Part IV.] Caccia : Selection method of treatment in India. 359 
we find the general possibility for every 1,000 exploitable trees to be— 
(1) If the explditable girth be 6 feet — 
(-43 X 4 ,000) + (- 25 X 11,000) = 444^008 
104 
(2) If the exploitable girth be 5 feet, it will be safe to suppose that 1,500 
out of the 4,000 II Class trees are below that girth, and that 75 per cent, 
of them will eventually reach that girth in the average time. The average time 
it takes a III Class tree of the lowest dimensions to become 5 feet in girth is 60 
years. 
■ 75 X 1,500 + -50 X 11,000 _ 
60 
It has been shown that a I Class tree contains about 100 cubic feet of 
timber and II Class tree 60 cubit feet. 
The general possibility in cubic feet of timber for every 1,000 exploitable 
trees would be therefore — 
Cubic feet. 
For an exploitable girth of 6 feet .... 44x100=4,400 
Ditto 5 „ .... 100 X 60=6,600 
It would thus seem best to fell our trees as close as possible to a girth of 5 
feet, but the smaller the tree the greater the loss in conversion and sawyers 
object to take trees below 5 feet 3 inches in girth. This we may, therefore, 
adopt as the exploitable age. 
The above calculation is based on the supposition that the present proportion 
of the diSerent classes, taking the forest as a whole, is fairly normal. The 
Inspector General of Forests (vide his remarks in the Appendix) does not 
consider this to be the case — a conclusion due, it is believed, to misconception 
(vide my letter No. 100 of 31st July 1897 in the same Appendix). However, he 
accepts for other reasons given in his remarks a girth of 5 feet 3 inches as 
approximating very closely to the correct exploitable size. The average age of 
chir trees of this size would be 135 years. 
In accordance with the wishes of the Inspector General of Forests the 
length of the felling rotation adopted is 20 years. The exploitable size has been 
fixed at a girth of 5 feet 3 inches. 
We may assume that half the present II Class trees are under 
5 feet 3 inches in girth and from what has gone before that 65 per cent, of these 
will become exploitable within the average time, as well as 50 per cent, of the 
III Class trees. The proportion of the different classes is : — 
I 1 
II 4 
III 11 
and this is fairly normal as already explained. Therefore the general possibility 
for every 1,000 I Class trees would be — 
•65 X 2,000 X •50x11,000 
7 Q —97 trees over 5'-3'’ girth 
There being at present in 
the — 
Ninglat Working Circle 
Manora ditto 
I Class 
trees. 
8,847 the general possibility 
• 4,710 ditto 
= 858 
= 456 
Total 
1,314 
