156 



HORSESHOEING. 



8. Hollow wedge-calks (Fig. 179). 



9. Perforated screw-calks (Fig. 180). 



There is no doubt that the grip that these calks take upon 

 the ground and their durability depend upon the diameter and 

 the arrangement of their surfaces of friction. From all ex- 



FiG. 177. 



Fig. 178. 



Fig. 179. 



Fig. 180. 



Hollow .calk. 



Perforated calk. 



Fig. 181. 



Universal screw-calk key with tap. 



Fig. 182. 



Felber's hand- 



to secure the hoof from twisting while changing the screw-calks. 



periments made thus far it is shown that those calks which 

 have narrow and comparatively few surfaces of friction are 

 the least durable. 



To introduce and remove the calks we use a calk key or 

 wrench. For the shop, the ordinary fork key (Fig. 181), the 

 jaws of which are tempered, is recommended. It fits all calks. 



