Peter Cooper Hewitt (May 5, 1861 - August 25, 1921) was an American electrical engineer, who demonstrated the mercury-vapor lamp for which he deposited a patent. May 5 is the 125th day of the year in the Gregorian Calendar (126th in leap years). ... 1861 is a common year starting on Tuesday. ... August 25 is the 237th day of the year in the Gregorian Calendar (238th in leap years), with 128 days remaining. ... 1921 was a common year starting on Saturday (see link for calendar). ...

He fabricated a discharge lamp in a vapor of mercury heated by the current passing through the liquid phase. The lamp was started by tilting the tube to make contact between the two electrodes, with the liquid mercury located on one side at rest. The efficiency was much higher than incandescent lamps but the emitted light was of a bluish-green unpleasant color, which limited its practical use to specific professional areas, like photography where the color was not an issue at a time where films were black and white. The 300,000-watt Plasma Arc Lamp in the Infrared Processing Center (IPC) at Oak Ridge National Laboratory An arc lamp is a device that produces light by the sparking (or arcing, from voltaic arc or electric arc) of a high current between two carbon rod electrodes. ... General Name, Symbol, Number Mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12 (IIB), 6, d Density, Hardness liquid 13,579 kg/m3 solid @ −39 °C 15,600 kg/m3 1. ... An electrode is a conductor used to make contact with a nonmetallic part of a circuit (e. ... The incandescent light bulb (archaically known as the electric lamp) uses a glowing wire filament heated to white-hot by electrical resistance, to generate light (a process known as thermal radiation or incandescence). ...

In 1902 Hewitt developed the first mercury arc rectifier, which was an efficient way of converting alternating current power to direct current for use in electric railways, industry, and HVDC power transmission. 1902 was a common year starting on Wednesday (see link for calendar). ... A mercury arc valve is a type of electrical rectifier which converts alternating current into direct current. ... An alternating current (AC) is an electrical current where the magnitude and direction of the current varies cyclically, as opposed to direct current, where the direction of the current stays constant. ... Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ... HVDC or high-voltage, direct current electric power transmission systems contrast with the more common alternating-current systems as a means for the bulk transmission of electrical power. ...