This one's for Gary S.

[nachoman]

Nutbar - that is a very impressive collection of steamers!

Gary - the feedwater heaters were for efficiency. They used exhaust to heat up the water before injecting it into the boiler. The warmer the water is going in, the less it has to be heated up in order to convert it to steam. But I have also heard that they reduced thermal stress on the boiler. Putting cold water into a heated boiler is likely to cause thermal stress. If the water was heated closer to the temperature of the boiler, the stress is reduced.

The various names for the wheel arraignments usually had something to do with the railroad or region where that arrangement was first used. Such as the "Allegheny" (Allegheny mountains) or "Mikado" (Japan). Some railroad used different names (such as Northern and Niagara for a 4-8-4)