6e 



{&)• In crops of considerable extent several plots should 

 be taken and not one of large size. 



4. Size-classes of the trees enumerated.— Whether the trees are 

 counted over the whole area or only on portions of it, the 

 number to be measured is so great that it is not practicable 

 te) record thd correct diameter of each individual stem. 

 Trees of more or less the same sizes are, therefore, grouped 

 together into girth or diameter-classes. 



Where, as often happens, timbei' is sold by, and tahles are prepared for, girth 

 measur^ements, the elassificfation mi^ht with advnntage be by girths ; the callipers ased 

 being marked so as to indicate girths not diameters. 



The range of girth or diameter included in each class 

 should vary with the degree of- accuracy sought and the size 

 attained by the trees themselves. In very accurate surveys, 

 differences of diameters as low as from 1 to 2 inches for 

 large trees and from ^ an inch to 1 inch for small trees is 

 ometimes taken ; but such minute work is out of place in 

 India where a variation of 6 inches in diameter can usually 

 be employed with advantage. Theoretically, the height 

 ought also to be taken into account in making tliis classifica- 

 tion ; as height even more than diameter is influenced by 

 the local factors of production. But this is impracticable in - 

 most cases, and diameter-classes alone are sufficient. Where, 

 however, heights should be recorded, they can be estimated 

 by eye or with the aid of instruments specjially constructed 

 for the purpose. Hitherto in India the classification usually 

 adopted has been the grouping together of all trees whose 

 diameters do not differ by more than 6 inches. Thus trees 

 having a diameter of 6 inches (or a girth of 1^ feet) and 

 under form one class ; those of from 6 inches to 12 inches 

 in diiameter, or from 1-|^ to 3 feet in girth, another ; those of 

 from 12 to 18 inches in diameter, or from 3 feet to 4^ feet 

 in girth, a third ; and so on. 



It would perhaps be more logical to clasBify according to the exploitable size of 

 each principal Bpeoies. In most mature forests of the ^iort genevallv met with there are 

 three natural classes of stems more or less easily recognisable, viz.: -(1) exploitable 

 trees of and above the exploitable dimensions ; (2) medium-aged trees runging from 

 the minimum exploitable diameter down to, say, two-thirds of that size ; and (3) 

 Jonng and suppressed stems the diameters of which are less than two-thirds of the 

 exploitable size. It is possible that the adoption of some such auiforin system would 

 be advantageous. 



5. The enumeration of the trees.— The enumeration and mea- 

 surement of the trees is usually performed by parties consist- 

 ing each of one recorder and as many gaugemen and coolies 

 as are necessary. The former is provided with a pencil and 



