DAMAGE CAUSED BY ATMOSPHERIC PRECIPITATIONS. 33 



Heavy hoar-frost, causing the formation of ice, does all the more 

 damage when immediately followed by a fall of snow, which then 

 finds an easier foothold on the ice-coated twigs and branches, 

 whilst the consequences of a repetition of snow'fall after the 

 previous formation of ice, through the thawing and then the 

 freezing of snow lying on the branches, or of a snowstorm after all 

 branches, twigs, needles, and dry leaves have been coated with 

 smooth sheet-ice, are also so much more injurious, that damage 

 on a most extensive scale may often be the result. Practicable 

 preventive measures against such natural calamities are only 

 adoptable in the most limited degree, and consist mainly in avoid- 

 ing the cultivation of the brittle Scots Pine in misty tracts, in 

 the retention of a good belt or fringe along all edges exposed to 

 danger, and also in some cases, to a certain extent, in strong 

 thinnings of the crops. The courses to be adopted, after damage 

 has taken place, are the same as in the case of damage done by 

 snow. 



Hail-storms sometimes do very considerable damage in beating 

 down and injuring the plants in young crops and plantations, and 

 occasionally injure older crops to such an extent by injuring the 

 bark, stripping off the foliage, twigs, and fruits, as to necessitate 

 their immediate clearance. Here again, Scots Pine is the chief 

 sufferer, being more sensitive to all such sorts of injuries, whilst 

 Spruce and Silver Fir are better protected by reason of their 

 denser foliage and closer branch -development. In Oak coppice 

 hail brings the disagreeable consequence that at all the damaged 

 and then cicatrised places the bark does not strip or peel easily, 

 whilst the withes of osiers from willow-beds that have suffered 

 from hail break off at the injured parts when beingutilised. 



Preventive measures against damage by hail are naturally not 

 at our disposal, but forests themselves seem to exert a certain 

 amount of influence on the formation of hail by modifying 

 extremes and equalising the distribution of atmospheric electricity 

 during violent storms, so that by forming and maintaining a 

 sufficient number of properly distributed woodlands some prac- 

 tical means do remain at our disposal for protection against and 

 mitigation of the damage wrought by hail-storms. 



