Wootten firebox

He saw the vast spoil tips (piles of anthracite waste) in the area as a possible plentiful, cheap source of fuel if he could develop a firebox that could burn it effectively.

Through experiments, he determined that a large, wide firebox with a slow firing rate worked best, with a thin layer of the fuel and moderate draft.

The successful design of a trailing truck with the firebox mounted behind the driving wheels (e.g. the Pacific or 4-6-2 class) not yet been developed.

The problem now was that it would be impossible for the locomotive's engineer (driver) to see forwards around the firebox shoulders with a cab floor at the then-standard tender deck height.

For example, the UK LNER Class A4 locomotives, of which "Mallard" holds the world speed record for steam traction, used a wide firebox.