"Unfortunately, most of the technical improvements in fireplace design have not yet emerged into common usage... in spite of the fact that improvements occurred as far back as 1624, when Louis Savot invented the first heat-circulating fireplace. His unit... became the prototype for Ben Franklin's 1742 Pennsylvania stove. The 1624 French fireplace achieved 30 to 45 percent more efficiency than... most American tract-home fireplaces today!"