Well, after MC said it was not a current symbol of how the old AstroPlane works, then I guess it is a lamp. Since he knows it is not the AP maybe he can tell us what it is.
I just saw it in an article and thought it looked a bit like the AP might. I presented it hoping somebody would know. I did look around on the Internet and only found some stuff that uses what seems like similar principals in MF broadcast radio antennas. From the descriptions of several Patents and design, it reads very much like the Patent of the AP, but no doubt I'm wrong. Never mind!