GENERALITIES OF THE GAITS. 485 



When all is in readiness, the animal is made to walk over the white paper, at the same time 

 that the diversely-colored liquids of the receptacles are emitted through the pointed end of the 

 brass tube. The points where the hoof touches the paper are indicated by small pools, while the 

 elevations are marked lines of a variable configuration connecting the pools. These lines are 

 regarded as representing the horizontal projection of the trajectories described by the feet in 

 motion. This method is completed by the photographing of the animal in motion, to obtain the 

 position of the members in the air. 



The hydrostatic method, applied to the horse, does not seem likely to 

 remain in use. The tracings which it furnishes are complicated, very diflScult 

 of interpretation, and often dissimilar even for the same gaits; they do not 

 exactly reproduce the horizontal projection of the trajectory of the hoofs, from 

 the fact that during the evolution of the members the liquid jets are not always 

 perpendicular to the soil, the inferior face of the feet looking sometimes behind, 

 sometimes inwardly, at other times forward. As to the trail, it is possible to 

 note it directly in a much more simple and exact manner. 



Data furnished by the Graphic Method.— The graphic notations, 

 which can be obtained by the process of the air needles or that of the electrical 

 needles, give us important results. They enable us to recognize: 



1st. The precise moment of the elevation and the contact of each member. 



2d. The duration of each of these phases, by the interval which exists be- 

 tween the instant of the resting and the raising of each foot. 



3d. The rhythm of the beats,— that is to say, the measure of the cadence 

 of the gait. 



4th. The number of feet in the air and on the ground at a given moment, 

 or the nature, the succession, and the number of the bases of support formed 

 during the execution of a complete step. 



5th. The duration of each period of suspension in the leaping gaits. 



6th. Finally, the velocity of the feet in relation to that of the body. This 

 velocity is proportional to the duration of their contact with the soil. 



It is possible, by calculation, to deduce from this last principle the position 

 of the feet in the air at any moment during the progression. This was known 

 long ago to M. Lenoble du Teil,' M. Raabe,' and their disciples. But let there 

 be no mistake here : if the situation or, better, the relative distances of the feet 

 in space can be determined, it does not follow that the attitude of the members 

 in movement is recognizable. Photography alone is capable of instructing us 

 on this point, as we will soon see. The graphic method, registering only the 

 duration of the contact, the rhythm of the beats, and the number of the feet 

 which participate in supporting the body, is naturally powerless to teach us the 

 amount of space passed over during the evolution of a complete step. It tells 

 us the nature and the duration of the bases of support, but leaves us igno- 

 rant of the extent of these bases and their direction ; it shows us in the leaping 

 gaits a phase of suspension when the body altogether leaves the ground ; but, 

 at the moment when the contact is re-established, we do not know whether the 

 body falls upon the same place or, on the contrary, has progressed while it was 

 in the air. 



Its indications, for example, will be identical for the trot and the trot upon 

 place, for the ordinary gallop and the gallop upon place ; it will be the same for 



1 Lenoble du Teil, loc. cit., 1877. 



2 E. Barroil, L'art iJquestre, p. 92, etsuiv., Paris, 1887. 



