ENERGY 89 



the direction of flow when a is open ; the piston p is 



forced toward , driving out the steam in that side 



through an opening e to the air outside. 



Follow the motion of p as it moves the 



rod r and turns the fly wheel f ; notice 



how this causes the valve v to move. 



When this valve has moved to the posi- 



Tri-p />/> 



tion shown in Fig. 66, steam goes through 



b to the cylinder, moving the piston the other way and 



driving out the used steam through a. 



101. Other Heat Engines. The locomotive is a steam 

 engine which moves itself on a track ; it carries a boiler 

 and two engines (one on each side) all on one frame. 

 The steam turbine contains a set of blades similar to a 

 water wheel; these blades are fastened to a shaft and 

 are made to turn around by jets of steam which strike 

 them. Grasoline engines explode a mixture of gasoline 

 and air; the energy of the explosion moves a piston 

 which is joined to a fly wheel. Naphtha engines burn 

 naphtha, using that heat to vaporize other naphtha in 

 a coiled tube. This vapor is allowed to expand in cyl- 

 inders, so that the action is somewhat like that of steam 

 engines. 



QUESTIONS 



1. Can energy be given from one body to another? If so 

 given, would the body which gave it still contain as much as it 

 had before ? 



2. What is meant by transformation of energy ? From what 

 source do we get our muscular energy ? Can this energy be used 

 so that we feel its loss ? 



