460 TRANSFERRING AND TRANSFORMING ENERGY 



HAND GRENADE THROWING 

 The utilization of hand throwing in modern warfare. 



U. S. Official 



no transportation facilities, none of the conveniences that 



make mocfern life comfortable. 



More and more man is relying upon machines driven by 



nature's energy to 

 do the work he has 

 heretofore done by 

 his own physical 



exertion. The mow- 



\ 



ing-machine, the sew- 

 ing-machine, and the 

 automobile are recent 

 examples of such in- 

 ventions. All these 

 intricate devices, 

 however, have a few 

 simple machines as 



U. S. Official 



BATTLE "TANK" 

 A modern complex war machine. 



