AN OLD RIDDLE runs as follows. An explorer walks one mile due south, turns and
walks one mile due east, turns again and walks one mile due north. He finds
himself back where he started. He shoots a bear. What color is the bear? The
time-honored answer is: “White,” because the explorer must have started at the
North Pole. But not long ago someone made the discovery that the North Pole is
not the only starting point that satisfies the given conditions! Can you think of
any other spot on the globe from which one could walk a mile south, a mile east,
a mile north and find himself back at his original location?