Museum of Communication at Burntisland

Telephony

This section is devoted to methods of comunicating via telephone systems. In basic terms, the telephone is an instrument designed to transmit speech and other sounds to a distant point by means of electricity, and to reproduce them. The telephone contains a diaphragm, which vibrates when struck by sound waves. The vibrations (wave motion) are converted into electrical impulses and transmitted to a receiver, which converts the impulses back into sound.

Although the basic components remain the same - transmitter/microphone (mouthpiece) and receiver (earpiece) - the telephone's appearance has changed considerably since its invention in 1876 by Alexander Graham Bell. The earliest phones consisted of separate Mouth and Ear Pieces, but in 1895 the Skeleton Telephone (known as the Eiffel Tower phone in the US) was introduced. The design is ingenious: the curved legs form the magnets for the hand generator and the turret below the handset houses the induction coil for the speech circuits (see picture opposite).

In the early days, it was necessary to call the operator to be put through to another number. This was achieved by turning a handle or pressing a button, which lit up a light at the local exchange. However, getting connected became easier with the advent of the rotary dial. The rotary dial’s output of electric pulses is well suited for controlling step-by-step switching equipment used in the first automatic exchanges. However, mechanical dials were a major source of repair costs in telephones and the rotary dialling process is slow, especially if a long string of digits is dialled. Today, most telephones have pushbuttons instead of a rotary dial.

At the turn of the 20th Century the candlestick telephone became popular before the invention of the one-piece handset. The first Candlestick phones were introduced when the magneto system was in use, which meant that the phone was connected to a large wooden box called a "subset" containing a battery, bell, and crank.

Click here for further information on the internal components of a candlestick telephone.

Mary J. MacDonald, 4 Oct 2005

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