THE CHIEF TIMBER-TREES OF INDIA. rts 
places; but, unless artificially protected, the seedlings which 
come up are for by far the most part either choked by young 
bamboos or weeds, or else are burned down year after year by 
jungle fires. Thus, in fire-swept areas, where jungle fires run over 
the ground every year some time during the hot season lasting 
from the middle of March to the middle of May, young shoots 
are thrown up time after time for ten to twenty years, and 
sometimes more, until at length a stronger growth or some happy 
chance enables them to shoot upwards and assert themselves in 
future. In the Burmese forests the association of teak with 
bamboos is taken advantage of to make sowings at the 
periodical flowering and dying off of the bamboo undergrowth, 
at intervals varying from 15 or 20 to over 50 years, according 
to the kind of bamboo, because it is only then that the seedlings 
can be expected to have any chance of getting their heads up 
high enough to escape being out-grown and suffocated by the 
young bamboo shoots thrown up in ever greater lengths year 
by year unless checked by shade overhead. Plantations are 
also largely formed to provide larger supplies in the future; and, 
besides this, much assistance is given in the way of protecting 
large forest areas from jungle fires, and of killing inferior species 
of trees by “girdling” or ringing them into the heartwood in 
order to increase the proportion of teak. It has a strong upward 
growth and a marked tendency to clean itself spontaneously of 
side branches, even when not grown in close canopy; and in 
plantations it runs up, straight as a plummet-line, to a height of 
about 75 to 80 feet in the course of 15 to 18 years. Working- 
plans have been introduced into all the chief forests in Burma 
to determine the number of mature trees that can be cut in each 
during the next 30 years, so that there may be no danger of 
overworking any tract; and it has been found that, on the 
average, it takes a teak-tree from 150 to 180 years of age to 
attain the mature marketable size of 7 feet in girth, measured 
at 6 feet above the ground, the rate of growth being of course 
quicker in the fairly moist than in the very dry forests. The 
investigations made in order to arrive at these practical con- 
clusions showed that, while the average rate of growth is about 
12 annual rings per inch of radius (a rate often equalled and 
even exceeded in the case of our own oaks and other hard- 
woods), the average age of a 3 feet tree is 68 years, and that 
after this it takes other 29 years to reach 44 feet girth, 35 more 
VOL. XIX. PART I. H 
