English mathematical physicist (1909–1991) who worked on the Manhattan Project and carried out calculations to predict the damage effects generated by the blast wave of an atomic bomb. Penney recommended Hiroshima and Nagasaki as the targets of the US bombings on Japan during WWII. ALS signed “Penney,” one page, 5.25 x 7, Orchard House letterhead, September 21, 1977. In part: “Thank you for your letter telling me about the display you are organizing to help the friends of the old folks committee.” In fine condition. Accompanied by the original mailing envelope addressed in his own hand. Pre-certified PSA/DNA.
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