MIRACLES OF SCIENCE 



spray spontaneously, so that its combustion is ef- 

 fected without the use of any igniter such as is used 

 with gasoline engines. This obviously simplifies the 

 action of the engine; and the method of operation 

 permits the use of any crude oil. 



It will be obvious that the Diesel engine is a modi- 

 fication of other types of oil engines, and not in itself 

 an absolutely new creation. It will be clear, also, that 

 its operation is the four-cycle stroke familiar as the 

 Otto cycle. Like the gasoline engine, it can be so 

 constructed as to operate on a two-cycle principle. 



In these respects the Diesel engine affords no nov- 

 elties. Its unique feature is the utilization of com- 

 pressed air, which does away with special apparatus 

 for igniting the oil. The fact that crude oil of any 

 type may be employed gives it vast commercial im- 

 portance. 



AN ALL-IMPORTANT MECHANISM 



The internal combustion engine, of which the 

 Diesel engine is the newest type, was in some respects 

 the most important mechanism developed in the 

 closing decades of the nineteenth century. Three 

 revolutionary craft the submarine, the dirigible 

 balloon, and the aeroplane owe their existence to 

 this engine. With its aid the depths of the sea and 

 the heights of the air are being made accessible. 



When we reflect, further, that the conditions of 

 land traffic are being revolutionized, thanks to the 

 automobile, through the same agency, and that the 

 motor-boat is becoming an institution of importance, 

 even should the Diesel engine fail to drive the 



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