The discovery of fire, Darwin wrote in The Descent of Man, “was
probably the greatest ever made, excepting language. It dates from
before the dawn of history.”
The earliest fireplaces were no more than open hearth fires, confined by
some arrangement of stones. As early man moved indoors, the smoke from
these fires was left to find its own way out - through the cave
entrance, a hole in the roof, or seeping through the loose stones of
When civilized man began building substantial houses, he developed the
chimney which brought a flue down close to the fire in the hopes of
drawing off smoke.
These early fireplaces were very inefficient, drawing a good deal of the
heat up the chimney while admitting an unbearable amount of smoke into
the room. In the late 1700’s, Benjamin Thompson, Count of Rumford,
recognizing that a fireplace heats an area by radiation, began a series
of experiments aimed at improving its performance.
He discovered through observations and various constructions that the
exaggerated width of the chimney of his time, necessitated by the need
for room for a chimney sweep to climb through the throat area into the
flue, was a primary cause of inefficiency and smokiness. He attributed
the problem not only to the chimney, but the width of the throat and
also specific fireplace dimensions and configurations.
Using the knowledge gained from his studies, Rumford modified the
traditional fireplace design into one that burned cleaner and hotter
and, most importantly, did not smoke. His efforts greatly improved the
performance of the fireplace.
2. Professor Peter 0. Rosin discovered, through scientific experiment,
that Rumford’s flue theory was incorrect. He observed that the hot
gasses steamed up the back wall of the flue in stratified layers and
that a smoke shelf in fact disrupted the efficient flow by creating