I'm sure many know what this is but it might be a stumper unless you have the instructions, which I'll post later if anyone is interested. The modern version has batteries and lights and is a very common homeowner tool.

Hello, John. I have one like yours here, but I wont spoil the fun. Regards, Lou

nice Stanley rule there

I am guessing it is a stud finder.   I figured it was, and looking it up confirmed my suspicion.

How do you use this? I admit, I'm only use to using electronic Zircons.

Cody wins! Here is some of the instruction sheet.

Ah, the young woman's dream: a stud finder.

I can't use those.  For some reason they go nuts around me...

Chilly