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FCE - DEVELOPMENTS IN UNDERWATER DIVING

Read the text below and think of the word which best fits each space. Use only one word in each space.

People have been diving without mechanical aids ancient times. In those days, divers mainly went underwater to search pearls or sponges. Various ways of supplying divers with air, and so permitting them to stay underwater for long periods of time, have been tried for well two thousand years. Alexander the Great said to have gone underwater in an early of diving machine, and Aristotle talked about apparatus permitted divers to breathe underwater. It was not the beginning of the 18th century that more advanced equipment was developed. In 1717, the first practical diving machine, or ‘diving bell’ it was called, was invented. This was a small wooden room with an open bottom, glass windows at the top to in light, and a supply of air coming through leather tubes. Something similar, made of steel, is use today for underwater work, as building the foundations of bridges. However, divers want to move freely underwater, they require a suit. Early suits were made up a leather jacket with a metal helmet over the head into which air was pumped down from the surface through tubes. Divers gained even freedom of movement when they could rid of these tubes and carry own air with them in cylinders.