air hole

This is the air-hole, which allows of gaseous exchanges between the atmosphere inside the box and that outside.

The adit of a military mine, is the aperture by which it is dug and charged: the name is also applied to an air-hole or drift.

One man fell into an air-hole below Forty Mile; another was killed and eaten by his dogs; a third was crushed by a falling tree.

"We know an air-hole when we see it—and I can't see any of them around here," replied Paul.