How to Find True North Without a Compass

Which way is north? Whether you're lost in the woods or you're trying to install a sundial in your yard, you're bound to want to find true north from time to time, and chances are when the time comes you won't have a compass.

これの「Watch Method: Northern Hemisphere」にある方法って、小学校の時使っていたノートの裏表紙に載っていた気がする。。。どこのメーカー（？）だったか忘れましたが、今でも売ってるのかな？