274 
TIMBEE 
Even the amount of moisture in so called " dry wood " is 
not always the same. The late Professor eT. B. Johnson, in 
his "Materials of Construction," says "the weight of a 
pailful of shavings varies with the time of day, being on a 
summer day greatest in the morning and least in the after- 
noon. Wood kept on a shelf in an ordinary dwelling-house 
retains 8 to 10 per cent, of its weight of water, and this 
percentage is always greater than the percentage of the 
surrounding air." 
The timbers of the temperate zone contain least sap if 
cut at the fall of the year and thus season more readily, 
but the time of felling does not affect their strength or 
durability. 
Artificial Seasoning. — Kiln drying, where the timber is 
stacked in a tank and exposed to temperatures of hot air 
from 150° to 180° Fahr., is a quick, useful, and satisfactory 
method of seasoning timber when it is required urgently. 
Some soft woods are put into the tank fresh from the saw ; 
hard woods are allowed to season in the air for some months 
previously so as to allow shrinkage to take place more 
gradually, as they are more liable to split by sudden drying. 
As a rule lower temperatures of 100° to 120° Fahr, are 
employed when the timber is kiln dried in a green state, and 
sometimes dry steam is applied to it during the process to 
enable the seasoning to take place more gradually and with 
less risk. In the above temperatures pines, spruce, cedar, 
and soft woods are generally allowed about four days for 
1-inch boards, and hard woods, after being air dried for three 
to six months to allow the first shrinkage to take place, are 
placed in the kiln for from six to ten days for the same 
thickness of boards. 
Careful stacking of the timber, so as to allow spaces 
around each piece, is as necessary in kiln drying as in 
