National Geographic : 1943 Jun
A Water-repellent "Handkerchief Map" Has aTest Bath The Army Air Forces wanted such amap for aviators forced down indeso late country or at sea. Immediately the Army Map Service devised this 18-inch map, printed on balloon cloth,and sent aconsignment tothe front. Folded like a handkerchief, the map maybecarried inapilot's pocket and pulled out in emergency (pages 765, 774). This Map Lights Up inthe Dark toGuide Pilots over Tunisia Lieut. Col. J.G.Strobridge, chief ofproduction, Army Map Service, shows how the chart, printed influorescent ink, gleams under an ultraviolet light. When American flyers switch on tiny ultraviolet lamps on their helmets, they can read such maps without betraying their presence toNazi spotters because the beams are visible for only afew feet (page 765).