70 Eleventh Annual Report 



Length to Main Branch. — 44 feet, 6 inches. 

 Length of Clear Bole, — 20 feet, 6 inches. 

 Width of Crown. — 25 feet. 



It was impossible because of press of other duties to consider 

 all of the data included with sufficient care to justify conclusions 

 which would be at all suggestive. It is fairly certain that on such 

 8, limited tract soil differences are not sufficiently marked to 

 seriously affect the rate of tree growth. The indications are that 

 under such conditions soil moisture and exposure are factors secur- 

 ing the most evident response. The data, however, are too meager 

 to warrant any definite statements as to their effect. 



The determination of the age of the specimen was by the fa- 

 miliar annual ring method. Evidently by counting these rings 

 and adding the time necessary for the tree to reach the height from 

 which the section was taken, the age of the tree from which the 

 specimen was cut can be obtained. Before counting the annual 

 rings several (usually four or five) diameter measurements were 

 taken. The results of these measurements were then averaged and 

 the resultant taken as the true diameter of the section. A place 

 on the disk was then found having the average diamieter. The rings 

 were then counted in groups of ten years, the limit of each group 

 being marked on a line of the radius. The decades were then 

 measured and tabulated in order of age with the growth for the 

 decade. The measurements are accurate to one-tenth of an inch. 

 Each of the ten specimens of the eighteen species was thus: meas- 

 ured and tabulated under its species heading. 



These measurements were made under my supervision at the 

 Forestry Laboratory at Purdue University by Messrs. C. J. Tay- 

 lor ai}d W. P. Brodie of the class of 1911. They were made with 

 extreme care and at my suggestion many of them were later re- 

 peated in order that no question might arise as to the accuracy of 

 the measurements. Without the skillful and intelligent work of 

 these young men this paper would not have been possible at the 

 present time. 



These tabulations were made the basis of a series of curves 

 which shoAved graphically the rate of growth of the species studied. 

 From this series of curves the conclusions drawn in this paper are 

 fieri ve<l. 



