known to have started during a single thunderstorm. But
such fires are not as serious as they once were, because the rangers are
on the watch for them and put them out before they get well started.

[Illustration: _H. W. Fairbanks_
Fires destroyed the forest that once covered this region and its place
is now mostly occupied by small bushes.]

Aside from those due to lightning, most forest fires are now either set
purposely or come from engine sparks or from somebody's carelessness.
Many fires are set purposely by stockmen who think by this means to
clear away the brush and thus obtain better feed for their cattle and
sheep. These men often care nothing for the forests or for the
preservation of the summer water flow. They would, indeed, be pleased to
see all the forests burned away if by that means they could increase
their feed. If you could travel through some of the mountainous portions
of the Southwest, you would see how much harm has been done in this way
to the trees, the streams, and the soil.

It is a hot summer day and two men are riding along a mountain road. One
of them thoughtlessly throws away a lighted cigarette, which falls upon
some dry pine needles. In a few moments the pine needles are ablaze. The
fire spreads with incredible rapidity and a great column of smoke rises
above the treetops. Before any one can reach it, the fire is sweeping up
the mountain side, and it may not be stopped before it has destroyed
thousands of acres of valuable timber. All this terrible loss is due to
one careless man who, in the first place, should not have been smoking
cigarettes, and in the second place should have known better than to
throw a spark into the forest powder magazine.

Some campers, enjoying the summer in the mountains, go away leaving
their fire burning. By and by a stick burns outward until the fire
reaches the leaves, or a gust of wind comes along and carries a spark to
them. In the hot sun the leaves and needles are almost as easy to ignite
as powder, and in a few moments another fire is making headway into the
surrounding forest.

A farmer clearing land thinks he can get rid of the brush and young
trees more easily by burning. But the undergrowth is drier than he
thought, and, the wind coming up unexpectedly, the fire is soon beyond
his control. It may destroy his own fences and buildings and, sweeping
on, ruin those of his neighbors also.

[Illustration: _H. W. Fairbanks_
The dead stub