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Edmund Halley`s Diving Bell
 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.
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.
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Turks and Caicos Is. |
1996 |
Edmund Halley's diving bell,1690 |
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