This is a view I found at Midwest Railway Preservation in Cleveland, Ohio. Reading 2100 is under restoration. This is the view from above the trailing truck. The square opening is into the cab. This is where the coal or oil is burned in the boiler. Google calls this an ash pan, but is it? Just guessing that an ash pan would be blocking this view, as it should collect ash.
Also, what are the white lines? I’m guessing they have something to do with checking steel for the restoration.