TVie Lever ^ the Bit and Curb^ etc, 173 



prop. There remains the mouthpiece, which is of equal 

 if not greater importance as the part of the instrument 

 through which the immediate impression is made on 

 the mouth, and therefore generally placed in the fore- 

 ground by writers on this subject. It appeared, how- 

 ever, to us to be a matter of great importance 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 fulcrum, 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 is intended to act, and these are, the 

 tongue in the centre and the bars of the mouth on each 

 side. It has been already pointed out that the relative 

 hardness or softness of the mouth, so far as this depends 

 on the conformation of this organ itself, is a consequence 

 of the greater or less thickness of the tongue and the 

 greater or less sharpness and sensitiveness of the bars. 

 The soft, fleshy tongue is, of course, much less sensitive 

 to pressure than the bony bars, covered only with a very 

 thin membrane ; and consequently, if we used a per- 

 fectly straight unjointed mouthpiece of a moderate thick- 

 ness, this resting wholly on the animal's tongue would, 

 notwithstanding a certain amount of lever action, be the 

 very lightest form of bit that could be well devised ; in 

 fact, a good snaffle would, on account of the joint, be 

 more powerful. On the other hand, if by means of 

 what is called a "port" we remove all pressure from 

 the tongue and transfer it to the peculiarly sensitive 

 bars, we obtain, with precisely the same amount of lever 

 action as before, a much greater amount of power — in 

 fact, the sharpest form of bit that it is generally advisa- 

 ble to use. Now between these two extremes there is a 

 15* 



