by care, will caliper up in good shape.

KINDS OF FILES.--Each file has five distinct properties; namely: the
length, the contour, the form in cross section, the kind of teeth, and
the fineness of the teeth.

There are nine well-defined shapes for files. These may be enumerated as
follows:

[Illustration: _Fig. 54. Cross Sections of Files._]

No. 1. The cotter file. The small kind is called a verge or pivot file.

No. 2. Square file, which may be tapering from end to end, or have
parallel sides throughout.

No. 3. Watch pinion file. This may have its sides parallel or tapering,
to make a knife-shaped file.

No. 4. Clock-pinion; which may be used for either nicking, piecing, or
squaring-off purposes.

No. 5. Round, with parallel sides for gulleting purposes, or rat-tail
when it tapers.

No. 6. Triangular, or three equally-sided body for saw filing.

No. 7. Equalizing file. This is parallel when used for making
clock-pinions or endless screws; or for slitting, entering, warding, or
making barrel holes, when the body of the file tapers.

No. 8. Cross, or double-round, half-file.

No. 9. Slitting file; which has parallel sides only. A cant file.

CHARACTER OF THE FILE TOOTH.--Files are distinguished principally by the
character of the oblique, or cross grooves and ridges which do the
cutting and abrading when the file is drawn across the surface.

This is really more important than the shape, because the files, by
their cuttings, are adapted for the various materials which they are to
be used upon.

The files are classified as _Double Cut_, of which there are the
_rough_, _middle_, _bastard_, _second cut_, _smooth_, and _dead smooth_.

The _Float Cut_, which is either _rough_, _bastard_ or _smooth_; and

The _Rasp Cut_, either _rough_, _bastard_ or _smooth_.

Several types are illustrated in Fig. 55, which show the characteristics
of the various cuts.

The rasps are used principally for soft material, such as wood or for
hoofs, in horse shoeing, hence they need not be considered in connection
with machine-shop work.

[Illustration: _Fig. 55. Files._]

HOLDING THE FILE.--The common mistake on the part of the beginner is to
drag the file across the work at an angle. The body of the file should
move across straight and not obliquely.

Note this movement in Fig. 56 where the dash shows the correct movement
of the file with relation to the work. Also observe that the file
cutting ridges are not strai