I found this photo of a printing office in 1912. It has really cool fixtures which used a cooper-hewitt mercury lamp and two incandescent bulbs. I think that it has a ballast in the center section, and does not use the incandescent lamps for ballasting. It also looks like it is a dc model of lamp.

Website with the photo: https://www.shorpy.com/node/4725

Close up of the fixture:

That light fixture is amazing!