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Forest Injury by Lightning 





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A bulletin has Ijeen issued from the government printing office at 

 Washington dealing with the injury to standing timber by lightning. 

 It was written by Fred S. Plummer, geographer in the Department 

 of Agriculture, and it brings together data of a most interesting 

 nature. Figures are compiled from various sources, but chiefly from 

 special investigations carried on to determine the frequency of forest 

 fires caused by lightning; the comparative number of trees struck, 

 and the extent of the damage done. 



The importance of the part played by lightning is indicated by the 

 fact that in the longleaf pine belt of the South alone thirty thousand 

 trees a year are .struck. The woods are not often set on fire in that 

 region by lightning, because the heavy rains which nearly always 

 accompany electrical storms put out the incipient fires. Still, many 

 trees are set on fire. It is declared that of all portions of the United 

 States, lightning is most frequent in Illinois and Florida. 



There are certain lightning zones in elevated regions. The sum- 

 mits of high mountains are often above the lightning area, and suffer 

 little, while lower down the sides and in the valleys below, the electric 

 storms are much more severe. 



A special investigation covered about two hundred million acres of 

 national forests, and extended over about fcrur years. This region 

 lies chiefly in the Far West. The number of trees struck was, by 

 actual count, 76,301. About one in fifty was set on fire. It is stated 

 that lightning is fourfold more frequent east of the Eocky Mountains 

 than west of that range, but no count or estimate is made of the 

 number of trees struck in the East, except for the southern pine belt, 

 and in small areas of Minnesota and Michigan. 



The wooCls may be set on fire by lightning anywhere, but it occurs 

 more frequently in the West than in the East because the climate of 

 the West is dryer. 



The investigation shows that in the national forests in six years 

 2,957 forest fires have been caused by lightning. Sometimes a tree 

 is ignited, and the fire spreads from that to the leaves and other 

 ground litter. In such a ease, the fixe might not appear for several 

 hours, or even days, after the storm had passed. In the majority of 

 cases where the exact process was discovered, it was found that the 

 lightning did not set a tree on fire, but ran down the trunk and ignited 

 the humus at the base. 



That lightning is amply able to do this is shown by the effect of a 

 stroke that enters the ground. It frequently develops enough heat to 

 melt the sand and fuse it into a core from a half inch to six inches 

 in diameter. This fused mass may extend twenty-five feet into the 

 earth, in the form of a hollow tube, vitrified or glassy on the inside 

 and coarse-grained or half used on the outside. These lightning- 

 formed bodies have long been known, and ignorant people supposed 

 they were the real thunderbolts that had struck there and lodged in 

 the ground. The}' are called also thunder stones, storm stones, Thor 's 

 bolts, ceraunia, and fulgurite. 



Lightning occasionally strikes the ground directly, but no instance 

 has been reported where a woods fire was started without the lightning 

 having first come in contact with a tree trunk. 



The common superstition or belief that some kinds of trees are more 

 liable to be struck than others, and that some are never struck, is 

 found to have no foundation, as any tree that is in the lightning's 

 path will be struck. The species appears to make no difference what- 

 ever. Circumstances do make a difference. Tall trees, isolated trees, 

 those on high ground, those deeply rooted in damp soils, and those 

 thoroughly soaked by rain, are more likely to be struck. The shape of 

 the tree's branches and its spread of roots seem .to have something 

 to do with its liability to be struck. It depends upon whether or not 

 the tree is a good or poor conductor of electricity at the moment. 



It is shown that a tree may be dry and thus a poor conductor, but 

 a dashing rain will wet it and its liability to be struck by lightning 

 is greatly increased. 



Lightning occasionally strikes twice in the same place, which is 

 contrary to the popular belief. Seven or eight strikes in the same 

 place are known. 



—36— 



It is usually taken for granted that when a tree is struck, the 

 lightning runs from the top downward. That is the usual manner, 

 but the reverse sometimes occurs. Mr. Plummer says : 



' ' A flash of lightning striking upward through the tree from its 

 base acts as an explosive. The trees may be torn into small frag- 

 ments, and cases have been recorded where these appeared like a piece 

 of hemp. If the upward flash is less violent, the tree may be split 

 radially. The tops of trees have been torn off while the lower parts 

 remained uninjured. On the other hand, the lower portion of a tree 

 has been demolished, while the upper part fell to the ground intact." 



The reason why lightning tears a furrow in the side of a tree trunk 

 or splits the tree into fragments has not been determined. The gen- 

 eral belief is that the passage of the current through the wood gen- 

 erates sufficient superheated steam, from the water in the wood, to 

 cause an explosion, and that the tearing and rending is really the 

 work of steam. Another view is that the lightning forces its way 

 through the wood, much as a bullet would do, and ruptures the wood 

 iu the same way. 



Microscopic e.Kamination does not show that the passage of light- 

 ning through wood, even when it is sufficiently violent to tear the 

 wood to pieces, produces any effect upon the wood colls and other 

 delicate elements in the immediate vicinity. 



Aside from the injury done by forest fires started by lightning, the 

 damage done to individual trees is no small item when the whole 

 country is considered. Some trees are struck lightly and little injury 

 follows, but usually the tree is so damaged that it soon ceases to be 

 valuable for lumber. On some of the western mountains — particularly 

 on the volcanic circular flats of the San Francisco mountains — nearly 

 one-half of the mature trees have been killed or injured by lightning. 

 In the eastern hardwood forests it is a common thing for trees to be 

 killed outright, while many others are wounded beyond recovery. No 

 protection of forest trees against lightning is possible. 



Construction in Russia 



A report from United States consul at Moscow, Kussia, shows that 

 building operations during 1911 were fully up to the expected figures 

 in that country. A great number of new buildings were erected in 

 the various distHcts and many old ones enlarged to meet the increased 

 requirements of municipalities, and for industrial and transportation 

 concerns. Lack of labor and material was felt in construction work, 

 this being particularly true of cement and brick, which showed a con- 

 stant rise in price. The adoption of so-called fireproof buildings in 

 villages was one of the chief contributing factors to this condition. 

 In fact, the excessive rise in price of building materials has resulted 

 in a serious consideration on the part of municipalities looking toward 

 the manufacture of their own raw materials. In addition there has 

 been wide agitation looking toward the abolition of duty on cement, 

 and the reduction of freight rates generally. 



In the city of Moscow various types of buildings were erected, and in 

 the summer of 1911 more than three hundred thousand five and seven 

 story residences were built. About three hundred million bricks 

 were manufactured in this district. 



Similar reports emanate from various other prominent cities of the 

 Empire, all of which show a continued increase in building constnic- 

 tion caused by the establishment of numbers of industrial and busi- 

 ness operations, which called for increased housing facilities and in- 

 creased facilities for manufacture. 



Another cause for renewed activity in building operations is the 

 increase in town population, and a consequent growing demand for 

 lodgings. An abundant harvest during the last two years, coupled 

 with the extensive renewal of construction work by the railroads, 

 has been one responsible factor in influencing city building. 



The fact that the unusual activity in building operations is evident 

 in all sections of the Russian Empire is fairly conclusive proof that 

 Eussia has entered upon a new era in prosperity as such pronounced 

 activity can only result from genei'ally improved conditions among 

 the individuals who make up the population of that vast country. 



