THE ANGLE OF TRACTION, ETC. 



225 



surface instead of being concentrated on a point. In 

 like manner, as the pressure of the rider's weight on 

 one end of a saddle tilts up the other end and causes 

 it to run forward, so will the pull on one end of the 

 collar cause it to gape away from the horse's neck at 

 the other end, and grind up or downwards as the case 

 may be. But the collar is in this respect worse than 

 the saddle, because the rider's weight falls directly 

 downwards for the most part, whereas the pull on the 

 trace may and very often does act altogether obliquely 

 on the collar, and then produces that grinding motion 



Fig. 17. 



which is sure to get up a raw. To have recourse once 

 more to our old familiar illustration : if the pull on the 



Q 



