190 



Studies in Forestry 



[CHAP. IX. 



I. In the first instance, that of a thirty-seven-year-old crop 

 of Spruce, raised by planting, the data 1 were : 



Previous to thinning: 



During the thinning there were removed 



In consequence of the thinning, the arithmetical mean 

 diameter at breast-height (4! ft.) of the stems that were left 

 was found to be 



On area I, 5-12 inches; 



On area II, 5-68 inches; 



On area III, 5-84 inches ; 



whilst five years later , just before another thinning was to take 

 place, it was found to have increased 



On area I to 5-48 inches, or an average diametral increment 

 of 0-36 inches per stem. 



1 These and. the following data are, by permission, excerpted from 

 Dr. M. Behringer's prize thesis Ueber den Einfluss wirthschaftlicher 

 Massregeln auf Zuwachsverhaltnisse und Rentabilitdt der IValdiuirthschaft, 

 1891, pp. 19 et seq. 



