HISTORY OF DIVING.
Men and women from an antiquity practised diving with a delay of breath. In the Ancient Greece divers got a sponge from under water, and also participated in military operations.

The most known historic fact has reached us owing to historian Gerodotu. During sea campaign Greek Silis has been grasped and taken aboard by the Persian king Kserksesom I. When Силис has understood, that the Persian king is going to attack the Greek flotilla, it has seized a knife and has jumped off for a board. Persians could not find it behind a board and have solved, that it has sunk. Силис has emerged at night and has floated between all ships перской flotillas, обрезая anchor cords of the ships. To be under water not noticed, it used an empty stem. Then it has floated 13 kilometers and has reunited with the Greek forces.

The desire to plunge under water existed always. It is hunting under water for reception of food, repair of the ships or потопление the ships of the opponent, and, probably, for research of a sea life. Before people have found a way to breathe under water, each immersing was short and complex.

How to remain under water on a lot of time? Breath through a stem allows the person to plunge, but, it is obvious, if the stem is more 0,5 m, will breathe through it difficultly. Breath from a bag filled by air and placed under water, also was used, but was not effective, and in some cases at all did not work owing to a breath of carbonic gas. In XVI-th century people have started to use bells filled by air. It was the first effective way to remain under water longer. Then in France and England have been made suits of a leather. In them air from a surface that enabled moved to plunge up to 18 meters. The helmets made of metal have soon been developed to resist to the big pressure, and divers, possessing this equipment, have begun more deep-water immersings.

In 1830 air submitted from a surface in helmets, was the most effective way of immersings which allowed to spend hard works under water.

In XIX-th century there were two basic directions in research: one scientific, another - technological. Scientific research was conducted by forces of Field Берта and John Skotta Khaldane, one was from France, other of Scotland.

Their works have helped to explain influence of pressure upon an organism, and also to define safe limits of time for immersings on compressed air. During too time, improvements in a technological direction had the results. For example, occurrence of pumps for compression of air and its submission, absorbers СО2, regulators, etc., have made possible for people to remain under water longer time.

Revolution in history of diving has occured in 1943 Jacque Iv Cousteau and Эмиль Ганьян have invented the first working device of the open cycle of breath.

WHAT KINDS of DIVING EXIST?
There is four basic kind or a method of diving in History of human desire to investigate sea depths among which diving with an aqualung is the last.

Diving with a delay of breath (free diving, skin diving)
It is diving the earliest forms of diving till now practise both for sports, and for commercial objectives (divers Japan and Korea, divers behind pearls archipelagoes Tuamoto.) Air cavities of the diver are squeezed by an increasing pressure of water during all immersing. Everyone immersing is limited to several factors, such as: time of a delay of breath and lack of oxygen. Usually it is minute or less.

Diving in what or the chamber.
Chambers allow to observe and support atmospheric pressure, preventing influence of pressure of water on members of crew.

There are some types of such chambers: an empty metal sphere falling from the ship c the help of a metal cable; a sphere with the control of buoyancy (in it cases the cable for descent and rise is not necessary); a submarine which is capable to move of greater distances in any direction by means of the forces. All these chambers require systems of maintenance with fresh air and removals of carbonic gas. The modern form of a submarine or the underwater device is the rigid suit possessing flexibility, capable to maintain pressure upon depth: Actually the diver becomes a submarine (submarine - a submarine in translation.) in this suit the diver is capable to work on depth up to hundreds meters.

Diving with the compressed air submitted from a surface.
Air moves to the diver through a hose, air acts in a regulator. In more developed systems air acts directly in a suit. Devices of this category include caissons (the greater spaces supplied compressed air and used more often for work with bridges and in tunnels). In all these devices the diver breathes air under pressure equal to surrounding pressure of water, therefore there is a risk of occurrence декомпрессии. Special mixes are used for deep-water immersings. These are гелиево-oxygen mixes or гелиево-азотно-oxygen.

Diving with compressed air or other gas mix which is being cylinders, носимых and used by the diver (скуба diving). Essentially there are two types of aqualungs: with the open and closed cycle of breath. Systems with the open cycle of the breath, throwing out all air in an environment, are popular in diving for entertainment.

Systems with the closed cycle of breath in which inhaled air acts back in a respiratory contour, and after absorption of carbonic gas and addition of oxygen, again it is used for дахания. These systems were widely used before occurrence of systems with the open cycle of breath, and used basically by military divers who tried to avoid occurrence пузырьков on a surface of water.