 In 1933, Le Prieur replaced the Fernez goggles, noseclip and valve by a full face mask, directly supplied from the air cylinder, which balanced the pressure in the mask with the external water pressure.Le Prieur remarked that the diver could breathe through the mouth or nose, or both, at will, and that it was even possible to speak with another diver by bringing the glass close to their ear, the glass forming a microphone.In 1934 Le Prieur was granted French patent 768083 for an improved hand-controlled self-contained underwater breathing apparatus with full face mask.