134 ^/Vi' a7id Bitting. 



vent — an Inch or two higher or lower does not matter 

 As far as the bit itself is concerned, half an inch, or even 

 a fidl inch, higher or lower, would not make much dif- 

 ference in its action ; but, as we shall presentl}^ see, the 

 curb has one fixed position in the chin-groove, and this 

 governs the whole arrangement. 



There are three dimensions of the interior of the horse's 

 mouth which must be accurately ascertained before at- 

 tempting to fit him with a proper bit, in addition to cer- 

 tain details connected with the tongue. The first, and 

 a very important one, is tJie transversal width of the 

 mouthy from side to side, measured at the same height 

 as the chin-groove., and including the thickness of the 

 lips — that is to say, from the point a?, fig. ii, to the cor- 

 responding point at the oft^side.* This gives the width 

 of the mouth-piece, which must be made to fit exactly, 

 as, if too narrow, the lips are subject to injury and their 

 being displaced so as to cover the bars, thereby neutral- 

 izing the action of the whole instrument ; whereas, if too 

 wide, it slips from side to side and displaces what is 

 termed the port — the curved portion of the mouth-piece 

 intended to moderate the pressure on the tongue — from 

 its i^roper position : it also determines the length of the 

 curb. The second dimension is the width of the cha?i- 

 nel in which the tongue lies, or the distance between the 

 two bars internally, wdiich determines how much of the 

 mouth-piece may be allowed for the port ; the remainder 

 must be reserved for the action on the bars. 



The third dimension is what we term the height of 

 the bars — that is to say, the distance between a straight 

 edge supposed to rest on the upper surface of the bars 

 at d^ fig. II, as above, and another straight edge placed 

 exactly parallel to it, and touching the undermost point 

 of the chin-groove — mathematically speaking, the tan- 



* The proper mode of ascertaining all these dimensions accuratelj 

 will be stated farther on. 



