PRACTICAL FORESTRY. 



coniferous trees this generally occurs at from seventy to 

 ninety years ; but with hardwoods, excepting the ash and 

 chestnut, which are of most value, say, up to fifty years' 

 growth, the period may he greatly extended. 



10. Thinning is usually performed in autumn and early 

 winter, but it may be well to remember that at the latter 

 period the lowest percentage of moisture (about 47 per cent.) 

 is present, and the timber consequently of the greatest value 

 for constructive purposes. 



140 



