LET ME BEGIN WITH TWO EPISODES TAKEN FROM A FASCINATING account of British scientific intelligence in the war of 1939-45, Most Secret War by R. V. Jones. In early April 1940 a British reconnaissance aircraft took photographs of Bremen harbor which showed it full of shipping. Unfortunately the information conveyed by these photographs was effectively zero, since it was the very first successful reconnaissance of the area since the outbreak of war, and so there was no knowledge about Bremen in wartime to interpret it. A few days later, the British acquired the knowledge that made these photographs very informative—but too late: the Germans invaded Norway, and the congregation of shipping in Bremen was not a normal phenomenon but a major part of the invasion fleet.