 The increased amount of exhaust gases present in the smokebox had the effect of stabilising and improving the draught.The date of this improvement can be pinned to 1891 when the second batch of Michael Stephens’ Cape Government Railways (CGR) 5th Class 4-6-0 locomotives with their lengthened smokeboxes entered service.This had such a profound effect on the boiler’s steaming ability that virtually every locomotive on the CGR and NGR had their smokeboxes extended.