Question: In 1896 my James Kenney was a milkman, and in 1900 he is listed as a Conductor for the B.E.R.R.? I am not sure what he may have been in charge of?
Answer: In 1900 your ancestor was an employee of the Boston Elevated Railroad / Railway. It was the parent organization of the "T" which many visitors today use the Green Line subway to reach NEHGS. This streetcar line was operational only a few years when your ancestor went to work for it. Before that time it was a horse drawn railway, before the streetcars became a common sight on the Boston streets.