l6o TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



i6. Observations on the Annual Increment of Spruce 

 and Scots Pine (Second Article). 



l!y J. H. MiL.NK-HoMK. 



A short account was given in last year's Transactions (vol. 

 xxiv. p. 52) of observations made during the growing season 

 of 19 10, on the increase in girth of spruce and Scots pine in 

 Dumfriesshire. The observations were made monthly during 

 the growing season, and since the methods adopted as well as 

 the detailed records were given, they need not now be further 

 alluded to except for purposes of comparison. 



The results of the second season's observations, conducted 



on similar lines in 19 11, may, however, be of some interest. 



In calculating the results as a percentage increase of the 



growing stock, the same formula has been adopted, viz., 



400 

 Percentage = _,; // being the number of rmgs in the last 



inch of radial growth, and d the diameter of the stem under 

 bark. ;/ has been estimated by tnulttplying^ the average annual 

 increase in circumference (as ascertained from the mean of 



7 



the two years' observations) by , in order to obtain the 



■' '•'22x2 



increase in radius, d has been calculated from the circumference 



after making a suitable allowance for bark. 



The following are the detailed results for 191 1 : — 



Plantation K. 

 Scots Pine. — Obsenuxtions of five trees. 



' Through an oversight in last year's article, the word *^ divtdwg" was used 

 instead of the word " iiiii//i/>tytng." 



