National Geographic: Part of our weekly "In Focus" series-stepping back, looking closer.
Even after a century of constant use and the passage of more than a million ships, the great steel gates of the Miraflores locks, at the Pacific entrance of the Panama Canal, still swing open with the precision of a Swiss watch.
So exquisitely fitted and balanced are they that each of the 672-ton leaves can be moved by a pair of 25-horsepower motors. The same can be said for the massive Gatun locks on the Caribbean side. Engineered...