SEASONING AND IMPKEGNATION OF TIMBER 273 



advantage, and is seldom practised except on a small scale 

 in a builder's yard. The planks are almost universally laid 

 horizontally in tiers, being often kept separate by laths, and 

 in the case of logs and larger timber each layer is or should 

 be placed in reverse directions. 



Pine timber, when cut, contains in round figures 40 to 60 

 per cent, of its weight of moisture, the larger proportion 

 of which is within a couple of inches of the outside, and it 

 is advisable that for good interior work not more than 10 to 



FIG. 39. Common Method of Stacking Planks for Seasoning. 



12 per cent, be left, although this is a condition of dryness 

 rarely attained by timber when it is put into buildings. 



In three months 16 per cent, of their moisture has 

 been abstracted from oak sleepers by open air exposure 

 in Arkansas, U. S., and in the drier climate of New Mexico 

 pine sleepers have lost 42 per cent, in six weeks. 



Absolutely dry wood cannot be attained by any process, 

 for chemical destruction takes place before that occurs ; 

 moreover, as we have already stated, timber will always 

 absorb the amount of moisture contained in the surround- 

 ing atmosphere, and it is useless drying it below that limit. 



T. T 



