POSTERIOR MEMBER. 303 



angle BOO, by antagonizing the muscular action, M, which is exercised at the 

 extremity, A, of the same lever. In this case, the fetlock becomes the fixed point 

 or fulcrum and the lever belongs to the first class. 



Let us determine, as above, the arms of the lever of the forces, BH and 

 AM, by inserting from the fixed point a line perpendicular to their direction; 

 these arms evidently are OH and OA. 



Now let us lengthen the lever OB to OD, and we will see that the arm of 

 the force, Bff, becomes 01, while that of A M will always remain OA. 



Thus, the longer the pastern the more the reaction of the soil 

 against the weight of the body augments and fatigues the tendons and 

 the ligaments which are inserted, at A, upon the sesamoid bones. The 

 causes which tend to augment the length of the phalangal region are 

 very significant, exception being made, of course, of the dimensions of 

 the bones. 



First among these we will place the elongation of the hoof, re- 

 sulting from the normal growth of the horn in a horse whose shoe 

 is not sufficiently often reset ; secondly, the error of the farrier in 

 not sufficiently paring the foot; finally, the tendency which farriers 

 or proprietors have, according to their interests, of applying too 

 thick a shoe in order not to have the trouble or the expense of re- 

 setting them at proper intervals, as often as the state of the hoof re- 

 quires it. 



Deficiency of the length of the pastern evidently has inverse draw- 

 backs. The short-jointed horse surcharges his bones beyond measure ; 

 he lacks suppleness in consequence of the insufficiency of the fetlock 

 as an apparatus of dispersion, and has, from this fact, hard reactions ; 

 besides, he is more predisposed to osseous blemishes of the bones of the 

 members, as ring-bones. 



The inconveniences of the long joints and the short joints have not, 

 by far, the same importance in the anterior as in the posterior mem- 

 bers, on account of their unequal distance from the centre of gravity. 

 It is beyond a doubt that the anterior extremities, incomparably more 

 loaded than the posterior in the sustentation of the body, show more 

 quickly and more gravely the injurious consequences of these defects. 

 In fact, experience has demonstrated this ; blemishes of the anterior 

 members are more common than those of the posterior, and the part 

 which the pastern takes is more marked in the former, this region 

 being always longer in the fore than the hind limbs, and also more 

 oblique, doubtless on account of their proximity to the centre of 

 gravity. 



Direction. The direction of the pastern is intimately allied to 

 its length, that is to say, a long pastern is in most cases too horizontal, 



