Need information on two enamel light shades

[Alec Burns]

I got this light shade and the biggest question I have is what was this triple spring with a ring in the center for? I guessed that it was for fitting the shade onto a kerosene lamp, but I'm not sure for I haven't seen another one.

And then there's this one that I bought last week. What I would like to know is which company, or companies, manufactured this type of shade? Additionally, what time frame were they made in? And what did the tops look like for these?

[Jeremy Woodoff]

I'm pretty sure these are both shades from the electric lamp era. My guess is that the first one was for use in an area subject to vibrations, and the socket with incandescent bulb in it would be held by the ring attached to the springs. This would keep the bulb from being shaken, causing the filament to break. The second shade is called a "radial wave" and was typically used for streetlights. I think the ring in the center would fit over the bulb socket or holder, and the bulb would hang down, with the white underside of the shade reflecting the light back down to the street.