86 
Indian Forest Records. 
[VoL. I. 
or central bureau for collating and recording the same. This work will 
now be undertaken by the officers of the Imperial Forest Research Insti- 
tute at Dehra Dun ; and it is hoped that all information bearing on the 
development of the Sal will be freely supplied to the Imperial Superin 
tendent of Forest Working-Plans in order that a more complete Note on 
the growth of the Sal may be issued at an early date. 
Statistical data, to be of any real practical utility, must be based on 
a sufficiently large number of observations. Increment or volume tables 
derived from insufficient measurements, from single trees or woods taken 
haphazard in different localities, can only be deceptive and misleading. 
The co-operation of all trained foresters, working in concert according 
to a pre-arranged plan, is therefore essential in order that the data col- 
lected may lead to the preparation of increment tables of real practical 
utility.* On this account it is desirable that the energies of the Depart- 
ment should be concentrated wholly in working out a few selected pro- 
blems. The subjects which probably call for more immediate considera- 
tion may be classified as follow : — 
I. — The Growth of Single Trees. 
(^) The mean annual girth increment. — The average number of years 
required in different localities by the principal Sal trees of a crop to attain 
girths ranging from 1 J to 7 feet. 
(it) The preparation of volume tables. — The girth increment of 
single Sal trees is dealt with in Section 3, Part I of this Note. Though 
a great deal has been done to solve this important problem, a great deal 
still remains to be done, not only in laying out additional experimental 
areas with the object of bringing a larger number of trees under obser- 
vation in different localities, but also in carefully checking, scrutinising, 
and if necessary reconstituting existing sample plots. 
The collection of data which will lead to the preparation of stem or 
timber volume tables calls for early attention. At this initial stage it 
is suggested that both the girth at breast height and the total height 
of the trees measured be recorded, so that the effect of height of tree 
may be given full weight in the preparation of volume tables. A question 
of even greater importance is that dealing with the object in view, namely, 
*Von Baur’s tables giving the height, diameter, volume, etc., of spruce of different ages 
are based on the measurement of 55,874 trees. Similar tables prepared by Schwappach 
for Scotch Pine result from the measurement of 17,059 trees. 
