GROWTH OF WOOD IN DIFFERENT YEARS. 



39 



this case perfectly uniform, or steadily changing from •wide to narrow, 

 according to the laws that govern the tree-growth. But as this con- 

 dition of growth is nowhere found, and might be impossible to secure 

 artificially for experiment, we must take the averages of the whole 

 period afforded by the section as our normal scale for comparison; and 

 may, by careful measurement, determine approximately the character 

 of past seasons from the growth of trees. 



An attemi)t has been made in this study by Prof. E. Gale, of the 

 Kansas Agricultural College, at Manhattan, the comparison being made 

 upon Cottonwood growth and the rain-fall at that place, through a period 

 of IG years.^ The growth is given in hundredths of an inch in diameter. 

 The average of the wLole period, and the greatest and least, are given: 

 Comparison of the growth of cottonwood and the rain-fall at Manhattan, Kans. 



The relation of quantities in the above table may be illustrated by a 

 diagram : 



Comparison of the growth of wood, and the' amount of rain-fall from April to August, as ohserved 

 in Kansas, from 1859 to 1874. 



i Tranaactions of Kansas State Horticultural Society, 1874, p. 91. 



