THE LEVEE,, THE BIT AND CUBE, ETC. 179 



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 

 mouth-piece, whether with or without a port, becomes 

 altogether irregular and cannot be depended on. On the 

 other hand, if the mouth-piece be too narrow, the lips 

 are jammed in over the bars, the mouth-piece 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 rule must be, therefore, in all cases to 

 make the mouth-piece precisely so wide that, when placed 

 in the mouth, it fits close to the outer surface of the lips 

 without either pressing on these or being subject to be dis- 

 placed laterally.-'' 



But it is also evident that the different parts of the 

 mouth-piece 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 mouth-pieces and such as have a port ; in fact, 

 it is only as regards the latter that the dimensions are 

 important. Where, then, a port exists, its width should 

 be exactly that of the tongue-channel, as otherwise it 

 would either intrench, on the space allotted to that 

 portion of the mouth-piece required for the bars, and 

 produce the inconveniences alluded to above ; or, if 

 * See note at foot of p. 137. 



