<p>circa early 1940's diagram of uranium isotope separation in the <a href="https://en.wikipedia.org/wiki/calutron" class="extiw" title="en:calutron">en:calutron</a> 
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<a href="https://en.wikipedia.org/wiki/Category:United_States_history_images" class="extiw" title="en:Category:United States history images">en:Category:United States history images</a>