After the Civil War, the New York City's East River was a massive unsolved and dangerous navigation problem. A major waterway into and out of the Harbor--where customs revenue equaled 42 percent of the U.S. Government's income--the river's many hindrances, centered around Hell Gate, included whirlpools, rocks and reefs. These, combined with swirling currents and powerful tides, led to deaths, cargo losses and destruction of vessels. Charged with...