THE LEVER, THE BIT AND CURB, ETC. 177 



that the portion of the mouthpiece destined to rest on 

 the tongue and the bars respectively should keep their 

 proper places, and this can be secured only by making 

 the mouthpiece of precisely the same width as the horse's 

 mouth. For it is very evident that if a mouthpiece 

 furnished with a port be too wide, a very slight pull 

 on one rein will suffice to displace it, so that the bar 

 at that side gets either altogether under the port, in 

 which case the whole pressure is thrown on the tongue, 

 or partially so, when the corner of the port will, by 

 being pressed into it, cause great pain in fact, the 

 action of the mouthpiece, whether with or without a 

 port, becomes altogether irregular and cannot be de- 

 pended on. On the other hand, if the mouthpiece be 

 too narrow, the lips are jammed in over the bars, the 

 mouthpiece rests more or less on them, and the whole 

 action is disturbed, besides which the horse is sure, 

 sooner or later, to get ulcerated lips. 



The first grand nde must be, therefore, in all cases 

 to make the mouthpiece precisely so wide that, when 

 placed in the mouth, it Jits close to the outer surface of 

 the lips 'without either pressing on these or being sub- 

 ject to be displaced laterally. 



But it is also evident that the different parts of the 

 mouthpiece must be exactly fitted to the interior of the 

 mouth : that is to say, that those portions destined to 

 act on the bars of the lower jaw should come into 

 contact with them, and with them alone, and in the 

 degree required; and that, on the other hand, that 

 portion destined to act on the tongue should be of 

 exactly the proper dimensions and form. Of course 

 there is a great difference in this respect between 

 smooth mouthpieces and such as have a port; in fact, 

 M 



