TIMBER 15 



less than O'l inch per 100, the shrinkage in width may 

 amount to 3 per cent, for soft pine, spruce, cedar, and light 

 conifers, 4 per cent, for hard pine, larch, locust, and old 

 oaks, 5 per cent, for elm, ash, walnut, maple, beech, and 

 sycamore, 6 per cent, for birch, chestnut, and basswood, 

 whilst hickory and young oaks may sometimes shrink up 

 to 10 per cent., or one inch in a 10-inch board. 



The narrower the plank the less noticeable the amount 

 of shrinkage ; hence in good work panelling is often done 

 in narrow strips three or four inches wide, which so 

 minimises the action as to be unnoticeable. 



Expansion of Timber. It must not be forgotten that 

 timber, in common with every other material, expands as 

 well as contracts. If we extract the moisture from a piece 

 of wood and so cause it to shrink, it may be swelled to its 

 original volume by soaking it in water, but owing to the 

 protection given to most timber in dwelling-houses it is 

 not much affected by wet or weather, the shrinkage is 

 more apparent, more lasting, and of more consequence to 

 the architect, builder, or owner than the slight expansion 

 which takes place, as although the amount of moisture 

 contained in wood varies with the time of day, the conse- 

 quence of damp or moisture on good timber used in 

 houses only makes itself apparent by the occasional 

 jamming of a door or window in wet or damp weather. 

 Considerable expansion, however, takes place in the wood 

 paving of streets, and when this form of paving was in its 

 infancy much trouble occurred owing to all allowances not 

 having been made for this contingency, the trouble being 

 doubtless increased owing to the blocks not being properly 

 seasoned ; kerbing was lifted or pushed out of line and 

 gully grids were broken by this action. As a rule in street 

 paving a space of one or two inches wide is now left next 

 to the kerb, which is filled with clay, sawdust and tar, or 



