WALKING, RUNNING, LEAPING. 209 



what is called the centre of gravity or the 

 point on which the greatest weight falls is borne 

 by turns upon each limb, and we move forwards 

 step by step. 



Running and leaping are varieties of the same 

 action, as when we run, we make a succession of 

 short leaps. These differ from walking, inasmuch 

 as in the latter action the body always rests on one 

 limb; whilst, in leaping and running, it is for a time 

 raised quite above the ground, and carried for- 

 wards by the impetus or force which has been 

 given to it. 



Now, how is this managed ? When we wish to 

 leap, we bend our body forward. In this state, we 

 exert violently all the extensor or stretching mus- 

 cles of these parts, as well as those of the arms; and 

 such is their power, that they lift us up, and throw 

 us to very considerable distances. When we run 

 fast, our bodies acquire so much velocity, that we 

 cannot stop at once, as we can in walking, but are 

 obliged to check ourselves by degrees. 



It is highly useful and necessary to exercise 

 ourselves in walking, running, leaping, and other 

 actions requiring the use of our muscles. By 

 these means, they become stronger, and capable of 

 more exertion, and we are less liable to fatigue. 

 This exercise is called gymnastics, but we should 

 be careful not to over exert ourselves, many injuries 

 and accidents having arisen from a want of due 

 caution. 



s2 



