March 20, 18 79 J 



NATURE 



465 



Let us take up the question at the point to which it has 

 been brought by the experimenters to whom^I have just 

 alluded. The succession of the movements of the horse' s 

 legs, since it is rhythmical, and since also we produce 



Transition from the trot to the foot-pace. 



Trans.tion from the trot to the callop of 3 steps. 



Trans.tion from the gallop of 3 steps to the trot. 

 Fig. 12. — ^Transitions between different paces. 



from each foot a different tone, forms a sort of music. 

 Now this music is very simple, because it is only com- 

 posed of four tones. The following arrangement will 



0-r 



iA. 



o 



- n 



Ar 



A-h 



D 



Ai 

 A 



5* 



Fig. 13. — Diagram of the tracks of horses in Afferent paces. 



permit us to obtain the notation of this music, written by 

 the horse himself. Under each of the horse's shoes we 

 place a bag {ampoulle) fuU of air, which, by means of a 

 tube is connected with another similar small bag, which, by 



its changes in bulk, acts upon a penciL When the horse 

 plants its foot upon the ground, it raises a pencil, which 

 remains raised as long as the foot is kept down. Four 

 pencils are placed in position, connected with the four 

 under the horse's feet, and these pencils placed in a 

 right line parallel with the axis of the cylinder, spon- 

 taneously trace the succession and duration of each 

 setting down of a foot. 



Fig. 8 shows the arrangement of the apparatus. The 

 four limbs of the horse bear four india-rubber tubes, 

 which converge to the hand of the jockey, and so to the 

 inscribing apparatus on the cylinder which he holds. 



The results thus obtained by the different paces are 

 shown side by side to the number often in Fig. 9. Each 

 ' foot, as in musical notation, has its characteristic sign, by 

 j the height of which the symbol of its stay on the ground 

 I is traced. We will agree that the fore feet shall mark 

 I upon the lines above, the rear feet upon the lines below. 

 I Now the horse can, with his four feet, execute the most 

 rapid movements, and yet nothing will be wanting from 

 ' the inscription. And in the first place, in order to give 

 ' you confidence in the employment of this method, let us 

 I show you how it solves a problem stiU more difficult. 

 When a clever pianist passes his fingers over the key- 

 board, who could describe the movements that he 

 ; executes, say what note has been touched first, and for 

 ; how long, then what notes followed, together or sepa- 

 rately, with their rhythms and tones ? But let us write, 

 down these movements, and when they are fixed upon 

 paper we can analyse them with ease. 

 I In the apparatus which I use, the keys act by pressure 

 upon the bags of air connected by tubes with other 

 : bags, which cause pencils to move. See with what 

 ease these little pencils reproduce all the movements of 

 I the fingers passing over the mute keyboard ; you will 

 I presently see the instrument in operation. I present to 

 i you, first of all, what it has just written (Fig. 10). Ob- 

 I serve these notes drawn up in gamuts and arpeggios, 

 i these varied accords, these changes of tone where sharps 

 j and flats reveal themselves by strokes drawn longitu- 

 dinally. This instrument, which is now in action for the 

 first time, has been constructed by our colleague, M. 

 I Tatin, whose skill has already excited the admiration of 

 ! all who know him. 



' And now that you no longer doubt, I trust, the faithful- 

 ness of the method, let us analyse the tracings on the 

 i diagram I have just now shoA\'n you (Fig. 9). In order 

 to understand it fully, let us borrow the ingenious idea of 

 ' Dug&s, and compare the horse or any other quadruped 

 I to two bipeds walking one behind the other. If the two 

 walkers execute the same actions at the same time, that 

 is to say, if they both simultaneously raise and set down 

 the right foot and then the left, it is the a7nble (No. i) 

 which is produced. The ear only detects two sounds at 

 each combined step, because two feet touch the ground 

 together. This is an example of lateral bipedal move- 

 ment. If the rearmost walker has half finished the rest- 

 ing of one of his feet when the foremost walker plants the 

 same foot on the ground, it represents \h&/oot-pace. Here 

 the four footsteps are separate, and the ear distinguishes 

 four equidistant sounds ; the order of succession would 

 be (commencing to count by the right foot), foremost 

 right, rearmost left, foremost left, rearmost right. Let us 

 imagine that the rearmost walker makes movements 

 absolutely the reverse of those of the walker in front, 

 that is to say, that one of the right feet strikes the ground 

 when the other right foot rises from it, we shall then have 

 the trot. Two feet will be always associated and will 

 give but one sound, and these feet will exemplify ^'^^iww/ 

 bipedal motion. 



Such, then, is our knowledge of the rhythm of paces, 

 or at least the points upon which all are agreed. But if 

 we desire to gather from divers authors the definition of 

 more complicated paces, intermediary to those we have 



