THE ATLANTIC AND PACIFIC LOCOMOTIVES 



WHAT gave us the " Atlantic ", and in 

 what way does the type mark an improve- 

 ment on the cheaper four-coupler? I think 

 we shall be safe in saying that our engineers 

 realised that if the four-coupler was to hold 

 its own (this before the merits of the six- 

 coupled express engine were even guessed 

 at) it must be given a much larger boiler. 

 To do this an extra pair of carrying wheels 

 must be given, since the extra weight could 

 not be added to the coupled wheels. So 

 the trailing wheels were added, and by 

 their small diameter they allowed the 

 fire-box to be greatly enlarged. In the 

 four-coupler the fire-box had to be placed 

 between the last pair of coupled wheels 

 thus restricting the width of the fire-box, 

 but in the " Atlantic " the fire-box could 



