The History of Diving activities around the world have taken many forms over many centuries. In fact the earliest recorded diving activity was 332 BC using a diving bell which was not much more than an overturned metal bucket. Much of the History of Diving has records of using contemporary tools to enter waters for underwater salvage and treasure recovery.
This has led to equipment evolution and improvement.
As science progressed so did the equipment. Diving bells became more and more sophisticated to the point of the creation of tethered surface air supply diving bells and submarines. Meanwhile, methods to deliver air to a diver from the surface went from hand pumps to steam and combustion engine pumps allowing for deeper and deeper diving depths.
How did this affect the public acceptance of diving as a commercial use of the activity? Did this lead to more participation in commercial and sport diving? Two major things occurred to bring diving into the modern age. The two World Wars and greater interest in the science and commercialization of diving equipment.
The Diving Bell advanced man’s knowledge of the underwater world beyond the depths that free diving allowed. Diving bells became more than over turned buckets when they were manufactured from metal and air was pumped under pressure to the explorers below while tethered to a surface support vessel. The modern diving bell is made of metal with enough ballast to achieve neutral buoyancy, has a tether to the surface to hold in place and supply air and communication and descend with their own additional compressed air tanks attached to the outside of the bell and is available to the occupants for emergency air supply and ballast.
The Diving Bell is still affected by water pressure that compresses the air within. In understanding the science of diving we must accept the concept for diving pressures that water is not compressible while air can be compressed with that increased pressure. This means that when the diving bell is lowered below the surface, the water pressure squeezes the air inside and the level of breathable gas rises up the bell’s wall reducing the breathable gas volume. This has the effect of decreasing the buoyancy of the bell and increasing the density of the internal air. Robert Boyle observed many properties of gases and published Boyle’s Law in 1662. The density and volume of a gas are inversely proportional to the pressure when temperature remains constant.
This results in a little known physiological affect on the human body in the early years of diving. The affect of diving at a depth that has a great enough pressure to have an affect results in a surfacing/ascending problem that may cause The Bends or Decompression Sickness.