170 Book of Steamships 



the black squad can be reduced to quite 

 insignificant proportions. The coming of 

 oil, whilst doubtless throwing many of our 

 colliers out of work, has conserved our 

 supply of the precious mineral. 



We must not overlook the immense 

 number of auxiliary engines at work on 

 such a ship as the " Mary ". There are 

 66 of these alone, and their duties range 

 from running dynamos for lighting and 

 other work, to pumping air throughout 

 the ship, and also pumping oil to keep the 

 turbines from running hot. The auxiliary 

 engines also operate the water-tight doors, 

 which, by a single lever from the captain's 

 bridge, can be entirely closed throughout 

 the ship. 



There are also flushing pumps, and 

 others for operating the fire appliances. 

 Nor must I forget to mention engines for 

 operating the huge rudder. 



With that brief description of some of 

 the wonders of the " Mary ", I must pass 

 on to the next entry on our " family tree ", 



