"As the immoderate size of the throats of Chimnies is the great fault of their construction, it is this fault which ought always to be first attended to in every attempt which is made to improve them; for... if the opening left for the passage of the smoke is larger than is necessary for that purpose, nothing can prevent the warm air of the room from escaping through it; and whenever this happens, there is not only an unnecessary loss of heat, but the warm air which leaves the room to go up the Chimney being replaced by cold air from without, the draughts of cold air... cannot fail to be produced in the room..."