Mr Trotman went down the air-shaft communicating with the other boilers.
We are under an air-shaft running up to the poop-deck, and we may go no further.
They live in lodgings and make acquaintance across the air-shaft.
You remember that I told you there was an air-shaft in the middle of the caisson?
In such cases a second well is dug to the right or left, as an air-shaft, ...