Nobody is really sure when exactly the first workable diving bell was used. What we do know is that people tried way before Christ to conquer the depths of the water. Many of these stories are probably just legends.
|A French picture from the 13th century with Alexander the Great (356-323 BC) sitting in a glass barrel at the bottom of the ocean. Alexander wanted to study fish. According to the legend he saw a sea monster so large it took the animal 3 days to swim by the barrel. (Maybe that's why he pulls such a weird face...)|
||Indian picture from the 16th century showing a similar scene.|
Many different diving bells were tried over the years. They all had the same problem in common: How do we get fresh air down to the bell ? The Frenchmen Papin came with the solution in 1689. He designed a diving bell that was supplied with fresh air through flexible hosepipes and bellows. A truly fantastic idea but there was one slight little problem: The bellows of his time did not have enough strength to press the air down to the bell. Bummer.....
The English scientist Edmund Halley came up with a different solution in 1690. He invented a way to force pressurized air down to the bell. Why does this air have to be pressurized ? Take a glass, hold it upside down and push it down in a bucket of water. The water pressure will press the amount of air together. This happens also when you lower a diving bell in the water. Every 10 meters the pressure will go up by 1 atm/bar. When you lower a 3 meter high diving bell to 200 meters, the remaining layer of air inside the bell will be about 15 centimeters ! Halley attached empty barrels to the diving bell. A hole in the bottom of these barrels let in water. The barrels were attached to the diving bell by flexible hoses. The divers could let the air in by turning a faucet. The pressure was equal to the amount of water moved by the bell. In this way, the pressure inside the bell stayed the same as the surrounding water. Halley tried his invention several times. He stayed below at 20 meters depth for more than 1.5 hours without suffering any bad consequences. Halley also came up with small bells to fit over the divers head, with air supply from the diving bell. However, he soon found out that it was not possible to breath in the surrounding high water pressure. John Lethbridge came up with the first armored diving suit. Have a look at the Armored Diving Suit section to learn more about this.
The Halley method was generally used until 1788 when the English scientist John Smeaton invented the first workable diving air pump. Finally Papin's bell could be used ! As more and more pumps were build. Halley went out of business and Papin's method became the general way of getting air down to a diving bell. Papin has never witnessed this.....
|An early 19th century wooden diving bell. Air supply is arranged through bellows on a surface ship.|
From wood to iron
Later bells were made of cast iron and very large and heavy compared to the traditional diving bells. Up to 12 workmen at the time could descend in it ! The bells kept evolving and by 1840 they looked like massive cubes of cast iron in which men could work for days at the time. They were used to lay harbor and lighthouse foundations, building docks, deepening harbors or salvation of wrecks. In these days not much was known about the physiology of diving. Many men died and nobody knew why. Without knowing it these brave men were exposed to decompression sickness.
Diving Bell developments in the 20st century
Until about 1930 it was not practically possible to fulfill diving jobs with standard diving equipment at depths greater that 50 meters. This was due to the restrictions of the breathing-gas, for which air was used. You can learn all about this in the Going Deep section.
For greater depths armored diving-suits were incidentally used, but the mobility was very restricted due to the increasing water pressure on the joints. You can learn all about this in the Armored Diving Suits section.
Diving-bells are constructions, that are closed at the top and the sides. The bottom is open. The air-pressure inside the bell is kept at the ambient water-pressure on the bottom of the bell, so that the inside is kept dry. Diving-bells in different forms and sizes have been used since ages to salvage cargoes and to fulfill underwater construction-works. To prevent floating up and capsizing, diving bells always have to be heavy, and can be used only when adequate lifting-capacity is available. The refreshment of the air inside the bell takes place from the surface. In general the diving-bells are electrically lighted on the inside, supplied by a cable from the surface and a telephone communication. .
Depending to the complexity and duration of the works underwater, the diving-bell was connected with the surface by means of a turret , that served as an air-lock. Personnel and equipment could then pass the airlock on their way to and from the diving-bell. These bells were also known as Caisson bells. They were less mobile and harder to use than the ordinary bells described above.
These developments were more or less a consequence of the activities of an English company (Risdon Beazly) and an Italian firm (Sorima), who were occupied in the recovery of large quantities of non-ferrous metals, steel and other valuable cargo, lost by enemy actions during the First World War.
At first the Sorima firm started with a Neufeldt & Kuhnke atmospheric suit, but due to practical reasons the use of this suit was abandoned and replaced by observation-chambers, built by English and Italian manufacturers. In fact these were cylindrical structures, that could be entered by the "diver/observer" by means of a lid. The chamber was provided with a couple of view-ports. The gas supply for the "diver" took place by means of air regenerating apparatus.
The chamber was lowered and raised by a steel cable from and to the diving-vessel on the surface. Communication took place by telephone equipment.
To stabilize the observation chamber it had a ballast weight, that functioned like an anchor and a buoyancy-tank. In case of emergency the ballast weight could be thrown off and by blowing off the water in the buoyancy-tank with air, the chamber would float up to the surface.
In general the submarine observation-chambers were used in combination with strong underwater electric lamps to provide illumination on the work-site.
Amongst others the Sorima company succeeded in the recovery of more than one million Pound Sterling on gold and silver from the liner "Egypt".
Diving bells and observation chambers evolved to the modern diving bells and chambers that are still in use today. Visit our Modern Diving Bell section to learn all about them.