In my dim distant past as a Police Diver we tried a variety of Hard Hats, Kirby Morgan neoprene helmets and of course re breathers.
These were what all countries brave divers wore to stop exhaust bubbles leaving the diver and coming to the surface as they today in a more sophisticated way.
Many of the English Royal Navy divers on chariots used to disappear as they fell off as salt water enter the rebreather pot that you used to have to level the crystals and tighten down the clamp. If you didn't do it up tight enough and sea water got in, thats what you breathed in.....lethal cocktail.
I suspect reading some of the Italian divers stories in the straits of Gibralter in WW2 they had the same problem too!!! All brave men!
