24 



N. H. AGR. EXPERIMENT STATION. 



[Bulletin 12 



DIAMETER DATA. 



As stated above it would seem to be desirable to take the 

 diameter increase of the trees as a better index of the growth than 

 is represented by measuring a limited number of twigs. This has 

 been done since 1913 and a few data are therefore available at 

 this time but they are not so complete as the twig data. The 

 method of obtaining these data is to mark with white paint a 

 point on the tree trunk about 2| feet from the ground, and also 

 another point at right angles to this one and at the same height. 

 The two diameters are then measured and averaged and this 

 figure is used as the diameter of the tree. In this way the tree 

 can be measured at the same point year after year and thus 

 reduce error. 



The following table gives the diameter increase since 1913: 



TABLE No. 8. 



Average Diameter Increase Woodman Orchard. 



1913-1916. 



Inches. 



It is of some interest in this connection to observe the relation- 

 ship which exists between the two sets of data, i. e. } the average 

 annual twig growth and the average annual diameter increase. 

 Chart No. 6, shows a graph giving the twig increase and the 

 diameter increase for an average of 3 years (1914, 1915, 1916) 

 and it fairly represents what data we have obtained in this 



