A good place to start is Dennis O'Berry's book, *The Mudhens: A Pictorial History.*
The Vauclain compound was a 4 cylinder machine. The low pressure cylinders were above the high pressure cylinders. Inside Stephenson valve gear. The Manitou & Pikes Peak (standard gauge) is the only place that has had an operational Vauclain compound in recent times. A narrow gauge Vauclain compound 2-8-0 is on display at Dawson, Yukon Territory. This is Klondike Mines Ry. No. 3, formerly a WP&Y locomotive.
Charlie
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