephone conversations for posterity. After the initial excitement Edison abandoned the phonograph to work on the electric light.
Ten years later, under pressure from Bell who was developing an improved version of the phonograph, Edison finally produced a commercial phonograph using an electric motor and hard wax-coated cylinders that delivered much better sound quality. Around the same time Emile Berliner was inventing a means of recording onto a flat wax-coated zinc disk. Even this was initially regarded and marketed as a toy, but eventually the gramophone formed the basis of a huge industry for selling recorded music.
Another of the branches led to radio and then mobile telephony. The work of Bell, Edison and others on improving the telegraph and transmitting sound along wires led eventually to wireless transmission – Marconi was transmitting Morse code messages from ship to shore in 1897 and eventually across the Atlantic in 1901. The first commercial transatlantic radio voice service began in 1927. The first radiotelephone service for vehicles was introduced in the US in 1946.
In 1947 microwave radio transmissions started to be used for long-distance telephony and by the early 1960s telecommunications satellites were being used for round-the-world contact. The first portable cellular phone appeared in 1979. Today's mobile phones might seem like a different product from Bell's early prototypes but there's a continuous line of scientific discoveries and developments in technology and materials connecting the two (Figure 6).