clockmaker Jeff Jeffrey works in his clock shop in Pennsylvania

A master of the grandfather clock reveals time's hidden history

To a veteran horologist, "time is still a man-made invention." In his Pennsylvania workshop, he fixes its flaws.

Horologist Theron "Jeff" Jeffery has been fixing clocks at his Ye Old Clock Shoppe in New Freedom, Pennsylvania for decades. "The most fun part of my job is trying to reach back in time," he says. Jeffery's work forms part of an occasional National Geographic series featuring individuals who have become "Masters of their Craft."

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