OAK TIMBER. 143 



spottiness of various kinds, and is sometimes twisted. 

 At the roots it is very often affected with burrs. It con- 

 tains gallic acid, and so corrodes iron nails, clamps, etc. 



(12) Uses. Owing to its high price and great spe- 

 cific weight, oak has suffered in competition with spruce, 

 larch, and pine so far as building is concerned ; but its 

 uses are very various and widespread nevertheless, and 

 it is invaluable to the engineer and builder wherever 

 strength and durability are aimed at. 



As already said, its great value depends on its mar- 

 velous combinations of several average properties ; and 

 considerable variations in the density, durability, ease 

 of working, and beauty when worked, and so forth, are 

 met with according to the situation and climate in which 

 the oak grows. Generally speaking, it is found that 

 when the oak grows isolated in plains, in rich soil and a 

 mild climate (habitat of Q. pedunculata), it grows rap- 

 idly, and produces a wood of very tough and horny con- 

 sistency, which is regarded as the best for naval and 

 hydraulic work, cartwrights, etc., and wherever strength, 

 tenacity, and solidity are required in high degree (Fig. 

 39, top). The best should have broad and equal rings, 

 but not broader than 7 to 8 mm., with narrow vascular 

 zone and the smallest possible vessels, and with a pale, 

 rather than dark, and even color on the fresh section. 

 It should also have long fibers and a strong, fresh smell. 



In close, high forest, on poor soil, and in a rougher 

 climate, it may take 300 years to reach 0'6 metre diame- 

 ter, and the wood is then softer and more porous, beau- 



