Peter Cooper Hewitt

Peter Cooper Hewitt was an American electrical engineer who invented the mercury-vapor lamp in 1901, a far more efficient light source than the carbon-filament bulbs of the day, and used the same underlying mercury-vapor conduction principle to build the mercury-arc rectifier, one of the first practical devices for converting alternating current into direct current at meaningful power levels. His rectifier became a standard piece of equipment in early twentieth-century power systems and industrial electrochemical plants that needed direct current drawn from an alternating current supply grid.