Trees that tend to split:  Certain species of trees, like the linden and
    elm, often tend to split, generally in the crotch of several limbs
    and sometimes in a fissure along the trunk of the tree.  Midwinter is
    the period when this usually occurs and timely action will save the
    tree.  The remedy lies in fastening together the various parts of the
    tree by means of bolts or chains.

A very injurious method of accomplishing this end is frequently resorted to, where each of the branches is bound by an iron band and the bands are then joined by a bar.  The branches eventually outgrow the diameter of the bands, causing the latter to cut through the bark of the limbs and to destroy them.

Another method of bracing limbs together consists in running a single bolt through them and fastening each end of the bolt with a washer and nut.  This method is preferable to the first because it allows for the growth of the limbs in thickness.

[Illustration:  FIG. 121.—­Diagram Showing the Triple-bar Method of Fastening Limbs.]

A still better method, however, consists in using a bar composed of three parts as shown in Fig. 121.  Each of the two branches has a short bolt passed through it horizontally, and the two short bolts are then connected by a third bar.  This arrangement will shift all the pressure caused by the swaying of the limbs to the middle connecting-bar.  In case of a windstorm, the middle bar will be the one to bend, while the bolts which pass through the limbs will remain intact.  The outer ends of the short bolts should have their washers and nuts slightly embedded in the wood of the tree, so that the living tissue of the tree may eventually grow over them in such a way as to hold the bars firmly in place and to exclude moisture and disease.  The washers and nuts on the inner side of the limbs should also be embedded.

A chain is sometimes advantageously substituted for the middle section of the bar and, in some cases, where more than two branches have to be joined together, a ring might take the place of the middle bar or chain.

Bolts on a tree detract considerably from its natural beauty and should, therefore, be used only where they are absolutely necessary for the safety of the tree.  They should be placed as high up in the tree as possible without weakening the limbs.

CHAPTER VII

FORESTRY

STUDY I. WHAT FORESTRY IS AND WHAT IT DOES

Although Forestry is not a new idea but, as a science and an art, has been applied for nearly two thousand years, there are many persons who still need an explanation of its aims and principles.

Forestry deals with the establishment, protection and utilization of forests.