PEEFACE 



desirable that societies, such as the Royal English 

 Arboricultural Society, or the Royal Scottish Arbori- 

 cultural Society, should endeavour to collect data from 

 their members as to the growth of any typical crops 

 under their charge. 



In all such cases it is imperative that exact data be 

 given on at least four points, besides a detailed descrip- 

 tion of the soil, situation, aspect, and altitude, and an 

 actual estimation of the contents of timber per acre. 



It is imperative to know : 



(1) The exact height to the very top of the trees. 



(2) The quarter girth at 5 feet from the ground, 



stating whether taken with a tape or string, 

 and whether over or under bark. 



(3) The number of trees per acre. These should be 



actually counted on several sample areas of 1 

 or 2 square chains each. A mere guess at the 

 number per acre is of very little value. 



(4) The age of the crop, stating whether from seed 

 or from the date of planting. 



And then, again, when such particulars are given, 

 it is most important to state whether the crop now 

 requires to be thinned, and if so what proportion of the 

 crop should be cut out ; or if no thinning is now neces- 

 sary, an opinion should be expressed as to when a 

 thinning will next become necessary. 



And lastly, when stating the volume of timber per 

 acre, such volume should be calculated both down to 6 

 inches quarter girth and also down to 3 inches " top- 

 diameter." And it should be expressly stated whether 

 the timber has been measured over or under bark, and 

 if the latter, what allowance for bark has been made. 



P. TRENTHAM MAW. 



NUTFIELD, December 1911. 



