...on the Pennsylvania Southern, ca. 1891.
(Apologies in advance for a rather tedious explanation!)
Basically... this is my idea of a generic, old-time freight engine in the eastern USA. Its a camelback design (meaning the cab is located in the middle, rather than behind, the boiler), but it doesnt have the huge Wooten firebox that generally necessitates this unusual placement. Rather, I like to think that a particular coal-hauling Pennsylvania railroad looked to their anthracite-burning neighbor, the Reading, and got the idea to build a middle-cab engine with the only goal being to improve forward visibility. Reportedly, as my line of thinking continues, the design wasnt a huge success, but neither was it a particular failure and as in many such cases, laissez-faire prevailed with the crews. The engine carried out its duties unbothered by modification.
If the ultimate conclusion arrived at by my watchers is that this engine is a camelback for the sake of being a camelback, so be it.
I'm actually pleased with it, all things considered, though I've been a bit torn from the start over whether or not to give it a slope-back firebox.