Do you ever wonder why the original lighting fixtures in your New York brownstone have one bulb facing upward and one bulb hanging downward? 

During the brownstone boom, electricity was still a new technology. It was sort of like the wireless home technology of today – desirable, but not totally reliable. So brownstone builders and buyers tended to back up electric conveniences with gas. That’s why those up-and-down lighting fixtures were so popular: the upward bulb was a gas light which allowed the heat to rise, while the downward bulb was electric. (Of course, today it seems dangerous having the gas running next to the electric filament.) 

Interestingly, the Biltmore mansion in North Carolina was created in the same era. It has the old manual serving elevator alongside an equal-sized, but unreliable, electric elevator. The extra expense was evidently no object compared to the peace of mind of knowing their dinner would never get cold downstairs just because the power went out.