What is a method of securing a good draught in chimneys by covering the top, leaving openings in the sides, or by carrying up two of the sides higher than the other two. [Written also hovelling.] called?

hoveling — A method of securing a good draught in chimneys by covering the top, leaving openings in the sides, or by carrying up two of the sides higher than the other two. [Written also hovelling.]. (Webster's 1913.)

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