44 TECHNICAL PKOPEKTIES OF WOOD, 



instruments, and the best kind for this purpose is finely ringed 

 wood grown on medium soil at altitudes of 2,000 to 4,000 feet 

 above sea-level. The properties of this wood for sounding 

 musical notes consist not only in its hi<,'h elasticity, but also in 

 its uniform texture, causing equable vibrations throughout the 

 wood, which therefore gives out pure musical notes. 



The value of the timber of our forest trees is greatly influenced 

 by its elasticity, as in cart- and carriage-building, planks and 

 beams, wood used for implements, Sec. ; since elasticity 

 depends on the density and clean growth of the timber, this 

 gives a clear indication of what the forester should produce. In 

 treating his woods he should follow all cultural rules which will 

 increase these valuable properties of timber. 



In the case of individual woods, owing to the varying circum- 

 stances which aff"ect their elasticity and the little experimental 

 knowledge already attained in this respect, it is very diflicult to 

 classify them according to their elasticity ; all that can be 

 done is to separate them into two classes from the results of 

 Nordlinger's investigations : — 



Very elastic : Yew, larch, spruce, Scotch pine, silver-fir, 

 robinia, oak, Spanish chestnut, ash, hickory, sycamore, Wey- 

 mouth-pine, lime. 



Less elastic : Poplar, Cembran pine, beech, juniper, aspen, 

 birch, alder, black pine, elm, walnut. 



8. Flexibility. 



It has been already stated that the quality of flexibility of a 

 wood is rarely combined with elasticity. Whilst to secure the 

 latter the wood should be as dry as possible, a damp or half 

 dried condition renders a wood more flexible, and only in such a 

 condition can economic advantage be taken of the flexibility 

 of a wood. It is also necessary that a piece of wood be of 

 moderate transverse dimensions if considerable change of form 

 is desired. A complete saturation of wood frequently nullifies 

 its elasticity, keeps its brittleness far in the background and 

 therefore considerably increases its flexibility. Steaming wood 

 is the best method for this purpose, there being hardly any 

 species of wood which cannot be thus rendered flexible. 



As a rule, the highest degree of flexibilitv is found in the case 



