196 AGRICULTURAL ENGINEERING 



Hickory is a very dense, heavy wood of great strength 

 and elasticity. It is the hardest and toughest wood used in 

 the construction of farm machinery and vehicles. It is 

 preferred to all others for axles, buggy spokes, shafts, etc. 



Oak is a hard wood but not so tough as hickory. It is 

 used to some extent for wagon axles, doubletrees, and gen- 

 erally for parts where stiffness is required. The best kind 

 of oak for these purposes is white oak. Red oak or black 

 oak is not so hard and stiff. 



Ash is hard, tough, and elastic, and for that reason is 

 quite generally used for handles of hand tools, such as forks. 

 It is a white, coarse-grained wood 



Maple. Hard, or "rock maple," is a hard, fine-grained 

 wood which is quite stiff, and is being used to some 

 extent as a substitute for hickory. 



Beech is a hard, strong and tough wood of very close 

 grain and will take a very high polish. 



Birch. Black birch is a dark, close-grained, tough 

 wood. It is used to some extent for wagon hubs, on account 

 of its resistance to checking. 



Poplar is a wood which may be obtained very free from 

 knots. It is light yellowish in color, has a close grain, and 

 is very tough compared with the lighter woods. It is the 

 standard material for wagon boxes and buggy panels. Cot- 

 tonwood, a very close relative of the poplar, is used to some 

 extent as a substitute. 



Pine. There are many varieties of pine to be had. 

 Long leaf yellow pine has a decided grain and is quite stiff. 

 It is used largely in the construction of field hay tools and 

 for similar purposes. White pine is used where soft, light 

 wood is desired. 



Cast-Iron. The cheapest metal used in the construc- 

 tion of farm machinery is cast-iron. It is crystalline in 



