S3(^ HORSE-SHOES AND HORSE-SHOEING. 



deprived of the power of resilience or re-action, which the 

 curve between the bar and the crust affords, will speedily 

 fall in.' 



Then the functions of the frog are enumerated, and 

 their description is strangely compounded of truth and error. 

 ' The foot is seldom put flush and flat upon the ground, but 

 in a direction downwards, yet somewhat forwards ; then the 

 frog evidently gives safety to the tread of the animal, for it, 

 in a manner, ploughs itself into the ground, and prevents 

 the horse from slipping. This is of considerable conse- 

 quence, when we remember some of the paces of the 

 horse, in which his heels evidently come first to the 

 ground, and in which the danger from slipping would be 

 very great. . . . The frog being placed at and filling the 

 hinder part of the foot, discharges a part of the duty sus- 

 tained by the crust ; for it supports the weight of the 

 animal. It assists, likewise, and that to a material degree, 

 in the expansion of the foot. ... It is also composed of a 

 substance peculiarly flexible and elastic. What can be so 

 well adapted for the expansion of the foot, when a portion 

 of the weight of the body is thrown on it ? How easily 

 will these irregular surfaces yield and spread out, and how 

 readily return again to their natural state ! In this view, 

 therefore, the horny frog is a powerful agent in opening 

 the foot ; and the diminution of the substance of the frog, 

 and its elevation above the ground, are both the cause 

 and the consequence of contraction : the cause, as being 

 able no longer powerfully to act in expanding the heels ; 

 and the consequence, as obeying a law of nature, by which 

 that which no longer discharges its natural function is 

 gradually removed. It is, however, the cover and defence 



