View from the Diving Bell (2000)
The first depictions of underwater devices are pointed out by Aristotle who mentioned that "one can allow divers to breathe by lowering a bronze tank into the water. Naturally the container is not filled with water but air, which constantly assists the submerged man." This device represented a jar, turned upside down, in which the diver thrust his head.
During his descent to the sea floor, he breathed the air that remained inside the jar. Actually, this is the prototype of the true diving bell.Alexander the Great and his comrade Nearch (the commander of the fleet) managed to go under surface to a depth of 25 meters with the aid of a huge diving bell. It consisted of colorless glass to help the diver see through it.A typical diving bell: leather bags to refresh the air were dropped by the surface; The diver went out from the diving bell with his breath held, to do some work under water. After he was out of breath, instead of ascending to the surface, he returned to the bell where he inhaled fresh air; Stones were attached to the brim of the wooden barrel to help the bell sink; When the air became unbreathable, the bell was taken to the surface for ventilation.
The diving bell is one of the earliest types of equipment for underwater work and exploration. Its use was described by Aristotle in the 4th century BC. In 1535, Guglielmo de Loreno created and used what is considered to be the first modern diving bell.
The earliest applications were probably for commercial sponge fishing. A diving bell was used to salvage cannon from the Swedish warship Vasa in the period immediately following its sinking in 1628.A further extension of the wet bell concept is the underwater habitat, where divers may spend long periods in dry comfort while acclimated to the increased pressure experienced underwater. By not needing to return to the surface they can avoid the necessity for decompression (gradual reduction of pressure), required to avoid problems with nitrogen bubbles releasing from the bloodstream (the bends, also known as caisson disease). Such problems occur at a pressure over two atmospheres, experienced below a depth of 32 feet. By not requiring a pressure resistant structure the habitat can be constructed at lower cost.
An early example of a contemporary experimental diving bell was the Purisima, invented by Dan Wilson in the 1960s. It was a double sphere system in which the top sphere was at atmospheric pressure, allowing diving supervisors to monitor the dive at depth rather than remain topside in front of a TV monitor, while the bottom sphere contained the divers at working pressure. Wilson envisioned the top sphere as also being a means by which customer representatives could be on site as observers, but he comments, wryly, "For some reason the customers never did line up to direct their undersea operations."
I admit my experience with diving bells is limited to Captain Nemo, Voyage to the Bottom of the Sea, and depictions in comics. You know. This stuff
You Too Can Build Your Own Sea Tractor!!
that fueled my imagination deeper than 20,000 leagues -- and, years later, shaped today's image.