http://swissbaync5d7ykaz7dh7v4qjrb4gmen5aj3bogxrcgbb43ij34bjuyd.onion/pdf/Books/Survival/Medicine/oddsnends.htm
"It is to use the Rouquayrol appartus, invented by two of your own countrymen,
which I have brought to perfection for my own use, and which will allow you to risk
yourself under these new physiological conditions, without any organ whatever suffering.
It consists of a reservoir of think iron plates, in which I stor the air under preessure
of fifty atmospheres.