More than likely it is an early form of marine engine which had a disastrous end to the cast iron column's which support the cylinder. The formed steel " side plates appear to be replacement's to extend the life of the engine...for whatever reason. This is my opinion and I could be wrong but the engine seems way to flimsy ( the way it is ) for real work. If it had cast iron supports the general arrangement would be much stiffer.
It's an early cylinder with long stroke and Stevenson reverse link. Picture's are too dark to comment on the connecting rod. I believe it to be an old marine engine with repair's. Interesting old thing.