EQUITATION 273 



4. The skill of the groove on the under surface of tlie lower 

 jaw just in front of the union of its branches. 



5. The lower premolar teeth, in some instances. 

 Classification of Bits. — Bits may be classified as snaffle, 



curb, and special. Snaffle bits consist of a straight or jointed 

 bar, in which the principle involved is a direct pull on the 

 mouth. The jointed snaffle (Fig. 139) is more severe, as it puts 

 the pressure chiefly on the bars of the mouth, while the plain 

 snaffle bears equally on the tongue, which has a cushioning 

 effect. 



The four-ring snaffle (Fig. 140) is doubly sever© on account 

 of the rings at the ends of the cheek pieces being drawn into tlie 

 mouth. 



Curb bits consist of a plain or port bar furnished with a 

 cheek lever or shank at each end, in place of snaffle rings, at the 



Fio. 139. — The jointed Fig. 140. — The four-ring 



snaffle bit. snaffle bit. 



upper ends of which are attached the chain or strap which bears 

 in the groove imder the lower jaw, wliile near the lower ex- 

 tremity of the shank the reins are attached. The length of the 

 shank is usually one^third above the mouth-piece and two-thirds 

 below. The principle involved with the curb is one of leverage, 

 the restraint of the u])per arm of the shank by the curb cliain 

 or strap constituting tlie fulcrum, the power being aj^plied on 

 the lower arm of the shank, the pasition of the attachment of 

 the reins determining the leverage, while the weight is the mouth- 

 piece of the bit borne by the bars and t>oiigue. The lower the loop 

 into which the reins are buckled, the stronger the leverage. The 

 possible attachments of reins are the plain cheek, the half cheek, 

 the first or second loop. The bearing of the curb chain is in- 

 tended to be sufficient only to establish the leverage of the shank 

 by holding its upper extremities stationary and establishing a 

 fulcnim. The severity of the bit may be increased, however, by 

 18 



