The Franklin stove is a metal-lined fireplace named after its inventor, Benjamin Franklin. It was invented in 1741. It had a hollow baffle near the rear (to transfer more heat from the fire to a room's air) and relied on an "inverted siphon" to draw the fire's hot fumes around the baffle. It was intended to produce more heat and less smoke than an ordinary open fireplace. It is also known as a "circulating stove" or the "Pennsylvania fireplace".
The two distinguishing features of Franklin's stove were a hollow baffle and a flue that acted as an inverted siphon.