. Bulletin (Pennsylvania Department of Forests and Waters), no. 35. Forests and forestry. riie side lines devolop at an an^i'le willi tlie wind or draft and bnrn more slowly. If much wind is present the windward .side maj' die ont entirely. As the faetors vary, the shape of the fire varies aeeord- injr to the resultant of their forees. As for example the apex or head may be acute or broad, accordin<i' to wind, fuel, oi- slope. A ehan^n' in topoji'raphy or in wind may result in the develo|)ment of several heads, or "; Other thinjxs bein' e(pial th«' sevei'ity of the fin' de
. Bulletin (Pennsylvania Department of Forests and Waters), no. 35. Forests and forestry. riie side lines devolop at an an^i'le willi tlie wind or draft and bnrn more slowly. If much wind is present the windward .side maj' die ont entirely. As the faetors vary, the shape of the fire varies aeeord- injr to the resultant of their forees. As for example the apex or head may be acute or broad, accordin<i' to wind, fuel, oi- slope. A ehan^n' in topoji'raphy or in wind may result in the develo|)ment of several heads, or "; Other thinjxs bein' e(pial th«' sevei'ity of the fin' depends upon the quantity and kind of fuel in its path, hut neeessarily the amount of moisture in the material determines the amount of fuel available for the fire. Dry nuiterial will burn readily and the heat from this fuel will dry out additioiud stuff I'enderino- it inflamnud)le. lint the heat may not be sufiHeient to dissipate the moisture from all the litter, eonsecpu'utly a ])art nujy be saved and the severity of the fire lessened to that extent. The aeeumulation of undecaye 1 leaves dei)eiuls ujion the species, season, soil, exposure, ami len'th oi' time siiu-e pi'cvious fire or litter removal. 8|)ecies havin«»- lai*'e crowns and lar<ie leaves, such as maph's and oaks, mak<' a heaviei- litter than ash and birch. A layer of resin- ous lu'edles burns more rapi(.ly and with a hotter fire than does a lay<u* of hardwood leaves. In some forests there is a ' amount of dead wood imule up of standin«i' dead trees or siuijis. fallen trees, dead branches, slashin^i^s, OI the debris of j)revious fii-es. Any of this nuiterial in a dry condi- tion means additional fuel and greater se\ei'ity for a fire. A surface fire runs uj) hill i'a])ii}ly beeause heated air currents draw flanu's u|)ward and more fuel is expo'-icd at the same time to the heat of the fire. After i)assino- the crest a fii'c travels slowly in its de- scent on the other side. On extensive level groun
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectforests, bookyear1923
