54 



MOTION AND LOCOMOTION 



the same, regardless of whether one end, or the middle^ 

 or the other end of the lever is the fulcrum, power, or 

 weight. 



Leverage in animal bodies. In animals, a joint is. 

 always the fulcrum and the muscles always furnish the 



10O 



FIG. 45. Examples of levers of the second class. 



power. The levers of the animal body are of the first 

 or third class, and, in order to give speed and range of 

 movement, the power arm is short and the weight arm 



Wiioo 



FIG. 46. Examples of levers of the third class. 



long. This arrangement necessitates great strength of 

 muscle applied to the short arm, in order to counter- 

 balance the weight applied to the long arm. 



