THE TURBINE ENGINE 259 



on exhibition near b}^, was guaranteed to develop 1,750 horse- 

 power. 



Compressed air engines, working upon the same princi- 

 ple as the reciprocating steam engine, are extensively used and 

 \\'ith considerable expense. The air which is first compressed 

 is stored in steel tanks under as high as 2,000 pounds pressure 

 to the square inch, and cooled before being passed through the 

 cyhnders, where heat is used to add to its expansive powers. 



Oil engines, using kerosene and other oils, ammonia, and 

 even ether engines, have been successfully operated on a large 

 scale, but, w^hilc the principle in all of them is intrinsically 

 the same as in the steam engine, their success has been far 

 less. 



One of the newest forms of power producing machinery 

 is the sun motor. This is essentially an engine which is run 

 by steam heated by the sun's rays, which are concentrated 

 upon the boiler by an ingenious arrangement of a system of 

 mirrors. The sun motor has become so successful that com- 

 panies have been organized for the purpose of estabhshing it 

 throughout sections of the country where there is plenty of 

 sunshine. The most successful of the motors now in opera- 

 tion is located at Los Angeles, Cal. The engine consists of an 

 immense reflecting surface composed of mirrors so arranged 

 as to focus the rays of the sun upon a boiler in the center. 

 The boiler holds a hundred gallons of water and has several 

 cubic feet for steam. From cold water a pressure of 150 

 pounds is obtained in an hour. The entire apparatus is on a 

 turntable that keeps it facing the sun all day. This size of 

 motor has an average capacity of about fifteen horsepower. 



The sun motor, however, has its limitations already fixed. 

 Of all the modern power machinery the one that engineers con- 

 fidently expect to see outstrip all the others in the race for 

 supremacy is the steam turbine, as yet in its early, if not to 

 say experimental, stages. 



