We find the saw, shears, and knife, the best instruments for pruning; in some cases of difficult approach, the long-handed pruning-iron may be resorted to. When the lopping is performed by a percussion tool, the wood and bark at the section is often shattered by the blow, and thence is less likely to cicatrize soundly; and even when executed in the best manner, the surface of the section is smooth and hard, consequently a good conductor of heat, dries much, and thence shrinks and cracks near the centre of the cut, opening a deep crevice, into which the rain penetrates, and often rots deep into the stem. When the section is made by the saw, a slight fibrous clothing is left upon the place, which in some measure protects the ends of the cut tubes from the frost and drying air, and excludes the heat; in consequence the wood at the section does not lose its vitality so far inward, and is not so liable to shrink {119} and crack in the centre and receive rain. The section can also generally be made much neater and closer by the saw than by any other instrument. The common erroneous belief, that a section by a sharp-edged instrument is less injurious than by the saw, is merely hypothetical, from wide analogy from animals. The pernicious influence on the whole individual, received and transmitted by the nerves from mangled section of animal fibre, is probably entirely awanting in vegetables; the whole process of life and of cicatrization is also totally different. The forester should also be very wary in cutting off a considerable branch, whose section would incline upwards, as such a section, when it has received a circle of new bark and wood, forms a cup which receives and contains rain water, which quickly corrupts the bottom of the cup, and often rots the centre of the tree down to the ground. It is better to crop such a branch several feet from the main stem, close by some small feeder, unless the branch be dead. In pruning, every considerable section should be as near as possible at right angles with the horizon, or rather inclining inward below. Of naval timber, the beech is by far the most likely to take rot by being pruned, and should never have a large limb cut off, as the divided fibres generally die {120} downward a number of feet below the section, and soon afterward decay, leaving a hole in the bole.