From 1939 catalogue of Malagamba italian company:
"One of our most useful patents is the RESPIRATOR which allows swimmers to stay with their head underwater, breathing through our device.
Our RESPIRATOR is equipped with two automatic valves, one in the upper part of the hose which remains above the surface, and one in its lower underwater part. At the smallest water contact, it obliges the float inside these valves to close automatically the air inlet; in this way, water cannot enter into the hose and imped swimmer’s breathing.
Swimmer can dive in any depth underwater; valves will close and will remain close until swimmer ascents, and the upper valve exits water. At this point, the upper valve opens automatically, allowing the swimmer to resume his normal breathing without having to lift his head out of water; his face can remain below water without interrupting his underwater vision.
RESPIRATOR hose is curved to surround the left side of the face, out of the visual field which remains completely clear.
RESPIRATOR is attached to the goggle left band (*) by means of two rubber bands in the band itself.
By opening his mouth, swimmer leaves respirator which remains attached to his goggles.
Lower valve is meant to empty the RESPIRATOR from saliva or water which accidentally enters from his mouth. This is made by simply lifting his head for a short moment from water. Lower valve opens immediately and the RESPIRATOR empties automatically; or, without lifting head from water, upper valve can be closed by putting a finger in the float and breathing inside, so that the lower valve opens and remains opened until liquid exits the RESPIRATOR. When this happens, valve then closes immediately without letting water in.
For the first trials, it is recommended to use the nose clip supplied with the RESPIRATOR to avoid breathing water from the nose (*). After some days, having the swimmer learned to breath only from the mouth, he/she can avoid using the nose clip. It is easy to learn how to breath exclusively from the mouth by means of the RESPIRATOR by exhaling from the nose.
RESPIRATOR allows fish hunting more effective and easier.
RESPIRATOR is made with simplicity, practice and perfection with which our company established a good worldwide reputation."
(*) It should be point out that, in 1939 masks did not exist but there were only single lens glasses called "monogoggle" on which nose was excluded, as it happened before with the previous "goggles", Polynesian style goggles.