[Festiniog Railway Locomotive] details

“In the example here given, the engine is on two trucks [bogies]. The one end can be turned so that the double sets of wheels are not in the same straight line. In practice it is found that bogie carriages bring a great strain on curves. In the “Little Wonder,” which works on the Festiniog Railway [in Wales], constructed to a gauge of 1 ft. 11½ in., or the two foot gauge, the boiler is double, with two fire boxes, two barrels and two sets of tubes, and two chimneys. A bogie or swivelling truck is placed under each barrel, and each bogie has two pairs of wheels coupled together, working independently by a pair of steam cylinders to each.” (p. 243)