The Franklin stove (name after its inventor, Benjamin Franklin) is a metal-lined fireplace with baffles in the rear to improve the airflow, providing more heat and less smoke than an ordinary open fireplace. It is also known as the circulating stove. Although in current usage the term "stove" implies a closed firebox, the front of a Franklin stove is open to the room. While Franklin is often credited with its invention, some historians believe the circulating stove was actually invented 70 years prior to Franklin's creation of Media stoves. The metallurgy at the time, however, required that it be made of cast iron, which cracked when fired. This caused smoke to pass through the cracks and into the room: as a result, the original inventors did not patent or sell their device. Franklin designed a similar stove with more advanced metallurgy and was successful in making it work—at some point in 1742, according to his own account.