The New York war workers shown here are the “millionth of an inch” girls of Reeves Sound Laboratories. They are etching quartz crystals to set the exact transmitting frequency of the completed crystal.

Prior to World War 2, quartz crystals were not manufactured in large quantities. But wartime needs called for crystals in massive quantities. One of the manufacturers that went to work to fill the need was Reeves Sound Laboratories of New York City. In October 1942, the company procured the equipment and leased a former furniture warehouse at 52 West 47th Street, near Times Square. In the first month of production, the company turned out sixteen crystals. The company had a contract to ship 1600 crystals by the end of December, and actually shipped 2200. By February, it was shipping 8700 per month.

The whole painstaking process of turning raw quartz from Brazil into precisely cut crystals can be seen in the army film in the video below. The purity of the crystal, the angle of the cut, and the exact thickness of the crystal are all critical in determining the crystal’s operating frequency. The “millionth of an inch girls” shown above were the last step in the manufacturing process. They carefully etched the crystal by hand that last millionth of an inch while checking their work with an oscillator showing whether the crystal was on frequency. It was highly skilled, but also highly monotonous, work.

References

• The Might of a Crystal, Michigan Alumnus Quarterly Review, Autumn 1944
• Buzz Reeves in War Time, Star and Lamp, Sept. 1944

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