hods of performing this is to draw the edges
of the crack together with an ordinary horse-nail.

On each side of the crack a small horizontal furrow is burned or cut into
the wall, leaving the horn for about 1/4 inch on each side of the crack
intact. This provides a groove for the ends of the clamping-nail to rest
in, and brings them flush with the outer surface of the wall. The nail is
then driven carefully home through the crack, and the pointed end grasped
by the farrier's pincers. The edges of the crack are then drawn tightly
together, and the nail firmly clenched.

[Illustration: FIG. 86.--THE SAND-CRACK FIRING-IRON.]

'The horse-nails are prepared in the ordinary way as for driving, with the
exception that each is pointed on the reverse side, to prevent puncturing
the sensitive structures. Before being used the nails are put in a vice,
and the head hammered to form a shoulder, to prevent their being driven too
far into the wall, and breaking out the hold.'[A]

[Footnote A: _Veterinarian_, vol. xlviii., p. 100.]

Before driving the nail some operators burn or bore a hole for it. Opinion
seems to differ as to whether this is at all necessary.

A method of clamping which, on account of its simplicity, has become
greatly popular, is that of Vachette. For this operation is needed the
outfit depicted in Figs. 86 and 87.

[Illustration: FIG. 87.--THE SAND-CRACK FORCEPS AND CLAMP.]

With the special firing-iron (Fig. 86) an indentation, sufficiently large
to admit the points of the clamp (Fig. 87), is made on each side of the
crack. The clamp is then adjusted, and pressed home tight by means of the
sand-crack forceps (Fig. 87). According to the length of the crack, one,
two, or three clamps may be necessary. Another useful clamp, though far
more complicated in its structure, is that of Professor McGill (Fig. 88).

[Illustration: FIG. 88.--MCGILL's SAND-CRACK CLAMP.]

'The object of this invention is to arrange on a spindle, which is
screw-threaded at one end with a right-hand thread and at the other with a
left-hand thread, two clips or clamps, free to travel on the thread, there
being a nut between the two which can be turned by a spanner. The clips
are placed on the hoof, one on each side of the sand-crack, the hoof being
prepared to receive the instrument by filing a groove or notch for the
clamps to fit into, and by turning the nut on the screw the clamps
are brought towards each other, and the crack thus pre