18 



PRINCIPLES OF 



P. I. 



The chain is fastened on one side to the 

 eye of the banquet where the head- stall is 

 fastened; on the other, to a hook hanging 

 from the same part. This chain, as it is at 

 present used, is composed of iron links or 

 rings, so bent, or indented, as to form, when 

 put together, one uniform nearly flat surface ; 

 and these links, by twisting or untwisting, 

 may be made to present a surface with any 

 degree of roughness to the chin. 



The larger and thicker the rings are, pro- 

 vided they are smooth and well polished, the 

 easier the effect of the chain. 



When great tenderness is required, this 

 chain may be covered with leather or cloth ; 

 or where still greater delicacy is desirable, 

 the curb may be made wholly of leather, 

 without any chain. 



In the view we are taking of the construc- 

 tion of the bit, the sides have been considered 

 as straight, plain levers of indeterminate 



