Maurice Fernez was born in Paris, France in August 1885. After a near drowning as a child, Fernez was driven to develop an underwater breathing device that would aid drowning victims and save their lives. Underwater diving was done by a tethered diving helmet and suit. Fernez went from a small balloon connect to the diver to a surface-mounted tube. But inhaling air down the tube and exhaling it thorough the exhaust valve became impossible because of the pressure of water compressing the chest. Air needed to be supplied to the diver under sufficient pressure to balance the pressure of the water. Fernez came up with a a T shaped mouthpiece with one side connected to the air hose through a one way non-return valve and the other side to an exhaust. Air was pumped continuously down the tube and flowed out of the exhaust valve of the mouthpiece, causing the pressure in the mouthpiece to be exactly the same as the external water pressure. The diver could breathe in and out from this stream of air without difficulty.
On October 27, 1912 the French Rescue Society organized an experiment in a swimming pool in Paris where a volunteer remained under water for 35 minutes and was then examined a doctor. Respiratory and cardiac rhythms were normal and the diver said that he hadn’t felt any discomfort and could stay underwater indefinitely.