GENERALITIES OF THE GAITS. 483 



" If I were to commence again, at the present day, experiments of this na- 

 ture, I would give up the compressed-air process and adopt the light electrical 

 needles, like those of M. Marcel Deprez. Thin conducting wires would be more 

 easily arranged along the members of the horse than the rubber tubes, and it 

 would be more easy, I believe, to attach under the hoof an apparatus which closes 

 and opens an electric current during the contacts and elevations of the foot than 

 to apply the pneumatic foot-bulb. . . . The notation of the gait would thus be 

 obtained directly, in a more precise and simpler manner than in my first ex- 

 periments." 



This registration of the gaits of the horse by means of electricity has just 

 been achieved by one of us. 1 



Our apparatus is composed : 1st, of four chaussures exploi-atrices ; 2d, four dry piles of chloride 

 of silver carried by the rider or placed in the vehicle drawn by the horse ; 3d, four electrical needles 

 of Marcel Deprez; 4th, a portable registering cylinder revolving at a uniform and known velocity. 



Thin conducting wires, all well isolated, place the piles in communication with the chaus- 

 sures exploratrices and the latter with the needles of Marcel Deprez; they follow the tract of the 

 members against which they are maintained. 



Our exploratory shoe consists essentially (Figs. 178 and 179) of a pedal, P, movable around 

 an axis, V, attached to the frame 6, which is solidly fixed to the shoe by means of two screws, E. 

 A spring, It, keeps the pedal separated whenever the foot is in the air. In front, the latter is 

 prolonged by a piece, P', which is slightly curved in front of the wall, while at its posterior ex- 

 tremity it is provided with a point of contact, C, which is placed in relation with another point 

 of contact, well isolated, adapted to the frame, and united to the knob B. A second knob, B', 

 receives the other conducting wire. Finally, a rubber membrane, M, preserves the points of 

 contact from mud or dust. 



It can be seen that, in front and on the side, the pedal forms a box to prevent the entrance 

 of foreign bodies between it and the frame, a disposition which assures the liberty of its move- 

 ments. 2 



So long as the foot is in the air the two points of contact touch each other 

 and complete the current ; but as soon as the hoof touches the ground they are 

 separated and interrupt it. At each raising and resting of the foot it is again 

 closed and broken. The closing and breaking being instantaneous, and, more- 

 over, the force of the spring and the projection of the pedal being capable of 

 modification at will, it is easy to give to this apparatus great strength with all 

 the precision and sensibility desirable. 



Although we have not yet had the opportunity to employ it in our researches, 

 its construction being but just completed, we have nevertheless been able to 

 assure ourselves of its accuracy, in all the gaits, upon such a resisting surface 

 as that of our macadamized roads. By its aid we expect to register with more 

 accuracy than has heretofore been accomplished the periods of the change of 

 contact, the rhythm of the beats, the number, the nature, and the diverse bases 

 of support which may exist during the accomplishment of the complete step of 

 any gait, normal or pathological. 



Hydrostatic Method. M. L. Hoffmann, of Berlin, has conceived the idea 

 of applying to the analysis of the gaits of the horse the method called the 

 hydrostatic, invented by H. Vierordt for the study of the gaits in man. 8 



1 G. Barrier, Explorateur electrique pour 1'enregistrement des allures du cheval, in Bulletin 

 de la Societe centrale de medecine v<H6rinaire ; seance du 28 Mars, 1889. 



2 Since the construction of this figure, we have given to the posterior part of the pedal an 

 analogous disposition, which dispenses with the rubber membrane, if needs be. 



3 L. Hoffmann, Das Exterieur des Pferdes, p. 308, et seq., Berlin, 1887. 



