HUMAN MOVEMENTS 133 



obtained without the help of photography ; moreover, 

 the latter method, although it could give exact details 

 of any particular, for instance, as to the length of any 

 stride considered by itself, could not furnish the re- 

 quired averages. 



Mechanical Record of Movements in Walking. — We 

 saw in Chapter I. how the duration and sequence of 

 the rise and fall of the foot in walking could be re- 

 corded by mechanical means. This chronographic re- 

 cord was effected by transmitting through the medium 

 of pneumatic tubes the pressure of the foot on the 

 ground to the registering tambours. We showed the 

 result of these observations, and shall now continue 

 the investigation. 



In ordinary walking on level ground one foot leaves 

 the ground as the other reaches it. In the case of a 

 man who carries a weight, or who walks uphill, or 

 mounts a staircase, the foot in contact with the ground 

 does not leave it until the other has been in contact 

 with it for some time. There is then a period, more or 

 less prolonged, during which both feet simultaneously 

 rest upon the ground.* 



In running, the body remains suspended in air for a 

 brief moment between two successive contacts, and 

 this suspension lasts longer as the speed of running 

 increases. 



Path described by any Particular Part of the Body 

 during Different Paces. — So extensive are the move- 

 ments in walking, and even more so in running, that 

 mechanical registration of these movements becomes 

 very difficult, and, further, they nearly always take 



* By substituting electric for pneumatic signals, M. Demeny believed 

 that he detected, even inordinary walking, a short period during which 

 both feet were simultaneously on the ground, and that this period was 

 prolonged as the pedestrian became more tired. These results would 

 be most important if, so to speak, they provided a means of measuring 

 fatigue. 



