20 SCIENCE REMAKING THE WORLD 



phia, the rival and superior of the steam engine was 

 born. Doctor Otto of Cologne, Germany, in that year 

 made the first practicable engine run by the explosion 

 of a mixture of gas and air instead of by the expansive 

 force of steam. The steam engine was not thereby put 

 out of business. It will continue in the service of man- 

 kind so long as the coal holds out and perhaps longer. 

 But the internal-combustion engine is more powerful 

 and compact, simpler and more economical, and it has 

 already within the observation of all of us gone farther 

 and come into our lives more intimately than the steam 

 engine ever did. The agile auto climbs mountain 

 trails where the railroad cannot go, and reaches com- 

 munities that have never been awakened by the whistle 

 of a locomotive. It has made engineers out of our boys 

 and girls. No schools could teach mechanics as widely 

 and practically as the auto has. Gasolene has given to 

 man the wings he has always longed for but which he 

 had despaired of getting until he got to heaven. It hag 

 enabled men to go down to the sea in ships on their 

 more or less lawful occasions. It has multiplied the 

 magnitude of man by giving him the power to contract 

 all four of the dimensions within which his activities are 

 confined, the three dimensions of space and the fourth 

 dimension of time. 



What is there about the gas engine that gives it this 

 manifold power and adaptability? Wherein does it 

 differ from the old steam engine? It is not merely in 

 using a different kind of fuel, as some seem still to sup- 

 pose. It is a different kind of motive power. In their 

 fundamental principles, however, the two are alike. 



