CHAPTER III. 



THE MECHANICAL FUNCTIONS OF THE FOOT. 



At rest the horse's weight is distributed over four columns, 

 the framework of each of which is formed by bones. Taking 

 any one of these columns we find the load finally falls on 

 the pedal bone, and is transmitted by it to the hoof, which 

 may be compared to a socle or plinth sustaining the entire 

 limb. The body- weight, however, is not distributed equally 

 over the four hoofs, the front feet, which lie nearer the centre 

 of gravity of the body, carrying a greater proportion than the 

 liind. 



Every object must be supported, at least at one point. If 

 all the parts surrounding this are themselves in equilibrium 

 the point of support will lie vertically below the centre of 

 gravity. Living objects, including the horse, have, instead of 

 a point, a surface of support, which, in the horse, may be 

 delimited by lines uniting the outer borders of the hoofs, 

 and will therefore be found to take the shape of an elon- 

 gated rectangle. The centre of gravity of the body falls at 

 a point somewhat in advance of the intersection of the two 

 diagonals. 



When the horse stands on three legs, the centre of gravity 

 is shifted, and the surface of support becomes triangular. If 

 a hind-foot is rested, the point wilLbe displaced in a back- 

 ward direction, if a fore-foot, forwards. As the feet can only 

 sustain weight when in contact with the ground, it follows 

 that in movement the surface of support may be an elongated 

 strip, i.e., a surface as broad as the hoof, and as long as the 

 space between the two hoofs (trot), or may even be diminished 

 to the area presented by the single hoof, which for the time 

 being carries the entire body-weight (gallop). In addition to 

 the weight of the body, the limbs have often to bear a con- 



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