Chap. XLIII.] 



WALKING. 



knee, but when the leg behind it leaves the ground, 

 it gradually becomes straightened (3, 4, 5 of Fig. 

 219, thick line), so that the body is kept from 

 being lowered. The leg behind is thus hanging, 

 so to speak, and performs a pendular movement 

 (indicated by the arrow between 4 and 5), swinging 

 forwards past the leg which is now supporting the 

 body, till it 

 reaches a posi- 

 tion as far in 

 front of the 

 supporting leg 

 as it was for- 

 merly behind 

 it, when it 

 toil c h e s the 



ground. It has Fig> 219.-Different Positions of the Legs 



now become Walking, 



the forward leg 



(had beg of 1, 2, and 3), while the leg formerly in front 

 lias come to occupy the posterior position (4, 5, dark 

 lines; and 1, thin line). In slow walking there is a 

 time when both feet are on the ground, the forward 

 foot acting as a fulcrum, on which the foot behind 

 pushes the body. But as the pace increases, the 

 period during which both feet touch the ground grows 



O O O 



less and less, till one foot has no sooner touched the 

 ground than the other leaves it. This is shown spe- 

 cially well by Marey's graphic method of registering 

 the movements of the two feet by a tambour in each 

 shoe, connected with a revolving cylinder. The same 

 method shows that in running there is an appreciable 

 period when both feet are off the ground. 



The forward impelling force urges the body on 

 wards against the resistance of the air, the friction 

 between the feet and the ground, etc. It is evident 

 from Fig. 218 that the horizontal component of the 



H H 7 



