A life-line for a Second World War pilot was the rubber tube.  Saint-Exupéry’s account vividly describes the physicality and encumbrance of flying a reconnaissance plane at the start of the war.

I am attached to the plane by a rubber tube as indispensable as an umbilical cord. 

Source: Antoine de Saint-Exupéry, Flight to Arras, trans. by Lewis Galantière (Harmondsworth: Penguin, 1961), p. 24

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