THE LEVERS OF THE BODY 55 



(i) The crowbar, when used to lift a weight at one end by 

 the application of power at the other. In this case a block of wood 

 usually forms the fulcrum. (Fig. 61.) 



Fig. 62. A Lever of the 

 Second Order. 



p, power ; w, weight ; F, fulcrum. 



Fig. 63. A Crowbar, used as a Lever of the 

 Second Order. 



(2) The see-saw. 



(3) The beam of a pair of scales. 



(4) The poker, when 

 resting on a bar of the 

 grate, and used to lift the 

 coals in the fire. 



Levers of the second 

 order are those in which 

 the weight is between the 

 fulcrum and the power. 

 The following re ex- 

 amples : 



(i) The crowbar, 

 when used for lifting a 

 weight, while one of its 



Fig. 64. A Lever of the 

 Third Order. 



w, weight : p, power ; F, fulcrum. 



Fig. 65. The Treadle, illustrating a Lever 

 of the Third Order. 



ends rests on the ground. (Fig. 63.) 



(2) The wheelbarrow. In this case the fulcrum is the point 

 where the wheel rests on the ground. 



Levers of the third order are those in which the power is 



