On the plus side, it appears that most of the examples could actually move, some doing actual useful work. With some coaxing.
But not something I'd want to scale up to pull 100 cars of iron ore. Or even handle the local wayfreight.
Ed
Despite a statement on the website, the engine could not start moving under its own power if the cylinder was stopped at a dead center.
Picture traction engines on rails
http://douglas-self.com/MUSEUM/LOCOLOCO/onecylinder/onecylinder.htm
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