What kind of electrical outlet is this? it's on an old house built in the 1930's It is some kind of outside light fixture. Any info?
That's not an electrical outlet; it's what they call a "weatherhead" (a device to keep water outof the electric system). This one is no longer in use.
It's an old weatherhead for connection of overhead supply to or from a building. Wires need to be fished through it into the building and are normally spliced in the air just near the head. It should connect to an (old) electric panel or meter. Here is a picture of a modern PVC version https://amzn.to/2FVz2Hb
So old and not usual. You need to change it and the wiring as it is very old wire too. Just to be safe. You would not find the bulb or it will cost you triple for the special bulb. Do it right or not at all.
it is so old junk it that is all you need to know
just a cone shaped metal fixture to light a dark alleyway businesss entrance is my guess
I don't know if Mark is correct about what that is, but he is correct that it IS NOT an outlet.
Ghost Of Christmas Past
Get the place checked out by a qualified electrician. If that device is still in use, your house has the original wiring and it's a fire waiting to happen.
I don't know, but I wouldn't trust it with new lights ........................