H2S

H2S, codename for centimetric British airborne radar device which displayed for bomber navigators the type of area (water, open country, conurbations) they were flying over. It was one of the war's most successful electronic navigation systems. In his book Most Secret War (London, 1978, p. 319), R. V. Jones relates how the codename originated from a remark—‘it stinks!’—made by Lindemann, Churchill's scientific adviser, referring to the reason given to him for a delay in developing the device. The remark subsequently led to researchers giving the radar the codename H2S (the chemical formula for hydrogen sulphide, the gas which comes from rotten eggs). When Lindemann then asked what the codename meant one bright individual replied: ‘Home Sweet Home’, which is the usual explanation of its meaning.

The Germans called it the ‘Rotterdam Gerät’, as the first set that fell into their hands came from an aircraft that had crashed near that city. By July 1944 they had produced a similar set, the ‘Berlin Gerät’, but it came too late for offensive use.