How do deep-sea divers operate?

           Since ancient times, man’s curiosity has led him to explore the dark, mysterious world of the deep seas. Diving has therefore developed to be an important sport over the years. But how do men stay under water for long periods of time?

          The first practical diving apparatus was devised by a German scientist, named Augustus Siebe in 1819. It comprised a metal helmet with a shoulder plate attached to a waterproof leather jacket. A tube running from the helmet was attached to an air pump. This was the first of many major experiments he carried out in trying to perfect a safe method of staying and working under-water. In 1830 he designed and developed a complete suit and helmet with air valves. Although many improvements have since been made, Siebe’s principles remain in universal use. 

          Deep sea divers, such as those who search shipwrecks for treasure, are divided into groups. They are skin divers who wear rubber suits that fit tightly like the skin, and divers known as ‘hard hats’ who wear heavy diving dress.

          A deep sea diver should use seven essentials: (a) An air pump for pushing air downwards to him. (b) A helmet, usually of steel, with glass windows to see. (c) A flexible waterproof suit fitting closely at wrists and ankles. (d) A length of air tubing that must be flexible, but must not collapse under the pressure of water. (e) A pair of heavy boots to keep the feet on the bottom. (f) Lead weights, hooked to chest and back, to prevent floating up to the surface. (g) A life-line to communicate with the surface by a system of jerks. One jerk may mean danger, and so on!

          Some divers also have a telephone so that they can talk to the ship. The wires for these telephones are built into the lifelines.

          Water pressure is a big problem for deep sea divers. The deeper a diver goes, more becomes the pressure of water around him. So the air pumped down must enable him to breathe properly and also balance the water pressure outside.

          In the past, deep sea divers used to breathe ordinary air, which contained nitrogen.

          This was very dangerous because when the pressure was very high, nitrogen would dissolve in the blood. When the diver surfaced, the pressure quickly returned to normal, which caused the nitrogen to bubble out of the blood. This led to a very painful illness which could even kill the diver, called as ‘Bends’ or ‘Caisson disease’. To avoid this, divers now breathe a mixture of oxygen and helium. Helium does not dissolve in the blood, so it is safer to use. But breathing helium makes divers speak with a high, squeaky voice because sound travels three times as fast as it does in air!

          In recent years, diving has not only become a popular sport, but is also useful in performing important jobs. Divers are needed for the construction and repair of bridges. They study plant and animal life beneath the surface of water. They aid in finding drowned people, and they also help in the search for buried treasure!