Three Billion Letters

On the morning of February 28, 1953, Francis Crick strode into the Eagle pub near Cambridge University and declared to the lunchtime crowd that he and James Watson had discovered something remarkable. At the nearby Cavendish Laboratory, using metal rods, cardboard cutouts, and critical X-ray crystallography data produced by Rosalind Franklin at King's College London, the two young scientists had built a model revealing DNA's architecture — a graceful double helix, its twin strands wound around each other like a spiraling staircase.…