54 Book of Locomotives 



Very soon after Mr. Johnson succeeded 

 to the reins at Derby he introduced the 

 leading bogie as the standard equipment of 

 Midland express engines. These 4-4-03 

 were graceful machines, with 6|-ft. driving 

 wheels, and inside cylinders 17^x26. 

 Subsequently, in the late 'seventies, some 

 seven-foot coupled wheels were used, a free 

 running engine of considerable power 

 resulting. 



The 'eighties saw a continued growth in 

 the dimensions of the 4-4-0, which was 

 the most popular type, if numbers count, 

 of express engine of that period. So we 

 pass rapidly to the mid- 'nineties, when the 

 increasing loads were making heavy demands 

 on the 4-2-2 and the four-coupled classes. 

 The introduction of the corridor coach, 

 which added considerable weight without 

 providing additional accommodation, was 

 one of the chief causes of a sudden leap 

 in train weights. 



Mclntosh, on the Caledonian, seems to 

 have been the first to realise that the answer 

 to this challenge of the coach was a big 



