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, &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 take300 yearstoreach 0-6 metre diameter, 
