In Franklin's day, colonists staved off the chilly Pennsylvania winters by stocking their roaring fireplaces with oak, hickory and maple logs carried in from the surrounding countryside. Only a few decades after the city's founding, however, the forests around Philadelphia were growing thin, forcing Philadelphians to travel as much as 100 miles to find fuel -- not an easy task on a horse and buggy. Franklin resolved to combat the growing energy crisis by finding a more efficient way to heat colonial homes.
Fireplaces are woefully inefficient: They consume fuel uncontrollably, and most of the heat shoots up the chimney. Franklin solved these problems by enclosing the fire in a cast-iron box positioned in the center of the room. The stove radiated heat from all four sides, and users could control the rate at which wood burned by adjusting the stove's airflow. Safely enclosed, the stove also eliminated the risk of fires being ignited by stray sparks. Versions of Franklin's original design are now a staple of cabins and cottages around the world.