Every fire, when it first starts, is nothing but a little blaze which might easily be extinguished; but as it grows and spreads it quickly gets beyond control, unless there is a force of well-trained men to fight it.
There are three kinds of forest fires,—"top fires," "ground fires," and the fires which burn the whole trees and leave nothing standing but stumps and blackened trunks.
The "top fire" is a fire in the tops of the trees. It is usually caused by a spark from an engine dropping on a dry twig or cone among the upper branches. A light breeze will then blow the fire from one tree to another high up in the air, and after it has swept through the forest and killed the tops, the trees will die. This is the hardest kind of a fire to fight, as it is impossible to reach it. The only thing to do is to cut a lane in the forest too wide for the flames to leap across; but there is not always time for this, as the fire travels rapidly.
The ground fire is not so difficult to cut off, as it spreads through the moss and the decaying vegetable matter among the roots of the trees. A broad furrow of fresh earth, turned up with a plow, or dug up with a spade, will stop the progress of the fire; but this kind of fire is especially treacherous, as it will live for days, or even weeks, smouldering in a slow-burning log or in a bed of closely-packed pine needles, and then burst out with renewed vigor.
As all large fires create air currents, masses of light gas, like large bubbles or balloons, are blown about in the air, ready to burst into flame from even a tiny spark. In this way new and mysterious fires are set, often at some distance from the original fire.
An ordinary forest fire travels slowly unless it is fanned by strong winds or driven by a hurricane. It will burn up-hill much faster than it burns down-hill, as the flames, and the drafts they create, sweep upward.
The noise from one of these great fires is terrifying. The flames roar with a voice like thunder, and the fallen trees crash to the ground, bringing down other trees with them.
Birds and wild animals flee before the fire, hurrying away to a place of safety. They seem to know by instinct which way to go, and deer, bears, coyotes, mountain sheep, and mountain lions will follow along the same trail without fear of each other in their common danger.
Some of our national forests, and some of the tracts of timber land owned by big lumber companies, are guarded by forest rangers and fire patrols, and many fires are put out before they do serious damage, by the quick thought and skilled work of these men and their helpers.
It has been estimated that forest fires in the United States destroy property to the value of $50,000,000 every year. In this way the timber in the country is being rapidly exhausted; and unless something is done to put a stop to this waste and to replenish the supply by planting new forests, there will be little timber left in another fifty years.