MOTION. 



473 



path described by the centre 

 of gravity in the time t, and the 

 distance of the centre from the 

 earth at the end of that time. 

 The time occupied in running 

 between the raising of the leg 

 from the ground and the setting 

 it down again is equal to the 

 duration of the step, together 

 with the portion of time during 

 which the body swings in the 

 air; or, it is the time in which 

 c (fig- 262) advances from r 2 to 

 c s , being the time between the 

 raising of the left leg and the 

 setting it down again, but this 

 time is divided into two por- 

 tions, namely, that whilst c 



Fig. 262. 



Fig. 263. 



Fig. 264. 



Figures designed by Weber, to illuatrate tlie laws of runniny. 



moves from c 2 to r 3 , and that whilst it moves 



From these principles it is obvious that n 



from c 3 to c s ; the latter portion is the duration man in the act of running could possibly be in 

 of the step ; the former the time in which the 

 body swings freely in the air. & 266. 



Fig. 265. 



Preparing to run, and running, from designs by Flagman. In Jig. 265 c A falls behind the advanced foot, so 

 that the posterior leg bears only a small portion oj the weight of the body, but is in a position to push the centre 

 of gravity forwards before quitting the ground. 



