I have used this technique before, and checked it against a compass to find what direction north is. I Have an idea about why it works, but it will be quite long winded. this is the link to MPI Outdoors

http://www.mpioutdoors.com/knowledge.htm

Scroll down the page a little bit. I originally got the technique from John Wisemans 'SAS Survival Manual'

BTW I am NOT Australian, thank your very much <img src="images/graemlins/blush.gif" alt="" />. I am a true, thoroughbred SOUTH AFRICA BOER!!! <img src="images/graemlins/grin.gif" alt="" />