Cros-section of a telephone cable, c 1900.
© Science Museum / Science & Society Picture Library
Manufactured by British Insulated and Helsby Cables Ltd, this paper-insulated telephone cable transmits signals in the form of electricity. Despite its large size it can only carry a few dozen calls at once. Although many advances in cabling were introduced in the early 20th century, it was not until the introduction of fibre optic cables in the 1970s and 1980s that significant advances were made. Fibre optic cables are only a fraction of the size of wire cables and can carry over 1000 calls at any one time.