Big Boy No. 4014, one of the world’s largest steam locomotives, will soon leave the Rain Giants Train Museum at Fairplex after 50 years, the topic of my Friday column. Above, Cub Scout Pack 650 from Claremont and parents pose with the engine after a recent tour. Below, from inside the cramped cab, Scouts peer into the firebox. At bottom, Bob Krave of the Railway and Locomotive Historical Society, which runs the museum, talks about the Big Boy’s finer points with one of its giant wheels behind him.