494 THE EXTERIOR OF THE HORSE. 



The notation of M. Marey, although almost identical with that of Vincent 

 and Goiffon, has, nevertheless, the preference over the latter in being clearer and 

 more explicit. 



FIG. 187. 



4th. Notation of M. Lenoble du Teil. 1 The method of Professor Le- 

 noble du Teil, of the School of the Stud of Pin, is without doubt the most perfect 

 from a point of view of the intelligence which it imparts from mere ocular in- 

 spection. Its principle is always that of the musical notation invented by 

 Vincent and Goiffon, but it adds a new idea : that of the path described by the 

 feet. Hence the name of hodochronometric scale is much more applicable to it than 

 to any other, and we would give to it the preference, had not its author desig- 

 nated it under that of method of the planes of the ground surface. 



It consists as follows (Fig. 188) : 



Upon a sheet of paper are traced a certain number of vertical columns rep- 

 resenting equal fractions of time. To the left of these columns is indicated the 

 trail of the gait, by marking in a known scale the intervals which separate the 

 imprints. 



The line XY indicates the direction of movement. 



We will suppose, for example, that the two feet of the anterior bipeds have 

 left upon the ground the imprints DD' (for the right) and GG' (for the left). 



Suppose, now, that this surface begins to glide from right to left at the 

 moment when the foot G commences its contact ; this foot, instead of leaving a 

 simple imprint of its shoe upon the ground, will trace a line, PI', so much longer 

 as the contact is prolonged. 



During this period of contact, what has the opposite foot done ? We know 

 that it was advanced after a short period of exchange of contact. As the surface, 

 however, continues to glide during this action, the foot Z>, which should rest at 

 D', will rest at P' at the instant of the end of the contact (/') of G. 



Consequently, the horizontal projection of each of the points described by 

 the foot D, through the air, instead of being a straight line parallel to the axis 

 of the trail, will be an oblique line, IP'. 



There a new transverse line, P'l", will represent the duration of the contact 

 of D' with the ground. 



During the period of contact of D', the foot G, beginning at the point I', 

 will execute its period of projection and touch at P", the moment correspond- 

 ing to the termination of the contact of D' ', etc. 



It only remains now to trace through any point a vertical line, KL, to be 

 immediately informed as to the respective positions of the two feet with the place 

 where this line intersects the lines of contact and those of projection. 



If to the notation of the anterior members alone were added that of the 

 posterior, the phenomena would net be more complicated. Likewise the construc- 

 tion of the diagram would be quite as simple in cases in which the number of 



1 J. Lenoble du Teil, Locomotion quadrupede 6tudi6e sur le cheval in Journal des Haras, 

 ann<e 1887, p. 224. 



