well. This novel police work has greatly reduced the number of
incendiary fires.

[Illustration: FOREST FIRES DESTROY MILLIONS OF DOLLARS WORTH OF
TIMBER EVERY YEAR]

A forest fire may destroy in a few hours trees that required
hundreds of years to grow. A heavy stand of timber may be reduced
to a desolate waste because some one forgot to put out a
campfire. Occasionally large forest fires burn farm buildings and
homes and kill hundreds of people. During the dry summer season
when a strong wind is blowing, the fire will run for many miles.
It always leaves woe and desolation in its wake. A mammoth
forest fire in Wisconsin many years ago burned over an area of
two thousand square miles. It killed about fourteen hundred
people and destroyed many millions of dollars worth of timber and
other property. A big forest fire in Michigan laid waste a tract
forty miles wide and one hundred and eighty miles long. More than
four billion feet of lumber, worth $10,000,000, was destroyed and
several hundred people lost their lives. In recent years, a
destructive forest fire in Minnesota caused a loss of $25,000,000
worth of timber and property.

There are several different kinds of forest fires. Some burn
unseen two to four feet beneath the surface of the ground. Where
the soil contains much peat, these fires may persist for weeks or
even months. Sometimes, they do not give off any noticeable
smoke. Their fuel is the decaying wood, tree roots and similar
material in the soil. These underground fires can be stopped only
by flooding the area or by digging trenches down to the mineral