THE GAITS IN PARTICULAR. 519 



that the rider falls upon the saddle a little after each diagonal biped 

 rests, when the axis of the members passes beyond its vertical direction. 

 He is raised, on the contrary, at the moment when each diagonal biped 

 leaves the ground, and remains in the air during the whole duration of 

 the phase of suspension. 



Length of the Step of the Trot. — It is extremely difficult to 

 formulate, or even to determine approximately, the absolute facts on 

 this point, for the experimental results obtained to elucidate this ques- 

 tion are only comparable when the researches are made upon subjects 

 identical and perfectly uniform in their gaits. When such is the case, 

 the successive steps are sensibly equal. 



But are the height, on the one part, and the length of the base of 

 support, on the other, in simple and constant relation with the length 

 of the strides ? In other words, is it the horse highest at the withers, 

 or that one whose base of support is the most extensive, which takes 

 the longest steps ? 



The man would be liable to commit an error who would answer 

 these questions a priori, because observation of the data in this respect 

 leads to results apparently contradictory. The problem is, indeed, so 

 complex, in consequence of its numerous factors, that its solution is 

 necessarily false, if we base it only upon some phenomena without 

 taking into accovmt all the elements capable of influencing it. 



The length of the space embraced at each step by the play of the 

 members is related, above all, to the length of the locomotory columns, 

 the degree of openness and mode of action of the articular angles, the 

 extent of the muscular contraction, the proper relations between the 

 height of the body, its largeness and its width, to the particular de- 

 velopment of certain regions, etc. All these points have already been 

 treated (I propos of the regions, the proportions, and the axes, to which 

 the reader is referred. 



But, to speak more definitely, let us state that the mean length of 

 a step in the ordinary trot is about 2.40 m. for a horse 1.60 m. in 

 height. The cavalry regulation of 1829 makes it only 2.20 m., which 

 seems to us rather short. 



Velocity of the Trot. — The mean velocity of this gait is about 

 240 metres per minute, as it has been fixed by the cavalry regulation. 

 This gives approximately a kilometre in a little more than four minutes, 

 and 4 kilometres in a little less than seventeen minutes. The distance 

 traversed at the trot in a given time varies according to several con- 

 ditions which must be recognized. 



In comparative experiments made with horses of unequal height, 



