1943
SCUBA
Emile Gagnan (1900–1979), Jacques-Yves Cousteau (1910–1997)
Just about anyone who has ever been swimming has had this simple dream: Wouldn’t it be great if I could breathe underwater? Following generations of inventors attempting to answer this question with human innovation, Emile Gagnan and Jacques Cousteau were able to create what they called the “Aqualung”—the first SCUBA or the Self Contained Underwater Breathing Apparatus, also known as an air supply in a backpack, in 1943.
The main component of a SCUBA system is about as simple and obvious as it gets: a tank full of compressed air. The air is highly pressurized to squeeze as much in as possible, so the tank is made of steel or aluminum, with 3,000 psi (207 bar) being a typical pressure. If the tank has a volume of 15 liters, it means that the tank holds approximately 207x that amount of air at standard atmospheric pressure, or 3,100 liters of air. If a person were to walk around on dry ground and breathe normally, at a rate of 30 liters of air per minute, the tank would hold about 100 minutes of air. (For comparison, firefighters estimate their air consumption at 40 liters per minute.)
But a person who is SCUBA diving is underwater, and the depth has a big effect on the amount of air per breath. The job of the regulator attached to the SCUBA tank is to regulate the pressure down from tank pressure (e.g., 3,000 psi) to the pressure necessary to breathe. The deeper a diver goes in the water, the more pressure the surrounding water is placing on the diver’s lungs, thus more pressure is required from the regulator to push air into the lungs so the diver can take a breath. This means that, deep underwater, a tank of air gets used up much more quickly than at the surface.
The other way to breathe underwater is a closed-circuit system, also known as a rebreather. A rebreather is engineered to use soda lime granules to absorb carbon dioxide and a small tank of pure oxygen to replenish the oxygen consumed by the diver.
SCUBA is a great example of how engineers can create reliable, inexpensive solutions that turn dreams into reality.
SEE ALSO Carbon Fiber (1879), Hall-Héroult Process (1889), Cabin Pressurization (1958), Mars Colony (c. 2030).
Modern SCUBA gear, pictured here, is considerably more streamlined than its original incarnation.