travelled in the unit of time are sensibly different; to 

 make these differences in velocity the more easily appre- 

 ciable we have constructed a curve of velocities (Fig. 2). 



A4 



^ a V J6 lb Ji 13 12 ] 



'^^ •! 



lay laJ 



Period, of Suspension 



10 3 6 7 e 5. 

 FIG. 2— CURVE OF VELOCITIES 



B 



P/>7 





The line A B is divided into 19 equal parts and v^e 

 have taken upon ordinates erected at the division points, 

 distances proportional to the velocity at each 1/50 second 

 (ordinate i, Fig. 2) is equal to four times the distance 

 o — I (Fig. i) ; ordinate 2 (Fig. 2) is equal to four times 

 the distance 2 — 3 (Fig i) and so on. By joining the 

 summits of these ordinates, we obtain the curve of velo- 

 cities. 



It is seen that, at Epoch 2, the grounding of the left 

 hind foot slightly diminishes the velocity ; it remains rela- 

 latively slow at Epoch 3, while the left hind leg is rotating, 

 then it quickly reaches its maximum at Epoch 4, when the 

 latter leg joins its propulsive force to that of the right 

 hind leg. This maximum is maintained practically until 

 Epoch 6, when the grounding of the right forefoot re- 

 tards it slightly ; another diminishing of velocity is pro- 

 duced at Epoch 8 when the left hind foot is raised. The 

 curve then reveals a really peculiar fact : the velocity 

 remains constant from Epoch 8 to Epoch 11, although 

 the left fore foot is grounded at Epoch 9; now it must 

 be noted that during this period both hind legs are in the 

 air and the translative impulse is fed only by the right 

 fore leg which acts after the manner of a pole pushing a 

 boat along. This action is made appreciable at Epoch 

 II when the right fore foot is raised and when the uni- 



14 



