I've seen some of the old floor lamps that had three bare bulbs in sockets surrounding a center bulb in a white glass bowl shade. I'm assuming the center bulb was a 3 way mogul base bulb of 100w/200w/300w, which I see some of these bulbs around. What was the point of the surrounding bulbs though, and are there other lamps that used mogul base bulbs.
Here's an example of these lamps:
http://www.lampshademaker.com/images/Mogul_Reflector_Lamp.jpg