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Wires and circuits

Electricity needs an unbroken,continuous path for the current to flow along. This path - the electric circuit - needs a voltage from a battery or an electrical generator to push the current around it, and it's the current that powers the machine at the other end. This machine is often referred to as the 'load' of the circuit.

Given a choice, electricity will take the easiest path round a circuit. If you put a wire directly across the load - a 'short circuit' - most or all of the current will go down this path. (For safety, fuses are used to break the circuit deliberately if the current gets too high.)

London & Globe telephone receiver

London & Globe receiver (c1881) : a battle for supremacy

There was fierce competition between companies setting up the telephone systems which bred a number of unscrupulous, if entertaining, battles.

Because the United Telephone Company held most of the patents for telephone equipment, it was almost impossible for competing companies to operate, or get the necessary equipment.

In 1881 the short-lived London and Globe Telephone and Maintenance Co tried by using equipment obtained from other suppliers. However, winning business proved trickier.

There are stories that the Globe hurriedly planted their own poles in holes dug by the United. They also claimed 'aerial rights' above their exchange building, over which many 'United' lines passed. When the United refused to move them, the Globe did it themselves, by throwing wires around them and heaving the United lines to one side. The crossed line they created caused huge problems for United customers.

The challenge ended when the United bought the Globe and its patents for £25,000.

Leclanche cell

Leclanche battery cell (1880s) : the power behind the phone

Before power was centralised in the exchanges, every telephone needed to have its own source of electricity and for many telephones this was what it looked like. The battery was hidden inside a wooden box, often fixed with the telephone on the wall.

The form of chemical cell was particularly suitable for early telephone installations. Compared to other types, it was relatively clean and needed minimum maintenance.

It proved less suitable as conversations lengthened, and for long-distance calls. In a prolonged call, the start might be fine, but the conclusion could well be inaudible, as the battery ran down. However, the Leclanche was to some extent self re-charging, thanks to the chemicals inside it reacting to the surrounding air and before too long the telephone would be ready for action again.

How does an electric circuit work? : the basics made simple

How does an electric circuit work? : the basics made simple
fun and games

Can you beat our games? Explode equipment to see what's inside, hear the changing sounds of telecommunications, see how telecommunications designs have changed over time or send an e-postacard.

what's on

The UK's first permanent gallery dedicated to the history of information and communication technologies opens in the new Information Age gallery at London’s Science Museum.

audio history

Take a trip down memory lane with extracts of the interviews which have been recorded as part of the Connected Earth oral history programme.

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100 years of automatic switching!
In 1912 the GPO installed Britain's first automatic telephone exchange in Epsom.

Discover the early days of the telephone...