On this day – 26th February

Watson-Watt demonstrates RADAR

The son of a steam engine pioneer, Watson-Watt developed a fascination for radio waves as a student. He wanted to work for Britain's War Office, but as there was no suitable position for him there, he instead joined the Meteorological Office, where he developed systems to detect thunderstorms. When lightning strikes, it ionizes the air and generates a radio signal, which Watson-Watt used to detect and map the positions of thunderstorms. His work with radio waves continued when the Air Ministry asked Watson-Watt to investigate rumours that the Germans had developed a "death ray" that could kill living beings hundreds of yards away. He concluded such a device was highly unlikely, but indicated he would turn his attention to "the difficult, but less unpromising, problem of radio-detection as opposed to radio-destruction."

On February 26th 1935 Watson-Watt demonstrated to the Air Ministry the first practical radio system for detecting aircraft. RADAR detects distant objects--in this case, airplanes or ships--by sending pulses of radio waves and measuring the reflected signal. By April he was granted a patent for the system and soon Britain was using RADAR to detect airplanes up to 130 kilometres away--just in the nick of time, it turned out. By WWII, Britain had constructed a network of radar stations known as Chain Home along the English coastline. The system successfully alerted Britain's Royal Air Force to approaching enemy bombers and proved a vital weapon in Britain's triumph over the German Luftwaffe in the Battle of Britain.

Watson-Watt's contributions to the war effort were so significant, he was knighted in 1942. Since then, his radar technology has been put to a great many uses, from meteorology to air traffic control to police radar guns. According to reports, Watson-Watt himself was pulled over in Canada for speeding by a radar-gun toting police officer. He told the officer, "Had I known what you were going to do with it I would never have invented it."

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