112 



Canadian Record of Science. 



If we next inquire into the relation which seasons bear 

 to the contained water, we shall observe that the percentage 

 continually rises from the midwinter period until spring, and 

 that it again falls from the close of summer to the midwin- 

 ter period. The extreme variations as exhibited in our 

 figures, show, between February and September, a difference 

 of 8.4 p. c. for the youngest growth, and *7.1 p. c. for that 

 which is older. 



Mean 



Hydration of Wood 



3. 







Per Cent. Water. 



No. for Average. 





1st Year. 



2nd Year. 



1st Year. 



2nd Year. 





44.7 

 47.2 

 51.7 

 53.1 

 48.3 



43.9 

 44.8 

 48.4 

 51.0 

 47.2 



37.0 

 59.0 

 6.0 

 19.0 

 61.0 



38.0 





60.0 





7.0 





18.0 





58.0 







Mean 



49.0 



47.1 



36.4 



36.2 







Our figures also indicate that the maximum hydration of 

 the tissues must occur either in September, or at some 

 period intermediate to this month and April. By graphic 

 representation of these results, it will become possible to 

 determine with approximate accuracy the true period at 

 which this maximum is reached. The figures show that, 

 from February to April, the rate of percentage increase is 

 much more rapid than the rate of percentage decrease from 

 September to December. A curve which will show this, 

 should also show the period of maximum percentage. By 

 reference to the chart, it will be seen that the curves for 

 both young and old wood run nearly parallel, but that they 

 tend to approach at their greatest depression, and to separ- 

 ate more widely at their greatest elevation. It is also seen 

 that, from midwinter to spring, the curve rises rapidly and 

 reaches its greatest elevation about May 18th for the 

 youngest wood, while that for the older wood attains its 

 maximum a few days later, or about the 22nd. From this 



