i8 



entry in such cases the discharge is dispersed in such a way as not 

 to cause visible mechanical injury to the tree. The girdling of a 

 larger or smaller area of the living zone or cambium layer of the 

 trunk would be sufficient to cause its death. Quite frequently this 

 is accomplished by the discharge taking a spiral course. In a very 

 large number of instances of lightning stroke neither death nor 

 mechanical injury of importance takes place. Hundreds of trees 

 -are annually struck by lightning that are never recognized except by 

 those who know how to interpret the small vertical lines or creases 

 which subsequently make their appearance on the trunk. (See Fig- 

 ure 9.) There are many cases of lightning stroke that appear to 

 offer examples of discharges from the earth. The effect of such dis- 

 charges on the tree are quite characteristic and not at all similar to 



the ordinary forms of 

 lightning strokes. Prob- 

 ably the nature of the soil 

 conditions have much to 

 do with such discharges, 

 although it must be con- 

 fessed that little light 

 has been shed upon 

 this subject. Our atten- 

 tion was called two 

 years ago to some tree 

 belts located in a town 

 in the eastern part of 

 the State, where light- 

 ning had apparently 

 caused some damage. 

 These trees are maples 

 from 5 to 18 inches in 

 diameter, growing in soil 

 composed in most places 

 of gravel containing 

 apparently oxide of iron, 



Fig. II Showing the effect of earth dis- and un derneath this I 

 charges througli the tree, causing splitting of the 

 .trunk and destruction of limbs. am informed there is a 



stratum of quick sand. 



