Man’s desire to enter the underwater world goes back to antiquity. Aristotle tells of Alexander the Great descending into the waters of the Mediterranean in something called a “diving bell”, as early as 332BC. The Italian polymath Leonardo da Vinci designed a similar apparatus, adding a face mask and reinforced supply hoses, to withstand the pressure of the depths.
The first on-demand underwater breathing valve came about in 1860s France, thanks to the work of inventors Benoît Rouquayrol, and Auguste Denayrouze. British diving engineer Henry Albert Fleuss developed the first commercially viable “rebreather” in 1878, using an air bag and rope fiber soaked in potash to “scrub” carbon dioxide from exhaled air.
The 20th century brought with it new and improved methods of pumping, and storing, compressed gas. By the 1930s every major belligerent of the coming war, had developed its own underwater breathing apparatus.
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