chronophotographic pictures given by Lieutenant-Colonel 

 Gossart in his work, " Les Allures du Cheval " ; these 

 pictures which follow one another at intervals of 1/25 

 seconds permit the recording of the raising and grounding 

 of each foot with an error of less than 1/50 second, a 

 sufficient approximation. 



X 



!9 17 16 13 



: 18 16 IV 



e ! V ?. j 



^c?y : Fad \ ^j fpd 



„ /<?/ isd Lpy Lpd 



c iispension 



FIG. I— A GALLOPING STRIDE ON THE LEFT FOOT. 



Ppd — Grounding of right hind foot. 

 Ppg — Grounding of left hind foot. 

 Pad — Grounding of right fore foot<» 

 Pag — Grounding of left fore foot. 

 Lpd — Raising of right hind foot. 

 Lpg — liaising of left hind foot. 

 Lad — Raising of right fore foot. 

 Lag — Raising of left fore foot. 



We projected upon a horizontal line X Y (Fig. i) the 

 position of a very conspicuous point of the body (the 

 girth, clearly defined in white on the pictures). The 

 space between two projections evidently shows the dis- 

 tance traversed in the unit of time, that is to say, the 

 velocity. These projections are numbered i, 3, 5, 7, 



9 19. \\'e assumed that between two consecutive 



projections the velocity of translation was constant and 

 we halved the spaces included between two projections, 



which gave us the series of number 2, 4, 6, 8 18. 



The divisions of the whole series i, 2, 3, 4 19 cor- 

 respond therefore to fiftieths of a second, and we were 

 able to show with regard to each of them and with a 

 sufficient approximation the raising and grounding of the 

 several feet. 



It is seen that the stride is completed 19/50 seconds. 

 A glance at figure i suffices to show that the distances 



13 



