The first people to be exposed to a pressure change in a vessel on the surface were patients exposed to higher or lower pressure as a therapy for various conditions – the start of hyperbaric medicine. The origins of diving medical research can also be traced to these experiments.
During the second half of the nineteenth century, reliable air pumps were developed. These were able to supply air against the pressures experienced by divers. Several people had the idea of using these pumps for diving and developed what are now called open helmets, which cover the head and shoulders. Air was pumped down to the diver, and the excess air escaped from the bottom of the helmet. The diver could breathe because the head and neck were in air, or at least they were until the diver bent over or fell. If this happened, or if the hose or pump leaked, the helmet flooded and the diver was likely to drown. The Deane brothers were the inventors and among the major users of this equipment, and John Deane continued to use it up to the time of the Crimean War.
Standard rig, or standard diving dress, was first produced in 1840 by Augustus Siebe (a Russian immigrant engineer who later became a naturalized British citizen). This equipment consisted of a rigid helmet sealed to a flexible waterproof suit (Figure 1.2). Air was pumped down from the surface into the helmet, and excess air bled off through an outlet valve. The diver could control buoyancy by adjusting the flow through the outlet valve and thus the volume of air in the suit. This type of equipment, with a few refinements, is still in use.
Siebe’s firm came to be the major manufacturer, but his role in the design may have been overstated, possibly for the marketing advantages gained by his firm, which marketed the first acceptable equipment of this type. The origins and evolution from open helmet and standard dress were the subject of a study by Bevan, who discussed several designs that were developed at the same time, with borrowing and stealing of ideas from each other.
By the mid-nineteenth century, several types of diving suits and a bell were used by the Royal Engineers on dives on the wreck of the Royal George, which obstructed the anchorage at Spithead. The Siebe suit was found to be greatly superior to the other designs. Siebe’s apparatus allowed the diver to bend over or even lie down without the risk of flooding the helmet. Also, the diver could control his depth easily. A diver in an open helmet had to climb a ladder or rely on his tenders to do this.
In more modern versions, the helmet is fitted with communications to allow the diver to confer with another diver or the surface. One of the developments from the Siebe closed helmet was the US Navy Mark 5 helmet. It probably set a record by being in service for 75 years.
The Royal Engineers were taught to dive by civilian divers in 1939–40 while on the Royal George. They then established a training facility at Gillingham in 1844 where they reintroduced diving to the Royal Navy, which set up their first diving school on HMS Excellent later that year.
Decompression sickness was noted, albeit not recognized in divers, following the development of these diving suits. Divers were given fresh dry undergarments because the ‘rheumatic’ pains they suffered were attributed to damp and cold. Other divers suffered paralysis that was attributed to fatigue from zeal and overexertion. Most of these men would have been suffering from decompression sickness because they were diving for up to three times the accepted limits for dives without decompression stops.
Decompression sickness was also observed in workers employed in pressurized caissons and tunnels. In these operations, the working area is pressurized to keep the water out. The history of decompression sickness is discussed in Chapter 10.
Paul Bert and J. S. Haldane are the fathers of diving medicine. Paul Bert published a text book La pression barométrique based on his studies of the physiological effect of changes in pressure. His book is still used as a reference text even though it was first published in 1878. Bert showed that decompression sickness was caused by the formation of gas bubbles in the body and suggested that it could be prevented by gradual ascent. He also showed that pain could be relieved by a return to higher pressures. Such cases were initially managed by the diver’s returning to the pressure of the caisson. However, specially designed recompression chambers were introduced and utilized at some job sites within a few years.
J.S. Haldane, a Scottish scientist, was appointed to a Royal Navy committee to investigate the problem of decompression sickness in divers. At that time the Royal Navy had a diving depth limit of 30 metres, but deeper dives had been recorded. Greek and Swedish divers had reached 58 metres in 1904, and Alexander Lambert had recovered gold bullion from a wreck in 50 metres of water in 1885, but he had developed partial paralysis from decompression sickness.
Haldane concluded from Paul Bert’s results that a diver could be hauled safely to the surface from 10 metres with no evidence of decompression sickness. He deduced from this that a diver could be surfaced from greater than 10 metres in stages, provided that time was spent at each stage to allow absorbed nitrogen to pass out of the body in a controlled manner. This theory was tested on goats and then on men in chambers. Haldane’s work culminated in an open water dive to 64 metres in 1906 and the publication of the first acceptable set of decompression tables. Haldane also developed several improvements to the diving equipment used.
In 1914, US Navy divers reached 84 metres. The next year they raised a submarine near Hawaii from a depth of 93 metres. This was a remarkable feat considering that the salvage techniques had to be evolved by trial and error. The divers used air, so they were exposed to a dangerous degree of nitrogen narcosis, as well as decompression sickness.