Very odd 3-way wiring

[jameslee]

I need help. I understand about 7 different ways to wire 3 way switches but this one that I ran up on is very unusual. The power goes to the switch. A 3 way wire runs from the switch to the light. From the switch box there also runs a 3 way wire across the room to another 3 way switch. Just how is this working.?

Jameslee

 

[Resqueline]

It's called a hallway or stairway switch I think. Its purpose is to be able to switch on and off the light at either end. There's no definite position of the switches that gives light, it depends on the position of the other switch. It's quite ingenious in all its simplicity. It uses SPDT (one pole, two way) switches (that for some odd reason seem to be called three-way switches).
Look at the world wide web here: .wfu.edu/~matthews/courses/p230/switches/SwitchesTut.html