286 



four points occupied by tlie feet of the auinial while standing at rest, 

 forming a square, the two fore legs are known as the anterior biped; 

 the two hinder, the jjo.s/erior; the two on one side, the lateral; and 

 one of either the front or hind biped with the opposite leg of the hind 

 or front biped will form the diagonal hiped. 



Considering, as it is proper to do, that in a condition of health each 

 separate biped and each individual leg is required to i^erform an 

 equal and uniform function and to carry an even or equ^l portion of 

 the weight of the body, it will be readily appreciated that the result 

 of this distribution will be a regular, evenly balanced, and smooth 

 displacement of the body thus supported by the four legs, and that 

 therefore, according to the rapidity of the motion in different gaits, 

 each single leg will be required at certain successive moments to 

 bear the weight which had rested upon its congener while it was 

 itself in the air, in the act of moving; or, again, two different legs of 

 a biped maj'- be called upon to bear the weight of the two legs of the 

 opposite biped while also in the air in the act of moving. 



To simplify the matter by an illustration, the weight of an animal 

 may be placed at 1,000, of which each leg, in a normal and healthy 

 condition, supports while at rest 250. When one of the fore legs is 

 in action, or in the air, and carrying no weight, its 250 share of the 

 weight will be thrown upon its congener or i)artner to sustain. If 

 the two legs of a biped are both in action and raised from the ground, 

 their congeners still resting in inaction, will carry the total weight of 

 the other two, or 500. And as the succession of movements contin- 

 ues, and the change from one leg to another or from one biped to 

 another, as may be required by the gait, proceeds, there will result a 

 smooth, even, and equal balancing of active movements, shifting the 

 weight from one leg or one biped to another, with symmetrical pre- 

 cision, and we shall be presented with an interesting example of the 

 play of vital mechanics in a healthy organization. 



Much jnay be learned from the accurate study of the action of a 

 single leg. Normally, its movements will be without variation or 

 failure. When at rest it will easily sustain the weight assigned to it, 

 without showing hesitancy or betraying pain, and when it is raised 

 from the ground in order to transfer the weight to its mate, it will 

 perform the act in such a manner that when it is again placed upon 

 the ground to rest it will bo with a firm tread, indicative of its ability 

 to receive again the burden to be tlirown back upon it. In planting 

 it upon the ground or raising it up again for the forward movement 

 while in action, and again replanting it upon the earth, each move- 

 ment will be the same for each leg and for each biped, whether the 

 act be that of walking or trotting, or even of galloping. In short, 

 the regular play of every part of the apparatus avIU testify to the 

 existence of that condition of orderly soundness and efficient activity 

 which is eloquently suggestive of the condition of vital integrity, 



