Arc lights of this physical type were fairly commonplace among the Main Streets of America during the 1880-1920 period. What changed was the internal workings of the basic fixture as street lighting technology continued to progress. This arc light was mounted on a span wire over an intersection. Like their long mast-arm-mounted counterparts, the fixture was regularly maintained by lowering it to the ground or via pulling it into close to the pole. A winch/pulley system was employed for this purpose. When high intensity incandescent street lightbulbs were introduced c.1912 many arc light fixtures like you see here were readily retrofitted via kits that GE and others offered. A big savings compared to outright fixture replacement...not to mention the much improved incandescent light source and their economy. FYI: The arc lights and incandescents typically operated from the same lighting circuits, so no wiring changes were required.