387 
after all it is the most difficult question to answer, and one they have 
never been called on to investigate, as there is more than sufficient 
timber for their wants. 
In India where dry deciduous mixed forests predominate, many 
of the more important timber trees have very clearly defined annual 
rings, due to the complete change in seasons, and a definite season of 
rest from growth, or to the sudden and quick growth in the spring 
when new leaves are put on. 
Thus with Teak the annual rings are so well defined that in any 
given forest the rate of growth may be accurately gauged by means of 
an instrument called “Pressler's borer.” 
This is simply a hollow steel borer which is screwed into the tree 
to a depth of 2 to 3 inches. Inside the tube is inserted a small steel 
wedge- like pin, when the borer has been inserted to a sufficient depth 
this pin is tapped smartly and then the borer withdrawn by turning to 
the left, bringing with it a clean cylinder of wood about 2 to 2g inches 
long. 
The rings are then counted and the length of the cylinder accu- 
rately measured. 
It is usual to take three borings from each tree. 
In gauging the rate of growth of teak in a forest the trees are 
divided into four classes as under : — 
Class. I 
do. II 
do. Ill 
do. IV 
6' to 7 ' in girth 
Ak’ to 6’ „ 
3' to AV 
under 3 „ 
A hundred or more borings are made in each of these classes so 
that trees of all sizes are gauged. Thus an absolutely reliable result 
is obtained. Some borings which were taken in making a working napl 
of a forest reserve in Burma may be of interest and I give them here. 
Class. IV. Trees under 3 ' in girth 63 bored, 189 borings average 
annual (annual ring) .097522.” Average radial increase girth incre- 
ment .612748”, therefore 59 years to attain a girth of 3 . 
Class. III. 3* to 4^' in girth 62 trees bored, 186 borings, 
average annual ring .106043”. Average annual girth increment 
.666287”, therefore it takes a teak tree 27 years to pass from 3 girth 
to Ai' in girth. 
Class. II. 4V to 6', 64 trees bored, 192 borings. Average 
annual ring .09408”, average annual girth increase .591128 \ therefore 
it takes a tree 30 years to pass from 4^' to 6' in girth. 
Class. I. 6' to 7' in girth, 68 trees bored, 204 borings. Average 
ring .073362”, average annual girth increase .460947”, it takes there- 
fore 26 years to pass from 6' to 7’ in girth. 
Adding these results together we get 
to reach a girth of 3 ' 
to pass from 3' — 4£' 
4*'-6' 
59 years 
27 „ 
30 „ 
26 
Therefore for a seedling to reach 7 ' in girth 
142 years. 
