8:! TKCHNR'AL I'lKiPEKTIES OK Wool). 



summer are the sesisoiis of greatest sup, aiul autumn and late 

 winter the seasons of least sap in trees. The latter point is the 

 most important of all as regards utilization, and leads us to the 

 question, when should trees he felled "? 



It is still a mueli disputed (jnestion whether winter- or summer- 

 felling is to he preferred to ensure the greater durahility of 

 timber, and this cannot be satisfactorily answered without 

 considering the future destination of the timber after it has 

 been felled. In case the wood is to be thoroughly dried 

 immediately after the felling, and then converted and utilized, 

 it is a matter of indifference whether it is felled during the 

 winter or summer, for the destructive agency of fungi is 

 excluded, as long as the timber is dry. As a matter of fact, 

 however, such an immediate drying of the felled timber is rarely, 

 if ever, thoroughly carried out. On this account, and since the 

 danger from infection by fungi is greater when the timber is 

 felled during summer than when it is felled during winter, in 

 most cases winter-felling is certainly to he preferred to summer- 

 felling. If, however, winter-felling is impossible, trees should 

 as a rule be felled as late as possible in autumn. 



"When trees are felled during winter they generally contain 

 less sap than in summer, the activity of wood-destroying fungi 

 is either very slight or altogether nil, and the new wood is fully 

 lignified. In winter, however, it is more difficult to bark logs 

 completely, or in many cases to bark them at all, so that winter- 

 felled trees lying in the forest dry very slowly, though they are 

 at any rate protected from cracks and splits. 



Wood felled during summer is usually completely barked, in 

 order to facilitate transport and to protect it from insects ; in 

 this condition, the wood, owing to the comparatively dry summer 

 air, dries rapidly in the forest ; it is thus liable to split and 

 crack, often in a serious manner, and during rainy weather is 

 thus exposed to the admission of the spores of fungi. The latter 

 might not cause any injury, if the wood were to become dry to 

 its centre ; but if, as is usually the case, this is not secured, and 

 the wood remains more or less damp for some time, the spores 

 of the fungi will develop into mycelia, and dry-rot ensues. 



In localities high up in the mountains, summer-felling is 

 frequently a necessity, on account of the depth of the snow till 



