20 Shrinkage, Sivelling, Waiting of Cros^-grained Woods 



Set B (Tables B i and B ii.) 



The next set of measurements {B) were made on the board as it was 

 compelled to swell by submersion under water: vernier callipers and 

 Professor Dalby'^ instrument being used for the observations. 



The main results as evidenced by the statistics given in Tables B i 

 and B ii, and as proved by the graphic records (unpublished) of 

 the curves, are: 



The absorption of water at first causes a sudden relatively consider- 

 able increase in length, which is relatively more marked than the increase 

 of width even at the ends. This is succeeded by a decrease in length, 

 which is synchronous with a more rapid gain in width. 



The water enters most largely by the ends ; the gain in width is 

 marked here at first, and only after some time does the middle of the 

 board display a similar full rate of widening. 



As water continues to be absorbed the board, after undergoing its 

 peculiar shortening, gradually lengthens and attains its maximum length 

 even before it has absorbed the maximum amount of water, after which 

 one or more times a shortening was noticeable. These contrary 

 fluctuations as regards length are probably to be attributed to the fact 

 that as the water penetrates from the ends the transverse belts at 

 increasing distances from the two ends successively go through the 

 shortening and lengthening phases, so that the measured result as regards 

 the whole board is the algebraic sum of a number of items that are 

 unequal and at times opposite in sense. 



Widening of the board continued as long as water was absorbed, 

 but the sHghtness of the increase in width towards the conclusion of 

 the soaking strongly suggests that the maximum width had been very 

 nearly reached. 



Table B i records the changes in linear dimensions of yang 1 during 

 the absorption of water. The results of these measurements are arranged 

 in Table B ii, by grouping together measurements made at short intervals 

 on the same day, and by taking the averages of the longitudinal, trans- 

 verse end, and transverse middle measurements. 



In reference to these Tables it was conceivable that two sources 

 of misinterpretation were possible. On the one hand curvature or 

 straightening of the board might cause a spurious appearance of 

 shortening or lengthening respectively. On the other hand the interval 

 necessarily intervening between the weighing of the board and the 

 recording of the measurements and curves would lead to a certain degree 



