Oil Engines. 



445 



the igniting device S on the inner end of the plug H ignites it at 

 the moment of maximum compression, or thereabout. The 

 ign ition device S consists of a hollow metallic plug with holes h 

 an da cage cap holding strips of asbestos and a central steel 

 needle. The needle and the asbestos are kept sufficiently hot by 

 the recurrent combustion in the combustion chamber to reach 

 the temperature necessar> for ignition by the further increment 

 resulting from compression. 



Formerly ignition in these engines was effected by an 

 ignition tube always kept hot by an exterior lamp. Such a 



Fig. 7.— Sectional Plan of Clayton & Shuttleworth 

 Oil Engine. 



tube is, however, now only used for starting purposes, and the 

 arrangement of lamp and burners adopted is shown by 

 Fig. 8. 



In this a tube U, the upper end of which enters the com- 

 bustion space as seen at U in Fig. 7, is heated by a row of 

 Bunsen burners on a tray B. These burners are supplied with oil 

 from an oil vessel W, the upper part of which contains air under 

 pressure forced in by the pump with the handle O. The tray B 

 being partly filled with petroleum, a piece of cotton waste is 

 put into it as a wick, the burners heated, the pump worked to 



