just touching the
face of the next one. The filing is continued, with one, two, or three
strokes, for each tooth, as the case may require, or just until each
tooth is sharp.

In filing a crosscut-saw, the file is held pointing upward and toward
the point of the saw. The file should cut in the direction of the
set. The angle of the cutting edge is determined by the horizontal
inclination of the file to the blade; the angle of the point is
determined by the perpendicular inclination of the file to the blade.
Finally the sides of the teeth are rubbed lightly with a slipstone to
remove the wire edge. It should always be remembered that a saw is an
edge tool, and its edges are as liable to injury as any edges.

PLANES.

The _plane_ is a modified chisel. The chief difference in action
between a chisel and a plane in paring is this: the back of the chisel
lies close down on the surface of the wood that is cut, and acts as a
guide; whereas, in the plane, the cutter is elevated at an angle away
from the surface of the wood, and only its cutting edge touches the
wood, and it is held and guided mechanically by the plane mechanism.
In other words, a plane is a chisel firmly held in a device which
raises the cutter at an angle from the work, regulates the depth of
the cut, and favors the cutting rather than the splitting action.
An illustration of a chisel converted into a plane is the adjustable
_chisel-gage_, Fig. 99.

[Illustration: Fig. 99. Adjustable Chisel-Gage.]

[Illustration: Fig. 100. Wooden Bench-Plane.]

[Illustration: Fig. 101. Section of Jack Plane.]

The plane has developed as follows: it was first a chisel held in
a block of wood. This is all that oriental planes are now, simply a
sharpened wedge driven into a block of wood. When the hole works too
loose, the Japanese carpenter inserts a piece of paper to tighten it,
or he makes a new block. The first improvement was the addition of
a wooden wedge to hold in place the "plane-iron", as the cutter was
formerly called. In this form, the cutter or plane-iron, tho still
wedge-shaped, was reversed, being made heavier at the cutting edge in
order to facilitate fastening it in the wooden plane-stock by means of
the wooden wedge. Then a handle was added for convenience. Then came
the cap, the object of which is to break back the shaving and thus
weaken it as soon as possible after it is cut. Until a few years ago,
this was all that there was in a plane, and such p