p. GrROOM 



17 



There is no absolute certainty that during soaking the boards had 

 attained their maximum dimensions, though it is probable that such 

 was at least approximately the case. The tangential board, yang 1, 

 had certainly attained its greatest length; and judging by the lengths 

 of the diagonals and widths so likewise had yang 2. When, as a 

 result of drying, the boards had shrunk to their minimal recorded 

 dimensions, these may be assumed to represent the true minimum 

 sizes in relation to the surrounding atmosphere (dry air of the 

 laboratory). 



The changes in length were small or exceedingly small ultimately, 

 being only •012-'075 % of the maximum length. The changes in 

 width at the ends were: tangentially, 5-92-6-29 % during drying, 

 and 6-98 % (in the one case measured) during soaking ; radially, during 

 drying 5 % of the maximum width. 



The subjoined Table gives the percentage changes of the (maximum) 

 linear dimensions. 



The shrinkage in both length and width was less in all cases than the 

 previous swelling, and this was so even when (in the radial board) 

 more water was lost than had originally been absorbed. This permanent 

 expansion of pieces of wood after soaking in water appears not to have 

 been recorded, and it remains to be seen whether or no straight-grained 

 woods show the same behaviour. That some change takes place in 

 wood by the prolonged action of water at high temperatures (steam) 

 is well known, and reveals itself in permanent decrease of elasticity 

 and strength. 



Although during drying and soaking respectively lengthening and 

 shortening may take place, the area of the faces of the board always 

 decreases and increases respectively during those processes. So much 

 does the change in width correct any reverse change in length that the 

 board yang 2 when drying lost in area to a greater extent than did the 

 other boards despite of the fact that its ultimate decrease in length was 

 much the smallest. 



Ann. Biol, in 2 



