"When you find... that opening the door or a window enables the chimney to carry up all the smoke, you may be sure that want of air from without was the cause of its smoking: I say from without, to guard you against a common mistake of those who may tell you, the room is large, [and] contains abundance of air sufficient to supply any chimney... These reasoners are ignorant, that the largeness of a room, if tight, is... of small importance, since it cannot part with a chimneyful of its air, without occasioning so much vacuum..."