Trefoil Warning Sign with Wavy Arrows Inside Blades (ca. 1950s)
Signs employing a wavy arrow within each of the three blades were often employed at medical facilities during the 1950s. My best guess is that this design was developed by Marshall Brucer at the Oak Ridge Institute of Nuclear Studies in the late 1940s. 

Donated by David Simpson 

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Last updated: 07/25/07
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