The history of diving with equipment is long and complex, and in the early stages it is mixed with legend. The exploits of Jonah are described with conviction in one text, but there is a shortage of supporting evidence. Further reference is made to him later, on the technicality that he was more a submariner than a diver. Because his descent was involuntary, Jonah was at best a reluctant pioneer diver. The history of submarine escape, when the submariner may become a diver, is discussed in Chapter 64.
Some claim that Alexander the Great descended in a diving bell during the third century BC. Details of the event are vague, and some of the fish stories attributed to him were spectacular. One fish was said to have taken 3 days to swim past him! It is most unlikely that the artisans of the time could make glass as depicted in most of the illustrations of the ‘event’. This may have been a product of artistic licence or evidence that the incident is based more in fable than in fact.
Snorkels, breathing tubes made from reeds and bamboo (now plastic, rubber or silicone), were developed in many parts of the world. They allow a diver to breathe with the head underwater. Aristotle inferred that the Greeks used them. Columbus reported that the North American Indians would swim toward wild fowl while breathing through a reed and keeping their bodies submerged. They were able to capture the birds with nets, spears or even their bare hands. The Australian aborigines used a similar approach to hunt wild duck. Various people have ‘invented’ long hose snorkels. The one designed by Vegetius, dated 1511, blocked the diver’s vision and imposed impossible loads on the breathing muscles.
Some have interpreted an Assyrian drawing dated 900 BC as an early diving set. The drawing shows a man with a tube in his mouth. The tube is connected to some sort of bladder or bag. It is more likely a float or life jacket. The tube length was a metre or more and so impossible to breathe through.
Leonardo da Vinci sketched diving sets and fins. One set was really a snorkel that had the disadvantage of a large dead space. Another of his ideas was for the diver to have a ‘wine skin to contain the breath’. This was probably the first recorded design of a self-contained breathing apparatus. His drawings appear tentative, so it is probably safe to assume that there was no practical diving equipment in Europe at that time.
Another Italian, Borelli, in 1680, realized that Leonardo was in error and that the diver’s air would have to be purified before he breathed it again. Borelli suggested that the air could be purified and breathed again by passing it through a copper tube cooled by sea water. With this concept, he had the basic idea of a rebreathing set. It could also be claimed that he had the basis of the experimental cryogenic diving set in which gas is carried in liquid form and purified by freezing out carbon dioxide.
Diving bells were the first successful method of increasing endurance underwater, apart from snorkels. These consist of a weighted chamber, open at the bottom, in which one or more people could be lowered under water. The early use of bells was limited to short periods in shallow water. Later, a method of supplying fresh air was developed. The first fully documented use of diving bells dates from the sixteenth century.
In 1691, Edmond Halley, the English astronomer who predicted the orbit of the comet that bears his name, patented a diving bell that was supplied with air in barrels (Figure 1.1). With this development diving bells became more widespread. They were used for salvage, treasure recovery and general construction work. Halley’s bell was supplied with air from weighted barrels, which were hauled from the surface. Dives to 20 metres for up to 1 1/2 hours were recorded. Halley also devised a method of supplying air to a diver from a hose connected to the bell. The length of hose restricted the diver to the area close to the bell. It is not known whether this was successful. Halley was one of the earliest recorded sufferers of middle ear barotrauma.
Swedish divers had devised a small bell, occupied by one person and with no air supply to it. Between 1659 and 1665, 50 bronze cannons, each weighing more than 1000 kg, were salvaged from the Vasa. This Swedish warship had sunk in 30 metres of water in Stockholm harbour.
The guns were recovered by divers working from a bell, assisted by ropes from the surface. This task would not be easy for divers, even with the best of modern equipment.