How the Chestatee Diving Bell Operatedby Manuel B. Carvalho 1.0 Historical Background
 The Chestatee River Diving Bell is a unique maritime
artifact used for underwater gold mining.
Its technology, however, is rooted
in the ancient past since the desire to go under water has probably always
existed: to hunt for food, uncover artifacts, sunken treasure, repair ships (or
sink them!), and perhaps just to observe marine life. Until humans found a way
to breathe underwater, however, each dive was necessarily short and frantic.
A diving bell
is an airtight chamber that is suspended underwater as a workstation for a
single or multiple divers; it will refresh divers with air without having to
come to the surface, allowing a diver to remain underwater for extended periods
of time. A diver could leave the bell for a minute or two to collect sponges,
pearls or explore the bottom, and then return for a short while until air in
the bell was no longer breathable. The
diver uses this reservoir of air to stay underwater longer than would otherwise
be possible.
In its simplest form the apparatus is named for its
resemblance to a bell, in that it is narrow at the top and open at the bottom. The concept of a diving bell goes as far back
to the ancient Greeks. Aristotle (384-322 BC) wrote about such a device in book
XXXII of his Problems saying that “
they enable the divers to respire equally well by letting down a cauldron; for
this does not fill with water, but retains the air, for it is forced down
straight into the water.”   According to legend
the Macedonian King, Alexander the Great,
used demolition divers to remove underwater obstacles from the harbor during
his famous 1332 BC siege of Tyre (Lebanon). It’s reported that Alexander himself made
several dives in a glass diving bell in order to observe the work in progress
as depicted in the 16th century painting at the left.
During the Renaissance
Leonardo DaVinci describes, in his book “Codex Atlanticus”, a breathing
apparatus that allows a diver to remain underwater for long periods of time. In 1535 the Italian
physicist, Guglielmo de Lorena, used a diving bell from a design by Leonardo da
Vinci to recover sunken items from two of Caligula’s sunken galleys from the bottom of Lake Nemi. The device was basically a
large "bell" that rested on the users shoulders and had a tube running from the
surface into the bell that piped fresh air in so the inhabitant could breathe.
 Diving bell design wouldn’t
reach its climatic point until the 17th century when Dr. Edmond Halley,
of the comet fame, improved the design by utilizing an air replenishing system
to overcome the effects of atmospheric pressure. The engraving at the left from
the National Maritime Museum, London depicts the use.
Air was added to the bell from separate lead weighted
barrels lowered from the ship above. A
hose from the barrel led to the bell, where a diver inside the bell could
simply turn a valve to allow fresh air from the barrel as water filled in
through a hole in the bottom forcing the air up and out into the bell. The
barrels were pulled to the surface for refilling and dropped back in. By this
means almost all the water could be expelled from the bell, allowing the divers
to operate in almost dry conditions. Warm stale air was expelled from an
orifice at the bell top. Halley’s bell worked in typical depths of 20 to 60
feet.
The English scientist John Smeaton
invented a workable diving air pump in 1788 which replaced the barrels.
Throughout the
nineteenth century various designers built bells of ever-increasing size and
complexity. These later bells were made
of cast iron and very large and heavy compared to the traditional wooden diving
bells. Although the diving bell allowed
for the exploration of underwater depths longer than any other apparatus its
main disadvantage is that it needed be pulled up to the surface for the workers
to be replaced which is a time and energy consuming process.
Later designs connected the diving bell with the surface by means of a turret that served as an air-lock. Personnel and equipment could then pass through the airlock, equalizing pressure, on their way to and from the diving-bell. These bells are also known as Caisson bells but the terms are often used interchangeably. The earliest air-lock design [ref 1] apparently is due to John Williams of Exeter, England who in 1691 petitioned a patent for a "submerged chamber. communicating with the surface by a rigid tube, up and down by which persons might pass." Further improvements continued such as those by Col. Pasley [ref 2] who, in the early 1850's, proposed to attach boat shaped ends to a diving bell in order to prevent the considerable vibrations when diving bells where used in rapid moving streams.  In 1862, Bindon Blood
Stoney, Chief Engineer of Dublin's Port and Docks, proposed using a 90 ton bell
as part of a process for deepening and laying huge cement blocks
for the foundation of the North Wall Harbor in Dublin, Ireland making it a deep water port. The bell chamber was rectangular box twenty by twenty feet, with six and a half feet of
headroom inside. The overall height of
the bell including the three foot diameter shaft and airlock chamber was forty-four feet. Working in compressed air may not have been fully understood by the crews working in the bell as there are several accounts of men suffering with ear trauma and bleeding from the nose and ears. The project was completed in the mid-1880s
but the bell was used several other times until the 1950s. Today, the restored bell, seen at right, stands in Dublin's Sir John
Rogerson’s Quay.
