WHEN was the submarine invented and when was it first used in a military attack? - Jeff Wilkinson, South Moor, Stanley.

ONE of the earliest ways of going underwater without getting wet was to be submerged in some kind of capsule, such as a diving bell or diving chamber. The container would of course have to be heavier than the water and once it was down in the depths there had to be some means to get it back to the surface. Early diving chambers made use of ballast that could be dropped to lessen their weight, although the containers could alternatively be hauled to the surface.

Some underwater vessels were no doubt invented simply to satisfy a curiosity for what lay at the bottom of the sea. According to legend one such vessel - a glass barrel - was constructed for Alexander the Great (356-323BC) who was placed inside the barrel and lowered from a boat using ropes. Further developments took place in Medieval times when experiments with diving bells were carried out by Roger Bacon in the 13th Century and Leonardo da Vinci (1452-1519).

Later diving bells were much more sophisticated and included a wooden diving vessel that could hold five people at a depth of 60 feet for an hour and a half. This was developed by Edmond Halley (of Comet fame) in the 1700s and worked on the principal of two alternate barrels of compressed air moving up and down from the surface, where new air was taken in and stale air released.

In the early 1600s, an underwater boat was constructed by a Dutchman called Cornelius Drebbel for King James I of England. The King is said to have been among its passengers during trips under the Thames.

Another submarine developed in the 1600s was the Rotterdam Boat built by a French inventor called De Son. This was designed for military purposes against the British Navy but the French and Dutch, who were the main potential customers at the time, showed no interest in the development. Major submarine developments took place in the 1700s under a British inventor called Symons who invented a feature called ballast tanks that are still used in submarines today.

More important developments were taking place in America in the late 1700s where submarine technology was gaining ground as a means of attacking the British during the War of Independence. The first attack by a submarine took place in 1776 when a submarine named Bushnell's Turtle attacked a British frigate called The Eagle, which was anchored in New York Bay. This early submarine was a small spherical wooden vessel often compared to a large coconut and had room for only one man.

Further developments took place in submarine technology during the 1800s, including a famous vessel called Nautilus built for Napoleon in his war against the British. The first torpedo-type submarine was developed in France in 1888. In the 20th Century submarines played an important part in the First and Second World Wars and the first nuclear powered submarine was launched in the USA in 1954. It was named Nautilus, after Napoleon's famous submarine.

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