14 TIMBER 



the harder wood than in that of a softer nature, in thin boards 

 than in thick boards, in wide boards than in narrow boards 

 or logs, but occurs in all timber, although no outward 

 manifestation may exist. Pine, spruce, and coniferous 

 timber, owing to its very regular structure, suffers less in 

 seasoning than oak and other hard woods, because, although 

 the same laws take effect, the softness of the material pro- 

 bably allows the cell walls to be crushed by the contracting 

 forces, and so the primary law is modified. Timber loses 

 water more rapidly at the ends than on the longitudinal 

 faces, and shrinks more quickly there and tends to split ; 

 a wet board having one side exposed to the sun, the water 

 is extracted from that side, and the board buckles. 



On examining floor- 

 ing or panelling one 

 often notices that there 

 is an opening at the 

 FlG 6 joints, although when 



originally laid or fixed 



the joints were perfectly flush (Fig. 6), and were it not 

 for the tongues and grooves the planks would often lift 

 up ; the timber has " pined " or shrunk on drying, 

 for however well seasoned timber may be when placed 

 in the dry atmosphere of a dwelling-house and much 

 of it is not well seasoned it will probably in time lose 

 some more of its moisture and tend to shrink. Owing 

 to its structure, as has been said, timber is not appreciably 

 affected in length, that is, along the grain, by seasoning. 

 Eondelet found many years ago that fir might shrink 

 from 7^5 to 3^0 f its length, and oak from ^ to 5^. 

 Mr. Hurst makes an allowance of | inch for northern 

 pine and ^ inch for white deals nine inches in width, being 

 ^Q and y\ respectively, and recent American experience 

 has shown that whilst the longitudinal shrinkage is usually 



