Patent for improved construction of spark-arresters, "so that they will be more efficient, and yet simple in construction and not liable to get out of repair; and the invention consists of a metallic circular cone, with winding or arched flanges or wings, which extend toward the side of the shall, and they are covered by a plate, to the upper side of which a perforated cylinder is attached, so that all the sparks are arrested and thoroughly extinguished, while the smoke can pass out through the perforations." (Lines 6-16) Includes instructions and illustrations.