50 Miracles Ahead! 



plugs would be in a gasoline engine, and the injection 

 pumps. 



The Diesel's piston compresses the air in the cylinder and 

 raises the temperature to about 1,000 degrees Fahrenheit. (You 

 may remember how a bicycle pump gets hot while you are 

 pumping up a tire.) When the piston is near the top of the 

 cylinder, fuel is injected into the heated air in the form of a 

 fine spray; and it starts to burn immediately. The burning 

 fuel then expands rapidly and forces the piston down. 



The best gasoline engines must use high-octane fuel, and 

 others generally use ordinary gasoline. But the Diesel will use 

 any fuel gaseous, liquid, or solid igniting at 1,000 degrees 

 Fahrenheit or under that can be sprayed into the cylinder. 

 Usually the Diesel burns heavy fuel oil. Diesel's first engine 

 used powdered coal, and even buttermilk has been used. The 

 Diesel is not choosy! 



Aside from the fuel-economy angle, the Diesel is the most 

 efficient of all types of heat engines. The steam engine is 6 to 

 8 per cent efficient; the steam-power plant, 15 to 27 per cent; 

 the gasoline engine, 22 to 28 per cent; the Diesel, 32 to 38 per 

 cent. The temperature of the Diesel never is as high as that of 

 the gasoline engine. High cylinder temperatures are always 

 transmitted to the surrounding air or cooling water, and are 

 carried off as waste energy. Therefore the Diesel wastes less 

 energy in this manner than the gasoline engine one of the 

 main reasons why it is more efficient. 



Charles F. Kettering, research chief of General Motors, 

 believes the Diesel is ready to go places after having expe- 

 rienced plenty of growing pains. 



"In old days," he said, " Diesels were large and terribly 

 heavy. They used to say a Diesel was 'a mountain of iron 

 with a rivulet of power/ Also, it made a lot of noise and a 

 bad smell. One trouble was that for the first 20 years, because 

 they put Diesels in boats, they tried to make them like gaso- 



