506 



WALKING. 



be examined with the 



represents the successive phases of locomotion. These phases may 



Strode ( 398, T) Marev estimated the time-relations of the individual acts, by transferring 

 ^e movement by means 6f his air-tambours to a recording surface. Recently, by means of a 

 r^voMng camVhe has succeeded in photographing, in in^antaneou^pic^res (^-J^ 



Of course this series, when 

 placed in the zoetrope, 

 represents the natural 

 movements. Figs. 349, 

 350, 351 represent these 

 acts. 



In walking, the legs 

 are active alternately; 

 while one the "sup- 

 porting" or "active" 

 leg carries the trunk, 

 the other is "inac- 

 tive " or " passive." 

 Each leg is alternately 

 in an active and a 

 Fig. 348. passive phase. Walk- 

 Phases of walking. The thick lines represent the active, the thin the ing may be divided 

 passive leg ; h, the hip-joint ; k, a, knee ; /, b, ankle ; c, d, heel ; into the following 

 m, e, ball of the tarso-metatarsal joint ; z, g, point of great toe. movements : 



I. Act (fig. 348, 2). The active leg is vertical, slightly flexed at the knee, and it alone 

 supports the centre of gravity of the body. The passive leg is completely extended, and 

 touches the ground onlv with the tip of the great toe (z). This position of the leg corresponds 

 to a right-angled triangle, in which the active leg and the ground form two sides, while the 

 passive leg is the hypothenuse. 



II. Act For the forward movement of the trunk, the active leg is inclined slightly from its 

 vertical position (cathetus) to an oblique and more forward (hypothenuse) position (3). In 

 order that the trunk may remain at the same height, it is necessary that the active leg be 

 lengthened. This is accomplished by completely extending the knee (3, 4, 5), as well as by 

 lifting the heel from the ground (4, 5), so that the foot rests on the balls or the heads of the 



Fig. 349. 

 Phases of slow walking. Instantaneous photograph {Marcy), only the side directed to the ob- 

 server is shown. From the vertical position of the right, active leg; (I.), all the phases of 

 this leg are represented in six pictures (I. to VI.), while after VI. the vertical position is 

 regained. The Arabic numerals indicate the simultaneous position of the corresponding 

 left leg; thus 1 I., 2 II.. &c, so that during the position IV. of the right leg, at the 

 same time the left leg has the position as 1. 



metatarsal bones, and, lastly, by elevating it on the point of the great toe (2, thin line). 

 During the extension and forward movement of the active leg, the tips of the toes of the passive 

 leg have left the ground (3). It is slightly flexed at the knee-joint (owing to the shortening), 

 it performs a " pendulum-like movement 5 ' (4, 5), whereby its foot is moved as far in front of 

 the active leg as it was formerly behind it. The foot is then placed flat upon the ground (1, 2, 



