WOOD IN GENERAL 245 



bility to stand satisfactorily the heavy loads and the alter- 

 nate drying and wetting to which they are subjected. 



Fences require wood as durable under similar exposure 

 but without the same mechanical strain. 



Poles, as for flags and wires, need similarly to resist decay 

 and also to meet about the same requirements as spars. 



Trestlework, as for bridges and the like, needs especially 

 stiffness with durability under exposure to weather. 



Piling, as the foundation for bridges, wharfs, and so forth, 

 needs not only to be stiff but to be durable under water or in 

 contact with moist soil. 



Mine timbering must be equally strong and at the same 

 time able to resist decay under conditions of dampness much 

 more trying than those of entire submergence. 



Industrial im-plements, machines, and weapons, mostly 

 require wood of especial toughness to serve for handles, cogs, 

 spindles, gunstocks, and the like. 



Canes and umbrellas call for fancy woods of attractive 

 appearance and considerable stiffness, small dimensions 

 being no drawl^ack. 



Surgiccd appliances such as splints, crutches, and artificial 

 limbs are best made of wood that is both stiff and light. 



Recreational appliances such as tennis-rackets, base-ball 

 or cricket-bats, hockey-sticks, golf-clubs, croquet-mallets and 

 balls, nine-pins, balls and bowling alleys, billiard cues, check- 

 ers, and chessmen, are made mostly of wood that is especially 

 tough or hard. 



Musical instruments such as violins, guitars, and pianos 

 depend for their quality of tone mainly upon the resonance 

 of the wood used in their construction. 



Toys are made generally of woods which are most easy to 

 work, and the same consideration largely influences the 

 selection of woods for various minor articles such as spools, 

 button-molds, shoe-pegs, toothpicks, and matches. Other 

 uses of wood apart from its value as constructive material 

 will be referred to later. 



To the plant which produces it, as to us who use it, wood 

 serves mainly for mechanical support. In large trees the 

 trunk must be a column of great strength in order to hold up 



