e old work but,
for the most part, design and proportions cannot be improved. The
angles of sides and back, size of opening and throat, location of
smoke shelf, size and proportions of smoke chamber, all were
determined through years of rule of thumb experiment where only the
best results survived. Therefore, the owner of an antique country home
with chimney and fireplaces intact should think twice before he gives
orders to demolish them. Similarly, he who is building a new house
can well plan to reproduce the old fireplaces in size and shape.

Building proper chimneys and hearths was slowly evolved through the
centuries. In the late 18th century, an American codified this masonic
lore and established the scientific basis for a proper fireplace so
cogently that even today his principles form the backbone of fireplace
building. He was born Benjamin Thompson, March 26, 1753, at Woburn,
Massachusetts, but is better known as Count von Rumford of the Holy
Roman Empire.

"The plague of a smoking fireplace is proverbial," began Rumford in
his treatise on the subject, written during his years in the service
of the Elector of Bavaria. Stripped of the involved terminology
characteristic of the natural philosopher of that day, his
specifications for a smokeless, heat-radiating fireplace are very
simple and depend on three fundamentals. First, the size of flue must
be in proportion to the fireplace opening. Second, the angles of back
and jambs must be such that they will reflect heat into the room.
Third, throat and smoke chamber of proper size and shape are essential
because the former improves the draft while the latter prevents smoke
from being blown out into the room by a down draft within the chimney
flue.

From this it is clear that the New England-reared count of the Holy
Roman Empire was really describing the type and design of fireplace in
general use at home in his boyhood and explaining the scientific
reasons for its superiority over European rectangular ones, built
throatless and without a smoke chamber. As stated before, technical
men today generally go back to Rumford's work and the American
tradition behind it, but in one particular they make a wise departure.
Instead of a single common flue, they advocate separate ones for each
fireplace.

These modern specifications, based on several centuries of good
practice, are as follows: The fireplace should be at least 18 inches
deep and have a hearth 20 inches wide. T