CHAPTER I. 



TECHNICAL PROPERTIES AND QUALITIES OF WOOD,* 



The wood of our different forest trees has, according to species, 

 very different properties, so that one kind of wood is better 

 adapted for any given purpose than other kinds. The technical 

 properties of any wood are those pecuharities Avhich render it 

 suitable for certain uses. They nmy vary for one and the same 

 species of tree according to the soil on which the tree has grown, 

 the climate, the rate of growth, the part of the trunk, the age of 

 the tree, the healthy or unhealthy condition of its wood and 

 other circumstances ; and even under each of these heads much 

 individuality may be shown. 



Hardly any material is so variable as wood, and it is, there- 

 fore, impossible to predicate any fixed technical qualities in the 

 wood of a certain species of tree. All we can do is to draw an 

 average, and estimate the influences which may modify this 

 average technical quality of the wood of any particular species. 



H. Mayr f lays-down a general rule, that, for every species of 

 tree, the quality and quantity of the wood produced falls-off in 

 proportion to the distance from the best locality for its growth, 

 although the quality of the soil may remain constant. 



As all differences in the technical value of wood depend on the 

 variability of its anatomical structure and its chemical and 

 physical nature, it is necessary to consider shortly the anatomy 

 and chemical composition of wood as far as our purpose 

 requires. 



Section I. — Anatomy of Wood. 



Wood consists of three kinds of elementary organs, which do 

 not, however, all occur in the wood of every species of tree — 

 namely, wood-vessels, virood-fibres and wood-cells. 



* Vide Laslett's Timber and Timber Trees, edited by Marshall "Ward, 1894. 

 + Die Waldungeu von Nordanierika, Munich, ]890, p. 73. 



