7 October 2012

Who would of his course be sure, when the   clouds the sky obscure, He an iron needle must in the cork wood firmly   thrust. Lest the iron virtue lack rub it with the   lodestone black, In a cup with flowing brim let the cork on   water swim. When at length the tremor ends, note the way   the needle tends; Though it's place no eye can see -- there the   polar star will be. William the Clerk circa 1230