Diving with Compressed Air Supplied for Surface
Surface supplied air, in its most basic form, can even include air fed through a short tube or reed. More sophisticated methods were developed as far back as the 16th century however, methods that included diving bells and primitive diving suits. The diving bell had the advantage of allowing a diver to replenish their own air supply before venturing out for minutes at a time to explore, hunt, or salvage at a deeper depth than they could otherwise maintain. Diving suits, which began to be developed in the early 13th century, provided a constant stream of air but limited a diver's range to the length of the attached hose.
Though very basic diving suits existed as far back as the early 1400s, real progress began to be made about 300 years later. Charles and John Deane were early innovators of the diving suit. Their original goal was actually to create a suit that would feed clean air to firefighters. This innovation eventually got modified into a diving helmet and Charles Deane used an early model to recover salvage from the Royal George, a sunken ship. They worked with engineer Augustus Siebe to improve the helmet. These early helmets had to be made from copper or metal to withstand water pressure.
In fact, water pressure was a big problem for early divers, one which took ingenuity to solve. While the earliest diving suits only allowed divers to descent about 60 feet, later suits were made of sturdier material that could withstand the increased pressure of the deeper ocean. This included bulky metal helmets, or even full metal suits that more closely resembled armor than they did modern diving suits. Weights were built into the suit to help counteract any buoyancy. Assistants on the surface needed to pump compressed air down to the submerged diver through a type of umbilical cord. Modern-day diving suits now have air-control valves, which gives the diver additional control over how much oxygen they receive.
Surface-supplied diving suits still exist today, though they are mode of more modern materials such as fiberglass. Modern divers can now go 10 times as deep as the original 60 feet diving suits allowed. But for all the advancements, the basic principle remains the same as 300 years ago. Weighted suits with compressed air fed down to a diver through a hose. What is most amazing about this type of diving is not the science behind the invention, but the courage of the original inventors.