150 THE OAK 
it grows. In return for this, however, it yields the 
best of all temperate timbers. ? 
As we have seen, the forester has to exercise con- 
siderable forethought—the outcome of long experience 
—in growing oak so as to obtain long, clean stems. The 
natural habit of the tree is to form a short, thick bole 
and a widely spreading crown, the main branches of 
which come off not far from the ground. To compel 
the stem to elongate into a long pole he has to plant 
other trees with it (as we have seen, beech, spruce, &c.), 
which, while they keep the light off the lower parts of 
the oaks, do not overtop them. This makes the trees 
long and spindly at first, as they run up their leaf- 
crowns higher and higher, and it is part of the forester’s 
art to select the exact time when he may cut away some 
of the nurse trees and let in just enough, and not too 
much, light and air, so that the crowns of the oaks shall 
fill out more and thicken the stems. For it must never 
be forgotten that the timber is laid on from substance 
prepared in the leaves. 
The natural shape, so to put it, of an oak-tree is 
that of a wide-spreading, short-stemmed mushroom, and 
such a shape is realised in the open; the forester com- 
pels it to lengthen its stem as much as possible before 
he lets it extend its crown. Hence he aims at length 
first, and then lets the tree put on timber in the mass. 
He does this, of course, by taking advantage of the tree’s 
peculiarities, and one of these is that it grows very 
rapidly when young. It will be obvious that the skilled 
