4 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
do not at present come into the discussion, revenue is ascertained 
by multiplying the quantity of timber produced by its value per 
cubic foot. Manifestly, therefore, forestry means something more 
than the mere production of the maximum mass of timber. It 
means, in fact, the continuous production of the maximum yield 
of high-priced timber. This object, however, will not be attained 
by trees which, from their earliest youth, have had space enough 
for the unrestricted development of their crowns. Such trees are 
only of moderate height, and their boles are short, conical, and 
clothed with numerous thick branches. However much a tree 
with a great mass of foliage may beautify a landscape or please 
an artist, it is not capable of yielding the maximum amount of 
profit, and the price which it will bring will be in inverse pro- 
portion to the requirements of a purchaser for a long, symmetrical, 
and cylindrical bole. A timber merchant looks out for trees 
as long, straight, and cylindrical as possible, with the minimum 
number of knots. Not only do knots detract from the appearance 
of timber, but recent investigations in Germany and America 
have shown that the strength of timber is also very prejudicially 
affected by their presence. 
Seeing that stems with the minimum of knots, and as cylindrical 
as possible, can only be obtained by curtailing the development 
of the crowns, the production of quantity must to a certain extent 
—under a system of intensive forestry—give place to the produc- 
tion of quality. The attention of a forester must therefore be 
directed towards selecting that particular density in a wood which 
will best combine the production of quantity and quality. Experi- 
ence, supported by careful investigation, has shown that this goal 
can only be reached in woods which show a high degree of closeness 
at an early age. 
The restriction in the quantity of light tends to diminish the 
production of leaves and branches, and it is found that under 
such circumstances the trees endeavour to grow in height as fast 
as possible in their attempt to obtain space for the development 
of their crowns. The most vigorous individuals will take the lead 
in this struggle, whereas their weaker neighbours will be over- 
grown and finally killed. The over-grown specimens, however, 
fulfil a useful function in the life of a wood; firstly, by shading 
the lower portions of the stems of the larger trees; secondly, by 
assisting in the removal of the lower branches of the dominant 
trees, against which they rub during gales; and thirdly, by 
