Do you know what are aircraft carriers? Aircraft carriers are warships that are like floating airfields. They are built so that the top deck is almost free from any kind of superstructure and can act as a runway for aircraft.
This is called the flight deck. The aircraft belonging to the carrier are stored and repaired in hangars inside the ship and raised and lowered to and from the flight deck by giant lifts.
The first true aircraft carriers were built just after the First World War. During the Second World War, great naval battles were fought between fleets of aircraft carriers, each fleet sending its aircraft to attack the other. Since the Second World War, fewer aircraft carriers have been built.
However, one famous carrier of today is the American USS Enterprise. She is nuclear powered, and one of the largest warships now afloat. Modern jet flightier aircraft can land and take off from her 240 m twin-runway flight deck, and she has her own guided missile defense system.
Why do we Need Lighthouses?
Along with many stretches of coast, lighthouses have been built to warn ships of special dangers such as rocks or to indicate a harbor entrance. During the day lighthouses, an e clearly saw, because they are usually tall, narrow structures often painted in broad bands of black and white.
It is at night that they are especially valuable to shipping, because at the top of their structure they house a powerful electric lamp, very much like a searchlight, which swings around and sends great beams of light out to sea.
When ships captains or navigators see this beam they can tell their exact position and steer clear of whatever dangers the lighthouse keepers used to warn approaching shipping by ringing a bell. Today lighthouses are equipped with electric horns or sirens.
The first lighthouse in the world was the pharos of Alexandria-one of the Seven Wonders of the World. It was built in about 300 B.C. and was 119 m high, with a fire burning at the top.
One of today’s most famous lighthouses is the Bishop Rick lighthouse off the Scilly Isles, which is the first sight of land for any ships approaching Europe from the Atlantic.
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