FIG. 90.--SAND-CRACK BELT.]

The binding of the wall may be accomplished in two ways. The simpler of the
two is to merely apply the sand-crack belt depicted in Fig. 90. Beneath
this should be applied a compress of tar and tow or other material, and the
whole tightened up and kept in position by means of the buckle and strap.
This method of binding admits of after-tightening should it unfortunately
work loose.

The older method of binding the wall, and one now often practised by the
smith, is to use a quantity of so-called 'tar-band' or other stout cord.
With this the foot is neatly bound after the manner of a cricket-bat
handle, and all movement of the crack apparently restricted. There is
always a tendency, however, for such a dressing to work loose, and in the
case of a complicated crack it has the disadvantage of permanently hiding
from view the changes taking place in the discharge from the fissure.

_(e) By wedging the Crack_.--This is the exact opposite of clamping.
Whereas in clamping we obtain immobility of the crack by keeping it fixed
in the position of greatest approximation of its edges, in wedging, the
crack is rendered free from movement by maintaining it in that position
where its edges are most widely separated. In this case the edges of the
crack are pared smooth, the cavity thoroughly cleansed, and a wedge of hard
wood firmly driven in so as to fit exactly the fissure.

On the face of it it appears that this procedure would really tend to force
open and so lengthen the crack, especially at its coronary extremity. What
one should really remember, however, is that the crack _is not made wider_
than before, but that it is simply maintained in a position occurring with
every contraction of the heels of the foot, when it is normally at
its widest. Movement of the edges is thereby stopped, the immediately
surrounding structures are rested, and a new growth of horn, free from
crack, induced to grow down from the coronet.

This method of treatment only serves to emphasize the fact that, with a
sand-crack once formed, it is the constant movement of the parts that tends
most to keep it in existence, and not any particularly marked exertion of
force.

Some practitioners, with the wedge, apply also a clamp, thus assuring
additional firmness and solidity to that portion of the wall under
treatment.

The method of wedging is undoubtedly successful, if neatly performed.

_(f) By Surgical Shoeing_.--A partial