Crystals Go to War

This 1943 documentary, produced by Reeves Sound Laboratories, offers a detailed visual chronicle of crafting quartz crystals for WWII radio communication. Filmed in black-and-white, it unfolds as a meticulous “story in pictures,” narrated by a U.S. Army Signal Corps scientist. The 41-minute reel begins with raw quartz—sourced mostly from Brazil after its 1942 Allied alignment—displayed with a “Handle Carefully” sabotage warning. It traces the labor-intensive process: women workers, often overdressed in Sunday finery, slice crystals into wafers, grind them with precision (some sans guards on whirring machines), and test them via oscilloscopes for exact frequencies. Close-ups highlight varieties of quartz and the delicate cutting angles—AT and BT cuts—crucial for stable radio signals in planes and tanks. The film skips deep chemistry, focusing on mechanical steps—cleaning, cutting, testing—reflecting wartime urgency after Japan cut off earlier supplies. A tribute to ingenuity and the unsung women of Reeves, it underscores crystals as the “vibrating hearts” of military telecom, second only to the Manhattan Project in scientific scale.