Forest Fires — Other Injuries. 159 



direction may be prevented, and allowing this fire to run till it 

 meets the principal fire. Great fires sometimes cause an inward 

 current of air that favors back-firing. As fires advance down hill 

 more slowly than they ascend, the counter-fires may often be set to 

 best advantage at the bottom of a valley. The crest of a ridge is, 

 however, a much better line of defense. 



639. After a fire has apparently been brought under control, it 

 should be carefully watched until it is entirely extinguished. If 

 neglected it will sometimes get under way with more energy than 

 before, even some days or weeks afterwards. On a rocky surface, 

 full of deep fissures, there is very great danger to be dreaded from 

 these concealed fires, that may smolder unobserved for a long time. 



640. It is always a safe precaution to have water, buckets, spades, 

 axes, etc., in readiness for use in case of fires. In some regions in 

 Europe, a system of signals is arranged, and persons are on watch 

 from towers on high hills, for the special purpose cf discovering 

 fires, and making known their locality. A system of telegrapliic 

 signals, consisting of willow-baskets by day, and of lanterns by 

 night, has been proposed in Spain for this use, and by a simple com- 

 bination representing numbers, a correspondent may receive a great 

 variety of messages in a brief space of time, by the aid of books in 

 which these messages are referred to by corresponding numbers. 



CHAPTER XVI. 



PROTECTION FROM OTHEE INJURIES THAN FIEES. 



641. A young woodland needs protection even more than a grain- 

 field, because the injuries done, may destroy the growth of several 

 years instead of one. These damages may be done by wild or do- 

 mestic animals, or by insects ; or they may be caused by disease, by 

 storms of wind, by the obstruction of water-courses that may over- 

 flow level lauds, and in various other ways, many of which can be 

 prevented or removed. 



Pasturage of Woodlands. 



642. In European governments, the rights of pasturage in the 

 public woodlands are regulated by law, and sometimes they are 

 sold, for one year at a time, at public auction. In many cases it is 

 a common right, subject to regulation by the local government. 



