80 THE EXTERIOR OF THE HOUSE. 



The Bit. This instrument (Fig. 27) is composed of a cylindrical 

 piece of metal, wood, or rubber, straight, curved, or broken, and two 

 branches, to which the reins, bridle, and curb-chain are attached. The 

 former, called the canon or bar of the bit, or the bitting, rests upon 



FIG. 27. Bit of bridle. 



the tongue and the bars ; the latter prevents deviation and increases 

 the power. 



The bit plays the part of a lever of the second class, in which the 

 curb A is the fulcrum or point of attachment, P the point of applica- 

 tion of the power, and R the place where the resistance is overcome by 

 pressure upon the bars. PA representing the power-arm of the lever, 

 it will be at once perceived that the longer the branches of the bit the 

 more powerful and energetic is its action. The latter augments, with 

 the diminution of the arm of resistance, the distance from the canon 

 to the attachment of the curb, AR ; also, if the bit be grooved instead 

 of round, or if the free portion of the tongue be large and the pressure 

 on the chin of increasing force, its effect will be more intense. 



