I agree with Aunt Phil. I think it is a track chisel, used for cutting rails.
I have been told of two different methods of cutting the rails, but have not witnessed either. One method was to use a rail bender to put the rail under tension and then strike the rail chisel against the side with another hammer. The other was to use the same cutting method to score the rail, then have a group of men pick it up with tongs and drop it. The first one was told to me by a guy I trust who said he witnessed his grandfather do it.