478 THE EXTERIOR OF THE HORSE. 



since ; ! M. Raabe 2 attaches great importance to this and deduces from 

 it this principle : " The relative velocity of the feet is proportional to 

 the duration of their contact." 



Time of Preparation. The horse, before taking a step in any 

 gait, first prepares himself by assuming an attitude which corresponds 

 to the point of departure of this gait. 



To use a familiar illustration, a man who, at the beginning of the 

 walk, wishes to make the initial step with the left foot, must first carry 

 the weight of his body on the right foot. This displacement of the 

 centre of gravity varies with each particular gait ; changing the situ- 

 ation of the head and a slight flexion of the members produce it, but 

 these movements always have for their result the greatest possible 

 disburdening of the member which is about to be carried forward. 

 This principle is often applied in equestrianism. Bringing the head 

 and neck of the horse to the right side, for example, facilitates the 

 initial movement by the left. 



Displacements of the Centre of Gravity. The movements 

 of the body over the ground implies displacements of the centre of 

 gravity, and, consequently, a destruction of the initial equilibrium, 

 which incessantly compels the members to form new bases of support. 

 Hence the members, each in their turn, come and prop it in front 

 according to the ingenious comparison of Richerand, 3 in the manner 

 of the spokes of a wheel in relation to the weight of the hub which 

 they sustain ; the rapidity with which they succeed each other is so 

 much more frequent as the imminence of a fall is greater. Here is the 

 reason of the correctness of the expression, that the instability of the 

 equilibrium , in these gaits, gives the measure of the velocity. 



As Lecoq 4 has easily recognized, the displacements of the centre 

 of gravity may take place either in a transverse sense, in consequence 

 of the alternate support by the right and the left members, or in a 

 vertical sense, from the successive degrees of the obliquity of the columns 

 of support. The vertical displacements at times acquire a remarkable 

 importance, as when the body is raised from the ground by the ener- 

 getic impulsion of the hind-limb. The name of period of suspension 

 is given to this phase of the leaping gaits. 



The disciples of the school of Raabe 5 call the displacement simple 



1 Lenoble du Teil, Note communique^, et loc. cit., p. 107. 



* C. Raabe, Regies du mecanisme des allures du cheval, in Spectateur militaire, ann6e 1883. 



3 Le Baron Richerand, Nouveaux elements de physiologic, lOe 6d., Paris, 1833, t. iii. p. 148. 



4 Lecoq, Extrieur du cheval, 5e 6d., p. 346. 



6 E. Barroil, L'art equestre, p. 20, Paris, 1887. 



