Yup, the sundial method...but, of course, it assumes you can see the sun...no problem in Texas <img src="/images/graemlins/smile.gif" alt="" /> but if you go north a bit we're having some pretty cruddy weather as of late.
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Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein