OAK TIMBER 143 



epottiness 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, &c. 



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

 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 

 marvellous 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 rapidly, and produces a wood of very tough and 

 horny consistency, which is regarded as the best for 

 naval and hydraulic work, cartwrights, &c., and wher- 

 ever 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 colour on 

 the fresh section. It should also have long fibres and 

 a strong, fresh smell. 



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

 climate, it may take 300 years to reach - 6 metre diameter, 



