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The World War II Photo of the Week
for 10 November 2003


Invisible Light ...

   This peculiar pipelike structure on an Amsterdam street is an "invisible light" guiding lamp for vehicular traffic during air raids. Invented by Dutch intelligence officer Capt. J. Bikker, the device throws an extremely narrow beam of light in a straight line, visible only when one is directly in its path. Incapable of casting a reflection in even the deepest darkness, the light cannot be seen above a height of 240 feet, 60 feet below the safety limit for night flying. Since only one such light is visible to a driver at a given time, the driver knows that he is in the correct position on the right-hand side of the road, thus enabling motorized antiaircraft guns, ambulances, and other emergency vehicles to move at top speed during the blacked-out periods the city is under attack.

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