What kind of physics teaching equipment do I have?

[bazzoookajoe]

I am currently student teaching at a school that has some old physics equipment that no one knows what the purpose is. We have six of them. We looked it up online but could not find out what it is or what it does.

The basics of what it is that there is a meter stick and a wire about the thickness of a guitar string across the meter stick. There is screws at either end of the meter stick that seem to be to run electricity through the wire. There is a metal piece that goes on top of the meter stick that can move horizontally along the meter stick.

What is this and what can it do?
Supposedly it looks like a sonometer. But simpler.