5T 



vrith a field book for recording the results of the enumera- 

 tion surveys : the latter are given callipers with which to 

 measure the diameter of the stems. 



The form of callipers in common use consists of a 

 graduated rule (A A), at the end of which is a fixed arm 

 (B B), and on and around which slides another arm. To 

 enable this arm to move freely, the hole (a, b, c, d) is made 

 oblique but la such a manner that, as soon as the arm (0 C) 

 comes in contact with the log or tree to be measured, the arm 

 assumes a position at right angles to the scale which it 

 touches at the edges (c) and (b). 



Instead of being graduated in the ordinary way, the rule 

 <A A), in callipers intended to be used by illiterate work- 

 men, may with advantage be painted in different colours 

 at intervals equal to the differences between diameter or 

 girth-classes, so that each colour corresponds to a class. It 

 has also been found a wise precaution to attach to the trees 

 measured paper labels of the same colours. 



Thus, supposing there were four classes of trees, the colours might be— 

 Class I, diametera above 2 feet, oorresponding colour, white. 

 „ II. « Uto2 „ „ ' „ green. 



„ III, „ Itollt „ „ „ red, 



» IV, „ itol „ ,, • „ blue. .^ 



