4.7 Has telephone design changed over time?
As you can see from Figure 5 the design of the telephone has changed considerably over its lifetime, reflecting the improvements in technology, materials, components and manufacturing processes. Figures 1(a) to (f) show some of the early progress. Figure 5(a) is a replica of Bell's ‘liquid transmitter’ of 1876 and Figure 5(b) is a Bell telephone and terminal panel from 1877 showing the adaptation for two-way conversation. Edison's wall telephone (Figure 5c) was developed by 1880 and the classic ‘candlestick’ table top phone (Figure 5d) by 1900. As the technology improved both transmitter and receiver were incorporated into a single handset (Figure 5e), and once automatic exchanges had been invented room had to be found for a dial (Figure 5f, the Strowger automatic dial telephone, 1905). The appearance of synthetic plastics, starting with Bakelite in the 1920s, permitted new shapes (Figure 5g, Bakelite handset), and later developments led to colour being used in telephones for the first time (Figure 5h, plastic handset from the 1960s; Figure 5i, Trimphone, 1970s). Dials were gradually superseded by push buttons (Figure 5j, Keyphone, 1972). Finally digitalisation and miniaturisation have challenged designers to fit an increasing number of functions into ever-smaller handsets. Figure 6(k) shows Motorola's MicroTAC personal cellular phone, which was the smallest and lightest on the market in 1989, and Figure 5(l) is Samsung's A800 ‘hinged’ mobile phone of 2004.