662 



PROTECTION AGAINST LIGHTNING. 



exposed to this danger, perhaps on account of their roots 

 forming better conductors to the moist subsoil than those of 

 shallow-rooted species. 



According to the valuable observations made annually by 

 Dr. Hess from 1874 to 1890 in the forests of Lippe-Detmold,* 

 among broadleaved trees the oak suffers most, among conifers 

 the Scots pine. Then follow spruce and beech. The birch, 

 poplars, ash, alder, willows, larch, and other trees suffer only 

 exceptionally. 



TREES STRUCK IN LIPPE-DETMOLD, 1874 1890. 



The forest was stocked as follows : 



Oak . 

 Beech . 

 Spruce . 

 Scots pine 



11 per cent. 

 70 

 13 ,, 

 6 ,, ,, 

 100 



The danger therefore, considering the beech as 1, was 6 for 

 a spruce, 37 for a Scots pine, and 60 for an oak. 



Other observations by Collodon,t Hellmann,t Cohn, and 

 Caspary give somewhat different results. 



* " Ztschrft. fr. Fret. u. Jgdw.," 18791889. 

 f " Allg. Frst. u. Jgdztg.," 1875, p. 440. 

 t '-Frstl. Blttrn.," 1889, p. 20. 



