TIMBER 
15 
less than 0"1 inch per 100, the shrinkage in width may 
amount to 3 per cent, for soft pine, spruce, cedar, and hght 
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 sHght 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 
