I was watching one of those Discovery Channel wilderness survival shows last night and one of the "survivors" made a compass from a piece of wire tie and an earbud's magnet.
He stripped the plastic from the tie and rubbed the magnet in a single direction on one end of half the wire, then suspended it from a thread.
How would he know which end of the wire was north? As best I can tell, if you don't know the orientation of the magnet, you can't determine the orientation of the needle. Did magnetizing only one end of the wire make a difference?
In their scenario, it was daytime, but in a jungle. The view of the sky was pretty obscured and I believe it was somewhat overcast. I figured if they couldn't actually determine east from west (they wanted to go east), they couldn't tell north from south to calibrate the compass by the light/sun. I believe it was midday.