Young Swedish Blonde Girl Reveals At The Fireplace

Newly constructed flues may feature a chase cover, a cap, and a spark arrestor at the top to keep small animals out and sparks from exiting the chimney cavity.
History
Ancient fire pits were sometimes built in the ground in the center of a hut or dwelling. Smoke escaped through holes in the roof. Smoke would be blown outside or back into the room. Chimneys, invented much later, partially fixed this problem, venting smoke outside.