510 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK iv. 



engine a movable gas-jet fires the mixture ; in Otto and Langen's 

 engine the gases are also kindled by a lighted jet, but in this case a 

 fixed one. We will rapidly examine the essential arrangements of 

 each of these prime movers. 



Lenoir's engine only differs, as far as external aspect is concerned, 

 from a steam-engine in the absence of a boiler and the particular 

 arrangement of the distributing machinery. 



The driving cylinder is a pump body of large diameter, resting 



Fio. 333. Lenoir's gas-engine. 



horizontally on the framework of the engine ; and its rod gives the 

 motion, by means of connecting rod and crank, to the shaft, on one 

 side of which is fixed the driving -pulley, and on the other a fly-wheel. 

 The cylinder is flanked on the side by two slide-valves, moved by 

 eccentrics ; one of them is for introducing the explosive mixture of 

 air and hydrogen coming by the piston (pipe) G on the two sides of 

 the driving- pis ton alternately, and the other for letting the products 

 of combustion escape. 



On the framework of the engine a Euhmkorff 's coil is fixed, which 

 is worked by a Bunsen battery. This furnishes the successive sparks 



