Let it be permitted to us to remind the reader in this connection that we have already been for twenty-one years occupied with this question, and that by means of an articulated figure, a sort of movable mannikin, we have endeavoured to demonstrate to artists the differences which characterize the various paces of the horse.[69] The arrangement then employed cannot, evidently, be used in the present volume, but we will inspire ourselves, in the preparation of the present chapter, with the elements of demonstration which we have employed, and which, in the course of our teaching, we have had the satisfaction of seeing favourably received. [69] Édouard Cuyer, 'Les Allures du Cheval,' demonstrated with the aid of a coloured, separable, and articulated table, Paris, 1883. This table was the subject of a note communicated to the Academy of Sciences by Professor Marey ('Comptes rendus de l'Académie de Sciences') at the meeting of June 26, 1882. On the other hand, it has been the subject of a presentation which we have had the honour of being permitted to make to the Academy of Fine Arts at the meeting of November 4, 1882. The fasciculus in question has been since united with a more complete whole as regards the study of the horse. E. Cuyer and E. Alex, 'Le Cheval: Extérieur, Structure et Fonctions, Races,' avec 26 planches coloriées, découpées et superposées, Paris, 1886. The progressive movements by which an individual transports himself from one place to another do not operate according to a unique method and with a constantly uniform velocity. These various modes of progression are designated under the name of _paces_. It is extremely difficult to analyze, by simple observation, the movements which characterize these gaits. Let us, for example, examine the displacements made by the limbs of a horse during that of walking; if we have no notion of these displacements, it will be, so to speak, impossible to determine in what order they are executed. The sight of the imprints left on the ground by the hoofs is not a sufficient means of demonstration, especially for artists. The noise made by the blows of these limbs, or by the little bells of different timbre suspended from them, are absolutely in the same case. Processes enabling us to fix or to register the paces are in every way preferable. Such really exist; they are: instantaneous photography and those which constitute the graphic method of Professor Marey. The results given by the photograph are certainly appreciable; but, from the didactic point of view, we give the preference to the graphic method, the general characters and the mode of application of which we now proceed to analyze.[70]