[ io5 ] 



Let us obferve the effects of the weight of 

 the body upon the Tendo Achillis in the fol- 

 lowing circumftances. 



If a horfe be mod with cramps, then there 

 is a great diftance between the frog and the 

 pavement : the weight of the body bears upon 

 the cramps -, the frog which is now free in the 

 air yields downwards, the tendon is ftretched, 

 and if the horfe makes a fudden violent, motion, 

 the rupture of the tendon is almoft inevitable : 

 becaufe the frog cannot reach the ground 

 to eafe the tendon, to which it ought to be the 

 point of fupport-, if the tendon is not ruptured, 

 yet the horfe will be lame a long time after, 

 becaufe of the great diftenfion of the fibres 

 which were fo much upon the ftretch as to be 

 near breaking. 



If we fet on fhoes with only ftrong heels, 

 the frog is not fo high from the ground j the 

 weight of the body may indeed force the frog 

 to touch the middle of a paved (lone, and 

 thereby prevent the great diftenfion of the ten- 

 don ; but as the thicknefs of thefe heels hinders 

 the fubftance of the frog to bear upon the 

 ground, to yield and reftore itfelf as much as 

 it is capable of by its natural elafticity, the 

 tendon muft fnap, by any violent and fudden 

 fpring, every other circumftance being equal. 



But if a horfe is fhod without fhoe-heels, 

 the frog which bears all the horfe's weight 

 gives way at every ftep, and by ic^ elafticity is 

 reftored to its natural ftate ; the tendon is never 



dragged 