  Workers, 30-50 per each eight hour shift, entered the caisson through an air lock tube to reach the pressurized work chamber, shown right, where they dug away at the sand and rock on the river bottom until reaching bedrock 78 feet below the surface. Stone was added to the top of the caisson as it went down and it eventually was filled with hydraulic concrete becoming a permanent part of the tower foundation when the project was completed in 1883.
 What is known is that in Aug. 27th, 1872 the Georgia Legislature incorporated the Georgia Gold Mining Company with $10,000 in capital stock and gave the exclusive right to Loud and four other people to work for precious metals on any state property for a period of thirty years. In 1875 the machinery for the Diving Bell arrived in Dahlonega and a boat to carry it was built of Southern Yellow Pine. The diving bell is constructed of ¼ inch boilerplate iron panels forged at the Pottstown Iron Works in Pottstown, PA according to forge marks on the panels. The panels are shaped and riveted together to form air tight joints. The front of the bell is wedge shaped in order to break river currents and reduce turbulence inside the bell. A pressure equalizing entry tube with two inner doors allows workers to enter the bell. Inside the bell's working chamber is an inner chamber used for ballast needed to weigh down the bell in order to sink it below the river surface. Five fixed portholes mounted on the top of the bell and one on the entry tube allow for light to enter inside the equipment. There is no bottom on the bell. The bell, less the entry tube, measures 6 feet wide by 14 feet long and 8 feet high. The whole craft weighs a bit over 5,000 pounds. Who designed the bell and where it was fabricated is not known.
The wench was powered by a steam engine that has not been located and its exact specifications are unknown. Full exact measurements are not know because the boat is partially buried under the river bank and covered by a large quantity of sand and silt. The rear section of the boat has not yet been seen and remains covered with about four feet of sand. About 15% or so of the left front side remains buried under the bank. However, the top view of the boat, including underwater photos of still attached machinery, is something like this: 
 In order to push the water out of the open bottomed bell, compressed air was pumped into the working chamber as it was submerged into the river. Once at the bottom the pressurized air would not only keep the water level at the miner's feet, it would also maintain a fresh air environment for them to work. When the men wished to enter the bell they passed through the top hatch and descended using a ladder secured to the side of the entry tube. Once the hatch was closed they equalized the pressure of the entry tube to be the same as in the bell's working chamber. They could then open the lower hatch and pass safely into the bell, closing the door after them. When returning to the surface, they reversed the operation, opening the lower hatch, entering the entry tube compartment and closing the hatch. They would then open a valve to release the air pressure and exit to ambient atmosphere through the top hatch. Once at the bottom the miners would spade up the gravel into
a suction tube, labeled R, in order to bring the gravel up from the river bottom into
the boat to be worked in the sluice box and extract the gold. Although no actual physical evidence
of the suction tube has yet been found there is a newspaper account that
describes it. Mr. J. A. Burns discusses
the diving bell operation in a letter extoling the virtues of Georgia to the Calaveras Citizen newspaper in California and reprinted in page 1 of the June 16, 1876 edition
of the Dahlonega Mountain Signal. In his
letter, Mr. Burns describes the diving bell operation consisting of “a monster boat, on the Chestatee river. It works by steam, and has a large iron caisson,
which is lowered into the water. The air
soon forces the water all out, and then the men go to work in the river-bed and
shovel the gravel to large pumps, which take it up to sluice boxes, water for
which is raised at the same time.”  P. H. Loud took the first dive into the murky waters of the Chestatee River in November of 1875. He emerged thinking that a fortune was within easy grasp and that he would build more boats to collect it. Unfortunately, bad weather, poor finances coupled with likely difficulties in Diving Bell operations resulted in legal problems that caused all operations to cease. These unfortunate circumstances culminated when the boat sank in October of 1876. The dreams of Loud Mining Company went with the boat. Today the Diving Bell remains as a monument to these dreams and perhaps to inspire others who dare to do something new and different. One might not always succeed, but like Philologous H. Loud don't ever give up. Posted 3 Apr 2012 16 Apr 2012: Boat diagram was modified due to new information from Bill Waldrop's dive on the boat during the April 13, 2012 weekend. |
Diving Bell >