French navy testing balloons for lifting submarines according to the magazine Mitteilungen aus dem Gebiete des Seewesens dated 1914 nos. 1-2

An item reported that the experiments in France with lifting submarines with the use of balloons were continued. The intention was to fit out each submarine with a number of balloons and that 6 balloons were enough for lifting 300 ton. Six folded balloons had a weight of 3 tons and needed a storage of 3 cubic metres to be stored in watertight compartments outside the hull. Opening of the compartments and filling of the balloons with compressed air was done from the inside of the submarine.