HYGROSCOPICITY. 



71 



The next statement gives the shrinkage in total volume in 

 passing from green to air-dry wood in pm'ent.agi) of the 

 volume of the green wood. The figures in brackets ( Wi'isbarh ) 

 refer to the increase in volume of air-dry wood that has 

 placed in water for the space of a month. 



[The percentages in the last tabular statement show how lo 

 calculate the reduction in volume, ''.//., of railway-sleepers, 

 from the green volume of the wood to its volume when 

 utili/al)le in an air-dry condition. This is very useful for 

 sleepers of somewhat doubtful dimensions, that would shrink 

 to perhaps a smaller size than that agreed to by a rail- 

 way company, and might consequently be rejected.' The 

 figures in brackets arc, useful when timber is lloatod, as it 



* Matliey o cit. 



