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A bathyscaphe ( or ) is a
free-diving Freediving, free-diving, free diving, breath-hold diving, or skin diving is a form of underwater diving that relies on breath-holding until resurfacing rather than the use of breathing apparatus such as scuba gear. Besides the limits of breath- ...
self-propelled deep-sea
submersible A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of ind ...
, consisting of a crew cabin similar to a
bathysphere The Bathysphere (Greek: , , "deep" and , , "sphere") was a unique spherical deep-sea submersible which was unpowered and lowered into the ocean on a cable, and was used to conduct a series of dives off the coast of Bermuda from 1930 to 1934. The ...
, but suspended below a float rather than from a surface cable, as in the classic bathysphere design. The float is filled with gasoline because it is readily available, buoyant, and, for all practical purposes, incompressible. The incompressibility of the gasoline means the tanks can be very lightly constructed, since the pressure inside and outside the tanks equalises, eliminating any differential. By contrast, the crew cabin must withstand a huge pressure differential and is massively built.
Buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...
at the surface can be trimmed easily by replacing gasoline with water, which is denser. Auguste Piccard, inventor of the first bathyscaphe, composed the name ''bathyscaphe'' using the
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
words βαθύς ''bathys'' ("deep") and σκάφος ''skaphos'' ("vessel"/"ship").


Mode of operation

To descend, a bathyscaphe floods air tanks with sea water, but unlike a
submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
the water in the flooded tanks cannot be displaced with compressed air to ascend, because the water pressures at the depths for which the craft was designed to operate are too great. For example, the pressure at the bottom of the
Challenger Deep The Challenger Deep is the deepest-known point of the seabed of Earth, with a depth of by direct measurement from deep-diving submersibles, remotely operated underwater vehicles and benthic landers, and (sometimes) slightly more by sonar bathym ...
is more than seven times that in a standard "H-type" compressed gas cylinder. Instead, ballast in the form of
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
shot is released to ascend, the shot being lost to the ocean floor. The iron shot containers are in the form of one or more hoppers which are open at the bottom throughout the dive, the iron shot being held in place by an electromagnet at the neck. This is a
fail-safe In engineering, a fail-safe is a design feature or practice that in the event of a specific type of failure, inherently responds in a way that will cause minimal or no harm to other equipment, to the environment or to people. Unlike inherent safe ...
device as it requires no power to ascend; in fact, in the event of a power failure, shot runs out by gravity and ascent is automatic.


History of development

The first bathyscaphe was dubbed ''
FNRS-2 The ''FNRS-2'' was the first bathyscaphe. It was created by Auguste Piccard. Work started in 1937 but was interrupted by World War II. The deep-diving submarine was finished in 1948. The bathyscaphe was named after the Belgian Fonds National ...
'', named after the Fonds National de la Recherche Scientifique, and built in
Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...
from 1946 to 1948 by Auguste Piccard. (''FNRS-1'' had been the balloon used for Piccard's ascent into the stratosphere in 1938). Propulsion was provided by
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
-driven
electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...
s. The float held of aviation gasoline. There was no access tunnel; the sphere had to be loaded and unloaded while on deck. The first journeys were detailed in the
Jacques Cousteau Jacques-Yves Cousteau, (, also , ; 11 June 191025 June 1997) was a French naval officer, oceanographer, filmmaker and author. He co-invented the first successful Aqua-Lung, open-circuit SCUBA (self-contained underwater breathing apparatus). T ...
book ''The Silent World''. As described in the book, "the vessel had serenely endured the pressure of the depths, but had been destroyed in a minor squall". ''
FNRS-3 The ''FNRS-3'' or ''FNRS III'' is a bathyscaphe of the French Navy. It is currently preserved at Toulon. She set world depth records, competing against a more refined version of her design, the ''Trieste''. The French Navy eventually replaced ...
'' was a new submersible, using the crew sphere from the damaged ''FNRS-2'', and a new larger float. Piccard's second bathyscaphe was actually a third vessel ''Trieste'', which was purchased by the
United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
from
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
in 1957. It had two water ballast tanks and eleven buoyancy tanks holding of gasoline.


Accomplishments

In 1960 ''Trieste'', carrying Piccard's son
Jacques Piccard Jacques Piccard (28 July 19221 November 2008) was a Swiss oceanographer and engineer, known for having developed underwater submarines for studying ocean currents. In the Challenger Deep, he and Lt. Don Walsh of the United States Navy were the ...
and
Don Walsh Don Walsh (born November 2, 1931) is an American oceanographer, explorer and marine policy specialist. He and Jacques Piccard were aboard the bathyscaphe ''Trieste'' when it made a record maximum descent into the Challenger Deep on January 2 ...
, reached the deepest known point on the Earth's surface, the
Challenger Deep The Challenger Deep is the deepest-known point of the seabed of Earth, with a depth of by direct measurement from deep-diving submersibles, remotely operated underwater vehicles and benthic landers, and (sometimes) slightly more by sonar bathym ...
, in the
Mariana Trench The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum know ...
in the Pacific Ocean. The onboard systems indicated a depth of 37,800 ft (11,521 m) but this was later corrected to 35,813 ft (10,916 m) by taking into account variations arising from salinity and temperature. Later and more accurate measurements made in 1995 have found the Challenger Deep to be slightly shallower at 35,798 ft (10,911 m). The crew of the ''Trieste'', which was equipped with a powerful light, noted that the seafloor consisted of
diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...
aceous ooze and reported observing "some type of flatfish, resembling a sole, about 1 foot long and 6 inches across" lying on the seabed."To the bottom of the sea"
, T. A. Heppenheimer, AmericanHeritage.com
This put to rest the question of whether or not there was life at such a depth in the complete absence of light.


See also

* 1948 * 1953 * 1953 * 1961 * 1964 * 1966 * 1964 * 1987 * 2012 ''
Deepsea Challenger ''Deepsea Challenger'' (DCV 1) is a deep-diving submersible designed to reach the bottom of Challenger Deep, the deepest-known point on Earth. On 26 March 2012, Canadian film director James Cameron piloted the craft to accomplish this goal i ...
'' * * * * * *


References


External links

*
The US Navy account of the dive, with photographs
*
History of the Bathyscape Trieste

"13,000 Feet Under the Sea in the French Bathyscaphe
''Popular Mechanics'', May 1954, pp. 110–111.
Deepsea Challenger – Mariana Trench Dive (03/25/2012).
{{authority control Ship types Crewed submersibles Deep-submergence vehicles Swiss inventions