GAS AND OIL ENGINES. 



Lower right-hand figure, a very early type of commercially successful gas engine. It 

 has a "free" piston, an arrangement that was first proposed for a gas engine in 1857, but only 

 brought into practical form by Langen & Otto under their patent of 1866. Upper figure, the 

 gas engine patented by Lenoir in 1860, one of the very first practically successful engines. 

 Lower left-hand figure, a sectional view of a modern gas' engine of the type used as the motor 

 of the automobile. 



