GENERALITIES OF THE GAITS. 479 



when there is perfect superposition of the imprints of the fore- and 

 hind-feet (normal trot), or when those of the diagonal bipeds are in the 

 same transverse line (normal gallop) ; projectile, when the imprint of a 

 posterior biped is in front of that of the corresponding (elongated trot) 

 or the diagonal (fast gallop) anterior biped. The knowledge of the 

 upivard and the lateral oscillations of the centre of gravity permits us 

 to understand how each particular gait gives to the rider as well as to 

 his mount more or less fatigue and exertion than any other. 



Reactions. — This term designates the more or less strong concus- 

 sions or tossings which the horse in motion experiences or communi- 

 cates to the rider. In a general manner, they are proportionate to the 

 height of the displacement of the centre of gravity, and, consequently, 

 to the energy of the propulsive force, the speed employed, and, all 

 things being equal, also to the length of the step, since the latter 

 augments the initial and final obliquity of the members in their contact 

 with the soil. 



A gait is sufficiently defined when in it can be recognized the 

 follo^ving characters : 



1st. The number, the intervals, and the mode of association of the 

 beats. 



2d. The duration of the contact and of the elevation. 



3d. The trajectory of the members in the air. 



4th. The trail 



5th. The speed. 



6th. The displacements of the centre of gravity. 



Let us see how each one of these diverse factors is deduced : 



Analysis of the Gaits 



1st. Direct Observation.— We must not lose sight of the fact that it is 

 by attentive, judicious, and patient observation of the horse in motion that the 

 largest number of data concerning his gaits has been collected. The veterina- 

 rians and horsemen of the last century had already, without recourse to any instru- 

 ments of precision, discovered most of the facts which the new methods have 

 since only verified. They recognized, for each gait, the order of raising and 

 resting the feet, the mode of association of the members, the number, succession, 

 and rhythm of the beats, the form of the trails, the length of the step, and the 

 nature, the extent, and the direction of the base of support. Some of them even 

 had endeavored to establish a relation between the dimensions of the animal and 

 the length of his strides. 



Unfortunately, our external senses being unable to perceive phenomena of 

 so short a duration as those which take place in the rapid gaits, the first observers 

 were unluckily led to commit errors and to leave blanks, doubts, and obscurities 

 in their writings, whence have originated some processes for more thorough 

 investigations. 



