“Lisa! Michael! It's time to hang your stockings on the mantel!" The fire crackles in the fireplace, its glow sending flickers of light through the room whose only other illuminations comes from the brightly colored bulbs on the Christmas tree. Acrid wood smoke mixes with pine scent, reminiscent of the forest. In scamper four-year-old Lisa and six-year-old Michael, respectively clad in nightgown and pajamas, cherubic faces shining in the firelight. The magic of the moment erases the past weeks' clamor and frustration, bathing the whole family in the warmth and serenity of Christmas Eve.
There's something about the dancing flames and smoky aroma of a hearth-bound fire that soothes and calms. Could it be that despite our hectic modern lives, we still have a common bond with ancestors who, centuries ago, gathered their families around the fireplace to watch the lighting of the Yule log on Christmas Eve?
Of Rome and Rumford
As cultures developed and differentiated, fire was used in various ways: it heated brick floors in Rome, radiated from tiled or porcelain stoves in Asia Minor, burned in open braziers in the Middle East and Mediterranean regions.
By medieval times, fireplaces were built next to European castle walls; their housings were ever bigger and more grand, with carved columns, marble mantels, and stone facings. At first fireplaces were vented through the walls, but gradually chimneys were developed to reduce the smoke these colossal fires spewed into the room.
Fireplaces remained essentially unchanged until the late eighteenth century. Suddenly London's elite were competing to have one Benjamin Thompson, Count Rumford, alter their fireplaces to make them more efficient. This undeservedly obscure figure made the most important changes in the history of fireplace design.
Rumford was born in Woburn, Massachusetts, in 1753. He remained loyal to King George during the Revolutionary War and so was fortunate to escape to London, rather than being executed as a Tory. A true renaissance man, Rumford made contributions in many areas. He used nutrition to improve the health and strength of soldiers and livestock, reorganized the Bavarian army, invented a system of naval signaling, and made great advances in military logistics.
Soon, Rumford turned his attention to heat. He was the first person to realize that heat is not a liquid form of matter and thus laid the foundation of the modern theory that heat is a form of motion. More important for home heating, Rumford discovered that heat is transmitted by moving particles - that heat works through radiation, as well as by the convection of moving air currents and by conduction through a solid object. All of this work led to Rumford's ideas about fireplace improvement. He agreed with his contemporary Benjamin Franklin that outside air would improve a fireplace's draft. But whereas Franklin recommended cutting an extra opening high on the wall near the chimney, Rumford theorized that the chimney itself could supply this air.
To keep wintry breezes from coming into the room, Rumford devised a smoke shelf - a ledge built into the chimney above the hearth. The smoke shelf diverts the downdraft of
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