"As the smoke and vapour which ascend from burning fuel rise in consequence of their being rarified by heat, and made lighter than the air of the surrounding atmosphere; and as the degree of their rarefaction, and consequently their tendency to rise, is in proportion to the intensity of their heat; and... as they are hotter near the fire than at a greater distance from it, it is clear that the nearer the throat of a Chimney is to the fire, the stronger will be... its draught, and the less danger there will be of its smoking."