It works the other way, too, if you have a watch but no compass, you can find out what direction you're facing.
Use a vertical pole, like a pencil, to cast a shadow from the little drawing of the man, and if you've got the sundial oriented in the right direction, it'll cast its shadow on the current time.
If you have a compass, align the sundial so "N" is true north. If you have a cheap compass that doesn't know about the local magnetic declination of Nevada, line up the marked "magnetic north" with your compass's north.
If you don't have a compass, stand on a "time" street, and align the dial such that the sundial's outer ring's mark for your street is pointed away from the man.
