The removed shoe should next be examined as to the coarseness or fineness
of its punching and the 'pitch' of its nail-holes, and close attention
given to the shape of its bearing surface.

From that we may pass to a consideration of the underneath surface of
the foot. The drawing-knife should be run lightly over the whole of its
surface, the first thing to be noticed being the point of entrance of the
nails as compared with the coarseness or fineness of the punching, and the
staining or otherwise of the horn immediately around. We may thus be guided
towards mischief arising from tight nailing apart from actual prick of the
foot.

This done, more than usual care should be taken in following up any other
small prick or dark spot that may show itself upon the white surface of the
cleaned sole. In any case, a suspicious-looking speck should be followed up
with the searcher until it is either cut out or is traced to the sensitive
structures.

While this is done, we should also have noticed the condition of the horn
at the seat of corn; should have noticed the shape of the heels, contracted
or otherwise; and the appearance of the frog, clean or discharging.

A point to be remembered in making this exploratory paring of the foot is
the peculiar consistency of the horn of the frog, and its tendency to hide
the existence of punctures. In like manner, as a pin pierces a piece of
indiarubber, and leaves no clearly visible trace of the hole it has made,
so does a nail or other sharp object penetrate the frog, leaving but little
to show for the mischief that has been done.