172 DISEASES OF THE HORSE’S FOOT 
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- 
CL 
Fig. 87.—THe Sanp-cRACK ForcErs AND CLAMP. 
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). 
‘The object of this invention is to arrange on a spindle, 
which is screw-threaded at one end with a right-hand 
Fie. 88.—McGuinu’s Sanp-crack CLamp. 
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 
