in course of time and which will later
    protrude from the cut, thus forming, between the paint and the wood,
    a suitable breeding place for the development of destructive fungi
    or disease.  The application of tin covers, burlap, or other bandages
    to the wound is equally futile and in most cases even injurious.

[Illustration:  FIG. 115.—­Result of a Wound not Covered with Coal Tar.  The exposed wood cracked and decay set in.]

SPECIAL CONSIDERATIONS

Pruning shade trees:  Here, the object is to produce a symmetrical crown
    and to have the lowest branches raised from the ground sufficiently
    high to enable pedestrians to pass under with raised umbrellas.  Such
    pruning should, therefore, necessarily be light and confined to the
    low limbs and dead branches.

Pruning lawn trees:  Here the charm of the tree lies in the low reach of
    the branches and the compactness of the crown.  The pruning should,
    therefore, be limited to the removal of dead and diseased branches
    only.

Pruning forest trees:  Forest trees have a greater commercial value when
    their straight trunks are free from branches.  In the forest, nature
    generally accomplishes this result and artificial pruning seldom has
    to be resorted to.  Trees in the forest grow so closely together that
    they shut out the sunlight from their lower limbs, thus causing the
    latter to die and fall off.  This is known as natural pruning.  In
    some European forests, nature is assisted in its pruning by workmen,
    who saw off the side branches before they fall of their own accord;
    but in this country such practice would be considered too expensive,
    hence it is seldom adopted.

TOOLS USED IN PRUNING

Good tools are essential for quick and effective work in pruning.  Two or three good saws, a pair of pole-shears, a pole-saw, a 16-foot single ladder, a 40-foot extension ladder of light spruce or pine with hickory rungs, a good pruning knife, plenty of coal tar, a fire-can to heat the tar, a pole-brush, a small hand brush and plenty of good rope comprise the principal equipment of the pruner.

SUGGESTIONS FOR THE SAFETY OF TREE CLIMBERS

1.  Before climbing a tree, judge its general condition.  The trunk of a tree that shows age, disease, or wood-destroying insects generally has its branches in an equally unhealthy condition.

2.  The different kinds of wood naturally differ in their strength and elasticity.  The soft and brash woods need greater precautions than the strong and pliable ones.  The wood of all the poplars, the ailanthus, the silver maple and the chestnut, catalpa and willow is either too soft or too brittle to be depended upon without special care.  The elm, hickory and oak have strong, flexible woods and are, therefore, safer than others.  The red oak is weaker than the other oaks.  The sycamore and beech have a tough, cross-grained wood which is fairly strong.  The linden has a soft wood, while the ash and gum, though strong and flexible, are apt to split.