Exhaust gases are channeled out of the smoke box though the smokestack or funnel (or chimney in England), accompanied by the distinctive chuffing sound. Over the years, many distinct styles of smokestack were developed; some denoting when the locomotive was built, some indicating type of fuel burned, and some mainly decorative additions. Some were extremely tall (to allow sparks to cool before reaching the ground) and some were very short (to give the locomotive more "back-pressure" and greater power).
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Preventing forest fires
Smokestacks in England