THE LEVER, THE BIT AND CURB, ETC. 175 



rangement. It was formerly the custom to have one 

 hook attached permanently at the near side of the bit, 

 and another of a somewhat different form to the off 

 side of the curb, but it has now become usual to attach 

 a pair of hooks of exactly the same shape and dimen- 

 sions, which is a great improvement : the proper length 

 for these is three-fourths the height of the upper bar, 

 or about 1J- inches. 



The above length of curb applies to what is really 

 employed between the two hooks, but it is usual to 

 have one reserve link at the offside, and two of these 

 at the near one, which latter are convenient, or rather 

 indispensable, for catching a proper hold of the curb 

 when being hooked on. 



We have now gone step by step through the several 

 details connected with the bit considered as a lever 

 namely, its cheeks or upper and lower bars, and the 

 curb with its hooks, which represent the fulcrum or 

 prop. There remains the mouthpiece, which is of 

 equal if not greater importance as the part of the in- 

 strument through which the immediate impression is 

 made on the mouth, and therefore generally placed 

 in the foreground by writers on this subject. It ap- 

 peared, however, to us to be a matter of great import- 

 ance to make it perfectly clear, in the first place, that 

 the entire action of the bit should be concentrated on 

 the mouthpiece, that the operation of the curb should 

 be confined wholly to the function of a painless ful- 

 crum, and that there are certain narrow limits to the 

 size of the upper and lower bars which form the cheeks 

 of the instrument. The form and proportions of the 

 mouthpiece must be deduced wholly from the interior 

 conformation of that part of the mouth on which it 



