178 BITS AND BITTING. 



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 mouthpiece required for the bars, and 

 produce the inconveniences alluded to above ; or, if 

 narrower, it would fail to answer the purpose for which 

 it is intended, namely, to admit the tongue.* The 

 width of the port must be, therefore, exactly that of the 

 tongue-channel and this is the second grand rule as 

 regards the mouthpiece. Now it has been already 

 shown that the width of the tongue-channel is very 

 constantly three -fourths of the height of the bars, 

 which, being equally constantly 1.8 inches, we have 1 J 

 inches for the maximum width of the port, even in 

 cases where the total width of the mouth, and conse- 

 quently of the mouthpiece, amounts to 4| and 5^ 

 English inches : for pony and hack bits, about 1 inch 

 will suffice ; whereas the common practice of the bit- 

 makers seems to be to make it one-third of the total 

 width in all cases. 



For the height of the port, of course, no rule can be 

 given, this being precisely the most variable dimension 

 of all, and depending altogether, so far as the interior 

 conformation of the mouth is concerned, on the relative 

 thickness of the tongue and sensitiveness of the bars ; 

 and further, as we have already shown, on the tempera- 

 ment and general conformation of the animal; finally, 

 too, on the description of service to which it is to be 

 applied ; to which must, in some cases, be added the 



* The Germans call the port of a bit the "tongue-freedom" 

 Zungenfreiheit which expresses exactly the purpose for which it is 

 intended. 



