THE ANATOMY OF THE FOOT. 273 



of forty -five degrees with the ground surface ; and 

 another noted writer sets the average depth of the foot 

 when ready to receive the shoe at three and one-half 

 inches from the coronary line to the toe, and the depth 

 of the heels he sets at from one and one-half to two 

 inches. The wall is thicker in the fore foot at the toe 

 than at any other part, averaging there about three- 

 eighths of an inch ; at the quarters, about midway 

 from the toe to the heel, the wall is from one-quarter to 

 three-eighths of an inch thick, and at the heels about 

 the same. 



The bars are a continuation of the wall, extending 

 therefrom at the heels, obliquely into the center of the 

 foot between the sole and the frog, "constituting two 

 inner walls or lateral fences between that body and the 

 sole." In a state of nature they bear some pressure. 



The natural function of the frog is that of a cushion, 

 and being spongy and elastic, when called upon to bear 

 weight it spreads, and to accommodate this action the 

 wall expands from the quarters back. Indeed, the 

 structure of the foot is such that even if the frog sus- 

 tains no pressure, the heel must spread at every stride 

 when the weight comes upon the foot. You can 

 imagine then what the efifect must be of shoeing a 

 horse so that the heels are held rigidly to an unyield- 

 ing shoe. 



We have seen that the wall is the natural bearing 

 part of the foot, and the frog an accessory. The bear- 

 ing of the shoe should be wholly on the wall, not on 

 the sole, and the ground surface of the wall is the only 

 part that should ever be pared. This is the part that 

 like the human nail grows exuberantly, and must be 



