 Air was supplied continually to the mouthpiece and ejected through a short exhaust pipe fitted with a valve as in the Fernez design.For the first time a man could breathe underwater with no connection to the surface at all – Le Prieur had invented the open circuit self-contained underwater breathing apparatus – scuba.Fernez's separate goggles didn't allow a dive deeper than ten metres because they were not pressurised, so as the diver went deeper the goggles were squeezed onto his face and eyeballs by the increasing water pressure, a phenomenon known as "mask squeeze".