514 



THE EXTERIOR OF THE HORSE. 



ascend (the fetlock first) during the shortening of the member, to descend simul- 

 taneously when the latter elongates and prepares to rest again. 



As to the trajectory of the foot, inversely disposed, convex at the beginning 

 of the elevation and oblique downward at the end, it crosses that of the fetlock 

 under the effect of strong flexion of the pastern at the instant when the foot 

 leaves the ground. 



2d. Posterior Member. Phase of Contact, A (Fig. 208). In a general 

 manner, all the articular trajectories are lowered during the period of disper- 



FIG. 208. Kinematic analysis of the play of the posterior member in the ordinary trot. 



(Messrs. Marey and Pages.) 

 A. Phase of contact. | S. Phase of elevation. 



sion, the inferior much more than the superior. The curves then rise gradually, 

 as in the anterior columns, during the period of extension. These trajectories are 

 convex, save that of the stifle, which remains concave and low, from the forward 

 notation of the tibia. 



During the elevation, S, a depression exists in the middle of the trajectories, 

 except upon those of the fetlock and the foot ; it corresponds to the phase of 

 dispersion, to 2, of the opposite member. It is preceded and followed by a 

 slight ascension, due to a greater or less raising of the body at the moment of 

 the periods of suspension. The trajectories of the fetlock and the foot resemble 

 those of the anterior member, only that of the foot approaches the former less, 

 on account of the more feeble flexion of the pastern. 



Rhythm of the Beats; Time of Projection; Tracing 

 and Notation. When the trot is regular, and its speed not 

 excessive, only two sounds, or two synchronous beats of equal intensity, 

 are heard. Tired and overdriven horses do not travel at this gait long 

 without irregularities, which must be considered as defects. We will 

 study these under the names racking, saut de pie, and canter. 



The duration of the time of projection l has been differently appre- 



1 Let us recall that in the leaped trot there is a simple suspension when the lateral imprints 

 are superposed, and a projection when the posterior imprints surpass the anterior. 



