By Melissa Glaser (amended by S. Mercier)

 Henry Fleuss invents a self contained underwater breathing unit.  Yves Le Prieur releases a more advanced breathing unit.  Jacques-Yves Cousteau and Emile Gagnan design and test the first Aqua-Lung.  First wetsuit was introduced by University of California. Ted Nixon introduces the red and white “Divers Down” flag.

Regular breathing makes use of differences in air pressure The water above a diver increases the atmospheric pressure. Therefore, Air must be pressurized to be able to breathe at a pressure of more than one Atmosphere (air pressure at sea level). (This is also why you have to pop your ears as you descend.) Underwater breathing

The part of the regulator that attaches to the tank and reduces the pressure of the air in the tank to an intermediate pressure.

The part of the regulator at the end of the hose that includes the mouthpiece. The second stage reduces the pressure in the hose to a breathable pressure. Second stage - diagram

Boyle’s Law “For any gas at a constant temperature, the volume of the gas will vary inversely with the pressure, and the density of the gas will vary directly with the pressure.” If T= constant, then V  1/P and Density  P (Never hold your breath!)

Charles’s Law For any gas at a constant pressure, the volume of the gas will vary directly with the absolute temperature. If P= constant, then V  T Or For any gas at a constant volume, the pressure of the gas will vary directly with the absolute temperature. If V= constant, then P  T (keep tanks cool and don’t fill them too fast.)

The pressure of a gas at constant volume is directly proportional to the absolute temperature.

Dalton’s Law The total pressure exerted by a mixture of gases is equal to the sum of the pressures of each of the gases making up the mixture, with each gas acting if it alone was present and occupied the whole volume. (Sum of parts equals the whole!)

Henry’s Law The amount of any given gas will dissolve in a liquid at a given temperature is proportional to the partial pressure of that gas in equilibrium with the liquid and the solubility coefficient of the gas in the particular liquid. An increase in pressure will increase absorption (Oxygen in your blood dissolves at a given pressure.)

Pressure can be reduced by 1/2 or less without a gas coming out of a solution. This is like carbonation in a coke can.

Nitrogen absorbed under pressure has a narcotic effect. (A diver can get “narked” at any depth, for no reliable reason, and it differs every dive. Past 100’ everyone is narked.)

An object is buoyed up by a force equal to the weight of the liquid it displaces

 SCUBA divers and even hard-hat divers are limited in how deep they can go by the principles of physics  Submarines and submersibles allow humans to explore deeper in to the oceans, but must contend with extreme conditions:  The average depth of the ocean is 4,000 meters (13,000 feet). At that depth there is no light, the temperature is just above freezing and the water pressure is almost 6,000 pounds per square inch

 Most submarines are designed for military purposes to travel great distances at high speed at moderate depth and so serve little purpose for research at great depth.  Submersibles are designed to go to great depths to observe and collect specimens.

 Cornelius van Drebel is credited with the first working submarine in It was made of wood and operated 15 feet below the surface

 In 1932 William Beebe and Otis Barton descended to 2,170 feet in a steel ball attached to a long cable called a bathysphere

 In 1960, Jacques Piccard and Don Walsh took the Bathyscaphe Trieste to the bottom of the Marianas Trench 35,797 feet. It was very difficult to operate and control. This descent remains the only time in history a manned vessel has reached the bottom of the ocean

Current state of the art research submersibles such as the Alvin, out of Woods Hole, and the Johnson SeaLink out of Harbor Branch are designed to operate in up to 15,000 ft of water

The Alvin was used by famed scientist Robert Ballard to find the Titanic, the Bismarck and the first known hydrothermal vents. It can operate down to 4,500 meters (14,764 feet)

Harbor Branch’s two Johnson SeaLink submersibles can operate in up to 3,000 feet of water. Among other accomplishments they were used to recover pieces of the space shuttle Challenger when it blew up in 1986 and were credited with finding the first whale fall ecosystems

ROV’s (Remotely Operated Vehicles) and AUV’s (Autonomous Underwater Vehicles) are now starting to replace manned submersibles and are capable of a wide range of tasks at great depth without the concern of the operator dying