PREVENTIVE MEASURES. 421 



assisted no doubt by the wind, have been known to be flung to a 

 distance of 500 yards. 



(10) Nature of the soil. Forest fires are fiercest in a loose dry 

 soil, and mildest in a compact or hygroscopic soil. When the soil 

 is compact, no current of air can rise up from its interior to fan up 

 the flames; and when the soil is moist, this current of air is so 

 charged with steam that, if it does not put out the fire above, it at 

 least moderates its intensity. 



From the foregoing discussion it is easy to see that the danger 

 and severity of a conflagration will be very dififerent according to 

 the prevailing conditions. In some forests the occurrence of fire 

 is physically impossible ; in other classes of forests large areas 

 remain safe for several years together without any special mea- 

 sures of protection at all; in others again the whole area must, 

 unless it is specially conserved, burn regularly every year; and 

 amongst these last, dififerent forests will require different degrees 

 of care, vigilance, and intensity of protection. Whereas in some 

 forests a conflagration will usually sweep over as much as 20 square 

 miles in the 24 hours, in others, even during the driest season of 

 the year, scarcely 5 square miles will be burnt in as many days ; 

 and indeed, in the Himalayas, an average of 100 acres burnt in 24 

 hours is an unusually heavy casualty. In one instance, in the 

 Mundali deodar forests, only 30 miles inside that range of moun- 

 tains, a fire, after smouldering, on for five days in a deposit of 

 dead leaves about 2 feet thick, spread over barely half an acre of 

 the hillside. On the other hand in Central India, the grass 

 standing in a continuous mass, a fire occurring in the hot weather 

 can seldom be put out before it has extended over several thousand 

 acres. 



Hence in comparing statistics of fire conservancy in the diffe- 

 rent forest regions of India, or in drawing, from particular instan- 

 ces, general conclusions regarding the success or failure, adequacy 

 or inadequacy, and cheapness or expensiveness of particular 

 measures and methods, we cannot be too careful to make full 

 allowance for the pecuHar circumstances of each case. For in- 

 stance, 1,000 acres burnt in fire-conserved sal forest along the 

 foot of the Himalayas will undoubtedly prove more inefiicient pro- 

 tection than 10,000 acres burnt in the open low teak forests of the 

 Central Provinces. 



SECTION III. 

 Means of prevention. 



The means for preventing fires in a forest naturally group them- 



